chore(plugins): regenerate bindings on top of main

- A marketplace index given as a local Windows path (`C:\market\index.json`)
  resolves its packages next to it; only URLs are joined with `/`.
- HTTP requests to `localhost` try IPv4 loopback first, then IPv6: local
  servers such as Ollama usually listen on IPv4, and on Windows a refused
  `::1` cost about two seconds per request.
- Tests that assumed Unix: an absolute program path is the platform's, a
  manifest rewritten by a test may have CRLF line ends, the precompiled-cache
  test replaces the cache file only after the host that maps it is gone, and
  the MyBatis test lets its first call build the index before asserting.
- The icon theme test's time limits guard against work growing faster than
  the icon count rather than measure the runner.

.agents/skills/issue-fix/SKILL.md

@@ -0,0 +1,91 @@
+---
+name: issue-fix
+description: Triage and fix a GitHub issue (or a user-reported bug) end to end — reproduce, find the root cause, generalise it to every sibling case, fix the class rather than the instance, verify, and open one PR. Use when given an issue URL/number or asked to fix a reported bug and open a PR ("看看这个 issue", "修一下这个 bug", "提 pr").
+---
+
+# Fix an issue: from one case to the whole class
+
+The reported case is one sample of a defect class. A fix that only makes the
+screenshot go away is not done: the next question is always "does this break for other
+languages / platforms / entry points too?". Answer that before anyone asks.
+
+## 1. Read and reproduce
+
+- `gh issue view <n> --comments` (repo `l0ng-ai/openidea`). Read attached logs/screenshots
+  closely: OS, language, toolchain versions, exact error text.
+- Locate the code path and confirm the claim in code, with `file:line` evidence.
+  Say plainly whether it is a real bug, a missing feature, or user environment.
+- Reproduce locally when possible (`fixtures/` projects, `/verify` for runtime). If the
+  reporter's platform (often Windows/Linux) can't be reproduced here, say so up front.
+- Do not ask for a generic environment/log checklist before trying the flow and inspecting the code.
+  Record the attempt and result; ask only for a fact that actually blocks the next diagnostic step.
+  Missing fields, limited time, or unavailable automation are not by themselves reasons to ask the reporter.
+- Treat a maintainer-confirmed bug as an investigation task even if local reproduction fails. Distinguish
+  “not reproduced here” from “not a bug”, and do not require the reporter to prove its existence again.
+
+## 2. Name the root cause as a class
+
+Write one sentence of the form "<mechanism> is missing/wrong, so any <X> hits it",
+not "<this button> is broken". Typical classes in this codebase:
+
+- Per-language config handled for one language only (`languages/*.toml`, `ide-sdk`).
+- Platform gaps: paths, executables, shells, `.cmd`/`.exe`, separators — macOS-only code.
+- Toolchain/version discovery: one probe location, no version check, no rescan.
+- Two features each implementing half a flow and never joined (feature isolation →
+  should go through an action/service).
+- State not reset on project switch / window reuse; events not scoped per window.
+- Failure surfaced as raw stderr/stack trace or retried until "crashed" instead of a
+  clear status with an action.
+- UI: same primitive styled differently in N places.
+
+## 3. Sweep for siblings
+
+Search systematically, not by memory:
+
+- Same pattern elsewhere: `git grep` the function, the config key, the error string,
+  the hard-coded path/flag. Check every `languages/*.toml` entry and every platform branch.
+- Same flow for other languages/runtimes (Java ↔ Kotlin/Gradle, Python ↔ venv/uv,
+  Node ↔ Deno/Bun, Go, Rust …): would they fail the same way?
+- Other callers/entry points of the same flow (menu, context menu, gutter, shortcut, CLI arg).
+- Neighbouring failure modes of the same mechanism (not installed / wrong version /
+  installed but crashes / slow start / installed mid-session).
+  For broad sweeps spawn one Explore agent with the class description, not the instance.
+
+## 4. Decide the fix at the right altitude
+
+- Fix the mechanism once (shared helper, action, config hook) so siblings are fixed
+  by construction; don't patch each call site.
+- Respect `AGENTS.md` rules (crate boundaries, no cross-feature imports, `IdeResult`,
+  UTF-16). If the right fix breaks a rule, pick the rule-respecting design and say why.
+- Compare with how established IDEs solve it when relevant; prefer the established answer.
+- Present: root cause, sibling table, proposed fix, what's deferred. When the user leaves
+  the choice to you, go ahead without asking again.
+
+## 5. Implement and test the class
+
+- Tests cover the class: table-driven over languages/platforms/states, not just the
+  reported input. Include the reporter's case verbatim.
+- Run the scoped checks (`pnpm vitest run <path>`, `cargo nextest run -p <crate>`), then
+  `/verify` in the app for UI or runtime behaviour.
+
+## 6. PR
+
+- One branch `fix/<slug>`, one PR unless the user asks otherwise; `Fixes #<n>` in the body.
+- Don't stage untracked IDE-state dirs (`.ideal/`, `.openidea/`) or screenshots.
+- PR body follows `.github/pull_request_template.md`: `Closes #<n>`, then
+  **What and why** (user-visible change + root cause at class level, 2–4 sentences),
+  **How it was verified** (commands run and results, siblings fixed/deferred, what could break and how
+  it was checked, what was not verified, e.g. "Windows not tested"; for UI changes the before/after
+  screenshot paths from `/verify`), **Review focus** (optional). Short and plain.
+
+## Report format
+
+Reply in the user's language:
+
+```
+Root cause: <one sentence, class level>
+Sibling sweep:
+| Location / case | Affected? | Action |
+Fixed / not covered (why) / not verified (platform)
+PR: <url>
+```

.agents/skills/verify/SKILL.md

@@ -0,0 +1,57 @@
+---
+name: verify
+description: Build, launch and drive the OpenIDEA desktop app through the Tauri MCP bridge to verify a change at runtime.
+---
+
+# Verify OpenIDEA in the running app
+
+## Launch
+
+- Run the app from the worktree that holds the change: `pnpm tauri dev` in the background, logging
+  into your task's scratch subdirectory. Use `pnpm dev:app` instead when your checks call
+  `window.__TAURI__` from `execute_js`. The wrapper gives each worktree its own app identity, data,
+  settings and Vite port, so other worktrees and the installed app don't interfere. If it reports a
+  session already running for this worktree, reuse that one.
+- Once the app is up, `pnpm dev:status` lists this worktree's MCP bridges. Pass the reported
+  `appIdentifier` (the port) on every `mcp__tauri__*` call. The MCP server is shared between
+  sessions: never `driver_session stop` without an `appIdentifier`, and re-check `document.title` /
+  `location.href` before acting if anything looks off.
+- Make sure the binary contains the change: a session already running for this worktree may be an
+  older build. Restart it after Rust changes; frontend changes reload through Vite.
+- After the app restarts, `driver_session start` again for your port (a stale session says "Already connected").
+- If the `pnpm tauri dev` process exits while the app window stays open, Vite is gone and any webview
+  reload shows an empty `#root`. Stop that app and start the session again.
+- Stop everything you started when done and nothing else; never use process-name kills.
+
+## Driving
+
+- `manage_window focus` before screenshots / timing-sensitive steps: a background window throttles timers
+  (debounced LSP / VCS refreshes stall, `setTimeout` promises in `execute_js` time out) and native
+  screenshots come back black.
+- Settings is a separate native window `settings-main`; pass `windowId`, focus it before screenshotting.
+- CodeMirror / xterm ignore MCP `type`. Focus the element, then `document.execCommand('insertText', false, text)`.
+  For xterm Enter, dispatch a `keydown` (`key: 'Enter', keyCode: 13`) on `.xterm-helper-textarea`.
+- MCP clicks arrive with `event.detail === 0`; CodeMirror treats them as line-select clicks. Set the caret
+  through the view instead: `document.querySelector('.cm-content').cmTile.view`.
+- MCP `text` strategy can resolve to a hidden node; prefer coordinates (CSS px = image px × 0.9) or CSS selectors.
+- CSS-module edits often trigger a full page reload in dev: dialogs close, Run sessions and terminal
+  scrollback reset, and each reload spawns a fresh shell. Re-open what you were testing.
+
+## Evidence
+
+- For UI or interaction changes, capture `before.png` (on `main` or with the fix reverted) and
+  `after.png` at the same state and window size, into your task's scratch subdirectory. Multi-step
+  flows: a numbered series (`after-1.png`, `after-2.png`, ...).
+- Report the absolute paths; they go into the PR's **How it was verified** section and the triage
+  acceptance entry. Never commit screenshots to the feature branch.
+
+## Fixture
+
+`fixtures/` has sample projects (go-app, rust-app, ts-app, kotlin-gradle, polyglot). Copy one into
+your scratch directory before editing it, and don't commit the IDE state it creates (`.openidea/`).
+
+## Flows worth driving
+
+⌘⇧O Goto File · ⌘⇧F Find in Files (preview scroll + highlight) · ⌘⇧A Find Action · editor edit/undo/autosave ·
+Terminal (Unicode, venv) · Commit view at the default narrow width · Problems · Run → Stop · Project view
+New / Delete (nested `a/b.txt` names) · ⌘, Settings search (+ Keymap filter) · Git Log on a repo without commits.

.claude/skills/issue-fix

@@ -0,0 +1 @@
+../../.agents/skills/issue-fix

.claude/skills/verify

@@ -0,0 +1 @@
+../../.agents/skills/verify

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -42,6 +42,12 @@ body:
         3. ...
     validations:
       required: true
+  - type: textarea
+    id: reproduction
+    attributes:
+      label: Minimal reproduction
+      description: A link to a small public repository, or the smallest files/snippet that trigger the problem. Optional, but it's the fastest way to get a fix.
+      placeholder: https://github.com/you/repro-project
   - type: textarea
     id: expected
     attributes:

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -27,6 +27,16 @@ body:
       description: How you'd like it to work. Mockups or examples from other tools are welcome.
     validations:
       required: true
+  - type: textarea
+    id: acceptance
+    attributes:
+      label: Acceptance criteria
+      description: How we'll know it's done. One observable behavior per line.
+      placeholder: |
+        - [ ] Right-clicking a test class shows "Run with Coverage"
+        - [ ] Coverage results open in the Coverage tool window
+    validations:
+      required: true
   - type: textarea
     id: alternatives
     attributes:

.github/pull_request_template.md

@@ -0,0 +1,17 @@
+Closes #
+
+## What and why
+
+<!-- 2–4 sentences: the change a user notices, and the root cause.
+     If it doesn't fit, the PR is probably too big; split it. -->
+
+## How it was verified
+
+<!-- Required. Commands you actually ran and their results; what else this could
+     affect and how you checked it still works.
+     UI changes: before/after screenshots. Multi-step interactions: a recording.
+     Backend changes: logs or command output. -->
+
+## Review focus
+
+<!-- Optional: anything you want reviewers to look at closely. -->

.github/workflows/ci.yml

@@ -71,6 +71,57 @@ jobs:
       - run: cargo build --locked -p ide-host --bin openidea-server --target x86_64-unknown-linux-musl
       - run: target/x86_64-unknown-linux-musl/debug/openidea-server --version
 
+  # The plugin SDK, the official plugins and the test fixtures build in their
+  # own workspaces (the root excludes them), so the jobs above don't see them.
+  plugins:
+    name: Plugins (SDK, official, fixtures)
+    runs-on: ubuntu-22.04
+    env:
+      CARGO_TARGET_DIR: ${{ github.workspace }}/target-plugins
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with: { targets: wasm32-wasip2, components: "clippy, rustfmt" }
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: plugins
+          cache-directories: target-plugins
+          save-if: ${{ github.ref == 'refs/heads/main' }}
+      - name: Format, lint (host and wasm) and test each crate
+        shell: bash
+        run: |
+          set -euo pipefail
+          for dir in sdk/rust/openidea-plugin plugins/official/*/ crates/ide-plugin/tests/fixtures/*/; do
+            [ -f "$dir/Cargo.toml" ] || continue
+            echo "::group::$dir"
+            cargo fmt --check --manifest-path "$dir/Cargo.toml"
+            cargo clippy --locked --all-targets --manifest-path "$dir/Cargo.toml" -- -D warnings
+            cargo clippy --locked --target wasm32-wasip2 --manifest-path "$dir/Cargo.toml" -- -D warnings
+            cargo test --locked --manifest-path "$dir/Cargo.toml"
+            echo "::endgroup::"
+          done
+      - uses: pnpm/action-setup@v4
+        with: { version: 11 }
+      - uses: actions/setup-node@v4
+        with: { node-version: 22 }
+      # Plugin web pages (`web-src/`, their own pnpm projects): typecheck and test.
+      - name: Web pages typecheck and test
+        shell: bash
+        run: |
+          set -euo pipefail
+          for dir in plugins/official/*/web-src/; do
+            [ -f "$dir/package.json" ] || continue
+            echo "::group::$dir"
+            pnpm --dir "$dir" install --frozen-lockfile --ignore-workspace
+            pnpm --dir "$dir" exec tsc --noEmit
+            pnpm --dir "$dir" test
+            echo "::endgroup::"
+          done
+      # The host's tests run the checked-in components: they must be built from these sources.
+      # Web pages aren't checked in: this builds them and checks the result.
+      - name: Checked-in components are up to date, web pages build
+        run: plugins/build.sh --check
+
   deny:
     name: Cargo deny
     runs-on: ubuntu-latest

.github/workflows/pr-check.yml

@@ -0,0 +1,69 @@
+name: PR check
+on:
+  # pull_request_target so the check can label PRs from forks. It never checks out
+  # or runs PR code: it only reads the PR title and description.
+  pull_request_target:
+    types: [opened, edited, reopened, ready_for_review]
+
+permissions:
+  issues: write
+  pull-requests: write
+
+concurrency:
+  group: pr-check-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  check:
+    if: github.event.pull_request.user.type != 'Bot' && !github.event.pull_request.draft
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@v7
+        with:
+          script: |
+            const pr = context.payload.pull_request;
+            const LABEL = 'needs-info';
+            const MARKER = '<!-- pr-check -->';
+            // Docs, CI and pure refactors may skip the linked issue.
+            const NO_ISSUE_TYPES = /^(docs|ci|build|chore|refactor|style|test)(\(.+\))?!?:/;
+
+            const body = (pr.body || '').replace(/<!--[\s\S]*?-->/g, '');
+            const problems = [];
+
+            const linksIssue =
+              /\b(close[sd]?|fix(e[sd])?|resolve[sd]?)\s*:?\s+(#\d+|https:\/\/github\.com\/[\w.-]+\/[\w.-]+\/issues\/\d+)/i.test(body);
+            if (!linksIssue && !NO_ISSUE_TYPES.test(pr.title)) {
+              problems.push('Link the issue this PR resolves, e.g. `Closes #123`.');
+            }
+
+            const verified = body.match(/^##+\s*How it was verified\s*$([\s\S]*?)(?=^##+\s|(?![\s\S]))/im);
+            if (!verified || !verified[1].trim()) {
+              problems.push('Fill in **How it was verified**: the commands you ran and their results. UI changes need before/after screenshots.');
+            }
+
+            const { owner, repo } = context.repo;
+            const issue_number = pr.number;
+            const comments = await github.paginate(github.rest.issues.listComments, { owner, repo, issue_number });
+            const existing = comments.find(c => c.user.type === 'Bot' && c.body.includes(MARKER));
+            const labeled = pr.labels.some(l => l.name === LABEL);
+
+            if (problems.length) {
+              const text = `${MARKER}\nThanks for the PR. Before review, please update the description (see [CONTRIBUTING.md](https://github.com/${owner}/${repo}/blob/main/CONTRIBUTING.md)):\n\n${problems.map(p => `- ${p}`).join('\n')}\n\nThis check reruns when you edit the description.`;
+              if (existing) {
+                await github.rest.issues.updateComment({ owner, repo, comment_id: existing.id, body: text });
+              } else {
+                await github.rest.issues.createComment({ owner, repo, issue_number, body: text });
+              }
+              if (!labeled) {
+                await github.rest.issues.addLabels({ owner, repo, issue_number, labels: [LABEL] });
+              }
+              return;
+            }
+
+            // Only undo what this check did: the label is cleared only when our comment exists.
+            if (existing) {
+              await github.rest.issues.deleteComment({ owner, repo, comment_id: existing.id });
+              if (labeled) {
+                await github.rest.issues.removeLabel({ owner, repo, issue_number, name: LABEL }).catch(() => {});
+              }
+            }

.github/workflows/release.yml

@@ -180,6 +180,69 @@ jobs:
           if command -v sha256sum >/dev/null; then sha256sum "$ASSET"; else shasum -a 256 "$ASSET"; fi > "$ASSET.sha256"
           gh release upload "$TAG" "$ASSET" "$ASSET.sha256" --clobber
 
+  # The official plugins, signed, and the marketplace index released apps read
+  # (releases/latest/download/plugins-index.json). They are not in the
+  # installers: users install them from Settings › Plugins. Without the
+  # signing key (secret PLUGIN_SIGNING_KEY: the file `openidea-plugin keygen`
+  # writes) nothing is published and the release goes on.
+  plugins:
+    needs: create-release
+    name: Official plugins
+    runs-on: ubuntu-22.04
+    env:
+      SIGNING_KEY: ${{ secrets.PLUGIN_SIGNING_KEY }}
+    steps:
+      - id: key
+        run: |
+          if [ -z "$SIGNING_KEY" ]; then
+            echo "::warning::PLUGIN_SIGNING_KEY is not set: the official plugins are not published"
+            echo "skip=true" >> "$GITHUB_OUTPUT"
+          fi
+      - uses: actions/checkout@v4
+        if: steps.key.outputs.skip != 'true'
+        with: { ref: "${{ env.TAG }}" }
+      - uses: dtolnay/rust-toolchain@stable
+        if: steps.key.outputs.skip != 'true'
+        with: { targets: wasm32-wasip2 }
+      - uses: Swatinem/rust-cache@v2
+        if: steps.key.outputs.skip != 'true'
+        with: { key: release-plugins }
+      - uses: pnpm/action-setup@v4
+        if: steps.key.outputs.skip != 'true'
+        with: { version: 11 }
+      - uses: actions/setup-node@v4
+        if: steps.key.outputs.skip != 'true'
+        with: { node-version: 22 }
+      # Builds the web pages; fails when a checked-in component isn't built from these sources.
+      - name: Build
+        if: steps.key.outputs.skip != 'true'
+        run: |
+          plugins/build.sh --check
+          cargo build --release --locked -p ide-host --bin openidea-plugin
+      - name: Pack, index and upload
+        if: steps.key.outputs.skip != 'true'
+        shell: bash
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          set -euo pipefail
+          tool="$PWD/target/release/openidea-plugin"
+          key="$RUNNER_TEMP/openidea.key"
+          out="$RUNNER_TEMP/market"
+          (umask 077 && printf '%s' "$SIGNING_KEY" > "$key")
+          trap 'rm -f "$key"' EXIT
+          mkdir -p "$out"
+          for dir in plugins/official/*/; do
+            id="$(sed -n 's/^id *= *"\(.*\)".*/\1/p' "$dir/plugin.toml" | head -1)"
+            version="$(sed -n 's/^version *= *"\(.*\)".*/\1/p' "$dir/plugin.toml" | head -1)"
+            "$tool" pack "$dir" --key "$key" --publisher openidea --out "$out/$id-$version.oiplugin"
+          done
+          # The published index's revocations and earlier keys carry over.
+          curl -fsSL "https://github.com/$GITHUB_REPOSITORY/releases/latest/download/plugins-index.json" \
+            -o "$out/plugins-index.json" || rm -f "$out/plugins-index.json"
+          "$tool" index "$out" --publisher openidea --name OpenIDEA --key "$key" --out "$out/plugins-index.json"
+          gh release upload "$TAG" "$out"/*.oiplugin "$out/plugins-index.json" --clobber
+
   # The updater manifest (latest.json), built once from the signed bundles every build uploaded.
   # Fails when a platform is missing, so a release never ships a manifest without it.
   updater-manifest:
@@ -243,7 +306,7 @@ jobs:
             core.info(`latest.json: ${Object.keys(platforms).sort().join(", ")}`);
 
   publish:
-    needs: [create-release, build, server, updater-manifest]
+    needs: [create-release, build, server, plugins, updater-manifest]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/github-script@v7

.gitignore

@@ -10,6 +10,9 @@ lerna-debug.log*
 node_modules
 dist
 dist-ssr
+# Plugin components are checked in (plugins/build.sh --check keeps them current).
+!plugins/official/*/dist
+!crates/ide-plugin/tests/fixtures/*/dist
 *.local
 
 # Editor directories and files
@@ -30,9 +33,13 @@ target/
 test-results/
 playwright-report/
 
-# Local AI agent files
-CLAUDE.md
-.claude/
+# Local AI agent files. Shared skills live in .agents/skills; .claude/skills links to them.
+CLAUDE.local.md
+.claude/*
+!.claude/skills/
+.claude/skills/*
+!.claude/skills/verify
+!.claude/skills/issue-fix
 
 # Local reference screenshots
 pycharm-screenshots/

.oxfmtrc.json

@@ -15,6 +15,8 @@
     "pnpm-lock.yaml",
     "**/*.toml",
     "fixtures",
+    "plugins/*/web",
+    "plugins/official/*/web",
     "crates/**/tests/fixtures"
   ],
   "overrides": [

AGENTS.md

@@ -0,0 +1,118 @@
+# OpenIDEA — contributor guide
+
+Rust + Tauri 2 desktop IDE with full-featured, multi-language code intelligence.
+Visual style: dark, low-contrast greys, one cool accent
+(`src/styles/tokens.css` is the source of truth for colours and metrics).
+
+## Layout
+
+- `crates/ide-*` — backend crates; one domain each. Depend on `ide-core` for shared
+  types; never reach into another crate's internals.
+- `src-tauri/` — glue only: `state.rs` (AppState / Project), `commands/<domain>.rs`
+  (thin typed IPC adapters), `events.rs`. No domain logic here.
+- `src/bindings.ts` — generated by tauri-specta (`pnpm gen:bindings`). Never edit.
+- `src/platform/` — ipc (`call`, `onIdeEvent`, `nextRequestId`), actions registry,
+  keymap + dispatcher, context keys / `when` clauses, project store.
+- `src/workbench/contributions.ts` — extension points (tool windows, status items,
+  overlays, editor kinds) and cross-feature services (editor, tool windows, notifications).
+- `src/ui/` — design-system primitives. `src/features/<name>/` — one feature each,
+  exporting `activate()` registered in `src/features/index.ts`.
+- `languages/<id>.toml` — language definitions (detection, comments, LSP, DAP).
+- `crates/ide-host` — the `openidea-server` binary for remote development.
+- `wit/` — plugin interface definitions; `plugins/` — sample and bundled plugins;
+  `templates/` — plugin starter templates.
+- `e2e/` — Playwright UI tests (`pnpm e2e`). `fixtures/` — sample projects per language
+  for manual and automated testing.
+
+## Rules
+
+- IPC coordinates: 0-based lines, **UTF-16** columns/offsets everywhere (`ide-core::text`).
+- Every command returns `IdeResult<T>`; convert internal errors at the crate edge.
+- Streaming → `tauri::ipc::Channel<T>`; cancellable → UI-allocated `RequestId` +
+  `cancel_request`. Backend → UI notifications → `IdeEvent` via `EventSink`.
+- Long work never blocks the UI thread or a Tauri command thread: use
+  `spawn_blocking`/rayon, honour `CancellationToken`.
+- Frontend features never import each other; communicate via actions, contributions
+  and services. All user-invocable behaviour is an action with a stable id; default
+  shortcuts live in `src/platform/keymaps/`.
+- Styling: CSS Modules + tokens only (no hex literals in components). Inline SVG
+  icons from `src/ui/icons.tsx`, never emoji. Real `<button>`/`<input>`; `aria-label` on icon buttons.
+- User-visible text goes through the text catalog: add every new string to both
+  `src/platform/locales/text/en.json` and `zh.json` (`textCatalog.test.ts` enforces it).
+- Keep comments sparse and purposeful; match surrounding style.
+- For GUI verification, prefer Tauri MCP; use Computer Use only when Tauri MCP is
+  unavailable or cannot cover the required checks.
+
+## Issues & PRs
+
+Follow `CONTRIBUTING.md` and `.github/pull_request_template.md`: one issue per PR with
+`Closes #<n>`, reproduce first, keep the diff focused, short plain description, and a
+**How it was verified** section with commands run, results and (for UI) before/after screenshots.
+Unclear product decisions → `needs-decision` and stop.
+
+## Skills
+
+Shared agent skills live in `.agents/skills/` (`.claude/skills/` links to them):
+`verify` drives the running app through Tauri MCP and captures screenshot evidence;
+`issue-fix` takes an issue from reproduction to one PR.
+
+## Commands
+
+- `pnpm tauri dev` — run the app with worktree isolation (Node 22.18+).
+  `pnpm dev:app` also enables the global Tauri API. `pnpm dev:status` reports
+  this worktree's running MCP bridges and actual ports.
+- `pnpm build` — typecheck + bundle frontend.
+- `cargo nextest run --workspace` (or `cargo test`), `cargo clippy --workspace --all-targets -- -D warnings`, `cargo fmt --all`.
+- `pnpm test`, `pnpm e2e`, `pnpm lint`, `pnpm format:check`, `pnpm knip`, `pnpm typecheck`,
+  `pnpm gen:bindings`.
+- `pnpm perf` (UI interaction latency / frames / leaks), `pnpm perf:rust` (criterion
+  benches vs budgets). Budgets: `perf/budgets.json`.
+
+## Before opening a PR
+
+Run what CI runs for the parts you touched:
+
+- Rust: `cargo fmt --all --check`, `cargo clippy --workspace --all-targets -- -D warnings`,
+  `cargo nextest run --workspace`. After changing IPC types, run `pnpm gen:bindings` and
+  commit `src/bindings.ts`; CI fails if it differs.
+- Frontend: `pnpm typecheck`, `pnpm lint`, `pnpm format:check`, `pnpm knip`, `pnpm test`,
+  `pnpm build`, and `pnpm e2e` for UI flows.
+- UI or runtime behaviour: verify in the running app (`.agents/skills/verify`).
+
+## Pitfalls
+
+- Run a subset of frontend tests with `pnpm vitest run <path>`. `pnpm test -- <path>` ignores
+  the filter and runs the whole suite, which takes several minutes.
+- Don't run clippy while iterating: `pnpm tauri dev` compiles anyway. Run
+  `cargo fmt --all` + `cargo clippy -p <crate> --all-targets -- -D warnings` once, right
+  before committing. A cold build cache can take around 5 minutes. Run long checks one at
+  a time, not chained in one shell call that may hit the 10-minute tool timeout.
+- `pnpm tauri dev` does a full debug build. Clippy only checks the code, so a passing clippy
+  doesn't make the first launch fast.
+
+## Parallel worktrees
+
+Several worktrees can be developed and run side by side.
+
+- Create one per task: `git worktree add ../<name> -b <branch> origin/main`, then
+  `pnpm install` in it.
+- Launch with `pnpm tauri dev` / `pnpm dev:app`, not the raw `pnpm exec tauri dev` CLI. The
+  wrapper starts Vite on a worktree-derived port (advancing if occupied), passes its actual
+  URL to Tauri, and reports an existing launcher instead of starting another for the same
+  worktree. HMR uses the Vite port.
+- Debug app identity, data, settings, logs and single-instance scope follow the canonical
+  worktree path captured at build time, independent of launch cwd. Launching the same debug
+  binary again focuses its existing instance and forwards its path argument. Different
+  worktrees and the installed release can coexist. `--release` uses normal release identity
+  and bypasses the development wrapper.
+- MCP bridge ports are dynamic (9223–9322). Use `pnpm dev:status`, connect to the reported
+  port, verify identifier/cwd, and pass `appIdentifier: <port>` explicitly. Do not assume the
+  default MCP session belongs to this worktree.
+- Keep each worktree's Cargo output directory separate; do not point `CARGO_TARGET_DIR` or
+  `target` symlinks at a shared directory.
+- Each worktree's first build is cold (around 5 minutes) and its Cargo output takes
+  15–30 GB. Avoid running several heavy builds on one machine at the same time.
+- Stop only processes started for the current worktree/session. Never use broad
+  process-name kills such as `pkill openidea`.
+- When done: stop that worktree's app and dev session, delete its build output, then
+  `git worktree remove ../<name>`.

CLAUDE.md

@@ -0,0 +1 @@
+AGENTS.md

CONTRIBUTING.md

@@ -0,0 +1,35 @@
+# Contributing to OpenIDEA
+
+These rules apply to everyone, and to any coding agent working on their behalf.
+Project layout, coding rules, commands and checks are in [AGENTS.md](AGENTS.md).
+
+## Issues
+
+- One problem or request per issue. Use the issue forms.
+- Bugs: steps that reproduce the problem from a fresh start. A minimal sample
+  project is the fastest way to get a fix.
+- Features: state the problem and the acceptance criteria. A feature is ready to
+  build once a maintainer labels it `planned`.
+- Labels track status: `needs-info` waits on the reporter, `needs-decision` waits
+  on a maintainer, `planned` is accepted, `needs-acceptance` has a fix waiting to be
+  checked.
+
+## Pull requests
+
+- One issue per PR, linked with `Closes #123`. Feature PRs need a `planned` issue.
+  Docs, CI and pure refactors may skip the issue.
+- Reproduce the problem first, or write a test that fails before the fix.
+- Fix the cause, and check whether the same cause breaks anything nearby.
+- Keep the diff focused. Unrelated refactors go in their own PR.
+- Title: [Conventional Commits](https://www.conventionalcommits.org/), e.g.
+  `fix(editor): keep the caret visible after folding`.
+- Fill in the template. Keep the description short and in plain words. If it
+  doesn't fit in a few sentences, the PR is probably too big.
+- **How it was verified** is required: the commands you ran and their results,
+  and what else the change could affect. UI changes need before/after screenshots;
+  multi-step interactions need a recording.
+- If a change needs a product decision you can't make, ask in the issue and stop
+  rather than guessing.
+
+A check on each PR adds `needs-info` when the issue link or the verification
+section is missing, and removes it once they're filled in.

Cargo.lock

@@ -4038,7 +4038,7 @@ checksum = "3d3067d79b975e8844ca9eb072e16b31c3c1c36928edf9c6789548c524d0d954"
 
 [[package]]
 name = "ide-agent"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "dunce",
  "encoding_rs",
@@ -4061,7 +4061,7 @@ dependencies = [
 
 [[package]]
 name = "ide-analysis"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ast-grep-core",
  "ide-core",
@@ -4075,7 +4075,7 @@ dependencies = [
 
 [[package]]
 name = "ide-build"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "dirs 6.0.0",
  "dunce",
@@ -4090,7 +4090,7 @@ dependencies = [
 
 [[package]]
 name = "ide-clipboard"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "objc2 0.6.5",
  "objc2-app-kit 0.3.2",
@@ -4099,7 +4099,7 @@ dependencies = [
 
 [[package]]
 name = "ide-core"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "dunce",
  "encoding_rs",
@@ -4116,7 +4116,7 @@ dependencies = [
 
 [[package]]
 name = "ide-coverage"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "ide-run",
@@ -4130,7 +4130,7 @@ dependencies = [
 
 [[package]]
 name = "ide-dap"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "ide-jsonrpc",
@@ -4148,7 +4148,7 @@ dependencies = [
 
 [[package]]
 name = "ide-db"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "bb8",
  "dirs 6.0.0",
@@ -4170,7 +4170,7 @@ dependencies = [
 
 [[package]]
 name = "ide-docker"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "serde",
@@ -4181,9 +4181,29 @@ dependencies = [
  "which",
 ]
 
+[[package]]
+name = "ide-extension"
+version = "0.1.35"
+dependencies = [
+ "base64 0.22.1",
+ "blake3",
+ "ed25519-dalek",
+ "ide-core",
+ "parking_lot",
+ "semver",
+ "serde",
+ "serde_json",
+ "specta",
+ "specta-typescript",
+ "tempfile",
+ "toml 0.9.12+spec-1.1.0",
+ "tracing",
+ "zip",
+]
+
 [[package]]
 name = "ide-fonts"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "objc2-core-foundation",
  "objc2-core-text",
@@ -4195,7 +4215,7 @@ dependencies = [
 
 [[package]]
 name = "ide-github"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "ide-vcs",
@@ -4208,11 +4228,15 @@ dependencies = [
 
 [[package]]
 name = "ide-host"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
+ "base64 0.22.1",
+ "criterion",
  "dirs 6.0.0",
  "dunce",
  "encoding_rs",
+ "getrandom 0.3.4",
+ "globset",
  "ide-agent",
  "ide-analysis",
  "ide-build",
@@ -4220,12 +4244,14 @@ dependencies = [
  "ide-coverage",
  "ide-dap",
  "ide-db",
+ "ide-extension",
  "ide-http",
  "ide-index",
  "ide-jsonrpc",
  "ide-language",
  "ide-lsp",
  "ide-notebook",
+ "ide-plugin",
  "ide-remote",
  "ide-run",
  "ide-sdk",
@@ -4239,7 +4265,9 @@ dependencies = [
  "ide-vcs",
  "ide-vfs",
  "ide-workspace",
+ "ignore",
  "parking_lot",
+ "reqwest",
  "rustix",
  "serde",
  "serde_json",
@@ -4247,15 +4275,17 @@ dependencies = [
  "specta-typescript",
  "tempfile",
  "tokio",
+ "toml 0.9.12+spec-1.1.0",
  "tracing",
  "tracing-subscriber",
  "uuid",
  "windows-sys 0.61.2",
+ "zip",
 ]
 
 [[package]]
 name = "ide-http"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "parking_lot",
@@ -4273,7 +4303,7 @@ dependencies = [
 
 [[package]]
 name = "ide-index"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "blake3",
  "criterion",
@@ -4295,7 +4325,7 @@ dependencies = [
 
 [[package]]
 name = "ide-jsonrpc"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "encoding_rs",
  "futures",
@@ -4311,11 +4341,12 @@ dependencies = [
 
 [[package]]
 name = "ide-language"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "blake3",
  "criterion",
  "ide-core",
+ "ide-extension",
  "ide-text",
  "parking_lot",
  "regex-lite",
@@ -4366,7 +4397,7 @@ dependencies = [
 
 [[package]]
 name = "ide-lsp"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "dunce",
  "futures",
@@ -4387,11 +4418,12 @@ dependencies = [
  "tokio",
  "toml 0.9.12+spec-1.1.0",
  "tracing",
+ "zip",
 ]
 
 [[package]]
 name = "ide-notebook"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "futures",
  "ide-core",
@@ -4414,26 +4446,27 @@ dependencies = [
 
 [[package]]
 name = "ide-plugin"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
+ "blake3",
  "ide-core",
- "ide-language",
+ "ide-extension",
  "parking_lot",
+ "semver",
  "serde",
  "serde_json",
  "specta",
  "tempfile",
  "thiserror 2.0.21",
- "toml 0.9.12+spec-1.1.0",
+ "tokio",
  "tracing",
  "wasmtime",
  "wasmtime-wasi",
- "zip",
 ]
 
 [[package]]
 name = "ide-profiler"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "ide-run",
@@ -4446,7 +4479,7 @@ dependencies = [
 
 [[package]]
 name = "ide-remote"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "globset",
  "ide-core",
@@ -4463,7 +4496,7 @@ dependencies = [
 
 [[package]]
 name = "ide-run"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "dunce",
  "encoding_rs",
@@ -4486,7 +4519,7 @@ dependencies = [
 
 [[package]]
 name = "ide-sdk"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "dunce",
  "ide-core",
@@ -4505,7 +4538,7 @@ dependencies = [
 
 [[package]]
 name = "ide-search"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "criterion",
  "globset",
@@ -4525,7 +4558,7 @@ dependencies = [
 
 [[package]]
 name = "ide-spell"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "parking_lot",
@@ -4538,7 +4571,7 @@ dependencies = [
 
 [[package]]
 name = "ide-ssh"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "dirs 6.0.0",
  "flate2",
@@ -4557,7 +4590,7 @@ dependencies = [
 
 [[package]]
 name = "ide-syntax"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "ide-language",
@@ -4572,7 +4605,7 @@ dependencies = [
 
 [[package]]
 name = "ide-terminal"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "libc",
@@ -4585,7 +4618,7 @@ dependencies = [
 
 [[package]]
 name = "ide-text"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "criterion",
  "ide-core",
@@ -4597,7 +4630,7 @@ dependencies = [
 
 [[package]]
 name = "ide-tools"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "flate2",
  "hex",
@@ -4618,7 +4651,7 @@ dependencies = [
 
 [[package]]
 name = "ide-vcs"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "dunce",
  "encoding_rs",
@@ -4637,7 +4670,7 @@ dependencies = [
 
 [[package]]
 name = "ide-vfs"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "chardetng",
  "dunce",
@@ -4659,7 +4692,7 @@ dependencies = [
 
 [[package]]
 name = "ide-web"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "ide-core",
  "open",
@@ -4675,7 +4708,7 @@ dependencies = [
 
 [[package]]
 name = "ide-workspace"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
  "blake3",
  "dunce",
@@ -6147,8 +6180,9 @@ dependencies = [
 
 [[package]]
 name = "openidea"
-version = "0.1.34"
+version = "0.1.35"
 dependencies = [
+ "base64 0.22.1",
  "blake3",
  "block2 0.6.2",
  "dirs 6.0.0",
@@ -6163,6 +6197,7 @@ dependencies = [
  "ide-dap",
  "ide-db",
  "ide-docker",
+ "ide-extension",
  "ide-fonts",
  "ide-github",
  "ide-host",
@@ -6194,6 +6229,8 @@ dependencies = [
  "objc2-foundation 0.3.2",
  "objc2-web-kit 0.3.2",
  "parking_lot",
+ "percent-encoding",
+ "security-framework",
  "serde",
  "serde_json",
  "specta",

Cargo.toml

@@ -1,9 +1,11 @@
 [workspace]
 resolver = "3"
 members = ["crates/*", "src-tauri"]
+# Plugins and the guest SDK build for wasm32-wasip2 in their own workspaces.
+exclude = ["sdk", "plugins"]
 
 [workspace.package]
-version = "0.1.34"
+version = "0.1.35"
 edition = "2024"
 rust-version = "1.96"
 license = "Apache-2.0"
@@ -41,6 +43,8 @@ ide-ssh = { path = "crates/ide-ssh" }
 ide-remote = { path = "crates/ide-remote" }
 ide-host = { path = "crates/ide-host" }
 ide-notebook = { path = "crates/ide-notebook" }
+ide-extension = { path = "crates/ide-extension" }
+ide-plugin = { path = "crates/ide-plugin" }
 
 # serialization & IPC typing
 serde = { version = "1", features = ["derive"] }
@@ -69,6 +73,7 @@ ropey = "1.6"
 encoding_rs = "0.8"
 chardetng = "0.1"
 ignore = "0.4"
+base64 = "0.22"
 globset = "0.4"
 notify = "8"
 notify-debouncer-full = "0.6"

THIRD_PARTY_LICENSES.md

@@ -65,6 +65,11 @@ from its tests (`LineComparisonUtilTest`, `WordComparisonUtilTest`,
 `SplitComparisonUtilTest`). Modified from the originals. Copyright 2000-2026
 JetBrains s.r.o. and contributors. Apache License 2.0 (below).
 
+`src/features/vcs/mergeDiff3.ts`, `chunkOptimizer.ts` and `mergeModel.ts` also adapt
+the IntelliJ Platform merge implementation (`MergeRangeUtil`, `MergeResolveUtil`,
+`ChunkOptimizer.LineChunkOptimizer` and `MergeConflictModel`). Modified from the
+originals. Copyright 2000-2026 JetBrains s.r.o. and contributors. Apache License 2.0 (below).
+
 `src/ui/openidea/**` holds OpenIDEA's own file-type icons drawn in the expui style for
 languages whose JetBrains icons are not open source (Go, Ruby, Dart, Lua, Zig,
 Svelte, …). Those using the page-with-corner-badge layout (`goMod`, `goWork`,

crates/ide-agent/src/config.rs

@@ -1,7 +1,9 @@
 //! Session settings (model, mode, thinking effort…), slash commands and context use, as
 //! the agent reports them over ACP.
 
-use crate::model::{AgentCommand, AgentConfigOption, AgentConfigValue, AgentConfigVia, AgentUsage};
+use crate::model::{
+    AgentCommand, AgentConfigOption, AgentConfigValue, AgentConfigVia, AgentCost, AgentLimit, AgentUsage,
+};
 use serde_json::{Value, json};
 
 /// Cursor exposes execution modes over ACP, but leaves approval policy to its client.
@@ -150,7 +152,27 @@ pub(crate) fn commands_of(update: &Value) -> Vec<AgentCommand> {
 /// `usage_update`: `{ used, size }`.
 pub(crate) fn usage_of(update: &Value) -> Option<AgentUsage> {
     let tokens = |key: &str| update.get(key)?.as_f64().map(|n| n.clamp(0.0, f64::from(u32::MAX)) as u32);
-    Some(AgentUsage { used: tokens("used")?, size: tokens("size").filter(|s| *s > 0)? })
+    let cost = update.get("cost").and_then(|c| {
+        Some(Box::new(AgentCost {
+            amount: c.get("amount")?.as_f64().filter(|a| a.is_finite() && *a >= 0.0)?,
+            currency: c.get("currency")?.as_str().filter(|c| !c.is_empty())?.to_owned(),
+        }))
+    });
+    Some(AgentUsage { used: tokens("used")?, size: tokens("size").filter(|s| *s > 0)?, cost })
+}
+
+/// The usage-limit windows a [`crate::LIMITS_UPDATE`] carries; malformed entries are skipped.
+pub(crate) fn limits_of(update: &Value) -> Vec<AgentLimit> {
+    let limits = update.get("limits").and_then(Value::as_array).into_iter().flatten();
+    limits
+        .filter_map(|l| {
+            Some(AgentLimit {
+                window: l.get("window")?.as_str().filter(|w| !w.is_empty())?.to_owned(),
+                used_percent: l.get("usedPercent")?.as_f64().filter(|p| p.is_finite())?.clamp(0.0, 100.0),
+                resets_ms: l.get("resetsMs").and_then(Value::as_f64),
+            })
+        })
+        .collect()
 }
 
 fn legacy(

crates/ide-agent/src/lib.rs

@@ -29,7 +29,7 @@ use serde::{Deserialize, Serialize};
 use serde_json::{Value, json};
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet, VecDeque};
 use std::path::{Path, PathBuf};
-use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU32, AtomicU64, Ordering};
 use std::sync::{Arc, Weak};
 use std::time::Duration;
 
@@ -44,11 +44,16 @@ const REPLAY_GRACE: Duration = Duration::from_millis(300);
 /// can trail its `session/prompt` response by this much.
 const TURN_GRACE: Duration = Duration::from_millis(100);
 const STDERR_LINES: usize = 20;
+/// An agent idle this long after its turn is stopped when it can reload its session
+/// (`session/load`): the next message starts it again where it left off.
+const IDLE_RELEASE: Duration = Duration::from_secs(5 * 60);
 /// Updates of a session's state rather than its conversation.
 const SESSION_STATE: [&str; 5] =
     ["session_info_update", "config_option_update", "current_mode_update", "available_commands_update", "usage_update"];
 /// A native agent's own update: it is about to retry a failed API request (see [`AgentRetry`]).
 pub(crate) const RETRY_UPDATE: &str = "openidea_retry";
+/// A native agent's own update: the usage limits of its account (see [`AgentLimit`]).
+pub(crate) const LIMITS_UPDATE: &str = "openidea_limits";
 /// Referenced files up to this size are embedded in the prompt (when the agent takes it).
 const MAX_EMBED: u64 = 256 * 1024;
 /// How long a probe waits for the agent to answer `initialize`.
@@ -90,6 +95,8 @@ struct Shared {
     providers: RwLock<Vec<provider::ProviderSpec>>,
     /// Last probe of each provider.
     probes: Mutex<HashMap<String, AgentProbe>>,
+    /// [`IDLE_RELEASE`], in milliseconds (shorter in tests).
+    idle_release_ms: AtomicU64,
 }
 
 /// What an agent offered in its last session, for the New Task page.
@@ -205,6 +212,8 @@ struct Live {
     capabilities: AgentCapabilities,
     /// `promptCapabilities.embeddedContext`: referenced files are sent with their text.
     embedded: bool,
+    /// `session/load`: the process can be stopped between turns and the session reloaded.
+    resumable: bool,
 }
 
 struct Task {
@@ -226,6 +235,8 @@ struct Task {
     cancel_pending: AtomicBool,
     /// The agent reported something for the current turn.
     turn_started: AtomicBool,
+    /// Turns sent so far: an idle release scheduled before the latest one is void.
+    turns: AtomicU64,
     /// Settings already sent this session (`(option, value)`), so a refusal is not retried.
     config_sent: Mutex<HashSet<(String, String)>>,
     dirty: Mutex<BTreeSet<(Session, usize)>>,
@@ -236,6 +247,11 @@ struct Task {
 }
 
 impl AgentManager {
+    #[cfg(test)]
+    fn set_idle_release(&self, delay: Duration) {
+        self.shared.idle_release_ms.store(delay.as_millis() as u64, Ordering::Relaxed);
+    }
+
     /// Loads the project's saved tasks. Spawned work runs on `runtime`.
     pub fn new(paths: AgentPaths, runtime: tokio::runtime::Handle) -> Self {
         let connector: Connector = Arc::new(|spec, cwd, client, on_stderr| match spec.driver {
@@ -260,6 +276,7 @@ impl AgentManager {
             known: Mutex::new(known),
             providers,
             probes: Mutex::new(HashMap::new()),
+            idle_release_ms: AtomicU64::new(IDLE_RELEASE.as_millis() as u64),
         });
         let mut tasks = HashMap::new();
         for file in std::fs::read_dir(&shared.paths.store_dir).into_iter().flatten().flatten() {
@@ -301,17 +318,11 @@ impl AgentManager {
         let specs = provider::load(self.shared.paths.custom_agents_dir.as_deref());
         let list = specs
             .iter()
-            .map(|p| AgentProvider {
-                id: p.id.clone(),
-                name: p.name.clone(),
-                command: std::iter::once(p.command.as_str())
-                    .chain(p.args.iter().map(String::as_str))
-                    .collect::<Vec<_>>()
-                    .join(" "),
-                installed: provider::installed(&p.command),
-                config: self.shared.known_config(&p.id),
-                commands: self.shared.known_commands(&p.id),
-                source: p.source.clone(),
+            .map(|p| {
+                let mut info = provider::describe(p);
+                info.config = self.shared.known_config(&p.id);
+                info.commands = self.shared.known_commands(&p.id);
+                info
             })
             .collect();
         let mut prev = self.shared.providers.write();
@@ -325,6 +336,15 @@ impl AgentManager {
         list
     }
 
+    /// Overrides built-in `id`'s command with `command` (the driver and arguments stay
+    /// the built-in's) through its agent file, or returns it to auto-detection with `None`.
+    pub fn set_builtin_command(&self, id: &str, command: Option<String>) -> IdeResult<()> {
+        let Some(dir) = self.shared.paths.custom_agents_dir.clone() else {
+            return Err(IdeError::unavailable("there is no custom agents directory"));
+        };
+        provider::set_builtin_command(&dir, id, command.as_deref())
+    }
+
     /// Re-reads configured/installed agents, drops cached probes, and notifies subscribers.
     pub fn reload_providers(&self) {
         let specs = provider::load(self.shared.paths.custom_agents_dir.as_deref());
@@ -883,6 +903,7 @@ impl Task {
             send_now: AtomicBool::new(false),
             cancel_pending: AtomicBool::new(false),
             turn_started: AtomicBool::new(false),
+            turns: AtomicU64::new(0),
             config_sent: Mutex::new(HashSet::new()),
             dirty: Mutex::new(BTreeSet::new()),
             flush_scheduled: AtomicBool::new(false),
@@ -1025,12 +1046,42 @@ impl Task {
             }
             match (next, result) {
                 (Some(queued), _) => prompt = queued.prompt,
-                (None, Ok(_)) => return self.set_status(AgentStatus::Ready, None),
+                (None, Ok(_)) => {
+                    self.set_status(AgentStatus::Ready, None);
+                    return self.release_when_idle();
+                }
                 (None, Err(failure)) => return self.fail(failure),
             }
         }
     }
 
+    /// Stops the agent's process once the task has stayed idle for [`IDLE_RELEASE`], so
+    /// finished tasks don't keep an agent (and what it started) running. Only an agent that
+    /// reloads its session: the next message starts it again with the conversation intact.
+    fn release_when_idle(self: &Arc<Self>) {
+        let turn = self.turns.load(Ordering::Acquire);
+        let delay = Duration::from_millis(self.shared.idle_release_ms.load(Ordering::Relaxed));
+        let task = Arc::downgrade(self);
+        self.shared.runtime.spawn(async move {
+            tokio::time::sleep(delay).await;
+            let Some(task) = task.upgrade() else { return };
+            if task.turns.load(Ordering::Acquire) != turn
+                || task.state.lock().busy
+                || !task.permissions.lock().is_empty()
+            {
+                return;
+            }
+            let live = {
+                let mut live = task.live.lock();
+                if live.as_ref().is_some_and(|l| l.resumable && !l.peer.is_closed()) { live.take() } else { None }
+            };
+            if let Some(live) = live {
+                tracing::debug!("agent task {}: idle, stopping the agent until the next message", task.id);
+                live.peer.kill();
+            }
+        });
+    }
+
     /// Ends a turn that failed: nothing it started stays open.
     fn fail(self: &Arc<Self>, failure: Failure) {
         self.cancel_permissions();
@@ -1091,6 +1142,7 @@ impl Task {
 
     /// Sends one prompt, starting the agent first if needed; returns the stop reason.
     async fn turn(self: &Arc<Self>, prompt: &AgentPrompt) -> Result<String, Failure> {
+        self.turns.fetch_add(1, Ordering::AcqRel);
         self.turn_started.store(false, Ordering::Release);
         self.state.lock().task.resets_ms = None;
         let attachments = prompt
@@ -1287,7 +1339,7 @@ impl Task {
         }
         self.persist();
         self.emit_task();
-        let live = Live { peer, session: session_id, capabilities, embedded };
+        let live = Live { peer, session: session_id, capabilities, embedded, resumable: can_load };
         *self.live.lock() = Some(live.clone());
         Ok(live)
     }
@@ -1369,6 +1421,13 @@ impl Task {
             }
             return;
         }
+        if kind == LIMITS_UPDATE {
+            if !self.replaying.load(Ordering::Acquire) {
+                let provider = self.state.lock().task.provider.clone();
+                self.shared.emit(AgentEvent::Limits { provider, limits: config::limits_of(update) });
+            }
+            return;
+        }
         if kind == "session_info_update" {
             // The agent's own title for the session replaces the first line of the prompt.
             let title = update.get("title").and_then(Value::as_str).map(str::trim).filter(|t| !t.is_empty());

crates/ide-agent/src/model.rs

@@ -154,6 +154,30 @@ pub struct AgentUsage {
     pub used: u32,
     /// Size of the context window.
     pub size: u32,
+    /// What the session has cost so far (ACP `usage_update.cost`), when the agent reports it.
+    // Boxed so that `AgentEvent::Task` stays within clippy's `large_enum_variant` bound on Windows.
+    #[serde(default)]
+    pub cost: Option<Box<AgentCost>>,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct AgentCost {
+    pub amount: f64,
+    /// ISO 4217 code, e.g. `USD`.
+    pub currency: String,
+}
+
+/// One usage-limit window of an agent's account.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct AgentLimit {
+    /// The window as the agent names it: `five_hour`, `seven_day`, `seven_day_opus`…
+    pub window: String,
+    /// Share of the window used, 0–100.
+    pub used_percent: f64,
+    /// When the window resets (ms since the epoch), if the agent said.
+    pub resets_ms: Option<f64>,
 }
 
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
@@ -322,6 +346,15 @@ pub struct AgentProvider {
     pub name: String,
     /// The command line that starts its ACP server.
     pub command: String,
+    /// Executable and arguments actually launched, without flattening paths containing spaces.
+    pub program: String,
+    pub args: Vec<String>,
+    pub default_program: Option<String>,
+    pub default_args: Vec<String>,
+    pub login_hint: Option<String>,
+    pub command_overridden: bool,
+    pub command_editable: bool,
+    pub command_read_only_reason: Option<AgentCommandReadOnlyReason>,
     /// Whether the command was found (on `PATH`).
     pub installed: bool,
     /// Settings (models, modes…) the agent offered last time it ran; empty before its first session.
@@ -331,6 +364,15 @@ pub struct AgentProvider {
     pub source: AgentSource,
 }
 
+/// Why the executable cannot be changed in built-in agent settings.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum AgentCommandReadOnlyReason {
+    PackageRunner,
+    Registry,
+    CustomAgent,
+}
+
 /// Where an agent comes from.
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
 #[serde(tag = "kind", rename_all = "camelCase")]
@@ -413,6 +455,11 @@ pub enum AgentEvent {
         index: u32,
         entry: AgentEntry,
     },
+    /// An agent reported the usage limits of its account (shared by every task of `provider`).
+    Limits {
+        provider: String,
+        limits: Vec<AgentLimit>,
+    },
     /// The installed or configured agent providers changed.
     Providers,
 }

crates/ide-agent/src/native/claude/cli.rs

@@ -98,6 +98,8 @@ impl Cli for Process {
         use std::process::Stdio;
         let mut cmd = tokio::process::Command::new(&l.program);
         ide_core::process::prepare(cmd.as_std_mut());
+        // `claude` may be a wrapper (`claude.cmd` → node): stopping it stops what it started.
+        ide_core::process::own_group(cmd.as_std_mut());
         cmd.args(&l.args)
             .current_dir(&l.cwd)
             .envs(ide_core::process::shell_env())
@@ -120,6 +122,9 @@ impl Cli for Process {
             tokio::select! {
                 _ = child.wait() => {}
                 _ = token.cancelled() => {
+                    if let Some(pid) = child.id() {
+                        let _ = tokio::task::spawn_blocking(move || ide_core::process::kill_tree_of(pid)).await;
+                    }
                     let _ = child.start_kill();
                     let _ = child.wait().await;
                 }

crates/ide-agent/src/native/claude/mod.rs

@@ -904,6 +904,7 @@ impl Session {
                     if info.get("status").and_then(Value::as_str) == Some("rejected") {
                         st.limit_resets_ms = info.get("resetsAt").and_then(Value::as_f64).map(|s| s * 1000.0);
                     }
+                    updates.extend(st.tr.on_rate_limit(&info));
                 }
                 "command_lifecycle" => {
                     let uuid = msg.get("command_uuid").and_then(Value::as_str);

crates/ide-agent/src/native/claude/tests.rs

@@ -1013,6 +1013,39 @@ fn streamed_text_is_not_sent_twice() {
     assert_eq!(usage[0].update, json!({"sessionUpdate": "usage_update", "used": 15, "size": 1000}));
 }
 
+#[test]
+fn rate_limits_and_cost() {
+    let mut t = Translator::new("s", PathBuf::from("/w"), false);
+    let info = json!({"status": "allowed", "rateLimitType": "five_hour", "unifiedWindows": {
+        "five_hour": {"utilization": 0.19, "resetsAt": 100, "status": "allowed"},
+        "seven_day": {"utilization": 0.09, "resetsAt": 200, "status": "allowed"},
+    }});
+    let limits = t.on_rate_limit(&info).unwrap();
+    assert_eq!(limits.session, "s");
+    assert_eq!(limits.update["sessionUpdate"], crate::LIMITS_UPDATE);
+    let windows: Vec<(&str, i64, f64)> = limits.update["limits"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|l| {
+            (
+                l["window"].as_str().unwrap(),
+                l["usedPercent"].as_f64().unwrap().round() as i64,
+                l["resetsMs"].as_f64().unwrap(),
+            )
+        })
+        .collect();
+    assert_eq!(windows, [("five_hour", 19, 100_000.0), ("seven_day", 9, 200_000.0)]);
+    // Older versions report the window that applies, alone.
+    let single = t.on_rate_limit(&json!({"rateLimitType": "seven_day", "utilization": 0.5})).unwrap();
+    assert_eq!(single.update["limits"], json!([{"window": "seven_day", "usedPercent": 50.0, "resetsMs": null}]));
+    assert_eq!(t.on_rate_limit(&json!({"status": "allowed", "resetsAt": 100})), None, "no utilization, no update");
+
+    t.used = Some(10);
+    let usage = t.on_result(&json!({"total_cost_usd": 0.5, "modelUsage": {"x": {"contextWindow": 1000}}}));
+    assert_eq!(usage[0].update["cost"], json!({"amount": 0.5, "currency": "USD"}));
+}
+
 #[test]
 fn tool_calls_plans_and_subagents() {
     let mut t = Translator::new("s", PathBuf::from("/w"), true);

crates/ide-agent/src/native/claude/translate.rs

@@ -5,7 +5,7 @@
 //! Agent tool use that launched them: their messages carry it as `parent_tool_use_id`.
 
 use super::tools;
-use crate::RETRY_UPDATE;
+use crate::{LIMITS_UPDATE, RETRY_UPDATE};
 use serde_json::{Value, json};
 use std::collections::{HashMap, VecDeque};
 use std::path::PathBuf;
@@ -58,6 +58,8 @@ pub(super) struct Translator {
     pub used: Option<u64>,
     pub model: Option<String>,
     windows: HashMap<String, u64>,
+    /// The session's cost so far in USD, as the last `result` reported it.
+    cost_usd: Option<f64>,
 }
 
 impl Translator {
@@ -75,6 +77,7 @@ impl Translator {
             used: None,
             model: None,
             windows: HashMap::new(),
+            cost_usd: None,
         }
     }
 
@@ -543,6 +546,9 @@ impl Translator {
                 self.windows.insert(model.clone(), w);
             }
         }
+        if let Some(cost) = result.get("total_cost_usd").and_then(Value::as_f64).filter(|c| c.is_finite()) {
+            self.cost_usd = Some(cost);
+        }
         self.usage_update().into_iter().collect()
     }
 
@@ -557,9 +563,33 @@ impl Translator {
                     .or_else(|| self.windows.iter().find(|(k, _)| k.starts_with(m.as_str())).map(|(_, v)| v))
             })
             .or_else(|| (self.windows.len() == 1).then(|| self.windows.values().next()).flatten())?;
-        Some(Update {
+        let mut update = json!({ "sessionUpdate": "usage_update", "used": used, "size": size });
+        if let Some(amount) = self.cost_usd {
+            update["cost"] = json!({ "amount": amount, "currency": "USD" });
+        }
+        Some(Update { session: self.root.clone(), update })
+    }
+
+    /// The usage-limit windows a `rate_limit_event` reports, as a [`LIMITS_UPDATE`]: every
+    /// window of `unifiedWindows`, or the single `rateLimitType` window older versions send.
+    pub fn on_rate_limit(&self, info: &Value) -> Option<Update> {
+        let window = |name: &str, w: &Value| {
+            let utilization = w.get("utilization")?.as_f64()?;
+            Some(json!({
+                "window": name,
+                "usedPercent": utilization * 100.0,
+                "resetsMs": w.get("resetsAt").and_then(Value::as_f64).map(|s| s * 1000.0),
+            }))
+        };
+        let limits: Vec<Value> = match info.get("unifiedWindows").and_then(Value::as_object) {
+            Some(windows) => windows.iter().filter_map(|(name, w)| window(name, w)).collect(),
+            None => {
+                info.get("rateLimitType").and_then(Value::as_str).and_then(|t| window(t, info)).into_iter().collect()
+            }
+        };
+        (!limits.is_empty()).then(|| Update {
             session: self.root.clone(),
-            update: json!({ "sessionUpdate": "usage_update", "used": used, "size": size }),
+            update: json!({ "sessionUpdate": LIMITS_UPDATE, "limits": limits }),
         })
     }
 }

crates/ide-agent/src/provider.rs

@@ -2,7 +2,8 @@
 //! `<config>/agents/<id>.toml` (written by hand, or by installing one from the ACP
 //! Registry, see `registry`).
 
-use crate::AgentSource;
+use crate::{AgentCommandReadOnlyReason, AgentProvider, AgentSource};
+use ide_core::{IdeError, IdeResult};
 use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
 use std::path::{Path, PathBuf};
@@ -92,6 +93,82 @@ pub(crate) fn builtin_name(id: &str) -> Option<&'static str> {
     BUILTIN.iter().find(|&&(bid, _, _, _, _)| bid == id).map(|&(_, name, _, _, _)| name)
 }
 
+/// The built-in spec of `id`.
+pub(crate) fn builtin_spec(id: &str) -> Option<ProviderSpec> {
+    builtins().into_iter().find(|s| s.id == id)
+}
+
+/// Public launch metadata, keeping the built-in defaults separate from agent-file overrides.
+pub(crate) fn describe(spec: &ProviderSpec) -> AgentProvider {
+    let builtin = builtin_spec(&spec.id);
+    let reason = if matches!(spec.source, AgentSource::Registry { .. }) {
+        Some(AgentCommandReadOnlyReason::Registry)
+    } else if let Some(default) = &builtin {
+        matches!(default.command.as_str(), "npx" | "bunx" | "uvx").then_some(AgentCommandReadOnlyReason::PackageRunner)
+    } else {
+        Some(AgentCommandReadOnlyReason::CustomAgent)
+    };
+    AgentProvider {
+        id: spec.id.clone(),
+        name: spec.name.clone(),
+        command: std::iter::once(spec.command.as_str())
+            .chain(spec.args.iter().map(String::as_str))
+            .collect::<Vec<_>>()
+            .join(" "),
+        program: spec.command.clone(),
+        args: spec.args.clone(),
+        default_program: builtin.as_ref().map(|b| b.command.clone()),
+        default_args: builtin.as_ref().map(|b| b.args.clone()).unwrap_or_default(),
+        login_hint: Some(spec.login_hint.clone()),
+        command_overridden: builtin.as_ref().is_some_and(|b| b.command != spec.command),
+        command_editable: reason.is_none(),
+        command_read_only_reason: reason,
+        installed: installed(&spec.command),
+        config: vec![],
+        commands: vec![],
+        source: spec.source.clone(),
+    }
+}
+
+/// Overrides built-in `id`'s command through its agent file, preserving other
+/// customizations. `None` restores the built-in command and removes a redundant file.
+pub(crate) fn set_builtin_command(custom_dir: &Path, id: &str, command: Option<&str>) -> IdeResult<()> {
+    let Some(builtin) = builtin_spec(id) else {
+        return Err(IdeError::invalid(format!("{id} is not a built-in agent")));
+    };
+    let file = custom_dir.join(format!("{id}.toml"));
+    let mut agent = if file.try_exists()? {
+        CustomAgent::read(&file).map_err(IdeError::invalid)?
+    } else {
+        CustomAgent {
+            name: Some(builtin.name.clone()),
+            driver: builtin.driver,
+            command: builtin.command.clone(),
+            args: builtin.args.clone(),
+            env: BTreeMap::new(),
+            registry: None,
+        }
+    };
+    if agent.registry.is_some() {
+        return Err(IdeError::invalid(format!("{id} is installed from the ACP Registry")));
+    }
+    if command.is_none()
+        && agent.name.as_deref() == Some(builtin.name.as_str())
+        && agent.driver == builtin.driver
+        && agent.args == builtin.args
+        && agent.env.is_empty()
+    {
+        match std::fs::remove_file(&file) {
+            Err(e) if e.kind() != std::io::ErrorKind::NotFound => return Err(e.into()),
+            _ => {}
+        }
+        return Ok(());
+    }
+    agent.command = command.unwrap_or(&builtin.command).to_owned();
+    agent.write(&file)?;
+    Ok(())
+}
+
 /// An agent file, `<config>/agents/<id>.toml`.
 #[derive(Debug, PartialEq, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
@@ -182,6 +259,9 @@ pub(crate) fn load(custom_dir: Option<&Path>) -> Vec<ProviderSpec> {
         match specs.iter_mut().find(|s| s.id == spec.id) {
             Some(existing) => {
                 spec.login_hint = existing.login_hint.clone();
+                if spec.source == AgentSource::Custom {
+                    spec.source = AgentSource::Builtin;
+                }
                 *existing = spec;
             }
             None => specs.push(spec),
@@ -221,6 +301,54 @@ fn is_executable(p: &Path) -> bool {
 mod tests {
     use super::*;
 
+    #[test]
+    fn launch_metadata_distinguishes_defaults_overrides_and_read_only_agents() {
+        let dir = tempfile::tempdir().unwrap();
+        let list = || load(Some(dir.path())).iter().map(describe).collect::<Vec<_>>();
+        let defaults = list();
+        let codex = defaults.iter().find(|p| p.id == "codex").unwrap();
+        assert_eq!(codex.program, "codex");
+        assert_eq!(codex.default_program.as_deref(), Some("codex"));
+        assert_eq!(codex.args, ["app-server"]);
+        assert_eq!(codex.default_args, codex.args);
+        assert_eq!(codex.command, "codex app-server");
+        assert_eq!(codex.login_hint.as_deref(), Some("Run `codex login` in a terminal."));
+        assert!(!codex.command_overridden);
+        assert!(codex.command_editable);
+        for p in &defaults {
+            assert_eq!(p.source, AgentSource::Builtin);
+            assert!(p.default_program.is_some());
+            assert_eq!(p.command_editable, !p.id.ends_with("-acp"));
+            assert_eq!(
+                p.command_read_only_reason,
+                p.id.ends_with("-acp").then_some(AgentCommandReadOnlyReason::PackageRunner)
+            );
+        }
+        set_builtin_command(dir.path(), "codex", Some("/path with spaces/codex")).unwrap();
+        let overridden = list().into_iter().find(|p| p.id == "codex").unwrap();
+        assert_eq!(overridden.program, "/path with spaces/codex");
+        assert_eq!(overridden.args, codex.args);
+        assert_eq!(overridden.default_program, codex.default_program);
+        assert!(overridden.command_overridden && overridden.command_editable);
+        assert_eq!(overridden.source, AgentSource::Builtin);
+        set_builtin_command(dir.path(), "codex", Some("codex")).unwrap();
+        assert!(!list().iter().find(|p| p.id == "codex").unwrap().command_overridden);
+        std::fs::write(
+            dir.path().join("gemini.toml"),
+            "command = \"/registry/gemini\"\n[registry]\nid = \"gemini\"\nversion = \"1.0\"\n",
+        )
+        .unwrap();
+        let registry = list().into_iter().find(|p| p.id == "gemini").unwrap();
+        assert_eq!(registry.default_program.as_deref(), Some("gemini"));
+        assert!(!registry.command_editable);
+        assert_eq!(registry.command_read_only_reason, Some(AgentCommandReadOnlyReason::Registry));
+        assert!(matches!(registry.source, AgentSource::Registry { .. }));
+        std::fs::write(dir.path().join("mine.toml"), "command = \"mine\"\n").unwrap();
+        let custom = list().into_iter().find(|p| p.id == "mine").unwrap();
+        assert_eq!(custom.default_program, None);
+        assert_eq!(custom.command_read_only_reason, Some(AgentCommandReadOnlyReason::CustomAgent));
+    }
+
     #[test]
     fn custom_agents_extend_and_override_the_builtins() {
         let dir = tempfile::tempdir().unwrap();
@@ -240,6 +368,90 @@ mod tests {
         assert!(installed("sh"));
     }
 
+    #[test]
+    fn set_builtin_command_overrides_and_clears_a_builtin() {
+        let dir = tempfile::tempdir().unwrap();
+        set_builtin_command(dir.path(), "not-a-builtin", Some("/x")).unwrap_err();
+        set_builtin_command(dir.path(), "claude", Some("/opt/claude")).unwrap();
+        let claude = load(Some(dir.path())).into_iter().find(|s| s.id == "claude").unwrap();
+        assert_eq!((claude.command.as_str(), claude.driver), ("/opt/claude", Driver::Claude));
+        assert!(claude.args.is_empty());
+        // A registry install is neither overwritten nor removed by a command override.
+        let path = dir.path().join("codex.toml");
+        CustomAgent {
+            name: None,
+            driver: Driver::Acp,
+            command: "amp".into(),
+            args: vec![],
+            env: BTreeMap::new(),
+            registry: Some(RegistryRef { id: "amp-acp".into(), version: "1.0.0".into() }),
+        }
+        .write(&path)
+        .unwrap();
+        set_builtin_command(dir.path(), "codex", Some("/x")).unwrap_err();
+        set_builtin_command(dir.path(), "codex", None).unwrap_err();
+        assert!(path.exists());
+        // Clearing (twice) returns the built-in to auto-detection.
+        set_builtin_command(dir.path(), "claude", None).unwrap();
+        set_builtin_command(dir.path(), "claude", None).unwrap();
+        assert!(!dir.path().join("claude.toml").exists());
+        assert_eq!(load(Some(dir.path())).iter().find(|s| s.id == "claude").unwrap().command, "claude");
+    }
+
+    #[test]
+    fn set_builtin_command_preserves_other_customizations_on_save_and_reset() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("claude.toml");
+        for field in ["name", "driver", "args", "env", "unnamed"] {
+            let mut agent = CustomAgent {
+                name: Some("Claude Code".into()),
+                driver: Driver::Claude,
+                command: "/old/claude".into(),
+                args: vec![],
+                env: BTreeMap::new(),
+                registry: None,
+            };
+            match field {
+                "name" => agent.name = Some("My Claude".into()),
+                "driver" => agent.driver = Driver::Acp,
+                "args" => agent.args.push("--verbose".into()),
+                "env" => {
+                    agent.env.insert("K".into(), "v".into());
+                }
+                "unnamed" => agent.name = None,
+                _ => unreachable!(),
+            }
+            agent.write(&path).unwrap();
+
+            set_builtin_command(dir.path(), "claude", Some("/new/claude")).unwrap();
+            agent.command = "/new/claude".into();
+            assert_eq!(CustomAgent::read(&path).unwrap(), agent, "{field}");
+
+            set_builtin_command(dir.path(), "claude", None).unwrap();
+            agent.command = "claude".into();
+            assert_eq!(CustomAgent::read(&path).unwrap(), agent, "{field}");
+        }
+    }
+
+    #[test]
+    fn resetting_a_command_only_override_removes_the_file() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("codex.toml");
+        std::fs::write(
+            &path,
+            "name = \"Codex\"\ndriver = \"codex\"\ncommand = \"/custom/codex\"\nargs = [\"app-server\"]\n",
+        )
+        .unwrap();
+
+        set_builtin_command(dir.path(), "codex", None).unwrap();
+
+        assert!(!path.exists());
+        assert_eq!(
+            load(Some(dir.path())).into_iter().find(|s| s.id == "codex").unwrap(),
+            builtin_spec("codex").unwrap()
+        );
+    }
+
     #[test]
     fn agent_files_round_trip_with_their_registry_table() {
         let dir = tempfile::tempdir().unwrap();

crates/ide-agent/src/registry.rs

@@ -826,15 +826,7 @@ mod tests {
         let mut providers: Vec<AgentProvider> = provider::load(Some(&p.agents_dir))
             .into_iter()
             .filter(|s| s.id == "amp-acp")
-            .map(|s| AgentProvider {
-                id: s.id,
-                name: s.name,
-                command: s.command,
-                installed: false,
-                config: vec![],
-                commands: vec![],
-                source: s.source,
-            })
+            .map(|s| provider::describe(&s))
             .collect();
         mark_updates(&p, &mut providers);
         assert_eq!(
@@ -1001,15 +993,7 @@ mod tests {
         assert_eq!(spec.login_hint, "Run `copilot` in a terminal and sign in.");
         assert_eq!(spec.source, AgentSource::Registry { version: "1.0.104".into(), update: None });
 
-        let mut providers = vec![AgentProvider {
-            id: spec.id,
-            name: spec.name,
-            command: spec.command,
-            installed: true,
-            config: vec![],
-            commands: vec![],
-            source: spec.source,
-        }];
+        let mut providers = vec![provider::describe(&spec)];
         mark_updates(&p, &mut providers);
         assert_eq!(
             providers[0].source,

crates/ide-agent/src/tests.rs

@@ -9,6 +9,8 @@ struct FakeAgent {
     /// Every connection's agent side, kept open.
     servers: Mutex<Vec<Peer>>,
     calls: Mutex<Vec<String>>,
+    /// Without `loadSession` (a session lives only as long as its process).
+    no_load: bool,
 }
 
 impl FakeAgent {
@@ -89,7 +91,7 @@ impl Handler for FakeAgent {
                 if params.pointer("/clientCapabilities/subagents").is_some_and(Value::is_object) {
                     self.calls.lock().push("subagents".into());
                 }
-                Ok(json!({"protocolVersion": 1, "agentCapabilities": {"loadSession": true,
+                Ok(json!({"protocolVersion": 1, "agentCapabilities": {"loadSession": !self.no_load,
                     "sessionCapabilities": {"fork": {}}, "_meta": {"openidea": {"rollback": true, "steer": true}}}}))
             }
             "session/new" => Ok(json!({"sessionId": "s1",
@@ -145,7 +147,16 @@ impl Handler for FakeAgent {
                     json!({"sessionUpdate": "available_commands_update",
                     "availableCommands": [{"name": "review", "description": "Review", "input": {"hint": "focus"}}]}),
                 );
-                self.update(&session, json!({"sessionUpdate": "usage_update", "used": 50, "size": 1000}));
+                self.update(
+                    &session,
+                    json!({"sessionUpdate": "usage_update", "used": 50, "size": 1000,
+                    "cost": {"amount": 0.25, "currency": "USD"}}),
+                );
+                self.update(
+                    &session,
+                    json!({"sessionUpdate": LIMITS_UPDATE,
+                    "limits": [{"window": "five_hour", "usedPercent": 19.0, "resetsMs": 5000.0}]}),
+                );
                 self.update(&session, json!({"sessionUpdate": "session_info_update", "title": "Lexer fix"}));
                 self.say(&session, "Hi");
                 self.update(
@@ -358,6 +369,10 @@ async fn a_task_runs_asks_for_permission_and_survives_a_restart() {
         assert_eq!((modes.via, modes.current.as_deref()), (AgentConfigVia::Mode, Some("ask")));
         assert_eq!(t.commands.iter().map(|c| c.name.as_str()).collect::<Vec<_>>(), ["review"]);
         assert_eq!(t.usage.as_ref().map(|u| (u.used, u.size)), Some((50, 1000)));
+        assert_eq!(
+            t.usage.as_ref().and_then(|u| u.cost.clone()),
+            Some(Box::new(AgentCost { amount: 0.25, currency: "USD".into() }))
+        );
         assert_eq!(t.title, "Lexer fix", "the agent's title replaces the prompt's first line");
     }
     mgr.set_config(&task.id, "mode", "code".into()).await.unwrap();
@@ -370,6 +385,18 @@ async fn a_task_runs_asks_for_permission_and_survives_a_restart() {
         assert!(
             events.iter().any(|e| matches!(e, AgentEvent::Task { task } if task.status == AgentStatus::NeedsInput))
         );
+        let limits = events.iter().find_map(|e| match e {
+            AgentEvent::Limits { provider, limits } => Some((provider.as_str(), limits.clone())),
+            _ => None,
+        });
+        assert_eq!(
+            limits,
+            Some((
+                task.provider.as_str(),
+                vec![AgentLimit { window: "five_hour".into(), used_percent: 19.0, resets_ms: Some(5000.0) }]
+            )),
+            "an agent's usage limits are its provider's"
+        );
         let last_entry = events.iter().rev().find_map(|e| match e {
             AgentEvent::Entry { index, entry, .. } if !matches!(entry, AgentEntry::User { .. }) => {
                 Some((*index, entry.clone()))
@@ -772,6 +799,18 @@ fn retry_updates_become_a_countdown() {
     assert_eq!(retry_of(&json!({"sessionUpdate": RETRY_UPDATE}), 0.0), None, "no attempt");
 }
 
+#[test]
+fn usage_limits_and_cost_skip_what_is_malformed() {
+    let limits = config::limits_of(&json!({"sessionUpdate": LIMITS_UPDATE, "limits": [
+        {"window": "seven_day", "usedPercent": 140.0},
+        {"window": "", "usedPercent": 10.0},
+        {"window": "five_hour"},
+    ]}));
+    assert_eq!(limits, [AgentLimit { window: "seven_day".into(), used_percent: 100.0, resets_ms: None }]);
+    let usage = config::usage_of(&json!({"used": 1, "size": 2, "cost": {"amount": -1.0, "currency": "USD"}}));
+    assert_eq!(usage.map(|u| u.cost), Some(None), "a negative cost is dropped, the context use kept");
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn cursor_approval_switch_resolves_pending_and_survives_restart() {
     let tmp = tempfile::tempdir().unwrap();
@@ -1017,3 +1056,56 @@ async fn reload_providers_updates_registry_install_clears_stale_probes_and_notif
     let probe = mgr.probe("copilot", false).await.unwrap();
     assert!(probe.error.is_none());
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn idle_agents_stop_and_resume_their_session_on_the_next_message() {
+    let new = || NewAgentTask {
+        project_root: None,
+        prompt: text("again"),
+        provider: "claude".into(),
+        config: Vec::new(),
+        isolation: Isolation::Local,
+        base: None,
+    };
+    let live =
+        |mgr: &AgentManager, id: &str| mgr.task(id).unwrap().live.lock().as_ref().is_some_and(|l| !l.peer.is_closed());
+
+    let tmp = tempfile::tempdir().unwrap();
+    let agent = Arc::new(FakeAgent::default());
+    let mgr = manager(tmp.path(), agent.clone());
+    mgr.set_idle_release(Duration::from_millis(200));
+    let task = mgr.create(new()).await.unwrap();
+    wait_for(&mgr, &task.id, AgentStatus::Ready).await;
+    assert!(live(&mgr, &task.id));
+    // The process is stopped once the task stays idle…
+    tokio::time::sleep(Duration::from_millis(600)).await;
+    assert!(!live(&mgr, &task.id));
+    assert!(agent.servers.lock()[0].is_closed(), "its connection is closed");
+    assert_eq!(mgr.task(&task.id).unwrap().state.lock().task.status, AgentStatus::Ready, "not an error");
+    // …and the next message starts it again on the same session.
+    mgr.prompt(&task.id, text("again"), false).await.unwrap();
+    wait_for(&mgr, &task.id, AgentStatus::Ready).await;
+    assert!(agent.calls.lock().contains(&"session/load".to_owned()));
+    assert_eq!(
+        mgr.entries(&task.id, None).unwrap().iter().filter(|e| matches!(e, AgentEntry::Agent { .. })).count(),
+        2
+    );
+
+    // A new turn before the delay ran out keeps the agent.
+    mgr.prompt(&task.id, text("again"), false).await.unwrap();
+    tokio::time::sleep(Duration::from_millis(100)).await;
+    wait_for(&mgr, &task.id, AgentStatus::Ready).await;
+    assert!(live(&mgr, &task.id));
+    mgr.shutdown();
+
+    // An agent that can't reload its session keeps running: stopping it would lose the conversation.
+    let tmp = tempfile::tempdir().unwrap();
+    let agent = Arc::new(FakeAgent { no_load: true, ..FakeAgent::default() });
+    let mgr = manager(tmp.path(), agent.clone());
+    mgr.set_idle_release(Duration::from_millis(200));
+    let task = mgr.create(new()).await.unwrap();
+    wait_for(&mgr, &task.id, AgentStatus::Ready).await;
+    tokio::time::sleep(Duration::from_millis(600)).await;
+    assert!(live(&mgr, &task.id));
+    mgr.shutdown();
+}

crates/ide-build/src/compile/mod.rs

@@ -158,8 +158,11 @@ fn detect_dir(dir: &Path, model: &BuildModel, root: &Path) -> Option<BuildSystem
 }
 
 /// `root/rel`, without a trailing separator for the root itself.
+/// `root` / `rel`, joined per `/`-separated component: on Windows a single join of
+/// `a/b` keeps the `/`, and such a path does not compare equal to the same directory
+/// as other tools (JDT LS) spell it.
 fn subdir(root: &Path, rel: &str) -> PathBuf {
-    if rel.is_empty() { root.to_path_buf() } else { root.join(rel) }
+    rel.split('/').filter(|part| !part.is_empty()).fold(root.to_path_buf(), |path, part| path.join(part))
 }
 
 fn rel_str(root: &Path, dir: &Path) -> String {
@@ -737,11 +740,11 @@ fn launch_class_dirs(system: BuildSystem, module: &Path, test: bool) -> Vec<Path
             .iter()
             .flat_map(|s| {
                 ["classes/kotlin", "classes/groovy", "classes/scala", "classes/java", "resources"]
-                    .map(|d| module.join("build").join(d).join(s))
+                    .map(|d| subdir(module, &format!("build/{d}/{s}")))
             })
             .collect(),
-        BuildSystem::Maven if test => vec![module.join("target/test-classes"), module.join("target/classes")],
-        BuildSystem::Maven => vec![module.join("target/classes")],
+        BuildSystem::Maven if test => vec![subdir(module, "target/test-classes"), subdir(module, "target/classes")],
+        BuildSystem::Maven => vec![subdir(module, "target/classes")],
         _ => Vec::new(),
     };
     dirs.into_iter().filter(|d| d.is_dir()).collect()
@@ -751,6 +754,30 @@ fn launch_class_dirs(system: BuildSystem, module: &Path, test: bool) -> Vec<Path
 mod tests {
     use super::*;
 
+    /// Launch outputs use the platform separator throughout, so they compare equal to
+    /// the same directories as JDT LS reports them.
+    #[test]
+    fn launch_dirs_use_one_separator() {
+        let root = tempfile::tempdir().unwrap();
+        let module = subdir(root.path(), "parent/app");
+        for dir in ["target/classes", "target/test-classes", "build/classes/java/main", "build/resources/test"] {
+            std::fs::create_dir_all(subdir(&module, dir)).unwrap();
+        }
+        let foreign = if std::path::MAIN_SEPARATOR == '\\' { '/' } else { '\\' };
+        let dirs = [
+            launch_class_dirs(BuildSystem::Maven, &module, true),
+            launch_class_dirs(BuildSystem::Gradle, &module, true),
+        ]
+        .concat();
+        assert_eq!(dirs.len(), 4, "{dirs:?}");
+        for dir in &dirs {
+            let suffix = dir.strip_prefix(root.path()).unwrap().to_string_lossy().into_owned();
+            assert!(!suffix.contains(foreign), "{suffix}");
+        }
+        assert_eq!(subdir(root.path(), ""), root.path());
+        assert_eq!(subdir(root.path(), "a//b/"), root.path().join("a").join("b"));
+    }
+
     fn write(root: &Path, rel: &str, text: &str) {
         let p = root.join(rel);
         std::fs::create_dir_all(p.parent().unwrap()).unwrap();

crates/ide-build/src/gradle-model.gradle

@@ -0,0 +1,40 @@
+// OpenIDEA Gradle sync: prints each project as Gradle evaluated it, one JSON line per project.
+// Read by `ide_build::gradle::parse_reported_projects`. Dependencies are not resolved: the
+// Java language server reads the classpath itself, and resolving is the slow part of an import.
+import groovy.json.JsonOutput
+
+def canon = { File f -> f.canonicalPath }
+// Init scripts also run in included builds and buildSrc, whose projects reuse `:`, `:core`…:
+// the identity path (`:lib:core`, `:buildSrc`) tells them apart and addresses their tasks
+// from the root build. Internal API, hence the fallback.
+def identity = { Project p -> try { p.identityPath.toString() } catch (ignored) { p.path } }
+
+def describe = { Project p ->
+    def m = [path: identity(p), dir: canon(p.projectDir), buildDir: canon(p.layout.buildDirectory.get().asFile)]
+    if (p.gradle.parent != null) m.build = identity(p.rootProject)
+    def sets = p.extensions.findByName('sourceSets')
+    if (sets != null) {
+        // Test source sets as IDEA classifies them: `test`, test fixtures, JVM test suites,
+        // and sets whose folders the `idea` plugin lists as test sources.
+        def suites = [] as Set
+        try { p.extensions.findByName('testing')?.suites?.each { suites << it.sources.name } } catch (ignored) {}
+        def ideaTests = [] as Set
+        try { p.extensions.findByName('idea')?.module?.testSources?.files?.each { ideaTests << canon(it) } } catch (ignored) {}
+        m.sourceSets = sets.collect { s ->
+            def res = s.resources.srcDirs.collect(canon)
+            def src = s.allSource.srcDirs.collect(canon) - res
+            def test = s.name == 'test' || s.name == 'testFixtures' || suites.contains(s.name) ||
+                s.name.endsWith('Test') || s.name.endsWith('Tests') ||
+                (!src.isEmpty() && src.every { ideaTests.contains(it) })
+            [name: s.name, test: test, src: src, res: res]
+        }
+    }
+    try {
+        def java = p.extensions.findByName('java')
+        def lv = java?.toolchain?.languageVersion?.getOrNull()
+        m.java = lv != null ? lv.asInt() : (java?.targetCompatibility?.majorVersion as Integer)
+    } catch (ignored) {}
+    println '@openidea-model\t' + JsonOutput.toJson(m)
+}
+
+gradle.projectsEvaluated { g -> g.rootProject.allprojects { describe(it) } }

crates/ide-build/src/gradle.rs

@@ -32,7 +32,8 @@ pub struct GradleModel {
 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
 #[serde(rename_all = "camelCase")]
 pub struct GradleProject {
-    /// Gradle path: `:` for the root project, `:app`, `:libs:core`.
+    /// Gradle path: `:` for the root project, `:app`, `:libs:core`; for a project of a
+    /// nested build its identity path (`:lib:core`), which addresses its tasks from the root.
     pub path: String,
     pub name: String,
     /// Project-relative directory.
@@ -40,6 +41,10 @@ pub struct GradleProject {
     /// Project-relative build script, if any.
     pub build_file: Option<String>,
     pub tasks: Vec<GradleTask>,
+    /// Identity path of the nested build holding the project (`:lib` for `includeBuild`,
+    /// `:buildSrc`); null for the opened build.
+    #[serde(default)]
+    pub build: Option<String>,
 }
 
 #[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize, Type)]
@@ -129,35 +134,88 @@ fn include_args(after: &str) -> Vec<String> {
     out
 }
 
-/// `(root project name, included project paths)` from a settings script.
-pub fn parse_settings(text: &str) -> (Option<String>, Vec<String>) {
+/// What a settings script declares, read statically.
+#[derive(Debug, Default, PartialEq)]
+pub struct Settings {
+    pub name: Option<String>,
+    /// Included project paths (`:app`), in declaration order.
+    pub includes: Vec<String>,
+    /// Project directories that differ from the default `<path>` under the build
+    /// dir, relative to it: `includeFlat` siblings and literal `projectDir = file(..)`.
+    pub dirs: BTreeMap<String, String>,
+}
+
+/// The included projects, root project name and directory overrides of a settings script.
+/// Interpolated (`"$m"`) names and directories cannot be read without Gradle and are skipped.
+pub fn parse_settings(text: &str) -> Settings {
     let text = strip_comments(text);
-    let mut name = None;
-    let mut includes: Vec<String> = Vec::new();
+    let mut s = Settings::default();
     for (i, _) in text.match_indices("rootProject.name") {
         let line = text[i + "rootProject.name".len()..].lines().next().unwrap_or_default();
         if let Some(n) = literals(line).into_iter().next() {
-            name = Some(n);
+            s.name = Some(n);
         }
     }
     let mut from = 0;
     while let Some(i) = text[from..].find("include") {
         let at = from + i;
         from = at + "include".len();
+        let flat = text[from..].starts_with("Flat");
+        if flat {
+            from += "Flat".len();
+        }
         let before_ok = at == 0 || !text[..at].ends_with(|c: char| c.is_alphanumeric() || c == '_' || c == '.');
         let after = &text[from..];
         let after_ok = after.starts_with(|c: char| c == '(' || c.is_whitespace());
         if !before_ok || !after_ok {
             continue;
         }
-        for p in include_args(after) {
+        for p in include_args(after).into_iter().filter(|p| !p.contains('$')) {
             let path = if p.starts_with(':') { p } else { format!(":{p}") };
-            if path.len() > 1 && !includes.contains(&path) {
-                includes.push(path);
+            if path.len() <= 1 {
+                continue;
+            }
+            // `includeFlat 'a'` is the sibling directory `../a` of the root project.
+            if flat {
+                s.dirs.insert(path.clone(), format!("../{}", path.trim_start_matches(':')));
+            }
+            if !s.includes.contains(&path) {
+                s.includes.push(path);
             }
         }
     }
-    (name, includes)
+    // `project(':a').projectDir = file('../a')`; a later assignment wins, as in Gradle.
+    for line in text.lines() {
+        let Some((left, right)) = line.split_once(".projectDir") else { continue };
+        let Some(right) = right.trim_start().strip_prefix('=') else { continue };
+        let Some(arg) = right.trim_start().strip_prefix("file") else { continue };
+        let (Some(path), Some(dir)) = (
+            left.rsplit_once("project").map(|(_, p)| literals(p)).and_then(|l| l.into_iter().next()),
+            literals(arg).into_iter().next(),
+        ) else {
+            continue;
+        };
+        if !path.contains('$') && !dir.contains('$') {
+            let path = if path.starts_with(':') { path } else { format!(":{path}") };
+            s.dirs.insert(path, dir);
+        }
+    }
+    s
+}
+
+/// `a/b/../c` → `a/c`, without touching the filesystem.
+fn normalize(p: &Path) -> PathBuf {
+    let mut out = PathBuf::new();
+    for c in p.components() {
+        match c {
+            std::path::Component::CurDir => {}
+            std::path::Component::ParentDir if out.file_name().is_some() => {
+                out.pop();
+            }
+            c => out.push(c),
+        }
+    }
+    out
 }
 
 /// The directory of the Gradle build under `root`: the root itself, or a direct
@@ -235,31 +293,159 @@ pub fn default_tasks(is_root: bool, script: &str) -> Vec<GradleTask> {
 }
 
 /// Reads the Gradle build under `root` (no Gradle run), or `None` when there is none.
+fn read_first(d: &Path, names: &[&str]) -> Option<(String, String)> {
+    names.iter().find_map(|n| std::fs::read_to_string(d.join(n)).ok().map(|t| (n.to_string(), t)))
+}
+
+/// The project `path` in `pdir`, with the default tasks of its build script.
+/// Outside `root` the directory stays absolute (`rel` falls back).
+fn project_at(root: &Path, path: String, name: String, pdir: &Path) -> GradleProject {
+    let script = read_first(pdir, BUILD_FILES);
+    let tasks = default_tasks(path == ":", script.as_ref().map(|(_, t)| t.as_str()).unwrap_or_default());
+    GradleProject {
+        build_file: script.map(|(n, _)| rel(root, &pdir.join(n))),
+        dir: rel(root, pdir),
+        path,
+        name,
+        tasks,
+        build: None,
+    }
+}
+
+/// A project as Gradle evaluated it (the sync's init script, `gradle-model.gradle`).
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ReportedProject {
+    pub path: String,
+    /// Absolute, canonical.
+    pub dir: String,
+    /// Absolute output folder (`layout.buildDirectory`).
+    #[serde(default)]
+    pub build_dir: Option<String>,
+    #[serde(default)]
+    pub source_sets: Vec<ReportedSourceSet>,
+    /// Toolchain language version, else target compatibility.
+    #[serde(default)]
+    pub java: Option<u32>,
+    /// Identity path of the nested build (included build, buildSrc) reporting the project.
+    #[serde(default)]
+    pub build: Option<String>,
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
+pub struct ReportedSourceSet {
+    pub name: String,
+    pub test: bool,
+    /// Absolute source folders (Java, Kotlin, Groovy, …), which need not exist.
+    #[serde(default)]
+    pub src: Vec<String>,
+    /// Absolute resource folders.
+    #[serde(default)]
+    pub res: Vec<String>,
+}
+
+const MODEL_LINE: &str = "@openidea-model\t";
+
+/// The projects printed by `gradle-model.gradle`; malformed lines are skipped.
+pub fn parse_reported_projects(output: &str) -> Vec<ReportedProject> {
+    output.lines().filter_map(|l| serde_json::from_str(l.trim_end().strip_prefix(MODEL_LINE)?).ok()).collect()
+}
+
+/// Source roots of the reported source sets: `(absolute folder, is test, is resources)`.
+pub fn reported_source_roots(reported: &[ReportedProject]) -> Vec<(PathBuf, ReportedRoot)> {
+    let mut out: Vec<(PathBuf, ReportedRoot)> = Vec::new();
+    for p in reported {
+        for set in &p.source_sets {
+            let (src, res) = if set.test {
+                (ReportedRoot::Test, ReportedRoot::TestResources)
+            } else {
+                (ReportedRoot::Source, ReportedRoot::Resources)
+            };
+            for (dir, kind) in set.src.iter().map(|d| (d, src)).chain(set.res.iter().map(|d| (d, res))) {
+                let dir = PathBuf::from(dir);
+                // A folder shared by `main` and another set is `main`'s, as in IDEA.
+                if !out.iter().any(|(d, _)| *d == dir) {
+                    out.push((dir, kind));
+                }
+            }
+        }
+        // IDEA excludes the build folder of every module.
+        if let Some(b) = &p.build_dir {
+            out.push((PathBuf::from(b), ReportedRoot::Excluded));
+        }
+    }
+    out
+}
+
+/// Role of a folder a Gradle sync reported.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum ReportedRoot {
+    Source,
+    Test,
+    Resources,
+    TestResources,
+    Excluded,
+}
+
+/// Replaces the statically read projects with the ones Gradle reported (root first):
+/// settings scripts may compute their projects, which no static reading sees.
+pub fn merge_reported_projects(root: &Path, model: &mut GradleModel, reported: &[ReportedProject]) {
+    if reported.is_empty() {
+        return;
+    }
+    let root_name = model.projects.iter().find(|p| p.path == ":").map(|p| p.name.clone());
+    model.projects = reported
+        .iter()
+        .map(|p| {
+            let name = match p.path.as_str() {
+                ":" => root_name.clone().unwrap_or_default(),
+                path => path.rsplit(':').next().unwrap_or_default().to_owned(),
+            };
+            let mut project = project_at(root, p.path.clone(), name, Path::new(&p.dir));
+            // buildSrc is built before the build, never addressable as `:buildSrc:<task>`.
+            if p.build.as_deref().is_some_and(|b| b.ends_with(":buildSrc")) {
+                project.tasks.clear();
+            }
+            project.build = p.build.clone();
+            project
+        })
+        .collect();
+    // Each build reports its projects when it is evaluated (nested builds first).
+    model.projects.sort_by(|a, b| a.path.cmp(&b.path));
+    // One JDK runs the whole build: the newest any module needs.
+    if let Some(v) = reported.iter().filter_map(|p| p.java).max() {
+        model.java_version = Some(v);
+    }
+}
+
+/// Project directories outside `root`, outermost only (`../svc`, not also `../svc/sources/app`):
+/// the folders IDEA shows as extra top-level module roots.
+pub fn external_roots<'a>(root: &Path, dirs: impl IntoIterator<Item = &'a str>) -> Vec<PathBuf> {
+    let mut dirs: Vec<PathBuf> = dirs.into_iter().map(|d| root.join(d)).filter(|d| !d.starts_with(root)).collect();
+    dirs.sort();
+    dirs.dedup();
+    let mut out: Vec<PathBuf> = Vec::new();
+    for d in dirs {
+        if !out.iter().any(|o| d.starts_with(o)) {
+            out.push(d);
+        }
+    }
+    out
+}
+
 pub fn load(root: &Path) -> Option<GradleModel> {
     let dir = build_dir(root)?;
-    let read = |d: &Path, names: &[&str]| {
-        names.iter().find_map(|n| std::fs::read_to_string(d.join(n)).ok().map(|t| (n.to_string(), t)))
-    };
-    let (name, includes) = read(&dir, SETTINGS_FILES).map(|(_, t)| parse_settings(&t)).unwrap_or_default();
+    let settings = read_first(&dir, SETTINGS_FILES).map(|(_, t)| parse_settings(&t)).unwrap_or_default();
     let root_name =
-        name.unwrap_or_else(|| dir.file_name().map(|n| n.to_string_lossy().into_owned()).unwrap_or_default());
-    let mut projects = Vec::new();
-    let mut add = |path: String, name: String, pdir: PathBuf| {
-        let script = read(&pdir, BUILD_FILES);
-        let tasks = default_tasks(path == ":", script.as_ref().map(|(_, t)| t.as_str()).unwrap_or_default());
-        projects.push(GradleProject {
-            build_file: script.map(|(n, _)| rel(root, &pdir.join(n))),
-            dir: rel(root, &pdir),
-            path,
-            name,
-            tasks,
-        });
-    };
-    add(":".into(), root_name, dir.clone());
-    for path in includes {
-        let pdir = dir.join(path.trim_start_matches(':').replace(':', "/"));
+        settings.name.unwrap_or_else(|| dir.file_name().map(|n| n.to_string_lossy().into_owned()).unwrap_or_default());
+    let mut projects = vec![project_at(root, ":".into(), root_name, &dir)];
+    for path in settings.includes {
+        let pdir = match settings.dirs.get(&path) {
+            Some(d) => normalize(&dir.join(d)),
+            None => dir.join(path.trim_start_matches(':').replace(':', "/")),
+        };
         let name = path.rsplit(':').next().unwrap_or_default().to_owned();
-        add(path, name, pdir);
+        projects.push(project_at(root, path, name, &pdir));
     }
     let java_version = projects
         .iter()
@@ -358,9 +544,32 @@ pub fn build_files(root: &Path, model: &GradleModel) -> Vec<PathBuf> {
     let dir = root.join(&model.dir);
     let mut out: Vec<PathBuf> = SETTINGS_FILES.iter().map(|f| dir.join(f)).filter(|p| p.is_file()).collect();
     out.extend(model.projects.iter().filter_map(|p| p.build_file.as_ref().map(|f| root.join(f))));
+    // The settings of each nested build (its root project's folder).
+    for p in model.projects.iter().filter(|p| p.build.as_deref() == Some(p.path.as_str())) {
+        let nested = root.join(&p.dir);
+        out.extend(SETTINGS_FILES.iter().map(|f| nested.join(f)).filter(|f| f.is_file()));
+    }
+    // What IDEA's auto-import also watches: properties, the wrapper and version catalogs.
+    let extra = ["gradle.properties", "gradle/wrapper/gradle-wrapper.properties"].map(|f| dir.join(f));
+    out.extend(extra.into_iter().filter(|p| p.is_file()));
+    if let Ok(entries) = std::fs::read_dir(dir.join("gradle")) {
+        let mut catalogs: Vec<PathBuf> = entries
+            .flatten()
+            .map(|e| e.path())
+            .filter(|p| p.to_string_lossy().ends_with(".versions.toml") && p.is_file())
+            .collect();
+        catalogs.sort();
+        out.extend(catalogs);
+    }
     out
 }
 
+/// A build script without comments and with whitespace runs collapsed, so editing a
+/// comment or reformatting does not make a sync stale (IDEA hashes lexer tokens alike).
+pub(crate) fn script_fingerprint(text: &str) -> String {
+    strip_comments(text).split_whitespace().collect::<Vec<_>>().join(" ")
+}
+
 /// `(project path, task)` from `gradle tasks --all` console output; tasks listed as
 /// `app:run` belong to `:app`, unqualified ones to the root project `:`.
 pub fn parse_tasks(output: &str) -> Vec<(String, GradleTask)> {
@@ -451,14 +660,60 @@ dependencies {
             /* include("block") */
             includeBuild("plugins")
         "#;
-        let (name, includes) = parse_settings(kts);
-        assert_eq!(name.as_deref(), Some("gradle-demo"));
-        assert_eq!(includes, [":app", ":lib", ":libs:core"]);
+        let s = parse_settings(kts);
+        assert_eq!(s.name.as_deref(), Some("gradle-demo"));
+        assert_eq!(s.includes, [":app", ":lib", ":libs:core"]);
+        assert!(s.dirs.is_empty());
 
         let groovy = "rootProject.name = 'demo'\ninclude 'a',\n        'b'\ninclude ':c'\nprintln 'x'\n";
-        let (name, includes) = parse_settings(groovy);
-        assert_eq!(name.as_deref(), Some("demo"));
-        assert_eq!(includes, [":a", ":b", ":c"]);
+        let s = parse_settings(groovy);
+        assert_eq!(s.name.as_deref(), Some("demo"));
+        assert_eq!(s.includes, [":a", ":b", ":c"]);
+    }
+
+    #[test]
+    fn settings_include_flat_and_project_dirs() {
+        let groovy = r#"
+            includeFlat 'svc-a'
+            includeFlat 'svc-b', 'svc-c' // trailing comment
+            ['x', 'y'].each { m -> include ":svc-a:$m" }
+            include ':wo'
+            project(':wo').projectDir = file('../svc-a/.worktrees/wo')
+            project(":dyn").projectDir = file("${rootDir}/dyn")
+            includeFlated 'not-a-call'
+        "#;
+        let s = parse_settings(groovy);
+        assert_eq!(s.includes, [":svc-a", ":svc-b", ":svc-c", ":wo"]);
+        assert_eq!(
+            s.dirs.into_iter().collect::<Vec<_>>(),
+            [
+                (":svc-a".into(), "../svc-a".into()),
+                (":svc-b".into(), "../svc-b".into()),
+                (":svc-c".into(), "../svc-c".into()),
+                (":wo".into(), "../svc-a/.worktrees/wo".into()),
+            ]
+        );
+
+        let kts = "includeFlat(\"k\")\nproject(\":k\").projectDir = file(\"../other\")";
+        let s = parse_settings(kts);
+        assert_eq!(s.includes, [":k"]);
+        assert_eq!(s.dirs.get(":k").map(String::as_str), Some("../other"));
+    }
+
+    #[test]
+    fn loads_include_flat_siblings() {
+        let tmp = tempfile::tempdir().unwrap();
+        let ws = tmp.path();
+        std::fs::create_dir_all(ws.join("root")).unwrap();
+        std::fs::create_dir_all(ws.join("svc")).unwrap();
+        std::fs::write(ws.join("root/settings.gradle"), "rootProject.name = 'Root'\nincludeFlat 'svc'").unwrap();
+        std::fs::write(ws.join("svc/build.gradle"), "plugins { id 'java' }").unwrap();
+        let root = ws.join("root");
+        let m = load(&root).unwrap();
+        let svc = m.projects.iter().find(|p| p.path == ":svc").unwrap();
+        assert_eq!(Path::new(&svc.dir), ws.join("svc"));
+        assert_eq!(svc.build_file.as_deref().map(Path::new), Some(ws.join("svc/build.gradle").as_path()));
+        assert!(root.join(svc.build_file.as_ref().unwrap()).is_file());
     }
 
     #[test]
@@ -539,4 +794,52 @@ Pattern: clean<TaskName>: Cleans the output files of a task.
         let none = tempfile::tempdir().unwrap();
         assert!(load(none.path()).is_none());
     }
+
+    #[test]
+    fn merges_included_builds_and_build_src_by_identity_path() {
+        let tmp = tempfile::tempdir().unwrap();
+        let ws = tmp.path();
+        for d in ["shop/app", "shop/buildSrc", "lib/core"] {
+            std::fs::create_dir_all(ws.join(d)).unwrap();
+        }
+        std::fs::write(ws.join("shop/settings.gradle"), "rootProject.name = 'shop'\ninclude 'app'").unwrap();
+        std::fs::write(ws.join("lib/settings.gradle"), "include 'core'").unwrap();
+        let root = ws.join("shop");
+        // In evaluation order, as the init script prints it: nested builds first.
+        let line = |path: &str, d: &str, build: Option<&str>| {
+            let project = ReportedProject {
+                path: path.into(),
+                dir: ws.join(d).to_string_lossy().into_owned(),
+                build: build.map(Into::into),
+                ..ReportedProject::default()
+            };
+            format!("{MODEL_LINE}{}\n", serde_json::to_string(&project).unwrap())
+        };
+        let out = [
+            line(":lib", "lib", Some(":lib")),
+            line(":lib:core", "lib/core", Some(":lib")),
+            line(":buildSrc", "shop/buildSrc", Some(":buildSrc")),
+            line(":", "shop", None),
+            line(":app", "shop/app", None),
+        ]
+        .concat();
+        let mut model = load(&root).unwrap();
+        merge_reported_projects(&root, &mut model, &parse_reported_projects(&out));
+        let projects: Vec<_> =
+            model.projects.iter().map(|p| (p.path.as_str(), p.name.as_str(), p.build.as_deref())).collect();
+        assert_eq!(
+            projects,
+            [
+                (":", "shop", None),
+                (":app", "app", None),
+                (":buildSrc", "buildSrc", Some(":buildSrc")),
+                (":lib", "lib", Some(":lib")),
+                (":lib:core", "core", Some(":lib")),
+            ]
+        );
+        let build_src = &model.projects[2];
+        assert!(build_src.tasks.is_empty(), "buildSrc tasks cannot run from the root build");
+        assert!(!model.projects[4].tasks.is_empty());
+        assert!(build_files(&root, &model).contains(&ws.join("lib/settings.gradle")));
+    }
 }

crates/ide-build/src/lib.rs

@@ -18,7 +18,7 @@ mod xml;
 
 pub use gradle::{GradleModel, GradleProject, GradleTask};
 pub use maven::{MavenDependency, MavenModel, MavenPlugin, MavenProfile, MavenProject, Omission};
-pub use sync::{SyncOptions, SyncProgress, sync_gradle, sync_maven};
+pub use sync::{SyncOptions, SyncProgress, maven_profiles, save_maven_profiles, sync_gradle, sync_maven};
 
 use serde::{Deserialize, Serialize};
 use specta::Type;
@@ -65,6 +65,18 @@ pub fn load_linked(
     BuildModel { maven, gradle }
 }
 
+/// Gradle project folders outside `root` as of the last sync (`includeFlat` siblings):
+/// extra content roots, as IDEA lists module roots beside the project folder.
+/// Reads only the sync's cached projects (no build script), so it is cheap enough for hot paths.
+pub fn gradle_external_roots(root: &Path, cache_dir: &Path) -> Vec<PathBuf> {
+    gradle::external_roots(root, sync::reported_gradle_projects(cache_dir).iter().map(|p| p.dir.as_str()))
+}
+
+/// Source, resource and build folders of the last Gradle sync, absolute.
+pub fn gradle_source_roots(cache_dir: &Path) -> Vec<(PathBuf, gradle::ReportedRoot)> {
+    gradle::reported_source_roots(&sync::reported_gradle_projects(cache_dir))
+}
+
 /// A library the project depends on, as `groupId:artifactId:version`.
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct DependencyCoordinate {

crates/ide-build/src/maven.rs

@@ -245,7 +245,8 @@ struct RawPom {
     plugins: Vec<RawPlugin>,
     managed_plugins: Vec<RawPlugin>,
     profiles: Vec<RawProfile>,
-    /// `<build><plugins>` `maven-compiler-plugin` `<release>` / `<source>`.
+    /// `maven-compiler-plugin` `<release>` / `<source>` of `<build><plugins>`, else of
+    /// `<pluginManagement>`.
     compiler_release: Option<String>,
 }
 
@@ -300,6 +301,16 @@ fn read_build(e: &Element, plugins: &mut Vec<RawPlugin>, managed: &mut Vec<RawPl
     managed.extend(e.list("build/pluginManagement/plugins", "plugin").into_iter().filter_map(read_plugin));
 }
 
+/// `maven-compiler-plugin` `<release>` / `<source>` among the plugins at `path`.
+fn compiler_level(project: &Element, path: &str) -> Option<String> {
+    project
+        .list(path, "plugin")
+        .into_iter()
+        .find(|p| p.text_of("artifactId").as_deref() == Some("maven-compiler-plugin"))
+        .and_then(|p| p.child("configuration"))
+        .and_then(|c| c.text_of("release").or_else(|| c.text_of("source")))
+}
+
 fn read_raw(project: &Element) -> RawPom {
     let parent = project.child("parent").and_then(|p| {
         Some(ParentRef {
@@ -328,13 +339,8 @@ fn read_raw(project: &Element) -> RawPom {
         ..RawPom::default()
     };
     read_build(project, &mut pom.plugins, &mut pom.managed_plugins);
-    if let Some(c) = pom.plugins.iter().position(|p| p.artifact_id == "maven-compiler-plugin") {
-        let plugin =
-            project.list("build/plugins", "plugin").into_iter().filter(|p| p.text_of("artifactId").is_some()).nth(c);
-        if let Some(cfg) = plugin.and_then(|p| p.child("configuration")) {
-            pom.compiler_release = cfg.text_of("release").or_else(|| cfg.text_of("source"));
-        }
-    }
+    pom.compiler_release =
+        compiler_level(project, "build/plugins").or_else(|| compiler_level(project, "build/pluginManagement/plugins"));
     for p in project.list("profiles", "profile") {
         let mut profile = RawProfile {
             id: p.text_of("id").unwrap_or_else(|| "default".into()),
@@ -411,6 +417,9 @@ struct Inherited {
     managed: Vec<RawDep>,
     plugins: Vec<RawPlugin>,
     managed_plugins: Vec<RawPlugin>,
+    /// The nearest `maven-compiler-plugin` `<release>` / `<source>`: a module usually
+    /// inherits its compiler level from the parent's (managed) plugin configuration.
+    compiler_release: Option<String>,
     /// `<id>`, `activeByDefault`: profiles of the POM and its ancestors —
     /// Maven lets a child enable a parent's profiles with `-P`.
     profiles: Vec<(String, bool)>,
@@ -538,6 +547,9 @@ impl Resolver {
         merge_by(&mut ctx.deps, &pom.deps, RawDep::key);
         merge_plugins(&mut ctx.plugins, &pom.plugins);
         merge_plugins(&mut ctx.managed_plugins, &pom.managed_plugins);
+        if pom.compiler_release.is_some() {
+            ctx.compiler_release = pom.compiler_release.clone();
+        }
         for p in pom.profiles.iter().filter(|p| p.active_by_default) {
             merge_by(&mut ctx.properties, &p.properties, |(k, _)| k.clone());
             merge_by(&mut ctx.deps, &p.deps, RawDep::key);
@@ -966,13 +978,19 @@ fn rel_path(root: &Path, p: &Path) -> String {
 }
 
 /// The POMs that are not modules of another one: the root `pom.xml`, else the
-/// shallowest `pom.xml` of each branch (a folder holding several builds).
+/// shallowest `pom.xml` of each branch (a folder holding several builds). An
+/// aggregate POM directly inside `src/` counts too (issue #1001: `src/pom.xml`
+/// with its modules beside it, `src/app/pom.xml` and so on).
 fn top_level_poms(root: &Path) -> Vec<PathBuf> {
     let top = root.join("pom.xml");
     if top.is_file() {
         return vec![top];
     }
     let mut out = Vec::new();
+    let src_pom = root.join("src").join("pom.xml");
+    if src_pom.is_file() {
+        out.push(src_pom);
+    }
     let mut queue: Vec<(PathBuf, usize)> = vec![(root.to_path_buf(), 0)];
     while let Some((dir, depth)) = queue.pop() {
         let Ok(entries) = std::fs::read_dir(&dir) else { continue };
@@ -986,9 +1004,16 @@ fn top_level_poms(root: &Path) -> Vec<PathBuf> {
         }
         dirs.sort();
         for d in dirs.into_iter().rev() {
-            if d.join("pom.xml").is_file() {
-                out.push(d.join("pom.xml"));
-            } else if depth + 1 < POM_SEARCH_DEPTH {
+            let pom = d.join("pom.xml");
+            if pom.is_file() {
+                out.push(pom);
+                continue;
+            }
+            let src_pom = d.join("src").join("pom.xml");
+            if src_pom.is_file() {
+                out.push(src_pom);
+            }
+            if depth + 1 < POM_SEARCH_DEPTH {
                 queue.push((d, depth + 1));
             }
         }
@@ -1110,7 +1135,7 @@ pub(crate) fn load_with_repo(root: &Path, local_repo: Option<PathBuf>) -> MavenM
         let jv = ["maven.compiler.release", "java.version", "maven.compiler.source", "maven.compiler.target"]
             .iter()
             .find_map(|k| props.get(*k).map(|v| i(v)))
-            .or_else(|| pom.compiler_release.as_deref().map(i))
+            .or_else(|| ctx.compiler_release.as_deref().map(i))
             .and_then(|v| java_version(&v));
 
         // The project can activate the profiles of its own POM and its ancestors'.
@@ -1183,6 +1208,40 @@ impl UnlinkedProjects {
         self.poms.iter().map(String::as_str)
     }
 
+    /// The POMs the Java language server should import when an unlinked POM is a module of a
+    /// linked reactor, else `None` (excluding the unlinked directories is enough then).
+    ///
+    /// jdtls imports an aggregator together with all of its modules, whatever its import
+    /// exclusions say, so a reactor keeping an unlinked module is left out; its other linked
+    /// modules are listed on their own. Such an aggregator (`pom` packaging) has no sources.
+    pub fn import_poms(&self, model: &MavenModel) -> Option<Vec<String>> {
+        let linked: Vec<&MavenProject> = model.projects.iter().filter(|p| !self.contains(&p.pom)).collect();
+        if !linked.iter().any(|p| p.modules.iter().any(|m| self.contains(m))) {
+            return None;
+        }
+        let by_pom: std::collections::HashMap<String, &MavenProject> =
+            model.projects.iter().map(|p| (normalized_pom(&p.pom), p)).collect();
+        // Whether `pom`'s module tree reaches an unlinked POM.
+        let reaches_unlinked = |pom: &str| {
+            let mut seen = std::collections::HashSet::new();
+            let mut pending = vec![normalized_pom(pom)];
+            while let Some(pom) = pending.pop() {
+                if !seen.insert(pom.clone()) {
+                    continue;
+                }
+                let Some(project) = by_pom.get(&pom) else { continue };
+                for module in &project.modules {
+                    if self.contains(module) {
+                        return true;
+                    }
+                    pending.push(normalized_pom(module));
+                }
+            }
+            false
+        };
+        Some(linked.into_iter().filter(|p| !reaches_unlinked(&p.pom)).map(|p| normalized_pom(&p.pom)).collect())
+    }
+
     pub fn filter(&self, model: &mut MavenModel) {
         model.projects.retain(|p| !self.contains(&p.pom));
         for project in &mut model.projects {
@@ -1511,6 +1570,52 @@ mod tests {
         assert!(model.projects.iter().any(|p| p.pom == "core/pom.xml" && p.aggregated));
     }
 
+    #[test]
+    fn modules_inherit_the_compiler_level_of_the_parent_plugin_configuration() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        let parent = |build: &str| {
+            format!(
+                r#"<project><groupId>demo</groupId><artifactId>parent</artifactId><version>1.0</version><packaging>pom</packaging>
+                  <modules><module>core</module><module>app</module></modules>
+                  <properties><jdk>17</jdk></properties>{build}</project>"#
+            )
+        };
+        let child = |name: &str, build: &str| {
+            format!(
+                r#"<project><parent><groupId>demo</groupId><artifactId>parent</artifactId><version>1.0</version></parent>
+                  <artifactId>{name}</artifactId>{build}</project>"#
+            )
+        };
+        let compiler = |level: &str| {
+            format!(
+                "<plugin><artifactId>maven-compiler-plugin</artifactId><configuration><source>{level}</source></configuration></plugin>"
+            )
+        };
+        let versions = |model: &MavenModel| -> Vec<(String, Option<u32>)> {
+            model.projects.iter().map(|p| (p.pom.clone(), p.java_version)).collect()
+        };
+        let app_build = format!("<build><plugins>{}</plugins></build>", compiler("21"));
+        write(root, "core/pom.xml", &child("core", ""));
+        write(root, "app/pom.xml", &child("app", &app_build));
+        for build in [
+            format!("<build><pluginManagement><plugins>{}</plugins></pluginManagement></build>", compiler("${jdk}")),
+            format!("<build><plugins>{}</plugins></build>", compiler("1.8")),
+        ] {
+            write(root, "pom.xml", &parent(&build));
+            let expected = if build.contains("1.8") { 8 } else { 17 };
+            assert_eq!(
+                versions(&load_with_repo(root, None)),
+                [
+                    ("pom.xml".to_owned(), Some(expected)),
+                    ("core/pom.xml".to_owned(), Some(expected)),
+                    ("app/pom.xml".to_owned(), Some(21)),
+                ],
+                "{build}"
+            );
+        }
+    }
+
     #[test]
     fn multi_module_parent_properties_and_managed_versions() {
         let tmp = tempfile::tempdir().unwrap();
@@ -1706,6 +1811,25 @@ mod tests {
         assert!(!is_maven_project(&root.join("c")));
     }
 
+    #[test]
+    fn aggregate_pom_in_src_is_a_build() {
+        // Issue #1001: `src/pom.xml` aggregating modules under `src/` is recognized,
+        // with its modules loaded — while `src` stays unsearched otherwise.
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        write(
+            root,
+            "src/pom.xml",
+            "<project><groupId>g</groupId><artifactId>parent</artifactId><packaging>pom</packaging>\
+             <modules><module>app</module></modules></project>",
+        );
+        write(root, "src/app/pom.xml", "<project><groupId>g</groupId><artifactId>app</artifactId></project>");
+        let model = load_with_repo(root, None);
+        let names: Vec<&str> = model.projects.iter().map(|p| p.artifact_id.as_str()).collect();
+        assert_eq!(names, ["parent", "app"]);
+        assert!(is_maven_project(root));
+    }
+
     #[test]
     fn property_interpolation() {
         let props: HashMap<String, String> =
@@ -1903,4 +2027,51 @@ mod linkage_tests {
         UnlinkedProjects::from_model(&original, &MavenSettings::default()).filter(&mut restored);
         assert_eq!(restored, original);
     }
+
+    #[test]
+    fn language_server_imports_reactor_modules_individually_once_one_is_unlinked() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        // r ─┬─ x
+        //    ├─ y ─┬─ y/y1
+        //    │     └─ y/y2
+        //    └─ z          other/ is a separate root.
+        for (dir, modules) in [
+            ("r", "<modules><module>x</module><module>y</module><module>z</module></modules>"),
+            ("r/x", ""),
+            ("r/y", "<modules><module>y1</module><module>y2</module></modules>"),
+            ("r/y/y1", ""),
+            ("r/y/y2", ""),
+            ("r/z", ""),
+            ("other", ""),
+        ] {
+            std::fs::create_dir_all(root.join(dir)).unwrap();
+            std::fs::write(
+                root.join(dir).join("pom.xml"),
+                format!("<project><artifactId>{dir}</artifactId>{modules}</project>"),
+            )
+            .unwrap();
+        }
+        let model = load_with_repo(root, None);
+        let cases: [(&[&str], Option<&[&str]>); 5] = [
+            // Nothing unlinked, or whole roots: the import exclusions do it.
+            (&[], None),
+            (&["other/pom.xml"], None),
+            (&["r/pom.xml"], None),
+            // A module of a linked reactor: every other linked POM, minus the aggregators above it.
+            (&["r/y/y1/pom.xml"], Some(&["other/pom.xml", "r/x/pom.xml", "r/y/y2/pom.xml", "r/z/pom.xml"])),
+            (&["./r/y/pom.xml"], Some(&["other/pom.xml", "r/x/pom.xml", "r/z/pom.xml"])),
+        ];
+        for (unlinked, expected) in cases {
+            let settings = MavenSettings {
+                unlinked_projects: unlinked.iter().map(|s| s.to_string()).collect(),
+                ..Default::default()
+            };
+            let mut poms = UnlinkedProjects::from_model(&model, &settings).import_poms(&model);
+            if let Some(poms) = &mut poms {
+                poms.sort();
+            }
+            assert_eq!(poms, expected.map(|e| e.iter().map(|s| s.to_string()).collect::<Vec<_>>()), "{unlinked:?}");
+        }
+    }
 }

crates/ide-build/src/sync.rs

@@ -4,14 +4,16 @@
 //! per project (`maven.json`, `gradle.json` in the cache directory) and merged
 //! into the static model by [`crate::load`]; a changed build file marks them stale.
 
-use crate::gradle::{self, GradleModel, GradleTask};
+use crate::gradle::{self, GradleModel, GradleTask, ReportedProject, parse_reported_projects};
 use crate::maven::{self, MavenDependency, MavenModel, MavenPlugin};
 use crate::process::{self, Output};
 use ide_core::{CancellationToken, IdeError, IdeResult};
 use serde::{Deserialize, Serialize, de::DeserializeOwned};
 use specta::Type;
-use std::collections::BTreeMap;
+use std::collections::{BTreeMap, HashMap};
 use std::path::{Path, PathBuf};
+use std::sync::{Arc, LazyLock, Mutex};
+use std::time::SystemTime;
 
 #[derive(Clone, Debug, Serialize, Deserialize, Type)]
 #[serde(rename_all = "camelCase")]
@@ -68,8 +70,14 @@ struct GradleCache {
     at_ms: f64,
     error: Option<String>,
     tasks: Vec<(String, GradleTask)>,
+    /// The projects as Gradle evaluated them; empty in caches from before they were read.
+    #[serde(default)]
+    projects: Vec<ReportedProject>,
 }
 
+/// Init script printing every project, its source sets and Java version once configured.
+const MODEL_INIT_SCRIPT: &str = include_str!("gradle-model.gradle");
+
 const MAVEN_CACHE: &str = "maven.json";
 const MAVEN_CACHE_VERSION: u32 = 1;
 
@@ -88,6 +96,24 @@ fn maven_sync_goals(effective: &Path, offline: bool) -> Vec<String> {
     ]
 }
 const GRADLE_CACHE: &str = "gradle.json";
+const MAVEN_PROFILES: &str = "maven-profiles.json";
+
+/// The Maven profiles (`-P` entries, `!id` deactivates) the project was last synced
+/// with: what the IDE resolves it with besides `mvn` (the Java language server, Build Project).
+pub fn maven_profiles(cache_dir: &Path) -> Vec<String> {
+    read_cache(cache_dir, MAVEN_PROFILES).unwrap_or_default()
+}
+
+/// Records the profiles of a sync for [`maven_profiles`]; `true` when they changed.
+pub fn save_maven_profiles(cache_dir: &Path, profiles: &[String]) -> IdeResult<bool> {
+    if maven_profiles(cache_dir) == profiles {
+        return Ok(false);
+    }
+    std::fs::create_dir_all(cache_dir)?;
+    let json = serde_json::to_vec(profiles).map_err(|e| IdeError::internal(e.to_string()))?;
+    std::fs::write(cache_dir.join(MAVEN_PROFILES), json)?;
+    Ok(true)
+}
 
 fn read_cache<T: DeserializeOwned>(dir: &Path, name: &str) -> Option<T> {
     serde_json::from_slice(&std::fs::read(dir.join(name)).ok()?).ok()
@@ -104,6 +130,20 @@ fn write_cache<T: Serialize>(dir: &Path, name: &str, value: &T) -> IdeResult<()>
 
 /// FNV-1a over the paths and contents of `files` (missing files count as empty).
 fn hash_files(files: &[PathBuf]) -> String {
+    hash_contents(files, |f| std::fs::read(f).unwrap_or_default())
+}
+
+/// Like IDEA's auto-import CRC: editing a comment or reformatting a build script
+/// does not make the last sync stale.
+fn hash_gradle_files(files: &[PathBuf]) -> String {
+    hash_contents(files, |f| {
+        let text = std::fs::read_to_string(f).unwrap_or_default();
+        let script = f.extension().is_some_and(|e| e == "gradle" || e == "kts");
+        if script { gradle::script_fingerprint(&text) } else { text }.into_bytes()
+    })
+}
+
+fn hash_contents(files: &[PathBuf], read: impl Fn(&Path) -> Vec<u8>) -> String {
     let mut h: u64 = 0xcbf29ce484222325;
     let mut feed = |bytes: &[u8]| {
         for b in bytes {
@@ -114,7 +154,7 @@ fn hash_files(files: &[PathBuf]) -> String {
     for f in files {
         feed(f.to_string_lossy().as_bytes());
         feed(&[0]);
-        feed(&std::fs::read(f).unwrap_or_default());
+        feed(&read(f));
         feed(&[0]);
     }
     format!("{h:016x}")
@@ -150,9 +190,33 @@ pub fn apply_maven_cache(root: &Path, cache_dir: &Path, model: &mut MavenModel)
     }
 }
 
+/// The projects of the last successful Gradle sync.
+/// Parsed once per change of the cache file (modification time and size): content and source
+/// roots are read on hot paths (every references search, Find in Files, repository scans).
+pub fn reported_gradle_projects(cache_dir: &Path) -> Arc<Vec<ReportedProject>> {
+    type Memo = HashMap<PathBuf, (Option<SystemTime>, u64, Arc<Vec<ReportedProject>>)>;
+    static MEMO: LazyLock<Mutex<Memo>> = LazyLock::new(Default::default);
+    let path = cache_dir.join(GRADLE_CACHE);
+    let Ok(meta) = std::fs::metadata(&path) else {
+        MEMO.lock().unwrap_or_else(|e| e.into_inner()).remove(&path);
+        return Arc::default();
+    };
+    let stamp = (meta.modified().ok(), meta.len());
+    let mut memo = MEMO.lock().unwrap_or_else(|e| e.into_inner());
+    if let Some((modified, len, projects)) = memo.get(&path)
+        && (*modified, *len) == stamp
+    {
+        return projects.clone();
+    }
+    let projects = Arc::new(read_cache::<GradleCache>(cache_dir, GRADLE_CACHE).map(|c| c.projects).unwrap_or_default());
+    memo.insert(path, (stamp.0, stamp.1, projects.clone()));
+    projects
+}
+
 /// Merges the cached task list into `model`.
 pub fn apply_gradle_cache(root: &Path, cache_dir: &Path, model: &mut GradleModel) {
     let Some(cache) = read_cache::<GradleCache>(cache_dir, GRADLE_CACHE) else { return };
+    gradle::merge_reported_projects(root, model, &cache.projects);
     if !cache.tasks.is_empty() {
         for p in &mut model.projects {
             let tasks: Vec<GradleTask> =
@@ -162,9 +226,11 @@ pub fn apply_gradle_cache(root: &Path, cache_dir: &Path, model: &mut GradleModel
             }
         }
     }
+    // A successful sync from before projects were cached has not seen computed includes.
+    let without_projects = cache.error.is_none() && cache.projects.is_empty();
     model.synced_at = Some(cache.at_ms);
     model.sync_error = cache.error;
-    model.stale = cache.hash != hash_files(&gradle::build_files(root, model));
+    model.stale = without_projects || cache.hash != hash_gradle_files(&gradle::build_files(root, model));
 }
 
 // ---------------------------------------------------------------- processes
@@ -304,8 +370,18 @@ pub fn sync_gradle(
     cancel: &CancellationToken,
     progress: &dyn Fn(SyncProgress),
 ) -> IdeResult<()> {
-    let model = gradle::load(root).ok_or_else(|| IdeError::not_found("no Gradle build in this project"))?;
-    let mut args: Vec<String> = vec!["--console=plain".into(), "-q".into(), "tasks".into(), "--all".into()];
+    let mut model = gradle::load(root).ok_or_else(|| IdeError::not_found("no Gradle build in this project"))?;
+    std::fs::create_dir_all(cache_dir)?;
+    let init_script = cache_dir.join("openidea-model.gradle");
+    std::fs::write(&init_script, MODEL_INIT_SCRIPT)?;
+    let mut args: Vec<String> = vec![
+        "--console=plain".into(),
+        "-q".into(),
+        "--init-script".into(),
+        init_script.to_string_lossy().into_owned(),
+        "tasks".into(),
+        "--all".into(),
+    ];
     if options.offline {
         args.push("--offline".into());
     }
@@ -318,11 +394,15 @@ pub fn sync_gradle(
         cancel,
         |_| {},
     )?;
+    let projects = if out.success { parse_reported_projects(&out.text) } else { Vec::new() };
+    // Hash the build files of the reported projects, or the model is stale right after the sync.
+    gradle::merge_reported_projects(root, &mut model, &projects);
     let cache = GradleCache {
-        hash: hash_files(&gradle::build_files(root, &model)),
+        hash: hash_gradle_files(&gradle::build_files(root, &model)),
         at_ms: now_ms(),
         error: (!out.success).then(|| error_summary(&out.text)),
         tasks: if out.success { gradle::parse_tasks(&out.text) } else { Vec::new() },
+        projects,
     };
     write_cache(cache_dir, GRADLE_CACHE, &cache)
 }
@@ -438,6 +518,93 @@ mod tests {
         assert!(model.projects[0].dependencies.iter().all(|d| d.artifact_id != "cached"));
     }
 
+    #[test]
+    fn gradle_reported_projects_replace_static_ones() {
+        let tmp = tempfile::tempdir().unwrap();
+        let ws = dunce::canonicalize(tmp.path()).unwrap();
+        let root = ws.join("app");
+        let billing = ws.join("billing");
+        std::fs::create_dir_all(root.join("shared")).unwrap();
+        std::fs::create_dir_all(billing.join("modules/core")).unwrap();
+        // Computed includes: nothing a static reading can see.
+        std::fs::write(root.join("settings.gradle"), "rootProject.name = 'Shop'\n['billing'].each { includeFlat it }")
+            .unwrap();
+        std::fs::write(billing.join("modules/core/build.gradle"), "apply plugin: 'java'").unwrap();
+        // Built with serde: a Windows path holds backslashes, which raw JSON text would leave unescaped.
+        let line = |p: ReportedProject| format!("@openidea-model\t{}\n", serde_json::to_string(&p).unwrap());
+        let (r, b) = (root.display().to_string(), billing.display().to_string());
+        let core_src = |p: &str| format!("{b}/modules/core/src/{p}");
+        let set = |name: &str, test: bool, src: &[&str], res: &[&str]| gradle::ReportedSourceSet {
+            name: name.into(),
+            test,
+            src: src.iter().map(|p| core_src(p)).collect(),
+            res: res.iter().map(|p| core_src(p)).collect(),
+        };
+        // A settings script's own println comes first; task listing lines follow.
+        let out = format!(
+            "configuring billing\n{}{}{}@openidea-model\t{{broken\n\nOther tasks\n-----------\nbilling:core:jar\n",
+            line(ReportedProject { path: ":".into(), dir: r.clone(), ..ReportedProject::default() }),
+            line(ReportedProject {
+                path: ":billing".into(),
+                dir: b.clone(),
+                java: Some(17),
+                ..ReportedProject::default()
+            }),
+            line(ReportedProject {
+                path: ":billing:core".into(),
+                dir: format!("{b}/modules/core"),
+                java: Some(21),
+                source_sets: vec![
+                    set("main", false, &["main/java"], &["main/resources"]),
+                    set("test", true, &["main/java", "test/java"], &[]),
+                ],
+                ..ReportedProject::default()
+            }),
+        );
+        let projects = parse_reported_projects(&out);
+        assert_eq!(projects.len(), 3, "the malformed line is skipped");
+        let src = |p: &str| PathBuf::from(core_src(p));
+        assert_eq!(
+            gradle::reported_source_roots(&projects),
+            [
+                (src("main/java"), gradle::ReportedRoot::Source),
+                (src("main/resources"), gradle::ReportedRoot::Resources),
+                (src("test/java"), gradle::ReportedRoot::Test),
+            ]
+        );
+        let mut model = gradle::load(&root).unwrap();
+        assert_eq!(model.projects.len(), 1);
+        gradle::merge_reported_projects(&root, &mut model, &projects);
+        let paths: Vec<_> = model.projects.iter().map(|p| (p.path.as_str(), p.name.as_str())).collect();
+        assert_eq!(paths, [(":", "Shop"), (":billing", "billing"), (":billing:core", "core")]);
+        assert_eq!(model.projects[0].dir, "");
+        assert!(root.join(model.projects[2].build_file.as_ref().unwrap()).is_file());
+        assert_eq!(
+            gradle::external_roots(&root, model.projects.iter().map(|p| p.dir.as_str())),
+            std::slice::from_ref(&billing)
+        );
+        assert_eq!(model.java_version, Some(21), "the newest version any module needs");
+        assert_eq!(
+            gradle::parse_tasks(&out),
+            [(":billing:core".into(), GradleTask { name: "jar".into(), group: "other".into(), description: None })]
+        );
+
+        // The cached projects are parsed once per change of the cache file.
+        let cache_dir = ws.join("cache");
+        let write = |projects: &[ReportedProject]| {
+            let cache = GradleCache { projects: projects.to_vec(), ..GradleCache::default() };
+            write_cache(&cache_dir, GRADLE_CACHE, &cache).unwrap();
+        };
+        write(&projects);
+        let first = reported_gradle_projects(&cache_dir);
+        assert!(Arc::ptr_eq(&first, &reported_gradle_projects(&cache_dir)), "unchanged: not parsed again");
+        assert_eq!(crate::gradle_external_roots(&root, &cache_dir), [billing]);
+        write(&projects[..1]);
+        assert_eq!(reported_gradle_projects(&cache_dir).len(), 1, "a new sync is read");
+        std::fs::remove_file(cache_dir.join(GRADLE_CACHE)).unwrap();
+        assert!(reported_gradle_projects(&cache_dir).is_empty());
+    }
+
     #[test]
     fn gradle_cache_replaces_tasks_per_project() {
         let tmp = tempfile::tempdir().unwrap();
@@ -448,16 +615,39 @@ mod tests {
         std::fs::write(root.join("app/build.gradle"), "apply plugin: 'java'").unwrap();
         let mut model = gradle::load(&root).unwrap();
         let cache = GradleCache {
-            hash: hash_files(&gradle::build_files(&root, &model)),
+            hash: hash_gradle_files(&gradle::build_files(&root, &model)),
             at_ms: 1.0,
             error: None,
             tasks: vec![(":app".into(), GradleTask { name: "hello".into(), group: "demo".into(), description: None })],
+            projects: [":", ":app"]
+                .iter()
+                .zip([root.clone(), root.join("app")])
+                .map(|(path, dir)| ReportedProject {
+                    path: (*path).into(),
+                    dir: dir.to_string_lossy().into_owned(),
+                    ..Default::default()
+                })
+                .collect(),
         };
         write_cache(&cache_dir, GRADLE_CACHE, &cache).unwrap();
         apply_gradle_cache(&root, &cache_dir, &mut model);
         assert_eq!(model.projects[1].tasks.len(), 1);
         assert!(model.projects[0].tasks.iter().any(|t| t.name == "wrapper"), "root keeps its defaults");
         assert!(!model.stale);
+
+        let stale_after = |script: &str| {
+            std::fs::write(root.join("app/build.gradle"), script).unwrap();
+            let mut m = gradle::load(&root).unwrap();
+            apply_gradle_cache(&root, &cache_dir, &mut m);
+            m.stale
+        };
+        assert!(!stale_after("// a note\napply   plugin: 'java'\n"), "comments and spacing don't count");
+        assert!(stale_after("apply plugin: 'groovy'"));
+        std::fs::write(root.join("app/build.gradle"), "apply plugin: 'java'").unwrap();
+        std::fs::write(root.join("gradle.properties"), "org.gradle.jvmargs=-Xmx2g").unwrap();
+        let mut m = gradle::load(&root).unwrap();
+        apply_gradle_cache(&root, &cache_dir, &mut m);
+        assert!(m.stale, "gradle.properties is watched");
     }
 
     #[test]

crates/ide-core/src/output_encoding.rs

@@ -13,7 +13,10 @@
 //!   they fork get them too (`spring-boot:run`, Surefire, `bootRun`, test workers).
 //!   Each JVM then reports "Picked up JAVA_TOOL_OPTIONS: …" on stderr (which a build tool
 //!   may copy to its stdout); that line is hidden again ([`NoticeFilter`]). `file.encoding` is left alone there: it would change
-//!   how a build reads sources that declare no encoding.
+//!   how a build reads sources that declare no encoding. The application JVMs a build
+//!   forks get `file.encoding=UTF-8` for a UTF-8 console instead, through the build's own
+//!   options: `-Dspring-boot.run.jvmArguments` for Maven `spring-boot:run`, an init script
+//!   ([`GRADLE_FILE_ENCODING_SCRIPT`]) for Gradle `JavaExec` tasks (`bootRun`, `run`).
 //! - Python: `PYTHONIOENCODING`.
 
 use std::collections::BTreeMap;
@@ -75,16 +78,34 @@ fn encoding_for_code_page(cp: u32) -> Option<&'static encoding_rs::Encoding> {
 const STD_PROPERTIES: &[&str] = &["stdout.encoding", "stderr.encoding", "sun.stdout.encoding", "sun.stderr.encoding"];
 const FILE_ENCODING: &str = "file.encoding";
 const TOOL_OPTIONS: &str = "JAVA_TOOL_OPTIONS";
+const SPRING_BOOT_JVM_ARGS: &str = "-Dspring-boot.run.jvmArguments=";
 
 /// Build tools and launcher scripts that run on (and may fork) JVMs.
-const JVM_TOOLS: &[&str] =
-    &["mvn", "mvnw", "mvnd", "gradle", "gradlew", "sbt", "ant", "kotlin", "kotlinc", "groovy", "scala", "jbang"];
+const JVM_TOOLS: &[&str] = &["sbt", "ant", "kotlin", "kotlinc", "groovy", "scala", "jbang"];
+const MAVEN: &[&str] = &["mvn", "mvnw", "mvnd"];
+const GRADLE: &[&str] = &["gradle", "gradlew"];
+
+/// Gradle init script giving the `JavaExec` tasks (`bootRun`, `run`, custom ones) a UTF-8
+/// default charset before the build configures them, so the build can override it.
+/// Gradle's own JVM and the compiler's source encoding are untouched.
+pub const GRADLE_FILE_ENCODING_SCRIPT: &str = "\
+// Written by OpenIDEA: a UTF-8 default charset for applications run by Gradle, as the Run console decodes UTF-8.
+allprojects {
+    tasks.withType(JavaExec).configureEach {
+        defaultCharacterEncoding = 'UTF-8'
+    }
+}
+";
 
 /// What a launch needs: `-D` options to put first on a `java` command line,
 /// environment variables to set, and the notice line its JVMs print because of them.
 #[derive(Debug, Default, PartialEq, Eq)]
 pub struct EncodingFix {
     pub java_args: Vec<String>,
+    /// The build tool's arguments, rewritten to pass options to the JVM it forks.
+    pub args: Option<Vec<String>>,
+    /// Gradle: pass [`GRADLE_FILE_ENCODING_SCRIPT`] with `--init-script`.
+    pub gradle_init_script: bool,
     pub env: Vec<(String, String)>,
     /// "Picked up JAVA_TOOL_OPTIONS: …" for a variable set here alone, to drop from the output.
     pub notice: Option<String>,
@@ -116,6 +137,8 @@ fn options(properties: &[&str], encoding: &str) -> Vec<String> {
 #[derive(Clone, Copy, PartialEq, Eq)]
 enum Kind {
     Java,
+    Maven,
+    Gradle,
     JvmTool,
     Python,
     Other,
@@ -125,6 +148,10 @@ fn kind(program: &str) -> Kind {
     let name = program_name(program);
     if name == "java" || name == "javaw" {
         Kind::Java
+    } else if MAVEN.contains(&name.as_str()) {
+        Kind::Maven
+    } else if GRADLE.contains(&name.as_str()) {
+        Kind::Gradle
     } else if JVM_TOOLS.contains(&name.as_str()) {
         Kind::JvmTool
     } else if is_python(&name) {
@@ -193,7 +220,17 @@ fn fix_kind(
                 out.java_args.push(format!("-D{FILE_ENCODING}=UTF-8"));
             }
         }
-        (Kind::Java | Kind::JvmTool, _) => {
+        (Kind::Java | Kind::Maven | Kind::Gradle | Kind::JvmTool, _) => {
+            if let Some(args) = args
+                && is_utf8(encoding)
+                && !sets(&tool_options, &[FILE_ENCODING])
+            {
+                match kind {
+                    Kind::Maven => out.args = spring_boot_file_encoding(args),
+                    Kind::Gradle => out.gradle_init_script = true,
+                    _ => {}
+                }
+            }
             if !sets(&tool_options, STD_PROPERTIES) {
                 let added = options(STD_PROPERTIES, encoding).join(" ");
                 let value = match tool_options.trim() {
@@ -214,6 +251,26 @@ fn fix_kind(
     out
 }
 
+fn spring_boot_file_encoding(args: &[String]) -> Option<Vec<String>> {
+    if !args.iter().any(|a| a == "spring-boot:run" || (a.contains(":spring-boot-maven-plugin:") && a.ends_with(":run")))
+    {
+        return None;
+    }
+    let option = format!("-D{FILE_ENCODING}=UTF-8");
+    let mut out = args.to_vec();
+    match out.iter_mut().rfind(|a| a.starts_with(SPRING_BOOT_JVM_ARGS)) {
+        Some(own) if sets(own, &[FILE_ENCODING]) => return None,
+        Some(own) => {
+            if own.len() > SPRING_BOOT_JVM_ARGS.len() {
+                own.push(' ');
+            }
+            own.push_str(&option);
+        }
+        None => out.push(format!("{SPRING_BOOT_JVM_ARGS}{option}")),
+    }
+    Some(out)
+}
+
 /// `vmArgs` of a launch by java-debug, which decodes the JVM's output as `encoding`
 /// (its launch attribute, UTF-8 when unset). java-debug sets `file.encoding` only
 /// when that attribute is nonblank; use the same defaults and user overrides as [`fix`].
@@ -435,6 +492,64 @@ mod tests {
         assert_eq!(run("python3", &[], &[], "GBK", false).env, [("PYTHONIOENCODING".to_owned(), "GBK".to_owned())]);
     }
 
+    #[test]
+    fn spring_boot_run_forks_get_a_utf8_default_charset() {
+        let boot = |args: &[&str], env: &[(&str, &str)]| run("mvn.cmd", args, env, "UTF-8", true).args;
+        let utf8 = "-Dspring-boot.run.jvmArguments=-Dfile.encoding=UTF-8";
+        assert_eq!(boot(&["spring-boot:run"], &[]).unwrap(), ["spring-boot:run", utf8]);
+        let plugin = "org.springframework.boot:spring-boot-maven-plugin:3.2.0:run";
+        assert_eq!(boot(&["-pl", "app", plugin], &[]).unwrap(), ["-pl", "app", plugin, utf8]);
+        // The user's VM options are kept; their own `file.encoding` wins.
+        assert_eq!(
+            boot(&["spring-boot:run", "-Dspring-boot.run.jvmArguments=-Xmx1g \"-Da=b c\""], &[]).unwrap(),
+            ["spring-boot:run", "-Dspring-boot.run.jvmArguments=-Xmx1g \"-Da=b c\" -Dfile.encoding=UTF-8"]
+        );
+        assert_eq!(boot(&["spring-boot:run", "-Dspring-boot.run.jvmArguments="], &[]).unwrap()[1], utf8);
+        assert!(boot(&["spring-boot:run", "-Dspring-boot.run.jvmArguments=-Dfile.encoding=GBK"], &[]).is_none());
+        assert!(boot(&["spring-boot:run"], &[(TOOL_OPTIONS, "-Dfile.encoding=GBK")]).is_none());
+        // Other goals and tools, other consoles, and other platforms are left alone.
+        assert!(boot(&["package"], &[]).is_none());
+        assert!(run("mvn", &["spring-boot:run"], &[], "GBK", true).args.is_none());
+        assert!(run("mvn", &["spring-boot:run"], &[], "UTF-8", false).args.is_none());
+    }
+
+    #[test]
+    fn forked_application_jvms_get_a_utf8_default_charset() {
+        // Reported: a Spring Boot app run by the build on Chinese Windows (JDK 8–17, GBK default).
+        for (tool, args) in [
+            ("C:\\p\\gradlew.bat", &["bootRun"][..]),
+            ("gradle", &[":app:run"]),
+            ("mvnw.cmd", &["spring-boot:run"]),
+            ("mvnd", &["org.springframework.boot:spring-boot-maven-plugin:2.7.18:run"]),
+        ] {
+            let f = run(tool, args, &[], "UTF-8", true);
+            let gradle = tool.contains("gradle");
+            assert_eq!(f.gradle_init_script, gradle, "{tool}");
+            assert_eq!(f.args.is_some(), !gradle, "{tool}");
+            // The build tool's own JVM keeps its default charset.
+            assert!(!tool_env(&f).unwrap().contains("file.encoding"), "{tool}");
+            // The user's choice, a GBK console and other platforms are left alone.
+            let own = run(tool, args, &[(TOOL_OPTIONS, "-Dfile.encoding=GBK")], "UTF-8", true);
+            assert!(!own.gradle_init_script && own.args.is_none(), "{tool}");
+            let gbk = run(tool, args, &[], "GBK", true);
+            assert!(!gbk.gradle_init_script && gbk.args.is_none(), "{tool}");
+            assert_eq!(run(tool, args, &[], "UTF-8", false), EncodingFix::default(), "{tool}");
+        }
+        // Shell command lines can't take arguments; other JVM tools fork no application.
+        assert!(!fix_command_line("gradlew bootRun", &BTreeMap::new(), |_| None, "UTF-8", true).gradle_init_script);
+        let sbt = run("sbt", &["run"], &[], "UTF-8", true);
+        assert!(!sbt.gradle_init_script && sbt.args.is_none());
+    }
+
+    #[test]
+    fn gradle_script_respects_the_builds_own_file_encoding() {
+        let s = GRADLE_FILE_ENCODING_SCRIPT;
+        assert!(s.contains("tasks.withType(JavaExec).configureEach"), "{s}");
+        assert!(s.contains("defaultCharacterEncoding = 'UTF-8'"), "{s}");
+        assert!(!s.contains("doFirst"), "the build must be able to override the default: {s}");
+        assert!(!s.contains("withType(Test)") && !s.contains("JavaCompile"), "{s}");
+    }
+
     #[test]
     fn shell_command_lines_get_variables_from_their_first_word() {
         let line = |l: &str| fix_command_line(l, &BTreeMap::new(), |_| None, "UTF-8", true);

crates/ide-core/src/process.rs

@@ -53,6 +53,31 @@ pub fn kill_tree(child: &mut Child) {
     let _ = child.wait();
 }
 
+/// [`kill_tree`] for a child known by its process id (a `tokio` child): `SIGKILL` to its
+/// process group (spawn it with [`own_group`]) or `taskkill /T /F`. Call it before the child
+/// is reaped, so the id still names it. The child itself is left to its owner to kill and reap.
+pub fn kill_tree_of(pid: u32) {
+    #[cfg(unix)]
+    if let Ok(pid) = libc::pid_t::try_from(pid) {
+        // SAFETY: plain syscall; see `signal_group`.
+        unsafe {
+            libc::kill(-pid, libc::SIGKILL);
+        }
+    }
+    #[cfg(windows)]
+    {
+        let mut taskkill = Command::new("taskkill");
+        prepare(&mut taskkill)
+            .args(["/T", "/F", "/PID", &pid.to_string()])
+            .stdin(Stdio::null())
+            .stdout(Stdio::null())
+            .stderr(Stdio::null());
+        let _ = taskkill.status();
+    }
+    #[cfg(not(any(unix, windows)))]
+    let _ = pid;
+}
+
 /// [`kill_tree`] that first asks the group to exit: `SIGTERM`, then `grace`, then `SIGKILL`.
 /// Git removes its `index.lock` on `SIGTERM`, where `SIGKILL` leaves it behind and the next
 /// git command fails. Windows has no such signal to send from outside the child's console,
@@ -395,6 +420,28 @@ fn append_path_entries(path: &OsStr, extra: &OsStr) -> OsString {
 mod tests {
     use super::*;
 
+    #[cfg(unix)]
+    #[test]
+    fn kill_tree_of_reaches_what_the_child_started() {
+        use std::io::BufRead;
+        let mut cmd = Command::new("sh");
+        own_group(&mut cmd).args(["-c", "sleep 30 & echo $!; wait"]).stdout(std::process::Stdio::piped());
+        let mut child = cmd.spawn().unwrap();
+        let mut line = String::new();
+        std::io::BufReader::new(child.stdout.take().unwrap()).read_line(&mut line).unwrap();
+        let grandchild: libc::pid_t = line.trim().parse().unwrap();
+        let alive = |pid: libc::pid_t| unsafe { libc::kill(pid, 0) } == 0;
+        assert!(alive(grandchild));
+        kill_tree_of(child.id());
+        let _ = child.wait();
+        // Reparented to init once its parent is gone, which reaps it.
+        let gone = (0..100).any(|_| {
+            std::thread::sleep(Duration::from_millis(20));
+            !alive(grandchild)
+        });
+        assert!(gone, "the grandchild {grandchild} survived");
+    }
+
     #[cfg(windows)]
     #[test]
     fn user_path_reads_the_current_users_path() {

crates/ide-core/src/remote_settings.rs

@@ -132,7 +132,7 @@ pub struct DeploymentServer {
 #[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize, Type)]
 #[serde(default, rename_all = "camelCase")]
 pub struct DeploymentMapping {
-    /// Project-relative folder; empty = the project root.
+    /// Project-relative folder, or absolute inside the project; empty = the project root.
     pub local: String,
     /// Remote folder, relative to the server root (a leading `/` is the root too).
     pub deployment: String,

crates/ide-core/src/settings.rs

@@ -59,6 +59,31 @@ pub struct Settings {
     /// Build, Execution, Deployment › Run Targets.
     pub run_targets: Vec<RunTarget>,
     pub cmake: CMakeSettings,
+    /// Tools › Agents › Chat.
+    pub agents: AgentSettings,
+    /// Plugin settings (`[contributes.settings]`): plugin id → its values by key.
+    #[specta(type = BTreeMap<String, BTreeMap<String, specta_typescript::Unknown>>)]
+    pub plugins: BTreeMap<String, serde_json::Map<String, serde_json::Value>>,
+}
+
+/// What the meters in an agent task's header show.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(default, rename_all = "camelCase")]
+pub struct AgentSettings {
+    /// Context window use.
+    pub show_context_usage: bool,
+    /// Time the agent spent on the task.
+    pub show_work_time: bool,
+    /// The account's usage-limit windows (Claude's 5-hour and weekly limits).
+    pub show_usage_limits: bool,
+    /// What the session has cost so far, as the agent reports it.
+    pub show_cost: bool,
+}
+
+impl Default for AgentSettings {
+    fn default() -> Self {
+        Self { show_context_usage: true, show_work_time: true, show_usage_limits: true, show_cost: false }
+    }
 }
 
 /// Absent profiles retain automatic discovery for existing projects.
@@ -192,6 +217,8 @@ impl Default for Settings {
             deployment: DeploymentSettings::default(),
             run_targets: Vec::new(),
             cmake: CMakeSettings::default(),
+            agents: AgentSettings::default(),
+            plugins: BTreeMap::new(),
         }
     }
 }
@@ -300,7 +327,8 @@ impl Default for NotificationGroupSettings {
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
 #[serde(default, rename_all = "camelCase")]
 pub struct AppearanceSettings {
-    /// `dark` | `light` | `system` | `dark-hc` (high-contrast dark)
+    /// A built-in theme id (`light`, `dark`, `dark-hc`, …), `system` (legacy
+    /// "Sync with OS"), or a plugin's theme: `plugin:<plugin-id>/<theme-id>`.
     pub theme: String,
     pub accent: String,
     pub ui_font_size: f32,
@@ -309,6 +337,8 @@ pub struct AppearanceSettings {
     pub sync_with_os: bool,
     pub preferred_light_theme: String,
     pub preferred_dark_theme: String,
+    /// A plugin's file icon theme (`<plugin-id>/<theme-id>`); empty = the built-in icons.
+    pub file_icon_theme: String,
     /// IDE zoom in percent (50–300).
     pub zoom: u32,
     /// Apply `ui_font_family` / `ui_font_size` (otherwise the theme's).
@@ -363,6 +393,7 @@ impl Default for AppearanceSettings {
             sync_with_os: false,
             preferred_light_theme: "light".into(),
             preferred_dark_theme: "dark".into(),
+            file_icon_theme: String::new(),
             zoom: 100,
             use_custom_font: false,
             ui_font_family: "Inter".into(),
@@ -543,26 +574,65 @@ impl Default for FileSettings {
 pub struct LanguagesSettings {
     pub python: PythonSettings,
     pub node: NodeSettings,
+    pub php: PhpSettings,
     pub rust: RustSettings,
     pub go: GoSettings,
     pub typescript: TypeScriptSettings,
-    pub prettier: PrettierSettings,
+    pub prettier: ExternalFormatterSettings,
+    pub oxfmt: ExternalFormatterSettings,
     pub java: JavaSettings,
     pub ruby: RubySettings,
+    pub markdown: MarkdownSettings,
 }
 
+/// Languages & Frameworks › Markdown. Like IDEA's, it is application-level only.
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
+#[serde(default, rename_all = "camelCase")]
+pub struct MarkdownSettings {
+    /// Preview (and notebook Markdown cell) font size in px; unset follows the editor font size.
+    pub preview_font_size: Option<u32>,
+}
+
+impl LanguagesSettings {
+    pub fn formatter(&self, tool: ExternalFormatter) -> &ExternalFormatterSettings {
+        match tool {
+            ExternalFormatter::Prettier => &self.prettier,
+            ExternalFormatter::Oxfmt => &self.oxfmt,
+        }
+    }
+}
+
+/// A formatter that runs outside the language servers, with its own settings group.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "lowercase")]
+pub enum ExternalFormatter {
+    Prettier,
+    Oxfmt,
+}
+
+impl ExternalFormatter {
+    /// The name of the tool in the tool registry.
+    pub fn name(self) -> &'static str {
+        match self {
+            Self::Prettier => "prettier",
+            Self::Oxfmt => "oxfmt",
+        }
+    }
+}
+
+/// An external formatter (Prettier, oxfmt) and the languages it formats.
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
 #[serde(default, rename_all = "camelCase")]
-pub struct PrettierSettings {
+pub struct ExternalFormatterSettings {
     /// Empty path: project node_modules, managed installation, then PATH.
     pub path: String,
     pub languages: Vec<String>,
-    /// Prefer Prettier even when a language server offers formatting.
+    /// Prefer this formatter even when a language server offers formatting.
     pub prefer: bool,
     pub run_on_save: bool,
 }
 
-impl Default for PrettierSettings {
+impl Default for ExternalFormatterSettings {
     fn default() -> Self {
         Self {
             path: String::new(),
@@ -606,6 +676,13 @@ impl Default for PythonSettings {
     }
 }
 
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
+#[serde(default, rename_all = "camelCase")]
+pub struct PhpSettings {
+    /// `php` CLI executable; empty = the one on `PATH`.
+    pub interpreter: String,
+}
+
 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
 #[serde(default, rename_all = "camelCase")]
 pub struct RubySettings {
@@ -717,6 +794,19 @@ pub struct GradleSettings {
     pub home: String,
     /// Empty = Gradle's default user home.
     pub user_home: String,
+    /// IDEA's "Build and run using": who builds and launches an Application main.
+    pub run_using: GradleRunUsing,
+}
+
+/// IDEA's "Build and run using" for Gradle builds; IDEA defaults to Gradle.
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum GradleRunUsing {
+    /// A `JavaExec` task on the source set's runtime classpath (`gradleRun.gradle`).
+    #[default]
+    Gradle,
+    /// The Java language server's classpath, launched by OpenIDEA.
+    Ide,
 }
 
 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
@@ -858,6 +948,20 @@ mod tests {
         }
     }
 
+    #[test]
+    fn agent_meters_default_and_round_trip() {
+        let old: Settings = serde_json::from_str(r#"{"agents":{"showCost":true}}"#).unwrap();
+        assert!(old.agents.show_cost);
+        assert!(old.agents.show_context_usage && old.agents.show_work_time && old.agents.show_usage_limits);
+        assert!(!Settings::default().agents.show_cost);
+        let mut settings = Settings::default();
+        settings.agents.show_usage_limits = false;
+        let json = serde_json::to_value(&settings).unwrap();
+        assert_eq!(json["agents"]["showUsageLimits"], false);
+        let restored: Settings = serde_json::from_value(json).unwrap();
+        assert_eq!(restored.agents, settings.agents);
+    }
+
     #[test]
     fn main_menu_style_defaults_and_round_trips() {
         let old: Settings = serde_json::from_str(r#"{"appearance":{"compactMode":true}}"#).unwrap();
@@ -943,6 +1047,7 @@ mod gradle_settings_tests {
                 distribution,
                 home: "/gradle".into(),
                 user_home: "/cache/gradle".into(),
+                run_using: GradleRunUsing::Ide,
             };
             let restored: Settings = serde_json::from_str(&serde_json::to_string(&settings).unwrap()).unwrap();
             assert_eq!(restored.languages.java.gradle, settings.languages.java.gradle);

crates/ide-core/src/task.rs

@@ -44,6 +44,39 @@ pub fn cancel(id: TaskId) -> bool {
     }
 }
 
+/// A progress title a tool reported, made readable: a leading absolute executable path
+/// (rust-analyzer reports `/…/bin/cargo check`) shows as its program name (`cargo check`).
+pub fn display_title(title: &str) -> String {
+    let is_sep = |c: char| c == '/' || c == '\\';
+    let b = title.as_bytes();
+    let absolute = title.starts_with(is_sep)
+        || (b.len() > 2 && b[0].is_ascii_alphabetic() && b[1] == b':' && is_sep(b[2] as char));
+    if !absolute {
+        return title.to_owned();
+    }
+    // The path runs on through spaces (`Application Support/…`) while the next word still
+    // continues it; the first word without a separator, an option or a new path ends it.
+    let mut end = title.find(' ').unwrap_or(title.len());
+    while end < title.len() {
+        let rest = &title[end + 1..];
+        let word = rest.split(' ').next().unwrap_or_default();
+        if word.is_empty() || !word.contains(is_sep) || word.starts_with(is_sep) || word.starts_with('-') {
+            break;
+        }
+        end += 1 + word.len();
+    }
+    let (path, rest) = title.split_at(end);
+    let name = path.rsplit(is_sep).next().unwrap_or(path);
+    let name = [".exe", ".cmd", ".bat"]
+        .iter()
+        .find_map(|ext| {
+            let cut = name.len().checked_sub(ext.len())?;
+            (name.is_char_boundary(cut) && name[cut..].eq_ignore_ascii_case(ext)).then(|| &name[..cut])
+        })
+        .unwrap_or(name);
+    if name.is_empty() { title.to_owned() } else { format!("{name}{rest}") }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -71,4 +104,28 @@ mod tests {
         assert!(!cancel(other), "an ended task is not cancelled");
         assert_eq!(hits.load(Ordering::SeqCst), 1);
     }
+
+    #[test]
+    fn display_title_shows_a_leading_executable_path_as_its_name() {
+        for (title, shown) in [
+            ("/Users/thomas/Library/Application Support/mbx/bin/cargo check", "cargo check"),
+            ("/home/me/.cargo/bin/cargo clippy (#2)", "cargo clippy (#2)"),
+            (
+                "/opt/my tools/bin/cargo check --manifest-path /x/Cargo.toml",
+                "cargo check --manifest-path /x/Cargo.toml",
+            ),
+            (r"C:\Users\me\.cargo\bin\cargo.exe check", "cargo check"),
+            (r"C:\Program Files\Rust\bin\cargo.EXE check", "cargo check"),
+            (r"\\server\share\tools\x.cmd build", "x build"),
+            ("/usr/bin/make", "make"),
+            ("cargo check", "cargo check"),
+            ("Indexing", "Indexing"),
+            ("Building compile-time-deps", "Building compile-time-deps"),
+            ("Loading /src/app (2/3)", "Loading /src/app (2/3)"),
+            ("/", "/"),
+            ("", ""),
+        ] {
+            assert_eq!(display_title(title), shown, "{title:?}");
+        }
+    }
 }

crates/ide-dap/src/adapter.rs

@@ -8,7 +8,7 @@
 
 use ide_core::process::executable_names;
 use ide_core::{IdeError, IdeResult};
-use ide_language::{DebuggerConfig, LanguageRegistry};
+use ide_language::{DebuggerConfig, LanguageRegistry, ProgramPin};
 use std::future::Future;
 use std::path::{Path, PathBuf};
 use std::pin::Pin;
@@ -44,6 +44,8 @@ pub struct AdapterSpec {
     /// `host:port` of an adapter inside another program (the Godot editor): connected to
     /// when it accepts, else `command` is started.
     pub connect: Option<String>,
+    /// A plugin language's adapter: start exactly this approved program.
+    pub pinned: Option<ProgramPin>,
 }
 
 /// Built-in adapters used when no language definition names `adapter`.
@@ -55,6 +57,7 @@ fn builtin(adapter: &str) -> Option<DebuggerConfig> {
         transport: transport.to_owned(),
         connect: None,
         install_hint: Some(hint.to_owned()),
+        pinned: None,
     };
     Some(match adapter {
         "codelldb" => cfg(
@@ -133,6 +136,7 @@ pub fn resolve(config: &DebuggerConfig, cwd: PathBuf) -> AdapterSpec {
         env: Vec::new(),
         server_host: None,
         connect: config.connect.clone(),
+        pinned: config.pinned.clone(),
     }
 }
 
@@ -426,12 +430,20 @@ impl AdapterLauncher for ProcessLauncher {
             if is_plugin_bundle(&spec.command) {
                 return Err(not_standalone(&spec));
             }
-            let (command, cwd) = (spec.command.clone(), spec.cwd.clone());
-            let binary = tokio::task::spawn_blocking(move || resolve_binary(&command, &cwd))
-                .await
-                .ok()
-                .flatten()
-                .ok_or_else(|| missing(&spec))?;
+            let binary = match spec.pinned.clone() {
+                Some(pin) => tokio::task::spawn_blocking(move || pin.verify().map(Path::to_path_buf))
+                    .await
+                    .map_err(|e| IdeError::internal(e.to_string()))?
+                    .map_err(|e| IdeError::new(ide_core::error::ErrorKind::PermissionDenied, e))?,
+                None => {
+                    let (command, cwd) = (spec.command.clone(), spec.cwd.clone());
+                    tokio::task::spawn_blocking(move || resolve_binary(&command, &cwd))
+                        .await
+                        .ok()
+                        .flatten()
+                        .ok_or_else(|| missing(&spec))?
+                }
+            };
             let port = match spec.transport {
                 // An embedded adapter started without `${port}` listens on its usual address.
                 Transport::Tcp => match &embedded {

crates/ide-dap/src/session.rs

@@ -405,7 +405,7 @@ async fn on_event(mgr: &Arc<DebugManager>, s: &Arc<Session>, event: &str, mut bo
                 let mut progress = s.progress.lock();
                 let id =
                     if done { progress.remove(&pid) } else { Some(*progress.entry(pid).or_insert_with(TaskId::next)) };
-                (id, str_("title").unwrap_or_else(|| s.name.clone()))
+                (id, str_("title").map(|t| ide_core::task::display_title(&t)).unwrap_or_else(|| s.name.clone()))
             };
             let Some(id) = id else { return };
             s.owner.sink.emit(IdeEvent::Task {

crates/ide-dap/src/tests.rs

@@ -915,6 +915,7 @@ fn godot_registry(port: u16, command: &str, args: &[&str]) -> Arc<LanguageRegist
             transport: "tcp".into(),
             connect: Some(format!("127.0.0.1:{port}")),
             install_hint: Some("Open the project in the Godot editor".into()),
+            pinned: None,
         }),
     };
     Arc::new(LanguageRegistry::from_configs(vec![lang]))
@@ -1147,3 +1148,58 @@ async fn java_stack_frames_without_breakpoints_normalize_windows_paths() {
         h.manager.stop(id).await.unwrap();
     }
 }
+
+/// A built-in language definition (GDScript) shipped by a plugin
+/// instead: its debugger starts the program approved for the plugin's
+/// `process:godot` grant, and refuses once that file changed.
+#[cfg(unix)]
+#[tokio::test]
+async fn a_plugin_language_runs_its_debug_adapter_from_the_approved_program() {
+    use ide_language::ProgramPin;
+    use ide_language::plugin_point::{PluginLanguages, parse_definition};
+    use std::os::unix::fs::PermissionsExt;
+
+    let dir = std::env::temp_dir().join(format!("openidea-plugin-dap-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    // Stands in for `godot --headless --editor …`.
+    let program = dir.join("godot");
+    std::fs::write(&program, "#!/bin/sh\nexec sleep 30\n").unwrap();
+    std::fs::set_permissions(&program, std::fs::Permissions::from_mode(0o755)).unwrap();
+
+    let port = std::net::TcpListener::bind(("127.0.0.1", 0)).unwrap().local_addr().unwrap().port();
+    let mut gdscript = parse_definition(include_str!("../../../languages/gdscript.toml")).unwrap();
+    let debugger = gdscript.debugger.as_mut().unwrap();
+    debugger.args.clear();
+    debugger.connect = Some(format!("127.0.0.1:{port}"));
+
+    // No built-in GDScript: it comes from the plugin.
+    let registry = Arc::new(LanguageRegistry::from_configs(Vec::new()));
+    let store = PluginLanguages::new();
+    registry.attach_plugins(store.clone());
+    let pin = ProgramPin::approve(&program).unwrap();
+    store.set_process_policy(Arc::new(move |plugin, cap| {
+        (plugin == "acme.godot" && cap.to_string() == "process:godot").then(|| pin.clone())
+    }));
+    let _language = store.add("acme.godot".into(), gdscript);
+
+    let log: Log = Arc::default();
+    let server_log = log.clone();
+    tokio::spawn(async move {
+        tokio::time::sleep(std::time::Duration::from_millis(300)).await;
+        let listener = tokio::net::TcpListener::bind(("127.0.0.1", port)).await.unwrap();
+        let (stream, _) = listener.accept().await.unwrap();
+        fake_adapter(stream, server_log, Script::default()).await;
+    });
+    let (owner, _events) = recording_owner("main");
+    let manager = DebugManager::new(registry.clone());
+    let id = manager.start(godot_launch(&dir), owner).await.unwrap();
+    assert!(log.lock().iter().any(|m| m["command"] == "launch"));
+    manager.stop(id).await.unwrap();
+
+    // Replaced after approval: refused before anything starts.
+    std::fs::write(&program, "#!/bin/sh\nexec sleep 31\n").unwrap();
+    let (owner, _events) = recording_owner("main");
+    let err = manager.start(godot_launch(&dir), owner).await.unwrap_err();
+    assert_eq!(err.kind, ide_core::error::ErrorKind::PermissionDenied, "{}", err.message);
+    let _ = std::fs::remove_dir_all(&dir);
+}

crates/ide-extension/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "ide-extension"
+description = "Plugin manifest, extension points, contribution registry and capability model (no Wasm runtime)"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+ide-core.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+specta.workspace = true
+specta-typescript.workspace = true
+toml.workspace = true
+tracing.workspace = true
+parking_lot.workspace = true
+semver = "1"
+blake3.workspace = true
+zip.workspace = true
+base64.workspace = true
+ed25519-dalek = "3"
+
+[dev-dependencies]
+tempfile.workspace = true

crates/ide-extension/src/capability.rs

@@ -0,0 +1,277 @@
+//! What a plugin may do beyond pure computation, and how risky each grant is.
+//!
+//! Capabilities are written as strings in the manifest (`project.read`,
+//! `net:crates.io`, `process:cargo`) and stored the same way in the grant
+//! ledger. The 0.1 permission names (`project-read`, …) parse as their 0.2
+//! equivalents.
+
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use specta::Type;
+use std::fmt;
+use std::str::FromStr;
+
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Capability {
+    /// Read files inside the project root; the project root itself.
+    ProjectRead,
+    /// The focused editor's file, selection and text.
+    EditorRead,
+    /// Edit the focused editor (versioned edits).
+    EditorWrite,
+    VcsRead,
+    VcsWrite,
+    /// The plugin's own key-value store and data directory.
+    Storage,
+    /// The plugin's own secrets (kept in the client's OS keychain).
+    Secrets,
+    /// Workbench events (file opened, saved, focus…), not keystrokes.
+    Events,
+    /// Keystrokes and editor input events.
+    InputEvents,
+    /// The system clipboard, from the plugin's web views.
+    Clipboard,
+    /// HTTP(S) to one host (`*.example.com` matches subdomains).
+    Net(String),
+    /// Run one external program. Full code execution: never fine-grained.
+    Process(String),
+    /// Read files outside the project under one path.
+    FsRead(String),
+}
+
+/// How a grant is presented (plan 4.2).
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum Risk {
+    /// Listed on the install page, one confirmation.
+    Low,
+    /// Listed separately with its purpose.
+    Medium,
+    /// Separate dialog: "equivalent to running arbitrary code on this machine".
+    High,
+}
+
+impl Capability {
+    pub fn risk(&self) -> Risk {
+        match self {
+            Self::ProjectRead | Self::EditorRead | Self::Storage | Self::Events | Self::VcsRead => Risk::Low,
+            Self::EditorWrite | Self::VcsWrite | Self::Net(_) | Self::Secrets | Self::InputEvents | Self::Clipboard => {
+                Risk::Medium
+            }
+            Self::Process(_) | Self::FsRead(_) => Risk::High,
+        }
+    }
+
+    /// Low-risk capabilities that the one-time migration of the 0.1 "declared
+    /// means granted" behaviour may grant automatically (plan 4.6).
+    pub fn auto_migrates(&self) -> bool {
+        self.risk() == Risk::Low
+    }
+
+    /// Short user-facing description for install and grant pages.
+    pub fn describe(&self) -> String {
+        match self {
+            Self::ProjectRead => "Read files in the open project".into(),
+            Self::EditorRead => "Read the focused editor's file and selection".into(),
+            Self::EditorWrite => "Change text in the editor".into(),
+            Self::VcsRead => "Read version control state".into(),
+            Self::VcsWrite => "Change version control state (commit, fetch, checkout)".into(),
+            Self::Storage => "Store its own data".into(),
+            Self::Secrets => "Store secrets in the system keychain".into(),
+            Self::Events => "Observe workbench events (files opened, saved, focus)".into(),
+            Self::InputEvents => "Observe keystrokes and editor input".into(),
+            Self::Clipboard => "Read and write the clipboard from its web views".into(),
+            Self::Net(host) => format!("Connect to {host} (from the machine the project is on)"),
+            Self::Process(bin) => format!("Run {bin} — equivalent to running arbitrary code on this machine"),
+            Self::FsRead(path) => format!("Read files under {path}, outside the project"),
+        }
+    }
+
+    /// Whether `self`, granted, also covers `wanted` (`net:*.x.com` covers `net:a.x.com`).
+    pub fn covers(&self, wanted: &Capability) -> bool {
+        match (self, wanted) {
+            (Self::Net(pattern), Self::Net(host)) => host_matches(pattern, host),
+            (Self::FsRead(base), Self::FsRead(path)) => {
+                std::path::Path::new(path).starts_with(std::path::Path::new(base))
+            }
+            _ => self == wanted,
+        }
+    }
+}
+
+/// `example.com` matches exactly; `*.example.com` matches any subdomain (not the apex).
+pub fn host_matches(pattern: &str, host: &str) -> bool {
+    let host = host.trim_end_matches('.').to_ascii_lowercase();
+    let pattern = pattern.to_ascii_lowercase();
+    match pattern.strip_prefix("*.") {
+        Some(suffix) => host.len() > suffix.len() + 1 && host.ends_with(&format!(".{suffix}")),
+        None => host == pattern,
+    }
+}
+
+impl fmt::Display for Capability {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::ProjectRead => f.write_str("project.read"),
+            Self::EditorRead => f.write_str("editor.read"),
+            Self::EditorWrite => f.write_str("editor.write"),
+            Self::VcsRead => f.write_str("vcs.read"),
+            Self::VcsWrite => f.write_str("vcs.write"),
+            Self::Storage => f.write_str("storage"),
+            Self::Secrets => f.write_str("secrets"),
+            Self::Events => f.write_str("events"),
+            Self::InputEvents => f.write_str("events.input"),
+            Self::Clipboard => f.write_str("clipboard"),
+            Self::Net(h) => write!(f, "net:{h}"),
+            Self::Process(b) => write!(f, "process:{b}"),
+            Self::FsRead(p) => write!(f, "fs.read:{p}"),
+        }
+    }
+}
+
+impl FromStr for Capability {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, String> {
+        let s = s.trim();
+        if let Some((kind, arg)) = s.split_once(':') {
+            let arg = arg.trim();
+            if arg.is_empty() {
+                return Err(format!("capability {s:?} needs a value after ':'"));
+            }
+            return match kind {
+                "net" => {
+                    let host = arg.strip_prefix("*.").unwrap_or(arg);
+                    let valid = !host.is_empty()
+                        && host.len() <= 253
+                        && host.split('.').all(|label| {
+                            !label.is_empty()
+                                && label.len() <= 63
+                                && label.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'-')
+                        });
+                    if valid { Ok(Self::Net(arg.to_ascii_lowercase())) } else { Err(format!("invalid host in {s:?}")) }
+                }
+                "process" => {
+                    if arg.contains(['/', '\\']) && !std::path::Path::new(arg).is_absolute() {
+                        return Err(format!("{s:?}: use a program name or an absolute path"));
+                    }
+                    Ok(Self::Process(arg.to_owned()))
+                }
+                "fs.read" => {
+                    if !std::path::Path::new(arg).is_absolute() && !arg.starts_with('~') {
+                        return Err(format!("{s:?}: use an absolute path (or ~/…)"));
+                    }
+                    Ok(Self::FsRead(arg.to_owned()))
+                }
+                _ => Err(format!("unknown capability {s:?}")),
+            };
+        }
+        Ok(match s {
+            "project.read" | "project-read" => Self::ProjectRead,
+            "editor.read" | "editor-read" => Self::EditorRead,
+            "editor.write" | "editor-write" => Self::EditorWrite,
+            "vcs.read" => Self::VcsRead,
+            "vcs.write" => Self::VcsWrite,
+            "storage" => Self::Storage,
+            "secrets" => Self::Secrets,
+            "events" => Self::Events,
+            "events.input" => Self::InputEvents,
+            "clipboard" => Self::Clipboard,
+            _ => return Err(format!("unknown capability {s:?}")),
+        })
+    }
+}
+
+impl Serialize for Capability {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        s.collect_str(self)
+    }
+}
+
+impl<'de> Deserialize<'de> for Capability {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        String::deserialize(d)?.parse().map_err(serde::de::Error::custom)
+    }
+}
+
+/// A capability as the UI shows it.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct CapabilityInfo {
+    /// `project.read`, `net:crates.io`, …
+    pub id: String,
+    pub risk: Risk,
+    pub description: String,
+    /// Declared under `optional`: the plugin runs without it.
+    pub optional: bool,
+    /// Currently granted.
+    pub granted: bool,
+}
+
+impl CapabilityInfo {
+    pub fn new(cap: &Capability, optional: bool, granted: bool) -> Self {
+        Self { id: cap.to_string(), risk: cap.risk(), description: cap.describe(), optional, granted }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_and_prints() {
+        for s in [
+            "project.read",
+            "editor.write",
+            "vcs.write",
+            "storage",
+            "secrets",
+            "events",
+            "events.input",
+            "net:crates.io",
+            "net:*.github.com",
+            "process:cargo",
+        ] {
+            assert_eq!(s.parse::<Capability>().unwrap().to_string(), s);
+        }
+        // Absolute paths are the platform's.
+        let (git, etc) = if cfg!(windows) {
+            (r"process:C:\Program Files\Git\bin\git.exe", r"fs.read:C:\Windows")
+        } else {
+            ("process:/usr/bin/git", "fs.read:/etc")
+        };
+        for s in [git, etc] {
+            assert_eq!(s.parse::<Capability>().unwrap().to_string(), s);
+        }
+        assert_eq!("project-read".parse::<Capability>().unwrap(), Capability::ProjectRead);
+        assert!("net:".parse::<Capability>().is_err());
+        assert!("net:a b".parse::<Capability>().is_err());
+        assert!("process:./evil".parse::<Capability>().is_err());
+        assert!("fs.read:rel".parse::<Capability>().is_err());
+        assert!("network".parse::<Capability>().is_err());
+    }
+
+    #[test]
+    fn risk_levels() {
+        assert_eq!(Capability::ProjectRead.risk(), Risk::Low);
+        assert_eq!(Capability::Net("x".into()).risk(), Risk::Medium);
+        assert_eq!(Capability::InputEvents.risk(), Risk::Medium);
+        assert_eq!("clipboard".parse::<Capability>().unwrap(), Capability::Clipboard);
+        assert_eq!(Capability::Clipboard.risk(), Risk::Medium);
+        assert_eq!(Capability::Process("cargo".into()).risk(), Risk::High);
+        assert!(Capability::Storage.auto_migrates() && !Capability::EditorWrite.auto_migrates());
+    }
+
+    #[test]
+    fn host_patterns() {
+        assert!(host_matches("crates.io", "crates.io"));
+        assert!(host_matches("crates.io", "CRATES.IO."));
+        assert!(!host_matches("crates.io", "static.crates.io"));
+        assert!(host_matches("*.github.com", "api.github.com"));
+        assert!(!host_matches("*.github.com", "github.com"));
+        assert!(!host_matches("*.github.com", "evilgithub.com"));
+        let any_gh: Capability = "net:*.github.com".parse().unwrap();
+        assert!(any_gh.covers(&"net:api.github.com".parse().unwrap()));
+        assert!(Capability::FsRead("/etc".into()).covers(&Capability::FsRead("/etc/hosts".into())));
+        assert!(!Capability::FsRead("/etc".into()).covers(&Capability::FsRead("/etcx".into())));
+    }
+}

crates/ide-extension/src/index.rs

@@ -0,0 +1,104 @@
+//! The contribution index: validated UI
+//! declarations of installed packages, kept on disk so start-up does not
+//! validate them again (sanitising thousands of icon SVGs, say).
+//!
+//! Only packages with a [`Package::digest`] are indexed: installed copies,
+//! which the host never modifies after install. An entry is keyed by that
+//! digest, the extension point, the declaration and a salt naming the
+//! validation logic (the IDE version), so a new package version, a changed
+//! declaration or an IDE upgrade simply misses. A miss or an unreadable entry
+//! only costs the validation.
+
+use crate::point::Package;
+use crate::ui::UiDecl;
+use std::collections::BTreeSet;
+use std::path::PathBuf;
+
+/// Bumped when [`UiDecl`]'s serialized shape changes.
+const FORMAT: u32 = 1;
+
+pub struct ContributionIndex {
+    dir: PathBuf,
+    salt: String,
+}
+
+impl ContributionIndex {
+    /// `salt` names the validators' version (the IDE version).
+    pub fn new(dir: PathBuf, salt: &str) -> Self {
+        Self { dir, salt: format!("{FORMAT}:{salt}") }
+    }
+
+    /// Entries start with a prefix of the package digest, for pruning.
+    fn file(&self, digest: &str, point: &str, decl: &toml::Value) -> PathBuf {
+        let mut h = blake3::Hasher::new();
+        for part in [self.salt.as_str(), digest, point, &decl.to_string()] {
+            h.update(part.as_bytes());
+            h.update(&[0]);
+        }
+        let key = h.finalize().to_hex();
+        self.dir.join(format!("{}-{}.json", prefix(digest), &key[..32]))
+    }
+
+    pub fn get(&self, pkg: &Package, point: &str, decl: &toml::Value) -> Option<UiDecl> {
+        let digest = pkg.digest.as_deref()?;
+        let bytes = std::fs::read(self.file(digest, point, decl)).ok()?;
+        serde_json::from_slice(&bytes).ok()
+    }
+
+    pub fn put(&self, pkg: &Package, point: &str, decl: &toml::Value, ui: &UiDecl) {
+        let Some(digest) = pkg.digest.as_deref() else { return };
+        let Ok(bytes) = serde_json::to_vec(ui) else { return };
+        let file = self.file(digest, point, decl);
+        let _ = std::fs::create_dir_all(&self.dir);
+        let tmp = file.with_extension(format!("tmp{}", std::process::id()));
+        if std::fs::write(&tmp, bytes).and_then(|()| std::fs::rename(&tmp, &file)).is_err() {
+            let _ = std::fs::remove_file(&tmp);
+        }
+    }
+
+    /// Removes entries of packages other than `live` (digests).
+    pub fn prune<'a>(&self, live: impl IntoIterator<Item = &'a str>) {
+        let keep: BTreeSet<String> = live.into_iter().map(|d| prefix(d).to_owned()).collect();
+        let Ok(entries) = std::fs::read_dir(&self.dir) else { return };
+        for e in entries.flatten() {
+            let name = e.file_name().to_string_lossy().into_owned();
+            if !name.split_once('-').is_some_and(|(p, _)| keep.contains(p)) {
+                let _ = std::fs::remove_file(e.path());
+            }
+        }
+    }
+}
+
+fn prefix(digest: &str) -> &str {
+    let d = digest.strip_prefix("blake3:").unwrap_or(digest);
+    let end = d.char_indices().nth(16).map_or(d.len(), |(i, _)| i);
+    &d[..end]
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::manifest::Manifest;
+
+    #[test]
+    fn hits_only_the_same_package_point_declaration_and_salt() {
+        let tmp = tempfile::tempdir().unwrap();
+        let index = ContributionIndex::new(tmp.path().join("idx"), "1.0");
+        let manifest =
+            Manifest::parse("id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n").unwrap();
+        let pkg = Package::new(manifest, tmp.path().to_path_buf()).with_digest("blake3:00aa11bb22cc33dd44ee");
+        let decl: toml::Value = toml::from_str("id = \"x\"").unwrap();
+        let ui = UiDecl::new("x", "X", serde_json::json!({ "id": "x" }));
+        assert!(index.get(&pkg, "pt", &decl).is_none());
+        index.put(&pkg, "pt", &decl, &ui);
+        assert_eq!(index.get(&pkg, "pt", &decl).unwrap().label, "X");
+        assert!(index.get(&pkg, "other", &decl).is_none());
+        assert!(index.get(&pkg, "pt", &toml::from_str("id = \"y\"").unwrap()).is_none());
+        assert!(ContributionIndex::new(tmp.path().join("idx"), "1.1").get(&pkg, "pt", &decl).is_none());
+        let unhashed = Package { digest: None, ..pkg.clone() };
+        assert!(index.get(&unhashed, "pt", &decl).is_none(), "not an installed copy");
+
+        index.prune(["blake3:ffff"]);
+        assert!(index.get(&pkg, "pt", &decl).is_none());
+    }
+}

crates/ide-extension/src/ledger.rs

@@ -0,0 +1,483 @@
+//! The grant ledger (plan 4.6): which capabilities the user granted to which
+//! plugin, saved as `grants.json` next to the installed plugins.
+//!
+//! - Installed plugins are keyed by id and remember the version and package
+//!   hash they were confirmed for. An update that needs no new capability is
+//!   accepted silently; one that does must be confirmed again.
+//! - Linked development plugins and project plugins (`.openidea/plugins/*`)
+//!   are keyed by their directory, not by hash, so rebuilding does not ask
+//!   again; new capabilities still do.
+//! - `process:<program>` grants record the program's absolute path and file
+//!   hash at grant time. Calls use that path, never a `PATH` lookup, and fail
+//!   when the file changed (re-confirmation needed).
+
+use crate::capability::{Capability, Risk};
+use serde::{Deserialize, Serialize};
+use std::collections::{BTreeMap, BTreeSet};
+use std::ffi::OsStr;
+use std::path::{Path, PathBuf};
+
+pub const LEDGER_FILE: &str = "grants.json";
+const FORMAT: u32 = 1;
+
+/// Whose grant an entry is.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+#[serde(tag = "kind", content = "value", rename_all = "camelCase")]
+pub enum Subject {
+    /// Installed under the plugins directory, by plugin id.
+    Installed(String),
+    /// A linked development plugin or a project plugin, by package directory.
+    Path(PathBuf),
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct BinaryGrant {
+    pub path: PathBuf,
+    /// blake3 of the file when granted.
+    pub hash: String,
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Grant {
+    pub plugin_id: String,
+    /// The version and package hash the user confirmed (installed plugins).
+    #[serde(default)]
+    pub version: String,
+    #[serde(default)]
+    pub package_hash: String,
+    /// The user confirmed the plugin (the install page or the project-plugin prompt).
+    #[serde(default)]
+    pub confirmed: bool,
+    /// Granted capabilities (`project.read`, `net:x`, …).
+    #[serde(default)]
+    pub granted: BTreeSet<String>,
+    /// Optional capabilities the user declined (not asked again until re-confirmed).
+    #[serde(default)]
+    pub declined: BTreeSet<String>,
+    /// `process:<program>` → the program confirmed for it.
+    #[serde(default)]
+    pub binaries: BTreeMap<String, BinaryGrant>,
+    /// Migrated from 0.1: capabilities not granted yet are asked for on first
+    /// use instead of blocking the plugin from loading.
+    #[serde(default)]
+    pub ask_on_use: bool,
+}
+
+impl Grant {
+    pub fn has(&self, cap: &Capability) -> bool {
+        self.granted.iter().filter_map(|s| s.parse::<Capability>().ok()).any(|g| g.covers(cap))
+    }
+}
+
+/// What a plugin (in its current form) needs, to compare with its grant.
+#[derive(Clone, Debug)]
+pub struct Request<'a> {
+    pub subject: Subject,
+    pub plugin_id: &'a str,
+    pub version: &'a str,
+    pub package_hash: &'a str,
+    pub required: Vec<Capability>,
+    pub optional: Vec<Capability>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum Decision {
+    /// Load with these capabilities. `pending` required ones are asked for when
+    /// the plugin is first used (plugins migrated from 0.1 only).
+    Allowed { granted: Vec<Capability>, pending: Vec<Capability> },
+    /// Ask the user first. `new` lists what was never granted (all of it on first use).
+    NeedsConfirmation { new: Vec<Capability>, first_time: bool },
+}
+
+#[derive(Debug, Default, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct File {
+    #[serde(default)]
+    format: u32,
+    /// The one-time migration from 0.1 ("declared means granted") ran.
+    #[serde(default)]
+    migrated: bool,
+    #[serde(default)]
+    grants: Vec<(Subject, Grant)>,
+}
+
+/// The ledger, loaded into memory; [`Ledger::save`] writes it atomically.
+#[derive(Debug, Default)]
+pub struct Ledger {
+    path: Option<PathBuf>,
+    migrated: bool,
+    grants: BTreeMap<Subject, Grant>,
+}
+
+impl Ledger {
+    /// Loads `<dir>/grants.json`; a missing or unreadable file gives an empty
+    /// ledger with `needs_migration()` true.
+    pub fn load(dir: &Path) -> Self {
+        let path = dir.join(LEDGER_FILE);
+        let file: Option<File> = std::fs::read_to_string(&path).ok().and_then(|s| match serde_json::from_str(&s) {
+            Ok(f) => Some(f),
+            Err(e) => {
+                tracing::warn!("{}: {e}; starting with an empty grant ledger", path.display());
+                None
+            }
+        });
+        let existed = file.is_some();
+        let file = file.unwrap_or_default();
+        Self { path: Some(path), migrated: file.migrated || existed, grants: file.grants.into_iter().collect() }
+    }
+
+    pub fn in_memory() -> Self {
+        Self { path: None, migrated: true, grants: BTreeMap::new() }
+    }
+
+    pub fn save(&self) -> std::io::Result<()> {
+        let Some(path) = &self.path else { return Ok(()) };
+        let file = File {
+            format: FORMAT,
+            migrated: self.migrated,
+            grants: self.grants.iter().map(|(s, g)| (s.clone(), g.clone())).collect(),
+        };
+        let json = serde_json::to_string_pretty(&file).map_err(std::io::Error::other)?;
+        let tmp = path.with_extension("json.tmp");
+        std::fs::write(&tmp, json)?;
+        std::fs::rename(&tmp, path)
+    }
+
+    pub fn get(&self, subject: &Subject) -> Option<&Grant> {
+        self.grants.get(subject)
+    }
+
+    pub fn remove(&mut self, subject: &Subject) -> Option<Grant> {
+        self.grants.remove(subject)
+    }
+
+    /// Puts back an earlier state of `subject`'s grant (`None`: none), e.g.
+    /// after rolling back an update.
+    pub fn restore(&mut self, subject: &Subject, grant: Option<Grant>) {
+        match grant {
+            Some(g) => {
+                self.grants.insert(subject.clone(), g);
+            }
+            None => {
+                self.grants.remove(subject);
+            }
+        }
+    }
+
+    /// The one-time migration of 0.1's "declared means granted" has not run yet.
+    pub fn needs_migration(&self) -> bool {
+        !self.migrated
+    }
+
+    /// Migrates plugins installed before the ledger existed: low-risk
+    /// capabilities are granted, the rest are asked on first use.
+    pub fn migrate(&mut self, installed: &[Request<'_>]) {
+        for req in installed {
+            let granted: BTreeSet<String> =
+                req.required.iter().chain(&req.optional).filter(|c| c.auto_migrates()).map(|c| c.to_string()).collect();
+            self.grants.entry(req.subject.clone()).or_insert_with(|| Grant {
+                plugin_id: req.plugin_id.to_owned(),
+                version: req.version.to_owned(),
+                package_hash: req.package_hash.to_owned(),
+                confirmed: true,
+                granted,
+                ask_on_use: true,
+                ..Grant::default()
+            });
+        }
+        self.migrated = true;
+    }
+
+    /// Compares what the plugin needs with what was granted.
+    pub fn decide(&mut self, req: &Request<'_>) -> Decision {
+        let Some(grant) = self.grants.get_mut(&req.subject) else {
+            return Decision::NeedsConfirmation { new: req.required.clone(), first_time: true };
+        };
+        if !grant.confirmed {
+            return Decision::NeedsConfirmation { new: req.required.clone(), first_time: true };
+        }
+        let new: Vec<Capability> = req.required.iter().filter(|c| !grant.has(c)).cloned().collect();
+        if !new.is_empty() && !grant.ask_on_use {
+            return Decision::NeedsConfirmation { new, first_time: false };
+        }
+        // Same or fewer needs: accept an update silently (plan 4.6).
+        if grant.version != req.version || grant.package_hash != req.package_hash {
+            grant.version = req.version.to_owned();
+            grant.package_hash = req.package_hash.to_owned();
+        }
+        let granted = req.required.iter().chain(&req.optional).filter(|c| grant.has(c)).cloned().collect();
+        Decision::Allowed { granted, pending: new }
+    }
+
+    /// Records the user's confirmation: `required` plus the accepted optional capabilities.
+    pub fn confirm(
+        &mut self,
+        req: &Request<'_>,
+        accepted_optional: &[Capability],
+        binaries: BTreeMap<String, BinaryGrant>,
+    ) {
+        let grant = self.grants.entry(req.subject.clone()).or_default();
+        grant.plugin_id = req.plugin_id.to_owned();
+        grant.version = req.version.to_owned();
+        grant.package_hash = req.package_hash.to_owned();
+        grant.confirmed = true;
+        grant.ask_on_use = false;
+        for cap in req.required.iter().chain(accepted_optional) {
+            grant.granted.insert(cap.to_string());
+        }
+        for cap in &req.optional {
+            let s = cap.to_string();
+            if accepted_optional.contains(cap) {
+                grant.declined.remove(&s);
+            } else if !grant.granted.contains(&s) {
+                grant.declined.insert(s);
+            }
+        }
+        grant.binaries.extend(binaries);
+    }
+
+    /// Grants or revokes one capability (Settings › Plugins › permissions).
+    pub fn set(&mut self, subject: &Subject, cap: &Capability, granted: bool) -> bool {
+        let Some(grant) = self.grants.get_mut(subject) else { return false };
+        let s = cap.to_string();
+        if granted {
+            grant.declined.remove(&s);
+            grant.granted.insert(s)
+        } else {
+            if let Capability::Process(_) = cap {
+                grant.binaries.remove(&s);
+            }
+            grant.granted.remove(&s)
+        }
+    }
+
+    /// Records the program approved for a `process:` grant.
+    pub fn set_binary(&mut self, subject: &Subject, cap: &Capability, binary: BinaryGrant) {
+        if let Some(grant) = self.grants.get_mut(subject) {
+            grant.binaries.insert(cap.to_string(), binary);
+        }
+    }
+
+    /// Checks a `process:` grant at call time: the program confirmed for it,
+    /// unchanged since. Errors name what to do.
+    pub fn check_binary(&self, subject: &Subject, cap: &Capability) -> Result<PathBuf, String> {
+        let Capability::Process(name) = cap else { return Err(format!("{cap} is not a process capability")) };
+        let grant = self.grants.get(subject).ok_or_else(|| format!("{cap} was not granted"))?;
+        let key = cap.to_string();
+        if !grant.granted.contains(&key) {
+            return Err(format!("{cap} was not granted"));
+        }
+        let bin = grant.binaries.get(&key).ok_or_else(|| format!("{cap}: no program was confirmed for {name}"))?;
+        match file_hash(&bin.path) {
+            Ok(hash) if hash == bin.hash => Ok(bin.path.clone()),
+            Ok(_) => Err(format!(
+                "{} changed since it was approved for {cap}; confirm the plugin's permissions again",
+                bin.path.display()
+            )),
+            Err(e) => Err(format!("{}: {e}; confirm the plugin's permissions again", bin.path.display())),
+        }
+    }
+
+    /// The program approved for a granted `process:` capability, without
+    /// checking the file: whoever starts it verifies the hash then
+    /// ([`check_binary`](Self::check_binary) or the pin's own check).
+    pub fn pinned_binary(&self, subject: &Subject, cap: &Capability) -> Option<BinaryGrant> {
+        let grant = self.grants.get(subject)?;
+        let key = cap.to_string();
+        if !grant.granted.contains(&key) {
+            return None;
+        }
+        grant.binaries.get(&key).cloned()
+    }
+
+    pub fn subjects(&self) -> impl Iterator<Item = (&Subject, &Grant)> {
+        self.grants.iter()
+    }
+}
+
+/// What a confirmation page shows: every capability with its risk, high risk first.
+pub fn by_risk(caps: &[Capability]) -> Vec<(Risk, Vec<Capability>)> {
+    let mut groups: BTreeMap<std::cmp::Reverse<Risk>, Vec<Capability>> = BTreeMap::new();
+    for c in caps {
+        groups.entry(std::cmp::Reverse(c.risk())).or_default().push(c.clone());
+    }
+    groups.into_iter().map(|(r, v)| (r.0, v)).collect()
+}
+
+/// Resolves a `process:` program to an absolute path once, at grant time:
+/// absolute names are taken as is, others are looked up in `path_var`.
+pub fn resolve_program(name: &str, path_var: Option<&OsStr>) -> Result<PathBuf, String> {
+    let candidate = Path::new(name);
+    if candidate.is_absolute() {
+        return if candidate.is_file() { Ok(candidate.to_path_buf()) } else { Err(format!("{name}: no such program")) };
+    }
+    let exts: Vec<String> = if cfg!(windows) {
+        std::env::var("PATHEXT").unwrap_or_else(|_| ".EXE;.CMD;.BAT".into()).split(';').map(str::to_owned).collect()
+    } else {
+        vec![String::new()]
+    };
+    for dir in std::env::split_paths(path_var.unwrap_or_default()) {
+        if !dir.is_absolute() {
+            continue; // `.` or relative entries could point into the project
+        }
+        for ext in &exts {
+            let p = dir.join(format!("{name}{ext}"));
+            if is_executable(&p) {
+                return Ok(dunce_canonical(&p));
+            }
+        }
+    }
+    Err(format!("{name} was not found on PATH"))
+}
+
+fn dunce_canonical(p: &Path) -> PathBuf {
+    std::fs::canonicalize(p).unwrap_or_else(|_| p.to_path_buf())
+}
+
+fn is_executable(p: &Path) -> bool {
+    let Ok(meta) = std::fs::metadata(p) else { return false };
+    if !meta.is_file() {
+        return false;
+    }
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        meta.permissions().mode() & 0o111 != 0
+    }
+    #[cfg(not(unix))]
+    true
+}
+
+/// blake3 of a file, hex.
+pub fn file_hash(path: &Path) -> std::io::Result<String> {
+    let mut hasher = blake3::Hasher::new();
+    hasher.update_reader(std::fs::File::open(path)?)?;
+    Ok(hasher.finalize().to_hex().to_string())
+}
+
+/// blake3 over a package's files (sorted relative paths and contents).
+pub fn package_hash(dir: &Path, files: &[PathBuf]) -> std::io::Result<String> {
+    let mut sorted: Vec<&PathBuf> = files.iter().collect();
+    sorted.sort();
+    sorted.dedup();
+    let mut hasher = blake3::Hasher::new();
+    for rel in sorted {
+        hasher.update(rel.to_string_lossy().as_bytes());
+        hasher.update(&[0]);
+        hasher.update_reader(std::fs::File::open(dir.join(rel))?)?;
+        hasher.update(&[0]);
+    }
+    Ok(hasher.finalize().to_hex().to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn caps(list: &[&str]) -> Vec<Capability> {
+        list.iter().map(|s| s.parse().unwrap()).collect()
+    }
+
+    fn req<'a>(version: &'a str, hash: &'a str, required: &[&str], optional: &[&str]) -> Request<'a> {
+        Request {
+            subject: Subject::Installed("p".into()),
+            plugin_id: "p",
+            version,
+            package_hash: hash,
+            required: caps(required),
+            optional: caps(optional),
+        }
+    }
+
+    #[test]
+    fn confirmation_then_silent_update_then_reconfirm_on_new_capability() {
+        let mut l = Ledger::in_memory();
+        let r1 = req("1.0.0", "h1", &["project.read"], &["net:crates.io"]);
+        assert_eq!(l.decide(&r1), Decision::NeedsConfirmation { new: caps(&["project.read"]), first_time: true });
+        l.confirm(&r1, &[], BTreeMap::new());
+        assert_eq!(
+            l.decide(&r1),
+            Decision::Allowed { granted: caps(&["project.read"]), pending: vec![] },
+            "declined optional"
+        );
+        assert!(l.get(&r1.subject).unwrap().declined.contains("net:crates.io"));
+
+        // Same needs, new version: silent.
+        let r2 = req("1.1.0", "h2", &["project.read"], &["net:crates.io"]);
+        assert!(matches!(l.decide(&r2), Decision::Allowed { .. }));
+        assert_eq!(l.get(&r2.subject).unwrap().version, "1.1.0");
+
+        // A new required capability: ask again, only for it.
+        let r3 = req("1.2.0", "h3", &["project.read", "editor.write"], &[]);
+        assert_eq!(l.decide(&r3), Decision::NeedsConfirmation { new: caps(&["editor.write"]), first_time: false });
+        l.confirm(&r3, &[], BTreeMap::new());
+        assert!(matches!(l.decide(&r3), Decision::Allowed { .. }));
+
+        // Revoking a required capability blocks loading again.
+        assert!(l.set(&r3.subject, &Capability::EditorWrite, false));
+        assert!(matches!(l.decide(&r3), Decision::NeedsConfirmation { .. }));
+    }
+
+    #[test]
+    fn migration_grants_low_risk_only() {
+        let tmp = tempfile::tempdir().unwrap();
+        let mut l = Ledger::load(tmp.path());
+        assert!(l.needs_migration());
+        let r = req("0.1.0", "h", &["project.read", "editor.write"], &[]);
+        l.migrate(std::slice::from_ref(&r));
+        // Loads with the low-risk part; the rest is asked for on first use.
+        assert_eq!(
+            l.decide(&r),
+            Decision::Allowed { granted: caps(&["project.read"]), pending: caps(&["editor.write"]) }
+        );
+        l.confirm(&r, &[], BTreeMap::new());
+        assert_eq!(
+            l.decide(&r),
+            Decision::Allowed { granted: caps(&["project.read", "editor.write"]), pending: vec![] }
+        );
+        l.save().unwrap();
+        let again = Ledger::load(tmp.path());
+        assert!(!again.needs_migration());
+        assert!(again.get(&r.subject).unwrap().has(&Capability::ProjectRead));
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn binaries_are_pinned_by_path_and_hash() {
+        use std::os::unix::fs::PermissionsExt;
+        let tmp = tempfile::tempdir().unwrap();
+        let bin_dir = tmp.path().join("bin");
+        std::fs::create_dir(&bin_dir).unwrap();
+        let tool = bin_dir.join("tool");
+        std::fs::write(&tool, "#!/bin/sh\necho v1\n").unwrap();
+        std::fs::set_permissions(&tool, std::fs::Permissions::from_mode(0o755)).unwrap();
+        let path_var = std::env::join_paths([PathBuf::from("relative"), bin_dir.clone()]).unwrap();
+        let resolved = resolve_program("tool", Some(&path_var)).unwrap();
+        assert!(resolved.is_absolute());
+        assert!(resolve_program("missing", Some(&path_var)).is_err());
+
+        let mut l = Ledger::in_memory();
+        let r = req("1.0.0", "h", &["process:tool"], &[]);
+        let cap: Capability = "process:tool".parse().unwrap();
+        let bin = BinaryGrant { path: resolved.clone(), hash: file_hash(&resolved).unwrap() };
+        l.confirm(&r, &[], [(cap.to_string(), bin)].into());
+        assert_eq!(l.check_binary(&r.subject, &cap).unwrap(), resolved);
+        std::fs::write(&tool, "#!/bin/sh\necho evil\n").unwrap();
+        assert!(l.check_binary(&r.subject, &cap).unwrap_err().contains("changed"));
+    }
+
+    #[test]
+    fn hashes_and_grouping() {
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::write(tmp.path().join("a"), "1").unwrap();
+        std::fs::write(tmp.path().join("b"), "2").unwrap();
+        let h1 = package_hash(tmp.path(), &["a".into(), "b".into()]).unwrap();
+        assert_eq!(h1, package_hash(tmp.path(), &["b".into(), "a".into()]).unwrap());
+        std::fs::write(tmp.path().join("b"), "3").unwrap();
+        assert_ne!(h1, package_hash(tmp.path(), &["a".into(), "b".into()]).unwrap());
+        let groups = by_risk(&caps(&["storage", "process:git", "net:x.io"]));
+        assert_eq!(groups.iter().map(|g| g.0).collect::<Vec<_>>(), [Risk::High, Risk::Medium, Risk::Low]);
+    }
+}

crates/ide-extension/src/lib.rs

@@ -0,0 +1,36 @@
+//! The plugin system's kernel, independent of the Wasm runtime:
+//!
+//! - [`Manifest`]: `plugin.toml` (0.2 format; 0.1 still parses);
+//! - [`Capability`]: what a plugin may do, with its [`Risk`] level;
+//! - [`ExtensionPoint`]: one kind of contribution, implemented by the crate that
+//!   owns the feature; [`ExtensionRegistry`] validates a package's declarations
+//!   ([`ExtensionRegistry::prepare`], no side effects), makes them take effect
+//!   all or nothing ([`ExtensionRegistry::commit`]) and withdraws them per plugin;
+//! - [`UiStore`] / [`UiPoint`]: UI contributions, validated here and projected
+//!   by the client without the possibility to fail;
+//! - [`ledger`]: which capabilities the user granted to which plugin;
+//! - [`package`]: the package file, its signature and the marketplace index.
+//!
+//! Dependency direction: `ide-core` ← `ide-extension` ← feature crates (their
+//! extension points) and `ide-plugin` (Wasm) ← `ide-host` (assembly).
+
+mod capability;
+mod index;
+pub mod ledger;
+mod manifest;
+pub mod package;
+mod point;
+mod registry;
+mod ui;
+mod when;
+
+pub use capability::{Capability, CapabilityInfo, Risk, host_matches};
+pub use index::ContributionIndex;
+pub use manifest::{
+    ActivationEvent, Capabilities, ENGINE_VERSION, EVENT_KINDS, LEGACY_API, MANIFEST_FILE, Manifest, check_relative,
+    engine_compatible, validate_item_id, validate_plugin_id, validate_point_id,
+};
+pub use point::{Commit, Disposable, ExtensionPoint, MAX_PACKAGE_FILE, Package, Placement, Prepared, decode};
+pub use registry::{ContributionInfo, ExtensionRegistry, PreparedSet};
+pub use ui::{UiContribution, UiDecl, UiPoint, UiStore, to_json};
+pub use when::validate_when;

crates/ide-extension/src/manifest.rs

@@ -0,0 +1,501 @@
+//! `plugin.toml`, the package manifest (plan 4.4).
+//!
+//! ```toml
+//! id = "acme.rust-tools"          # optional publisher namespace before the first '.'
+//! name = "Rust Tools"
+//! version = "1.2.0"
+//! engines.openidea = "^1.0"
+//! wasm = "plugin.wasm"
+//! activation = ["on-language:rust", "on-command:check"]
+//!
+//! [capabilities]
+//! required = ["project.read", "editor.write"]
+//! optional = ["net:crates.io", "process:cargo"]
+//!
+//! [[contributes.commands]]
+//! id = "check"
+//! title = "Check"
+//! ```
+//!
+//! `contributes` is kept as raw TOML: each `contributes.<point>` is parsed and
+//! validated by the extension point registered under that id
+//! ([`crate::ExtensionRegistry`]), so new contribution types need no change here.
+//!
+//! Manifests in the 0.1 format (`openidea-api = "0.1"`, `permissions = [...]`)
+//! still parse: permissions become required capabilities and the plugin is
+//! activated at start-up, as before.
+
+use crate::capability::Capability;
+use serde::Deserialize;
+use std::collections::BTreeSet;
+use std::path::{Component, Path, PathBuf};
+
+pub const MANIFEST_FILE: &str = "plugin.toml";
+/// The plugin API (engine) version this host implements.
+pub const ENGINE_VERSION: &str = "1.0.0";
+/// The 0.1 API, still accepted for contribution-only packages and 0.1 components.
+pub const LEGACY_API: &str = "0.1";
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Manifest {
+    pub id: String,
+    pub name: String,
+    pub version: String,
+    pub description: String,
+    pub authors: Vec<String>,
+    pub homepage: Option<String>,
+    pub license: Option<String>,
+    /// Release notes of this version (Settings › Plugins › What's New).
+    pub change_notes: Option<String>,
+    /// `engines.openidea` (a semver requirement), or the legacy `openidea-api`.
+    pub engine: String,
+    /// Written in the 0.1 format.
+    pub legacy: bool,
+    /// Component file relative to the package directory.
+    pub wasm: Option<PathBuf>,
+    pub activation: Vec<ActivationEvent>,
+    pub capabilities: Capabilities,
+    /// `contributes.<point>` → its declarations, validated by the extension points.
+    pub contributes: toml::Table,
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct Capabilities {
+    pub required: Vec<Capability>,
+    pub optional: Vec<Capability>,
+}
+
+impl Capabilities {
+    pub fn all(&self) -> impl Iterator<Item = &Capability> {
+        self.required.iter().chain(&self.optional)
+    }
+
+    pub fn is_optional(&self, cap: &Capability) -> bool {
+        self.optional.contains(cap) && !self.required.contains(cap)
+    }
+}
+
+/// When a plugin's code is instantiated (plan 4.4). Contributions are live
+/// without it; code only runs once one of these fires.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum ActivationEvent {
+    /// One of the plugin's commands is run (`on-command:<id>`; `*` = any).
+    Command(String),
+    /// A file of this language is opened.
+    Language(String),
+    /// A file matching this glob (project-relative) is opened.
+    File(String),
+    /// One of the plugin's views is shown.
+    View(String),
+    /// Periodically: `on-schedule:<seconds>`. Does not keep the plugin alive.
+    Schedule(u32),
+    /// A workbench event of this kind (`on-event:file-saved`): the plugin is
+    /// subscribed from the start, and activated to receive it.
+    Event(String),
+    /// Shortly after the workbench is ready.
+    StartupFinished,
+}
+
+impl ActivationEvent {
+    pub fn parse(s: &str) -> Result<Self, String> {
+        let s = s.trim();
+        if s == "on-startup-finished" {
+            return Ok(Self::StartupFinished);
+        }
+        let (kind, arg) = s.split_once(':').ok_or_else(|| format!("unknown activation event {s:?}"))?;
+        let arg = arg.trim();
+        if arg.is_empty() {
+            return Err(format!("activation event {s:?} needs a value"));
+        }
+        Ok(match kind {
+            "on-command" => Self::Command(arg.into()),
+            "on-language" => Self::Language(arg.into()),
+            "on-file" => Self::File(arg.into()),
+            "on-view" => Self::View(arg.into()),
+            "on-schedule" => {
+                let secs: u32 =
+                    arg.trim_end_matches('s').parse().map_err(|_| format!("{s:?}: expected seconds, e.g. 300"))?;
+                if secs < 60 {
+                    return Err(format!("{s:?}: the shortest schedule is 60 seconds"));
+                }
+                Self::Schedule(secs)
+            }
+            "on-event" => {
+                if !EVENT_KINDS.contains(&arg) {
+                    return Err(format!("{s:?}: unknown event kind (one of {})", EVENT_KINDS.join(", ")));
+                }
+                Self::Event(arg.into())
+            }
+            _ => return Err(format!("unknown activation event {s:?}")),
+        })
+    }
+}
+
+/// Workbench event kinds (`on-event:<kind>`, WIT `events.event-kind`).
+/// `scheduled` comes from `on-schedule` instead.
+pub const EVENT_KINDS: &[&str] = &["file-opened", "file-saved", "editor-focused", "action-performed", "vcs-changed"];
+
+impl std::fmt::Display for ActivationEvent {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Command(c) => write!(f, "on-command:{c}"),
+            Self::Language(l) => write!(f, "on-language:{l}"),
+            Self::File(g) => write!(f, "on-file:{g}"),
+            Self::View(v) => write!(f, "on-view:{v}"),
+            Self::Schedule(s) => write!(f, "on-schedule:{s}"),
+            Self::Event(k) => write!(f, "on-event:{k}"),
+            Self::StartupFinished => f.write_str("on-startup-finished"),
+        }
+    }
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case", deny_unknown_fields)]
+struct Raw {
+    id: String,
+    name: String,
+    version: String,
+    #[serde(default)]
+    description: String,
+    #[serde(default)]
+    authors: Vec<String>,
+    #[serde(default)]
+    homepage: Option<String>,
+    #[serde(default)]
+    license: Option<String>,
+    #[serde(default)]
+    change_notes: Option<String>,
+    #[serde(default)]
+    engines: Option<Engines>,
+    /// 0.1 format.
+    #[serde(default)]
+    openidea_api: Option<String>,
+    #[serde(default)]
+    wasm: Option<PathBuf>,
+    #[serde(default)]
+    activation: Option<Vec<String>>,
+    #[serde(default)]
+    capabilities: Option<RawCapabilities>,
+    /// 0.1 format.
+    #[serde(default)]
+    permissions: Option<Vec<String>>,
+    #[serde(default)]
+    contributes: toml::Table,
+}
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Engines {
+    openidea: String,
+}
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct RawCapabilities {
+    #[serde(default)]
+    required: Vec<String>,
+    #[serde(default)]
+    optional: Vec<String>,
+}
+
+impl Manifest {
+    pub fn parse(src: &str) -> Result<Self, String> {
+        let raw: Raw = toml::from_str(src).map_err(|e| e.to_string())?;
+        let (engine, legacy) = match (raw.engines, raw.openidea_api) {
+            (Some(e), None) => (e.openidea, false),
+            (None, Some(api)) => (api, true),
+            (Some(_), Some(_)) => return Err("use `engines.openidea`, not `openidea-api`".into()),
+            (None, None) => return Err("missing `engines.openidea` (e.g. \"^1.0\")".into()),
+        };
+        if legacy && raw.capabilities.is_some() {
+            return Err("`capabilities` requires `engines.openidea`; 0.1 manifests use `permissions`".into());
+        }
+        if !legacy && raw.permissions.is_some() {
+            return Err("`permissions` is the 0.1 format; use `[capabilities] required = [...]`".into());
+        }
+        let parse_caps = |list: Vec<String>| -> Result<Vec<Capability>, String> {
+            let mut out: Vec<Capability> = Vec::new();
+            for s in list {
+                let cap: Capability = s.parse()?;
+                if !out.contains(&cap) {
+                    out.push(cap);
+                }
+            }
+            Ok(out)
+        };
+        let capabilities = match (raw.capabilities, raw.permissions) {
+            (Some(c), _) => Capabilities { required: parse_caps(c.required)?, optional: parse_caps(c.optional)? },
+            (None, Some(p)) => Capabilities { required: parse_caps(p)?, optional: Vec::new() },
+            (None, None) => Capabilities::default(),
+        };
+        let activation = match raw.activation {
+            Some(list) => list.iter().map(|s| ActivationEvent::parse(s)).collect::<Result<Vec<_>, _>>()?,
+            // 0.1 plugins were activated at start-up; keep that until they move to 1.0.
+            None if legacy && raw.wasm.is_some() => vec![ActivationEvent::StartupFinished],
+            None => Vec::new(),
+        };
+        let m = Manifest {
+            id: raw.id,
+            name: raw.name,
+            version: raw.version,
+            description: raw.description,
+            authors: raw.authors,
+            homepage: raw.homepage,
+            license: raw.license,
+            change_notes: raw.change_notes,
+            engine,
+            legacy,
+            wasm: raw.wasm,
+            activation,
+            capabilities,
+            contributes: raw.contributes,
+        };
+        m.validate()?;
+        Ok(m)
+    }
+
+    pub fn load(dir: &Path) -> Result<Self, String> {
+        let path = dir.join(MANIFEST_FILE);
+        let src = std::fs::read_to_string(&path).map_err(|e| format!("{}: {e}", path.display()))?;
+        Self::parse(&src).map_err(|e| format!("{}: {e}", path.display()))
+    }
+
+    fn validate(&self) -> Result<(), String> {
+        validate_plugin_id(&self.id)?;
+        if self.name.trim().is_empty() {
+            return Err("`name` must not be empty".into());
+        }
+        if semver::Version::parse(&self.version).is_err() {
+            return Err(format!("`version` must be a semantic version like 1.2.3, got {:?}", self.version));
+        }
+        if !engine_compatible(&self.engine, self.legacy) {
+            return Err(if self.legacy {
+                format!(
+                    "unsupported openidea-api {:?} (this IDE implements {LEGACY_API} and {ENGINE_VERSION})",
+                    self.engine
+                )
+            } else {
+                format!("engines.openidea {:?} does not match this IDE's plugin API {ENGINE_VERSION}", self.engine)
+            });
+        }
+        if let Some(wasm) = &self.wasm {
+            check_relative(wasm, "wasm")?;
+        }
+        if self.wasm.is_none() && !self.activation.is_empty() {
+            return Err("`activation` needs `wasm`: there is no code to activate".into());
+        }
+        let mut seen = BTreeSet::new();
+        for event in &self.activation {
+            if !seen.insert(event) {
+                return Err(format!("duplicate activation event {event}"));
+            }
+        }
+        for (point, decls) in &self.contributes {
+            validate_point_id(point)?;
+            if !matches!(decls, toml::Value::Array(_) | toml::Value::Table(_)) {
+                return Err(format!("`contributes.{point}` must be a table or an array of tables"));
+            }
+        }
+        Ok(())
+    }
+
+    /// The declarations of one extension point: `[[contributes.x]]` gives
+    /// several, `[contributes.x]` one.
+    pub fn declarations(&self, point: &str) -> Vec<toml::Value> {
+        match self.contributes.get(point) {
+            Some(toml::Value::Array(items)) => items.clone(),
+            Some(single @ toml::Value::Table(_)) => vec![single.clone()],
+            _ => Vec::new(),
+        }
+    }
+
+    /// Number of declarations per extension point (for listings before loading).
+    pub fn declaration_counts(&self) -> Vec<(String, u32)> {
+        self.contributes.keys().map(|p| (p.clone(), self.declarations(p).len() as u32)).collect()
+    }
+
+    /// Publisher namespace: the id's part before the first `.` (`acme` in `acme.tools`).
+    pub fn publisher(&self) -> Option<&str> {
+        self.id.split_once('.').map(|(p, _)| p)
+    }
+
+    /// Whether `cap` is declared (required or optional).
+    pub fn declares(&self, cap: &Capability) -> bool {
+        self.capabilities.all().any(|c| c.covers(cap))
+    }
+}
+
+/// Whether this host can load a plugin written for `engine`.
+pub fn engine_compatible(engine: &str, legacy: bool) -> bool {
+    if legacy {
+        return engine == LEGACY_API || engine.strip_prefix(LEGACY_API).is_some_and(|rest| rest.starts_with('.'));
+    }
+    let Ok(req) = semver::VersionReq::parse(engine) else { return false };
+    let host = semver::Version::parse(ENGINE_VERSION).expect("valid engine version");
+    req.matches(&host)
+}
+
+/// Segments of `[a-z0-9][a-z0-9_-]*` joined by `.` (an optional publisher
+/// namespace first), at most 64 chars.
+pub fn validate_plugin_id(id: &str) -> Result<(), String> {
+    let ok = id.len() <= 64 && !id.is_empty() && id.split('.').all(segment_ok);
+    if ok {
+        Ok(())
+    } else {
+        Err(format!(
+            "invalid plugin id {id:?}: use a-z, 0-9, '-', '_' in '.'-separated parts (e.g. acme.tools), max 64"
+        ))
+    }
+}
+
+/// `[a-z0-9][a-z0-9._-]*`, at most 64 chars (commands, themes, views…).
+pub fn validate_item_id(id: &str, what: &str) -> Result<(), String> {
+    let ok_first = id.chars().next().is_some_and(|c| c.is_ascii_lowercase() || c.is_ascii_digit());
+    let ok_rest = id.chars().all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || matches!(c, '-' | '_' | '.'));
+    if ok_first && ok_rest && id.len() <= 64 {
+        Ok(())
+    } else {
+        Err(format!("invalid {what} {id:?}: use a-z, 0-9, '.', '-', '_', starting with a letter or digit (max 64)"))
+    }
+}
+
+/// Extension point ids: `camelCase` or `kebab-case` words, dots allowed (`iconThemes`, `menus`).
+pub fn validate_point_id(id: &str) -> Result<(), String> {
+    let ok = !id.is_empty()
+        && id.len() <= 64
+        && id.starts_with(|c: char| c.is_ascii_lowercase())
+        && id.chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '-' | '.'));
+    if ok { Ok(()) } else { Err(format!("invalid contribution point {id:?}")) }
+}
+
+fn segment_ok(s: &str) -> bool {
+    s.chars().next().is_some_and(|c| c.is_ascii_lowercase() || c.is_ascii_digit())
+        && s.chars().all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '-' || c == '_')
+}
+
+/// Package paths must stay inside the package directory.
+pub fn check_relative(path: &Path, what: &str) -> Result<(), String> {
+    let ok = !path.as_os_str().is_empty() && path.components().all(|c| matches!(c, Component::Normal(_)));
+    if ok { Ok(()) } else { Err(format!("{what} {:?} must be a relative path inside the plugin", path.display())) }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const FULL: &str = r#"
+        id = "acme.rust-tools"
+        name = "Rust Tools"
+        version = "1.2.0"
+        engines.openidea = "^1.0"
+        wasm = "plugin.wasm"
+        activation = ["on-language:rust", "on-command:check", "on-schedule:300"]
+
+        [capabilities]
+        required = ["project.read", "editor.write"]
+        optional = ["net:crates.io", "process:cargo"]
+
+        [[contributes.commands]]
+        id = "check"
+        title = "%check.title%"
+
+        [[contributes.menus]]
+        menu = "editor.context"
+        command = "check"
+        when = "editorLang == rust"
+
+        [contributes.settings]
+        schema = "settings.schema.json"
+    "#;
+
+    #[test]
+    fn event_activation() {
+        assert_eq!(ActivationEvent::parse("on-event:file-saved"), Ok(ActivationEvent::Event("file-saved".into())));
+        assert_eq!(ActivationEvent::Event("vcs-changed".into()).to_string(), "on-event:vcs-changed");
+        let err = ActivationEvent::parse("on-event:keystroke").unwrap_err();
+        assert!(err.contains("unknown event kind") && err.contains("action-performed"), "{err}");
+        assert!(ActivationEvent::parse("on-event:scheduled").is_err(), "declared with on-schedule");
+    }
+
+    #[test]
+    fn parses_the_02_format() {
+        let m = Manifest::parse(FULL).unwrap();
+        assert_eq!(m.publisher(), Some("acme"));
+        assert!(!m.legacy);
+        assert_eq!(m.activation.len(), 3);
+        assert_eq!(m.activation[2], ActivationEvent::Schedule(300));
+        assert_eq!(m.capabilities.required, vec![Capability::ProjectRead, Capability::EditorWrite]);
+        assert!(m.capabilities.is_optional(&Capability::Process("cargo".into())));
+        assert_eq!(m.declarations("commands").len(), 1);
+        assert_eq!(m.declarations("settings").len(), 1, "a single table is one declaration");
+        assert!(m.declarations("nope").is_empty());
+        let counts: Vec<_> = m.declaration_counts();
+        assert!(counts.contains(&("menus".into(), 1)));
+    }
+
+    #[test]
+    fn parses_the_01_format() {
+        let m = Manifest::parse(
+            "id = \"hello\"\nname = \"Hello\"\nversion = \"0.1.0\"\nopenidea-api = \"0.1\"\nwasm = \"dist/plugin.wasm\"\n\
+             permissions = [\"project-read\", \"editor-write\"]\n[[contributes.commands]]\nid = \"x\"\ntitle = \"X\"",
+        )
+        .unwrap();
+        assert!(m.legacy);
+        assert_eq!(m.capabilities.required, vec![Capability::ProjectRead, Capability::EditorWrite]);
+        assert_eq!(m.activation, vec![ActivationEvent::StartupFinished]);
+        assert_eq!(m.publisher(), None);
+    }
+
+    fn err(src: &str) -> String {
+        Manifest::parse(src).unwrap_err()
+    }
+
+    #[test]
+    fn rejects_invalid_manifests() {
+        let base = |extra: &str| format!("id = \"ok\"\nname = \"N\"\nversion = \"1.0.0\"\n{extra}");
+        assert!(err(&base("")).contains("engines.openidea"));
+        assert!(err(&base("engines.openidea = \"^0.3\"")).contains("does not match"));
+        assert!(err(&base("engines.openidea = \"^2\"")).contains("does not match"));
+        assert!(err(&base("engines.openidea = \"^0.2\"")).contains("does not match"));
+        assert!(err(&base("openidea-api = \"0.2\"")).contains("unsupported"));
+        assert!(err(&base("engines.openidea = \"^1.0\"\npermissions = [\"project-read\"]")).contains("0.1 format"));
+        assert!(
+            err(&base("engines.openidea = \"^1.0\"\n[capabilities]\nrequired = [\"network\"]")).contains("unknown")
+        );
+        assert!(err(&base("engines.openidea = \"^1.0\"\nwasm = \"../x.wasm\"")).contains("relative path"));
+        assert!(err(&base("engines.openidea = \"^1.0\"\nactivation = [\"on-command:x\"]")).contains("needs `wasm`"));
+        assert!(
+            err(&base("engines.openidea = \"^1.0\"\nwasm = \"p.wasm\"\nactivation = [\"on-boot\"]"))
+                .contains("unknown")
+        );
+        assert!(
+            err(&base("engines.openidea = \"^1.0\"\nwasm = \"p.wasm\"\nactivation = [\"on-schedule:5\"]"))
+                .contains("60 seconds")
+        );
+        assert!(err(&base("engines.openidea = \"^1.0\"\nbogus = 1")).contains("unknown field"));
+        assert!(err(&base("engines.openidea = \"^1.0\"\ncontributes.commands = 3")).contains("table"));
+        assert!(
+            err("id = \"Bad\"\nname = \"N\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"").contains("plugin id")
+        );
+        assert!(
+            err("id = \"a..b\"\nname = \"N\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"").contains("plugin id")
+        );
+        assert!(err("id = \"ok\"\nname = \"N\"\nversion = \"1.0\"\nengines.openidea = \"^1.0\"").contains("version"));
+    }
+
+    #[test]
+    fn ids() {
+        assert!(validate_plugin_id("openidea.material-icons").is_ok());
+        assert!(validate_plugin_id("hello_2").is_ok());
+        assert!(validate_plugin_id(".x").is_err());
+        assert!(validate_item_id("word-count.v2_x", "command id").is_ok());
+        assert!(validate_item_id("-x", "command id").is_err());
+        assert!(validate_point_id("iconThemes").is_ok());
+        assert!(validate_point_id("Icon").is_err());
+        assert!(engine_compatible("1.0", false));
+        assert!(engine_compatible(">=1.0, <2", false));
+        assert!(!engine_compatible("^0.2", false), "0.x components don't run on 1.0");
+        assert!(engine_compatible("0.1.3", true));
+        assert!(!engine_compatible("0.10", true));
+    }
+}

crates/ide-extension/src/package.rs

@@ -0,0 +1,465 @@
+//! Plugin distribution: the package file, its
+//! signature, and the static marketplace index.
+//!
+//! - **Package** (`<id>-<version>.oiplugin`): a zip of the manifest, the files
+//!   its declarations reference, the component and licence files, plus
+//!   [`SIGNATURE_FILE`] when signed.
+//! - **Signature**: Ed25519 over `openidea-plugin/1\n<id>\n<version>\n<digest>`,
+//!   `digest` being [`package_digest`] of the unpacked files. A signature
+//!   proves who published the bytes; whether to trust that publisher is the
+//!   index's call.
+//! - **Index** (`index.json`): the publishers and their keys (the trust root),
+//!   the published plugins, and revocations. A publisher owns the id prefix
+//!   `<publisher>.`; a revoked key invalidates everything it signed, a
+//!   revoked plugin version is disabled where it is installed.
+
+use crate::MANIFEST_FILE;
+use base64::Engine as _;
+use ed25519_dalek::{Signature, Signer, SigningKey, VerifyingKey};
+use serde::{Deserialize, Serialize};
+use std::io::{Read, Write};
+use std::path::{Component, Path, PathBuf};
+
+pub const SIGNATURE_FILE: &str = "SIGNATURE.json";
+pub const PACKAGE_EXTENSION: &str = "oiplugin";
+pub const INDEX_FORMAT: u32 = 1;
+/// Limits when unpacking an untrusted package.
+const MAX_ENTRIES: usize = 10_000;
+const MAX_TOTAL: u64 = 512 << 20;
+
+const B64: base64::engine::GeneralPurpose = base64::engine::general_purpose::STANDARD;
+
+/// Content digest of a package: the manifest plus `files` (relative paths).
+pub fn package_digest(dir: &Path, files: &[PathBuf]) -> std::io::Result<String> {
+    let mut all = files.to_vec();
+    all.push(PathBuf::from(MANIFEST_FILE));
+    crate::ledger::package_hash(dir, &all)
+}
+
+fn signed_message(id: &str, version: &str, digest: &str) -> Vec<u8> {
+    format!("openidea-plugin/1\n{id}\n{version}\n{digest}").into_bytes()
+}
+
+/// `SIGNATURE.json` of a signed package.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PackageSignature {
+    pub publisher: String,
+    /// Ed25519 public key, base64.
+    pub key: String,
+    /// Ed25519 signature, base64.
+    pub signature: String,
+}
+
+/// A publisher's key pair (the 32-byte seed, base64, in a file only the publisher has).
+pub struct PublisherKey(SigningKey);
+
+impl PublisherKey {
+    pub fn from_seed(seed: [u8; 32]) -> Self {
+        Self(SigningKey::from_bytes(&seed))
+    }
+
+    /// The seed as written by `openidea-plugin keygen`.
+    pub fn from_base64(text: &str) -> Result<Self, String> {
+        let bytes = B64.decode(text.trim()).map_err(|e| format!("key file: {e}"))?;
+        let seed: [u8; 32] = bytes.try_into().map_err(|_| "key file: expected a 32-byte key".to_owned())?;
+        Ok(Self::from_seed(seed))
+    }
+
+    pub fn seed_base64(&self) -> String {
+        B64.encode(self.0.to_bytes())
+    }
+
+    pub fn public_base64(&self) -> String {
+        B64.encode(self.0.verifying_key().to_bytes())
+    }
+
+    pub fn sign(&self, publisher: &str, id: &str, version: &str, digest: &str) -> PackageSignature {
+        let sig = self.0.sign(&signed_message(id, version, digest));
+        PackageSignature {
+            publisher: publisher.into(),
+            key: self.public_base64(),
+            signature: B64.encode(sig.to_bytes()),
+        }
+    }
+}
+
+impl PackageSignature {
+    /// Whether the signature is valid for `id`, `version` and `digest` (the
+    /// key's validity is checked against an [`Index`]).
+    pub fn check(&self, id: &str, version: &str, digest: &str) -> Result<(), String> {
+        let key: [u8; 32] = B64
+            .decode(&self.key)
+            .ok()
+            .and_then(|b| b.try_into().ok())
+            .ok_or_else(|| "signature: malformed public key".to_owned())?;
+        let key = VerifyingKey::from_bytes(&key).map_err(|_| "signature: invalid public key".to_owned())?;
+        let sig: [u8; 64] = B64
+            .decode(&self.signature)
+            .ok()
+            .and_then(|b| b.try_into().ok())
+            .ok_or_else(|| "signature: malformed".to_owned())?;
+        key.verify_strict(&signed_message(id, version, digest), &Signature::from_bytes(&sig))
+            .map_err(|_| "the signature does not match the package (it was changed after signing)".to_owned())
+    }
+}
+
+/// Writes the package `out` from `dir`: the manifest, `files`, and the signature if any.
+pub fn pack(dir: &Path, files: &[PathBuf], out: &Path, signature: Option<&PackageSignature>) -> Result<(), String> {
+    let io = |e: std::io::Error| e.to_string();
+    let file = std::fs::File::create(out).map_err(io)?;
+    let mut zip = zip::ZipWriter::new(file);
+    let options = zip::write::SimpleFileOptions::default().compression_method(zip::CompressionMethod::Deflated);
+    let mut names: Vec<PathBuf> = std::iter::once(PathBuf::from(MANIFEST_FILE)).chain(files.iter().cloned()).collect();
+    names.sort();
+    names.dedup();
+    for rel in names {
+        let name = rel.to_str().ok_or("non UTF-8 file name")?.replace('\\', "/");
+        zip.start_file(name, options).map_err(|e| e.to_string())?;
+        let bytes = std::fs::read(dir.join(&rel)).map_err(|e| format!("{}: {e}", rel.display()))?;
+        zip.write_all(&bytes).map_err(io)?;
+    }
+    if let Some(sig) = signature {
+        zip.start_file(SIGNATURE_FILE, options).map_err(|e| e.to_string())?;
+        zip.write_all(serde_json::to_string_pretty(sig).map_err(|e| e.to_string())?.as_bytes()).map_err(io)?;
+    }
+    zip.finish().map_err(|e| e.to_string())?;
+    Ok(())
+}
+
+/// What [`unpack`] wrote.
+#[derive(Debug)]
+pub struct Unpacked {
+    /// Every file but the manifest and the signature, relative.
+    pub files: Vec<PathBuf>,
+    pub signature: Option<PackageSignature>,
+}
+
+/// `name` as a relative path that stays inside the package.
+fn safe_path(name: &str) -> Option<PathBuf> {
+    let p = Path::new(name);
+    (!name.is_empty() && p.components().all(|c| matches!(c, Component::Normal(_)))).then(|| p.to_path_buf())
+}
+
+/// Archiver metadata at the top of an archive, not part of a package
+/// (`__MACOSX/…`, `.DS_Store`, AppleDouble `._…` files).
+fn archiver_metadata(name: &str) -> bool {
+    let top = name.split('/').next().unwrap_or_default();
+    top == "__MACOSX" || top == ".DS_Store" || (top.starts_with("._") && top.len() > 2)
+}
+
+/// Where the package is inside an archive: at its root (`.oiplugin`, or a zip
+/// of the package's contents) or in its only folder (a zip of the package
+/// folder). `None` when neither holds a manifest.
+fn package_prefix(names: &[String]) -> Option<String> {
+    if names.iter().any(|n| n == MANIFEST_FILE) {
+        return Some(String::new());
+    }
+    let mut tops = names.iter().filter(|n| !archiver_metadata(n)).map(|n| n.split('/').next().unwrap_or_default());
+    let top = tops.next()?;
+    if tops.any(|t| t != top) {
+        return None;
+    }
+    let prefix = format!("{top}/");
+    names.iter().any(|n| *n == format!("{prefix}{MANIFEST_FILE}")).then_some(prefix)
+}
+
+/// Extracts the package `archive` (an `.oiplugin`, or a `.zip` of a package
+/// folder or of its contents) into the empty directory `dest`, refusing
+/// paths leaving it, links, and oversized contents.
+pub fn unpack(archive: &Path, dest: &Path) -> Result<Unpacked, String> {
+    let file = std::fs::File::open(archive).map_err(|e| format!("{}: {e}", archive.display()))?;
+    let mut zip =
+        zip::ZipArchive::new(file).map_err(|e| format!("{}: not a plugin package ({e})", archive.display()))?;
+    if zip.len() > MAX_ENTRIES {
+        return Err(format!("more than {MAX_ENTRIES} files"));
+    }
+    let mut names = Vec::with_capacity(zip.len());
+    for i in 0..zip.len() {
+        let entry = zip.by_index(i).map_err(|e| e.to_string())?;
+        if !entry.is_dir() {
+            names.push(entry.name().map_err(|e| e.to_string())?.into_owned());
+        }
+    }
+    // An IntelliJ plugin or any other zip: say what is missing rather than fail later.
+    let prefix = package_prefix(&names).ok_or_else(|| {
+        format!("{} is not an OpenIDEA plugin: no {MANIFEST_FILE} at its root or in its only folder", archive.display())
+    })?;
+    std::fs::create_dir_all(dest).map_err(|e| e.to_string())?;
+    let (mut files, mut signature, mut total, mut manifest) = (Vec::new(), None, 0u64, false);
+    for i in 0..zip.len() {
+        let mut entry = zip.by_index(i).map_err(|e| e.to_string())?;
+        if entry.is_dir() {
+            continue;
+        }
+        let full = entry.name().map_err(|e| e.to_string())?.into_owned();
+        // Outside the package folder there is only archiver metadata (`package_prefix` checked).
+        let Some(name) = full.strip_prefix(&prefix).map(str::to_owned) else { continue };
+        if archiver_metadata(&name) {
+            continue;
+        }
+        if entry.is_symlink() {
+            return Err(format!("{full}: links are not allowed in packages"));
+        }
+        let rel = safe_path(&name).ok_or_else(|| format!("invalid path {full:?} in package"))?;
+        let mut bytes = Vec::new();
+        entry.by_ref().take(MAX_TOTAL - total + 1).read_to_end(&mut bytes).map_err(|e| e.to_string())?;
+        total += bytes.len() as u64;
+        if total > MAX_TOTAL {
+            return Err(format!("the package unpacks to more than {} MiB", MAX_TOTAL >> 20));
+        }
+        if rel == Path::new(SIGNATURE_FILE) {
+            signature = Some(serde_json::from_slice(&bytes).map_err(|e| format!("{SIGNATURE_FILE}: {e}"))?);
+            continue;
+        }
+        let to = dest.join(&rel);
+        if let Some(parent) = to.parent() {
+            std::fs::create_dir_all(parent).map_err(|e| e.to_string())?;
+        }
+        std::fs::write(&to, bytes).map_err(|e| e.to_string())?;
+        if rel == Path::new(MANIFEST_FILE) {
+            manifest = true;
+        } else {
+            files.push(rel);
+        }
+    }
+    if !manifest {
+        return Err(format!("the package has no {MANIFEST_FILE}"));
+    }
+    files.sort();
+    Ok(Unpacked { files, signature })
+}
+
+// ---- index -------------------------------------------------------------------
+
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct Index {
+    pub format: u32,
+    #[serde(default)]
+    pub publishers: Vec<Publisher>,
+    #[serde(default)]
+    pub plugins: Vec<IndexEntry>,
+    #[serde(default)]
+    pub revoked: Vec<Revocation>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct Publisher {
+    /// Owns plugin ids `<id>.…`.
+    pub id: String,
+    pub name: String,
+    pub keys: Vec<KeyEntry>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct KeyEntry {
+    /// Ed25519 public key, base64.
+    pub key: String,
+    /// Packages signed with it are no longer trusted.
+    #[serde(default)]
+    pub revoked: bool,
+}
+
+/// A published plugin version.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct IndexEntry {
+    pub id: String,
+    pub name: String,
+    pub version: String,
+    #[serde(default)]
+    pub description: String,
+    #[serde(default)]
+    pub authors: Vec<String>,
+    pub publisher: String,
+    /// The package, relative to the index (or an absolute URL).
+    pub download: String,
+    /// [`package_digest`] of its contents.
+    pub digest: String,
+    #[serde(default)]
+    pub capabilities: Vec<String>,
+}
+
+/// A plugin (all versions when `versions` is empty) that must not run.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct Revocation {
+    pub id: String,
+    #[serde(default)]
+    pub versions: Vec<String>,
+    pub reason: String,
+}
+
+impl Index {
+    pub fn parse(text: &str) -> Result<Self, String> {
+        let index: Index = serde_json::from_str(text).map_err(|e| format!("index: {e}"))?;
+        if index.format != INDEX_FORMAT {
+            return Err(format!("index format {} is not supported (this IDE reads {INDEX_FORMAT})", index.format));
+        }
+        Ok(index)
+    }
+
+    /// The revocation that applies to `id` at `version`.
+    pub fn revocation(&self, id: &str, version: &str) -> Option<&Revocation> {
+        self.revoked.iter().find(|r| r.id == id && (r.versions.is_empty() || r.versions.iter().any(|v| v == version)))
+    }
+
+    /// Whether `key` (base64) belongs to a publisher and was revoked.
+    pub fn key_revoked(&self, key: &str) -> bool {
+        self.publishers.iter().flat_map(|p| &p.keys).any(|k| k.key == key && k.revoked)
+    }
+
+    /// The trusted publisher of a signed package: the signature is valid, its
+    /// key is one of the publisher's and not revoked, and the publisher owns
+    /// the plugin's id prefix.
+    pub fn verify(&self, sig: &PackageSignature, id: &str, version: &str, digest: &str) -> Result<String, String> {
+        let publisher = self
+            .publishers
+            .iter()
+            .find(|p| p.id == sig.publisher)
+            .ok_or_else(|| format!("unknown publisher {:?}", sig.publisher))?;
+        let key = publisher
+            .keys
+            .iter()
+            .find(|k| k.key == sig.key)
+            .ok_or_else(|| format!("the key is not one of {}'s", publisher.name))?;
+        if key.revoked {
+            return Err(format!("{}'s signing key was revoked", publisher.name));
+        }
+        if !id.starts_with(&format!("{}.", publisher.id)) {
+            return Err(format!("{} may only publish plugins named {}.*", publisher.name, publisher.id));
+        }
+        sig.check(id, version, digest)?;
+        Ok(publisher.id.clone())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn package(dir: &Path) -> Vec<PathBuf> {
+        std::fs::create_dir_all(dir.join("dist")).unwrap();
+        std::fs::write(dir.join(MANIFEST_FILE), "id = \"acme.tools\"\nversion = \"1.0.0\"").unwrap();
+        std::fs::write(dir.join("dist/plugin.wasm"), b"\0asm").unwrap();
+        vec![PathBuf::from("dist/plugin.wasm")]
+    }
+
+    fn index(key: &PublisherKey) -> Index {
+        Index {
+            format: INDEX_FORMAT,
+            publishers: vec![Publisher {
+                id: "acme".into(),
+                name: "ACME".into(),
+                keys: vec![KeyEntry { key: key.public_base64(), revoked: false }],
+            }],
+            plugins: Vec::new(),
+            revoked: vec![Revocation {
+                id: "acme.bad".into(),
+                versions: vec!["1.0.0".into()],
+                reason: "malware".into(),
+            }],
+        }
+    }
+
+    #[test]
+    fn signed_packages_round_trip_and_tampering_is_caught() {
+        let tmp = tempfile::tempdir().unwrap();
+        let src = tmp.path().join("src");
+        let files = package(&src);
+        let digest = package_digest(&src, &files).unwrap();
+        let key = PublisherKey::from_seed([7; 32]);
+        let sig = key.sign("acme", "acme.tools", "1.0.0", &digest);
+        let out = tmp.path().join("acme.tools-1.0.0.oiplugin");
+        pack(&src, &files, &out, Some(&sig)).unwrap();
+
+        let dest = tmp.path().join("dest");
+        let unpacked = unpack(&out, &dest).unwrap();
+        assert_eq!(unpacked.files, files);
+        assert_eq!(package_digest(&dest, &unpacked.files).unwrap(), digest);
+        let index = index(&key);
+        assert_eq!(index.verify(unpacked.signature.as_ref().unwrap(), "acme.tools", "1.0.0", &digest).unwrap(), "acme");
+
+        // Changed bytes, another id, someone else's prefix, a revoked key.
+        assert!(index.verify(&sig, "acme.tools", "1.0.0", "0000").is_err());
+        assert!(index.verify(&sig, "acme.tools", "1.0.1", &digest).is_err());
+        let other = PublisherKey::from_seed([9; 32]).sign("acme", "acme.tools", "1.0.0", &digest);
+        assert!(index.verify(&other, "acme.tools", "1.0.0", &digest).unwrap_err().contains("not one of"));
+        let foreign = key.sign("acme", "evil.tools", "1.0.0", &digest);
+        assert!(index.verify(&foreign, "evil.tools", "1.0.0", &digest).unwrap_err().contains("acme.*"));
+        let mut revoked = index.clone();
+        revoked.publishers[0].keys[0].revoked = true;
+        assert!(revoked.verify(&sig, "acme.tools", "1.0.0", &digest).unwrap_err().contains("revoked"));
+        assert!(revoked.key_revoked(&sig.key));
+        assert_eq!(index.revocation("acme.bad", "1.0.0").unwrap().reason, "malware");
+        assert!(index.revocation("acme.bad", "1.0.1").is_none());
+        assert_eq!(PublisherKey::from_base64(&key.seed_base64()).unwrap().public_base64(), key.public_base64());
+    }
+
+    #[test]
+    fn unpacking_refuses_paths_leaving_the_package() {
+        let tmp = tempfile::tempdir().unwrap();
+        let out = tmp.path().join("evil.oiplugin");
+        let mut zip = zip::ZipWriter::new(std::fs::File::create(&out).unwrap());
+        let o = zip::write::SimpleFileOptions::default();
+        zip.start_file(MANIFEST_FILE, o).unwrap();
+        zip.write_all(b"id = \"x\"").unwrap();
+        zip.start_file("../outside.txt", o).unwrap();
+        zip.write_all(b"x").unwrap();
+        zip.finish().unwrap();
+        let err = unpack(&out, &tmp.path().join("dest")).unwrap_err();
+        assert!(err.contains("invalid path"), "{err}");
+        assert!(!tmp.path().join("outside.txt").exists());
+        assert!(Index::parse(r#"{"format": 2}"#).is_err());
+    }
+
+    fn zip_of(path: &Path, entries: &[(&str, &str)]) {
+        let mut zip = zip::ZipWriter::new(std::fs::File::create(path).unwrap());
+        for (name, body) in entries {
+            zip.start_file(*name, zip::write::SimpleFileOptions::default()).unwrap();
+            zip.write_all(body.as_bytes()).unwrap();
+        }
+        zip.finish().unwrap();
+    }
+
+    #[test]
+    fn a_zip_holds_the_package_at_its_root_or_in_its_only_folder() {
+        let tmp = tempfile::tempdir().unwrap();
+        let manifest = "id = \"acme.tools\"";
+        let at_root = tmp.path().join("root.zip");
+        zip_of(&at_root, &[(MANIFEST_FILE, manifest), ("dist/plugin.wasm", "w"), (".DS_Store", "x")]);
+        let got = unpack(&at_root, &tmp.path().join("a")).unwrap();
+        assert_eq!(got.files, [PathBuf::from("dist/plugin.wasm")]);
+
+        // What zipping the folder in Finder makes: the folder plus `__MACOSX`.
+        let folder = tmp.path().join("folder.zip");
+        zip_of(
+            &folder,
+            &[
+                ("acme-tools/plugin.toml", manifest),
+                ("acme-tools/dist/plugin.wasm", "w"),
+                ("__MACOSX/acme-tools/._plugin.toml", "x"),
+            ],
+        );
+        let dest = tmp.path().join("b");
+        let got = unpack(&folder, &dest).unwrap();
+        assert_eq!(got.files, [PathBuf::from("dist/plugin.wasm")]);
+        assert!(dest.join(MANIFEST_FILE).is_file());
+        assert!(!dest.join("__MACOSX").exists() && !dest.join("acme-tools").exists());
+
+        // Two folders, a manifest one level too deep, or none (an IntelliJ plugin): not a package.
+        for (name, entries) in [
+            ("two.zip", &[("a/plugin.toml", manifest), ("b/x.txt", "x")][..]),
+            ("deep.zip", &[("a/b/plugin.toml", manifest)][..]),
+            ("intellij.zip", &[("my-plugin/lib/my-plugin.jar", "jar")][..]),
+        ] {
+            let path = tmp.path().join(name);
+            zip_of(&path, entries);
+            let err = unpack(&path, &tmp.path().join(name).with_extension("out")).unwrap_err();
+            assert!(err.contains("is not an OpenIDEA plugin"), "{name}: {err}");
+        }
+    }
+}

crates/ide-extension/src/point.rs

@@ -0,0 +1,175 @@
+//! The extension point contract (plan 4.1).
+
+use crate::capability::Capability;
+use crate::manifest::{Manifest, check_relative};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+/// Where a contribution takes effect (plan 3, placement rules).
+#[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub enum Placement {
+    /// Projected to the client (menus, keybindings, themes, icons).
+    Ui,
+    /// Takes effect on the machine the project is on (languages, LSP, run configurations).
+    Workspace,
+}
+
+/// The package a declaration comes from, as extension points see it.
+#[derive(Clone, Debug)]
+pub struct Package {
+    pub manifest: Arc<Manifest>,
+    /// Package directory.
+    pub dir: PathBuf,
+    /// Hash of the package's files when they never change (an installed
+    /// copy): validated declarations are then reused from the
+    /// [`ContributionIndex`](crate::ContributionIndex).
+    pub digest: Option<Arc<str>>,
+}
+
+/// Largest single package file an extension point reads.
+pub const MAX_PACKAGE_FILE: u64 = 8 << 20;
+
+impl Package {
+    pub fn new(manifest: Manifest, dir: PathBuf) -> Self {
+        Self { manifest: Arc::new(manifest), dir, digest: None }
+    }
+
+    pub fn with_digest(mut self, digest: &str) -> Self {
+        self.digest = Some(digest.into());
+        self
+    }
+
+    pub fn id(&self) -> &str {
+        &self.manifest.id
+    }
+
+    /// Resolves a package-relative path, refusing anything that leaves the
+    /// package (`..`, absolute paths, symlinks pointing outside).
+    pub fn resolve(&self, rel: &Path) -> Result<PathBuf, String> {
+        check_relative(rel, "path")?;
+        let joined = self.dir.join(rel);
+        let real = joined.canonicalize().map_err(|_| format!("{}: no such file in the plugin", rel.display()))?;
+        let root = self.dir.canonicalize().map_err(|e| format!("plugin directory: {e}"))?;
+        if !real.starts_with(&root) {
+            return Err(format!("{}: points outside the plugin", rel.display()));
+        }
+        Ok(real)
+    }
+
+    pub fn read_bytes(&self, rel: &Path) -> Result<Vec<u8>, String> {
+        let real = self.resolve(rel)?;
+        let meta = std::fs::metadata(&real).map_err(|e| format!("{}: {e}", rel.display()))?;
+        if !meta.is_file() {
+            return Err(format!("{}: not a file", rel.display()));
+        }
+        if meta.len() > MAX_PACKAGE_FILE {
+            return Err(format!("{}: larger than {} MiB", rel.display(), MAX_PACKAGE_FILE >> 20));
+        }
+        std::fs::read(&real).map_err(|e| format!("{}: {e}", rel.display()))
+    }
+
+    pub fn read_text(&self, rel: &Path) -> Result<String, String> {
+        String::from_utf8(self.read_bytes(rel)?).map_err(|_| format!("{}: not UTF-8 text", rel.display()))
+    }
+}
+
+/// Undoes one committed contribution. Dropping without [`dispose`](Self::dispose) also disposes.
+#[must_use = "dropping a Disposable undoes the contribution"]
+pub struct Disposable(Option<Box<dyn FnOnce() + Send>>);
+
+impl Disposable {
+    pub fn new(f: impl FnOnce() + Send + 'static) -> Self {
+        Self(Some(Box::new(f)))
+    }
+
+    /// A contribution with nothing to undo.
+    pub fn noop() -> Self {
+        Self(None)
+    }
+
+    pub fn dispose(mut self) {
+        if let Some(f) = self.0.take() {
+            f();
+        }
+    }
+}
+
+impl Drop for Disposable {
+    fn drop(&mut self) {
+        if let Some(f) = self.0.take() {
+            f();
+        }
+    }
+}
+
+impl std::fmt::Debug for Disposable {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("Disposable")
+    }
+}
+
+pub type Commit = Box<dyn FnOnce() -> Result<Disposable, String> + Send>;
+
+/// A validated declaration, ready to take effect.
+pub struct Prepared {
+    /// Capabilities this declaration needs (a language with an LSP → `process:<binary>`).
+    pub capabilities: Vec<Capability>,
+    /// Package files the declaration references (copied on install).
+    pub files: Vec<PathBuf>,
+    /// Identity within the point: a later declaration with the same key replaces
+    /// the earlier one of the same plugin (re-registering a command).
+    pub key: Option<String>,
+    /// User-facing one-liner for the plugin details page ("Insert Date").
+    pub label: String,
+    /// Makes it take effect. Must not fail for reasons `prepare` could have checked.
+    pub commit: Commit,
+}
+
+impl Prepared {
+    pub fn new(label: impl Into<String>, commit: impl FnOnce() -> Result<Disposable, String> + Send + 'static) -> Self {
+        Self { capabilities: Vec::new(), files: Vec::new(), key: None, label: label.into(), commit: Box::new(commit) }
+    }
+
+    pub fn key(mut self, key: impl Into<String>) -> Self {
+        self.key = Some(key.into());
+        self
+    }
+
+    pub fn file(mut self, path: impl Into<PathBuf>) -> Self {
+        self.files.push(path.into());
+        self
+    }
+
+    pub fn capability(mut self, cap: Capability) -> Self {
+        if !self.capabilities.contains(&cap) {
+            self.capabilities.push(cap);
+        }
+        self
+    }
+}
+
+impl std::fmt::Debug for Prepared {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Prepared").field("key", &self.key).field("label", &self.label).finish_non_exhaustive()
+    }
+}
+
+/// A kind of contribution (`contributes.<id>` in the manifest). Implemented by
+/// the crate that owns the feature; registered once in an [`crate::ExtensionRegistry`].
+pub trait ExtensionPoint: Send + Sync {
+    /// `"languages"`, `"iconThemes"`, …
+    fn id(&self) -> &'static str;
+
+    fn placement(&self) -> Placement;
+
+    /// Parses and validates one declaration without side effects, and works
+    /// out the capabilities it needs. `Ui` points validate completely here: the
+    /// client's projection is not allowed to fail.
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String>;
+}
+
+/// Deserializes a declaration with serde, prefixing errors with the point id.
+pub fn decode<T: serde::de::DeserializeOwned>(point: &str, decl: toml::Value) -> Result<T, String> {
+    decl.try_into().map_err(|e: toml::de::Error| format!("contributes.{point}: {}", e.message()))
+}

crates/ide-extension/src/registry.rs

@@ -0,0 +1,305 @@
+//! Extension points plus the contributions committed to them, accounted per plugin.
+
+use crate::capability::Capability;
+use crate::point::{Disposable, ExtensionPoint, Package, Placement, Prepared};
+use parking_lot::{Mutex, RwLock};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+/// A contribution as the plugin details page lists it.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ContributionInfo {
+    pub point: String,
+    pub label: String,
+}
+
+struct Entry {
+    point: &'static str,
+    key: Option<String>,
+    label: String,
+    disposable: Disposable,
+}
+
+/// Every declaration of a package, validated; nothing has taken effect yet.
+pub struct PreparedSet {
+    pub plugin: String,
+    /// Union of what the declarations need (beyond the manifest's own list).
+    pub capabilities: Vec<Capability>,
+    /// Package files the declarations reference.
+    pub files: Vec<PathBuf>,
+    /// Declarations for extension points this host does not know (skipped).
+    pub warnings: Vec<String>,
+    items: Vec<(&'static str, Prepared)>,
+}
+
+impl PreparedSet {
+    pub fn is_empty(&self) -> bool {
+        self.items.is_empty()
+    }
+
+    pub fn len(&self) -> usize {
+        self.items.len()
+    }
+}
+
+impl std::fmt::Debug for PreparedSet {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("PreparedSet")
+            .field("plugin", &self.plugin)
+            .field("items", &self.items.len())
+            .field("warnings", &self.warnings)
+            .finish()
+    }
+}
+
+#[derive(Default)]
+pub struct ExtensionRegistry {
+    points: RwLock<BTreeMap<&'static str, Arc<dyn ExtensionPoint>>>,
+    /// plugin id → its contributions in commit order.
+    entries: Mutex<BTreeMap<String, Vec<Entry>>>,
+}
+
+impl ExtensionRegistry {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Adds an extension point. Ids are unique.
+    pub fn register(&self, point: Arc<dyn ExtensionPoint>) -> Result<(), String> {
+        let id = point.id();
+        crate::manifest::validate_point_id(id)?;
+        let mut points = self.points.write();
+        if points.contains_key(id) {
+            return Err(format!("extension point {id:?} is already registered"));
+        }
+        points.insert(id, point);
+        Ok(())
+    }
+
+    pub fn point_ids(&self) -> Vec<&'static str> {
+        self.points.read().keys().copied().collect()
+    }
+
+    pub fn placement(&self, point: &str) -> Option<Placement> {
+        self.points.read().get(point).map(|p| p.placement())
+    }
+
+    fn point(&self, id: &str) -> Option<Arc<dyn ExtensionPoint>> {
+        self.points.read().get(id).cloned()
+    }
+
+    /// Validates every `contributes.<point>` declaration of `pkg`. Fails as a
+    /// whole on the first invalid declaration; unknown points are skipped with
+    /// a warning (forward compatibility).
+    pub fn prepare(&self, pkg: &Package) -> Result<PreparedSet, String> {
+        let mut set = PreparedSet {
+            plugin: pkg.id().to_owned(),
+            capabilities: Vec::new(),
+            files: Vec::new(),
+            warnings: Vec::new(),
+            items: Vec::new(),
+        };
+        for point_id in pkg.manifest.contributes.keys() {
+            let Some(point) = self.point(point_id) else {
+                let msg = format!("contributes.{point_id}: not supported by this version of the IDE; skipped");
+                tracing::warn!(plugin = %pkg.id(), "{msg}");
+                set.warnings.push(msg);
+                continue;
+            };
+            for (i, decl) in pkg.manifest.declarations(point_id).into_iter().enumerate() {
+                let prepared = point
+                    .prepare(pkg, decl)
+                    .map_err(|e| format!("contributes.{point_id}[{i}]: {}", strip_prefix(&e, point_id)))?;
+                for cap in &prepared.capabilities {
+                    if !set.capabilities.contains(cap) {
+                        set.capabilities.push(cap.clone());
+                    }
+                }
+                for f in &prepared.files {
+                    if !set.files.contains(f) {
+                        set.files.push(f.clone());
+                    }
+                }
+                set.items.push((point.id(), prepared));
+            }
+        }
+        Ok(set)
+    }
+
+    /// Makes a prepared set take effect, all or nothing: if one commit fails,
+    /// the ones before it are disposed in reverse order.
+    pub fn commit(&self, set: PreparedSet) -> Result<(), String> {
+        let mut committed: Vec<Entry> = Vec::with_capacity(set.items.len());
+        for (point, prepared) in set.items {
+            let Prepared { key, label, commit, .. } = prepared;
+            match commit() {
+                Ok(disposable) => committed.push(Entry { point, key, label, disposable }),
+                Err(e) => {
+                    tracing::error!(plugin = %set.plugin, "contributes.{point}: commit failed: {e}");
+                    while let Some(entry) = committed.pop() {
+                        entry.disposable.dispose();
+                    }
+                    return Err(format!("contributes.{point}: {e}"));
+                }
+            }
+        }
+        let replaced = {
+            let mut entries = self.entries.lock();
+            let list = entries.entry(set.plugin).or_default();
+            let mut replaced = Vec::new();
+            for new in &committed {
+                if let Some(key) = &new.key
+                    && let Some(pos) = list.iter().position(|e| e.point == new.point && e.key.as_ref() == Some(key))
+                {
+                    replaced.push(list.remove(pos));
+                }
+            }
+            list.extend(committed);
+            replaced
+        };
+        for old in replaced.into_iter().rev() {
+            old.disposable.dispose();
+        }
+        Ok(())
+    }
+
+    /// Withdraws everything `plugin` contributed, newest first.
+    pub fn dispose_plugin(&self, plugin: &str) -> bool {
+        let list = self.entries.lock().remove(plugin).unwrap_or_default();
+        let any = !list.is_empty();
+        for entry in list.into_iter().rev() {
+            entry.disposable.dispose();
+        }
+        any
+    }
+
+    pub fn contributions(&self, plugin: &str) -> Vec<ContributionInfo> {
+        self.entries
+            .lock()
+            .get(plugin)
+            .map(|list| {
+                list.iter().map(|e| ContributionInfo { point: e.point.into(), label: e.label.clone() }).collect()
+            })
+            .unwrap_or_default()
+    }
+
+    /// How many contributions `plugin` has at `point`.
+    pub fn count(&self, plugin: &str, point: &str) -> usize {
+        self.entries.lock().get(plugin).map_or(0, |list| list.iter().filter(|e| e.point == point).count())
+    }
+
+    /// Plugins with at least one contribution.
+    pub fn plugins(&self) -> Vec<String> {
+        self.entries.lock().iter().filter(|(_, l)| !l.is_empty()).map(|(id, _)| id.clone()).collect()
+    }
+}
+
+fn strip_prefix<'a>(e: &'a str, point: &str) -> &'a str {
+    e.strip_prefix(&format!("contributes.{point}: ")).unwrap_or(e)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::manifest::Manifest;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    /// Records live items in a shared list; `fail = true` makes commit fail.
+    struct Recording {
+        id: &'static str,
+        live: Arc<Mutex<Vec<String>>>,
+        commits: Arc<AtomicUsize>,
+    }
+
+    impl ExtensionPoint for Recording {
+        fn id(&self) -> &'static str {
+            self.id
+        }
+        fn placement(&self) -> Placement {
+            Placement::Ui
+        }
+        fn prepare(&self, _pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+            let name = decl.get("name").and_then(|v| v.as_str()).ok_or("missing name")?.to_owned();
+            let fail = decl.get("fail").and_then(|v| v.as_bool()).unwrap_or(false);
+            let (live, commits) = (self.live.clone(), self.commits.clone());
+            let label = name.clone();
+            let mut p = Prepared::new(label, move || {
+                commits.fetch_add(1, Ordering::SeqCst);
+                if fail {
+                    return Err("boom".into());
+                }
+                live.lock().push(name.clone());
+                Ok(Disposable::new(move || live.lock().retain(|n| *n != name)))
+            });
+            if let Some(f) = decl.get("file").and_then(|v| v.as_str()) {
+                p = p.file(f);
+            }
+            if decl.get("key").and_then(|v| v.as_bool()).unwrap_or(false) {
+                p = p.key("k");
+            }
+            Ok(p)
+        }
+    }
+
+    fn setup() -> (ExtensionRegistry, Arc<Mutex<Vec<String>>>) {
+        let reg = ExtensionRegistry::new();
+        let live = Arc::new(Mutex::new(Vec::new()));
+        let commits = Arc::new(AtomicUsize::new(0));
+        reg.register(Arc::new(Recording { id: "things", live: live.clone(), commits: commits.clone() })).unwrap();
+        reg.register(Arc::new(Recording { id: "others", live: live.clone(), commits })).unwrap();
+        (reg, live)
+    }
+
+    fn pkg(contributes: &str) -> Package {
+        let src = format!("id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n{contributes}");
+        Package::new(Manifest::parse(&src).unwrap(), PathBuf::from("/nonexistent"))
+    }
+
+    #[test]
+    fn commits_and_disposes_per_plugin() {
+        let (reg, live) = setup();
+        assert!(
+            reg.register(Arc::new(Recording { id: "things", live: live.clone(), commits: Default::default() }))
+                .is_err()
+        );
+        let p = pkg(
+            "[[contributes.things]]\nname = \"a\"\nfile = \"x.json\"\n[[contributes.things]]\nname = \"b\"\n[contributes.others]\nname = \"c\"",
+        );
+        let set = reg.prepare(&p).unwrap();
+        assert_eq!(set.len(), 3);
+        assert_eq!(set.files, [PathBuf::from("x.json")]);
+        assert!(live.lock().is_empty(), "prepare has no side effects");
+        reg.commit(set).unwrap();
+        assert_eq!(*live.lock(), ["c", "a", "b"]);
+        assert_eq!(reg.count("p", "things"), 2);
+        assert_eq!(reg.contributions("p").len(), 3);
+        assert!(reg.dispose_plugin("p"));
+        assert!(live.lock().is_empty());
+    }
+
+    #[test]
+    fn a_failed_commit_rolls_back() {
+        let (reg, live) = setup();
+        let p = pkg("[[contributes.things]]\nname = \"a\"\n[[contributes.things]]\nname = \"b\"\nfail = true");
+        let err = reg.commit(reg.prepare(&p).unwrap()).unwrap_err();
+        assert!(err.contains("boom"));
+        assert!(live.lock().is_empty(), "a was undone");
+        assert!(reg.contributions("p").is_empty());
+    }
+
+    #[test]
+    fn invalid_declarations_fail_prepare_and_unknown_points_warn() {
+        let (reg, _) = setup();
+        let err = reg.prepare(&pkg("[[contributes.things]]\nnope = 1")).unwrap_err();
+        assert_eq!(err, "contributes.things[0]: missing name");
+        let set =
+            reg.prepare(&pkg("[[contributes.futureThing]]\nx = 1\n[[contributes.things]]\nname = \"a\"")).unwrap();
+        assert_eq!(set.len(), 1);
+        assert_eq!(set.warnings.len(), 1);
+        assert!(set.warnings[0].contains("futureThing"));
+    }
+}

crates/ide-extension/src/ui.rs

@@ -0,0 +1,247 @@
+//! UI contributions: validated declarations projected to the client.
+//!
+//! A `Ui` extension point validates a declaration completely in Rust and
+//! commits it as JSON into the [`UiStore`]; the client receives the store's
+//! snapshot and projects each item onto an existing `register*` function
+//! (`defineUiPoint` in `src/features/plugins/projection.ts`). Large payloads
+//! (icon SVGs) go into the store's assets and are fetched on demand.
+
+use crate::index::ContributionIndex;
+use crate::point::{Disposable, ExtensionPoint, Package, Placement, Prepared};
+use parking_lot::RwLock;
+use serde::{Deserialize, Serialize};
+use specta::Type;
+use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+/// One projected declaration.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct UiContribution {
+    pub plugin_id: String,
+    /// Extension point id (`commands`, `iconThemes`, …).
+    pub point: String,
+    /// Stable within (plugin, point): the client keys its registrations on it.
+    pub key: String,
+    /// The validated declaration, shaped by the point.
+    #[specta(type = specta_typescript::Unknown)]
+    pub decl: serde_json::Value,
+}
+
+struct Item {
+    seq: u64,
+    contribution: UiContribution,
+}
+
+/// Committed UI contributions of all plugins.
+#[derive(Default)]
+pub struct UiStore {
+    items: RwLock<Vec<Item>>,
+    /// (plugin, asset id) → content.
+    assets: RwLock<BTreeMap<(String, String), Arc<str>>>,
+    seq: AtomicU64,
+    revision: AtomicU64,
+    index: RwLock<Option<Arc<ContributionIndex>>>,
+}
+
+impl UiStore {
+    pub fn new() -> Arc<Self> {
+        Arc::new(Self::default())
+    }
+
+    /// Adds an item; the returned disposable removes it.
+    pub fn insert(self: &Arc<Self>, contribution: UiContribution) -> Disposable {
+        let seq = self.seq.fetch_add(1, Ordering::Relaxed);
+        self.items.write().push(Item { seq, contribution });
+        self.revision.fetch_add(1, Ordering::Release);
+        let store = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(store) = store.upgrade() {
+                store.items.write().retain(|i| i.seq != seq);
+                store.revision.fetch_add(1, Ordering::Release);
+            }
+        })
+    }
+
+    /// Stores assets of a plugin (ids are unique per plugin; later ones replace).
+    pub fn insert_assets(self: &Arc<Self>, plugin: &str, assets: Vec<(String, String)>) -> Disposable {
+        let keys: Vec<(String, String)> = assets.iter().map(|(id, _)| (plugin.to_owned(), id.clone())).collect();
+        {
+            let mut map = self.assets.write();
+            for (id, content) in assets {
+                map.insert((plugin.to_owned(), id), Arc::from(content));
+            }
+        }
+        let store = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(store) = store.upgrade() {
+                let mut map = store.assets.write();
+                for k in keys {
+                    map.remove(&k);
+                }
+            }
+        })
+    }
+
+    pub fn asset(&self, plugin: &str, id: &str) -> Option<Arc<str>> {
+        self.assets.read().get(&(plugin.to_owned(), id.to_owned())).cloned()
+    }
+
+    /// Assets of `plugin` whose id starts with `prefix`.
+    pub fn assets_with_prefix(&self, plugin: &str, prefix: &str) -> Vec<(String, Arc<str>)> {
+        self.assets
+            .read()
+            .range((plugin.to_owned(), prefix.to_owned())..)
+            .take_while(|((p, id), _)| p == plugin && id.starts_with(prefix))
+            .map(|((_, id), v)| (id.clone(), v.clone()))
+            .collect()
+    }
+
+    /// Where [`UiPoint`]s keep validated declarations of installed packages.
+    pub fn set_index(&self, index: Option<Arc<ContributionIndex>>) {
+        *self.index.write() = index;
+    }
+
+    /// Bumped on every change: clients compare it to skip re-projection.
+    pub fn revision(&self) -> u64 {
+        self.revision.load(Ordering::Acquire)
+    }
+
+    pub fn snapshot(&self) -> Vec<UiContribution> {
+        self.items.read().iter().map(|i| i.contribution.clone()).collect()
+    }
+
+    /// Items of one point, optionally of one plugin.
+    pub fn items(&self, point: &str, plugin: Option<&str>) -> Vec<UiContribution> {
+        self.items
+            .read()
+            .iter()
+            .filter(|i| i.contribution.point == point && plugin.is_none_or(|p| i.contribution.plugin_id == p))
+            .map(|i| i.contribution.clone())
+            .collect()
+    }
+}
+
+/// What a [`UiPoint`]'s validator produces for one declaration.
+#[derive(Debug, Serialize, Deserialize)]
+pub struct UiDecl {
+    pub key: String,
+    pub label: String,
+    pub json: serde_json::Value,
+    /// Package files referenced (copied on install).
+    pub files: Vec<PathBuf>,
+    /// Large validated payloads fetched separately by the client.
+    pub assets: Vec<(String, String)>,
+}
+
+impl UiDecl {
+    pub fn new(key: impl Into<String>, label: impl Into<String>, json: serde_json::Value) -> Self {
+        Self { key: key.into(), label: label.into(), json, files: Vec::new(), assets: Vec::new() }
+    }
+}
+
+type Validate = dyn Fn(&Package, toml::Value) -> Result<UiDecl, String> + Send + Sync;
+
+/// A `Ui` extension point defined by a validator: committing stores the
+/// validated JSON (and assets) in the [`UiStore`]. Most UI contribution types
+/// (menus, keybindings, status bar items, icon themes) are one of these.
+pub struct UiPoint {
+    id: &'static str,
+    store: Arc<UiStore>,
+    validate: Box<Validate>,
+}
+
+impl UiPoint {
+    pub fn new(
+        id: &'static str,
+        store: Arc<UiStore>,
+        validate: impl Fn(&Package, toml::Value) -> Result<UiDecl, String> + Send + Sync + 'static,
+    ) -> Self {
+        Self { id, store, validate: Box::new(validate) }
+    }
+}
+
+impl ExtensionPoint for UiPoint {
+    fn id(&self) -> &'static str {
+        self.id
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Ui
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let index = pkg.digest.as_ref().and_then(|_| self.store.index.read().clone());
+        let ui = match index.as_ref().and_then(|i| i.get(pkg, self.id, &decl)) {
+            Some(ui) => ui,
+            None => match &index {
+                Some(i) => {
+                    let ui = (self.validate)(pkg, decl.clone())?;
+                    i.put(pkg, self.id, &decl, &ui);
+                    ui
+                }
+                None => (self.validate)(pkg, decl)?,
+            },
+        };
+        let UiDecl { key, label, json, files, assets } = ui;
+        let store = self.store.clone();
+        let contribution =
+            UiContribution { plugin_id: pkg.id().to_owned(), point: self.id.to_owned(), key: key.clone(), decl: json };
+        let plugin = pkg.id().to_owned();
+        let mut prepared = Prepared::new(label, move || {
+            let item = store.insert(contribution);
+            if assets.is_empty() {
+                return Ok(item);
+            }
+            let assets = store.insert_assets(&plugin, assets);
+            Ok(Disposable::new(move || {
+                item.dispose();
+                assets.dispose();
+            }))
+        })
+        .key(key);
+        prepared.files = files;
+        Ok(prepared)
+    }
+}
+
+/// TOML declaration → JSON for the client.
+pub fn to_json(v: &toml::Value) -> serde_json::Value {
+    serde_json::to_value(v).unwrap_or(serde_json::Value::Null)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::manifest::Manifest;
+    use crate::registry::ExtensionRegistry;
+
+    #[test]
+    fn ui_point_projects_into_the_store() {
+        let store = UiStore::new();
+        let reg = ExtensionRegistry::new();
+        reg.register(Arc::new(UiPoint::new("badges", store.clone(), |_pkg, decl| {
+            let text = decl.get("text").and_then(|v| v.as_str()).ok_or("missing text")?.to_owned();
+            let mut d = UiDecl::new(text.clone(), text.clone(), serde_json::json!({ "text": text }));
+            d.assets.push((format!("badge/{text}"), "<svg/>".into()));
+            Ok(d)
+        })))
+        .unwrap();
+        let src = "id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n\
+                   [[contributes.badges]]\ntext = \"hi\"";
+        let pkg = Package::new(Manifest::parse(src).unwrap(), PathBuf::from("/x"));
+        let rev = store.revision();
+        reg.commit(reg.prepare(&pkg).unwrap()).unwrap();
+        assert!(store.revision() > rev);
+        let items = store.items("badges", Some("p"));
+        assert_eq!(items.len(), 1);
+        assert_eq!(items[0].decl["text"], "hi");
+        assert_eq!(store.asset("p", "badge/hi").as_deref(), Some("<svg/>"));
+        assert_eq!(store.assets_with_prefix("p", "badge/").len(), 1);
+        reg.dispose_plugin("p");
+        assert!(store.snapshot().is_empty());
+        assert!(store.asset("p", "badge/hi").is_none());
+    }
+}

crates/ide-extension/src/when.rs

@@ -0,0 +1,136 @@
+//! Syntax check for `when` clauses in UI declarations. The client evaluates
+//! them (`src/platform/context.ts`); validating here keeps the client's
+//! projection from failing. Grammar (same as the client):
+//!
+//! ```text
+//! expr := or ; or := and ("||" and)* ; and := unary ("&&" unary)*
+//! unary := "!" unary | "(" expr ")" | cmp ; cmp := key (("==" | "!=") value)?
+//! ```
+
+const MAX_LEN: usize = 512;
+
+#[derive(Debug, PartialEq)]
+enum Tok<'a> {
+    Id(&'a str),
+    Str,
+    Op(&'a str),
+}
+
+fn tokenize(src: &str) -> Result<Vec<Tok<'_>>, String> {
+    let mut out = Vec::new();
+    let b = src.as_bytes();
+    let mut i = 0;
+    while i < b.len() {
+        let c = b[i] as char;
+        if c.is_whitespace() {
+            i += 1;
+        } else if ["&&", "||", "==", "!="].iter().any(|op| src[i..].starts_with(op)) {
+            out.push(Tok::Op(&src[i..i + 2]));
+            i += 2;
+        } else if matches!(c, '!' | '(' | ')') {
+            out.push(Tok::Op(&src[i..i + 1]));
+            i += 1;
+        } else if c == '\'' || c == '"' {
+            let end = src[i + 1..].find(c).ok_or_else(|| format!("unterminated string in when clause: {src}"))?;
+            out.push(Tok::Str);
+            i += end + 2;
+        } else {
+            let len = src[i..]
+                .find(|ch: char| !(ch.is_alphanumeric() || matches!(ch, '_' | '.' | '-' | ':' | '/')))
+                .unwrap_or(src.len() - i);
+            if len == 0 {
+                return Err(format!("unexpected '{c}' in when clause: {src}"));
+            }
+            out.push(Tok::Id(&src[i..i + len]));
+            i += len;
+        }
+    }
+    Ok(out)
+}
+
+/// Checks a `when` clause; empty means "always".
+pub fn validate_when(src: &str) -> Result<(), String> {
+    if src.len() > MAX_LEN {
+        return Err(format!("when clause longer than {MAX_LEN} bytes"));
+    }
+    if src.trim().is_empty() {
+        return Ok(());
+    }
+    let toks = tokenize(src)?;
+    let mut p = 0;
+    parse_or(&toks, &mut p, src)?;
+    if p != toks.len() {
+        return Err(format!("unexpected token in when clause: {src}"));
+    }
+    Ok(())
+}
+
+fn parse_or(t: &[Tok], p: &mut usize, src: &str) -> Result<(), String> {
+    parse_and(t, p, src)?;
+    while t.get(*p) == Some(&Tok::Op("||")) {
+        *p += 1;
+        parse_and(t, p, src)?;
+    }
+    Ok(())
+}
+
+fn parse_and(t: &[Tok], p: &mut usize, src: &str) -> Result<(), String> {
+    parse_unary(t, p, src)?;
+    while t.get(*p) == Some(&Tok::Op("&&")) {
+        *p += 1;
+        parse_unary(t, p, src)?;
+    }
+    Ok(())
+}
+
+fn parse_unary(t: &[Tok], p: &mut usize, src: &str) -> Result<(), String> {
+    match t.get(*p) {
+        Some(Tok::Op("!")) => {
+            *p += 1;
+            parse_unary(t, p, src)
+        }
+        Some(Tok::Op("(")) => {
+            *p += 1;
+            parse_or(t, p, src)?;
+            if t.get(*p) != Some(&Tok::Op(")")) {
+                return Err(format!("missing ')' in when clause: {src}"));
+            }
+            *p += 1;
+            Ok(())
+        }
+        Some(Tok::Id(_)) => {
+            *p += 1;
+            if matches!(t.get(*p), Some(Tok::Op("==" | "!="))) {
+                *p += 1;
+                match t.get(*p) {
+                    Some(Tok::Id(_) | Tok::Str) => *p += 1,
+                    _ => return Err(format!("missing value after comparison in when clause: {src}")),
+                }
+            }
+            Ok(())
+        }
+        _ => Err(format!("expected a context key in when clause: {src}")),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::validate_when;
+
+    #[test]
+    fn accepts_the_client_grammar() {
+        for ok in [
+            "",
+            "editorFocus",
+            "editorLang == rust",
+            "editorLang != 'rust' && !readOnly",
+            "(a || b) && toolWindow.project.active",
+            "resourceScheme == file:/x",
+        ] {
+            assert!(validate_when(ok).is_ok(), "{ok}");
+        }
+        for bad in ["a &&", "(a", "a == ", "== a", "a b", "a $ b", "'x", "!()"] {
+            assert!(validate_when(bad).is_err(), "{bad}");
+        }
+    }
+}

crates/ide-host/Cargo.toml

@@ -30,15 +30,23 @@ ide-terminal.workspace = true
 ide-run.workspace = true
 ide-sdk.workspace = true
 ide-http.workspace = true
+reqwest.workspace = true
+ignore.workspace = true
+base64.workspace = true
+getrandom = "0.3"
+globset.workspace = true
 ide-db.workspace = true
 ide-ssh.workspace = true
 ide-remote.workspace = true
 ide-jsonrpc.workspace = true
 ide-agent.workspace = true
 ide-notebook.workspace = true
+ide-extension.workspace = true
+ide-plugin.workspace = true
 ide-tools = { path = "../ide-tools" }
 serde.workspace = true
 serde_json.workspace = true
+toml.workspace = true
 specta.workspace = true
 specta-typescript.workspace = true
 tokio = { workspace = true, features = ["io-std"] }
@@ -53,9 +61,15 @@ tempfile.workspace = true
 [dev-dependencies]
 ide-ssh = { workspace = true, features = ["testing"] }
 tokio = { workspace = true, features = ["rt-multi-thread", "macros", "io-util", "test-util"] }
+criterion = { version = "0.5", default-features = false }
+zip.workspace = true
 
 [target.'cfg(unix)'.dependencies]
 rustix = { version = "1.1", features = ["fs", "process"] }
 
 [target.'cfg(windows)'.dependencies]
 windows-sys = { version = "0.61", features = ["Win32_Storage_FileSystem"] }
+
+[[bench]]
+name = "plugins"
+harness = false

crates/ide-host/benches/plugins.rs

@@ -0,0 +1,149 @@
+//! `cargo bench -p ide-host`: the plugin runtime budgets, checked by `pnpm perf:rust` against
+//! `perf/budgets.json` › rust (`plugins/…`).
+//!
+//! - `load_50`: start-up load of 50 installed plugins (20 with code, 10
+//!   languages with a syntax provider, 10 icon themes, 10 declarations only),
+//!   from the contribution index; no Wasm is instantiated.
+//! - `cold_activation`: an idle-reclaimed plugin's next command: activation
+//!   from the precompiled component plus the call.
+//! - `syntax_highlights_2k_lines`: an edit-path call (Solidity highlighting).
+
+use criterion::{Criterion, black_box, criterion_group, criterion_main};
+use ide_core::LanguageId;
+use ide_host::plugins::{Consent, PluginHost};
+use ide_plugin::{Invocation, Limits};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::time::Duration;
+
+fn repo() -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../..").canonicalize().unwrap()
+}
+
+fn copy_dir(from: &Path, to: &Path) {
+    std::fs::create_dir_all(to).unwrap();
+    for e in std::fs::read_dir(from).unwrap().flatten() {
+        let name = e.file_name();
+        if matches!(name.to_str(), Some("target" | "src" | "Cargo.lock" | ".gitignore")) {
+            continue;
+        }
+        let dst = to.join(&name);
+        if e.path().is_dir() { copy_dir(&e.path(), &dst) } else { std::fs::copy(e.path(), &dst).map(|_| ()).unwrap() }
+    }
+}
+
+/// A copy of `src` installed under a new id (and new language / theme ids).
+fn variant(work: &Path, src: &Path, n: usize, rename: &[(&str, String)]) -> PathBuf {
+    let dir = work.join(format!("pkg{n}"));
+    copy_dir(src, &dir);
+    for file in ["plugin.toml", "languages/solidity.toml"] {
+        let path = dir.join(file);
+        if let Ok(mut text) = std::fs::read_to_string(&path) {
+            for (from, to) in rename {
+                text = text.replace(from, to);
+            }
+            std::fs::write(&path, text).unwrap();
+        }
+    }
+    dir
+}
+
+fn sink() -> Arc<dyn ide_host::plugins::PluginEventSink> {
+    Arc::new(|_: Option<&str>, _| {})
+}
+
+fn install_50(plugins: &Path, work: &Path) {
+    let host = PluginHost::new(plugins.to_path_buf(), sink(), Limits::default()).unwrap();
+    host.load_all();
+    let root = repo();
+    let mut n = 0;
+    let mut install = |src: PathBuf, rename: Vec<(&str, String)>| {
+        let pkg = variant(work, &src, n, &rename);
+        n += 1;
+        host.install_from_dir(&pkg, &Consent::default()).unwrap();
+    };
+    for i in 0..20 {
+        install(
+            root.join("crates/ide-plugin/tests/fixtures/hello"),
+            vec![("id = \"hello\"", format!("id = \"bench.hello{i}\""))],
+        );
+    }
+    for i in 0..10 {
+        install(
+            root.join("plugins/official/solidity"),
+            vec![
+                ("openidea.solidity", format!("bench.solidity{i}")),
+                ("id = \"solidity\"", format!("id = \"solidity{i}\"")),
+                ("extensions = [\"sol\"]", format!("extensions = [\"sol{i}\"]")),
+                ("on-language:solidity", format!("on-language:solidity{i}")),
+                ("id = \"forge-", format!("id = \"f{i}-")),
+                ("id = \"hardhat-", format!("id = \"h{i}-")),
+            ],
+        );
+    }
+    for i in 0..10 {
+        install(
+            root.join("plugins/official/material-icons"),
+            vec![
+                ("openidea.material-icons", format!("bench.icons{i}")),
+                ("id = \"material\"", format!("id = \"material{i}\"")),
+            ],
+        );
+    }
+    for i in 0..10 {
+        let dir = work.join(format!("static{i}"));
+        std::fs::create_dir_all(&dir).unwrap();
+        std::fs::write(
+            dir.join("plugin.toml"),
+            format!(
+                "id = \"bench.static{i}\"\nname = \"Static {i}\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n\
+                 [[contributes.commands]]\nid = \"a\"\ntitle = \"Static {i}: A\"\nwhen = \"editorLang == rust\"\n"
+            ),
+        )
+        .unwrap();
+        host.install_from_dir(&dir, &Consent::default()).unwrap();
+    }
+}
+
+fn bench(c: &mut Criterion) {
+    let tmp = tempfile::tempdir().unwrap();
+    let plugins = tmp.path().join("plugins");
+    install_50(&plugins, &tmp.path().join("work"));
+
+    let mut g = c.benchmark_group("plugins");
+    g.sample_size(20);
+    g.bench_function("load_50", |b| {
+        b.iter(|| {
+            let host = PluginHost::new(plugins.clone(), sink(), Limits::default()).unwrap();
+            host.load_all();
+            assert_eq!(host.instances(), 0, "start-up instantiates no Wasm");
+            black_box(host.list(None).plugins.len())
+        })
+    });
+
+    let limits = Limits { idle_timeout: Some(Duration::ZERO), ..Limits::default() };
+    let host = Arc::new(PluginHost::new(plugins.clone(), sink(), limits).unwrap());
+    host.load_all();
+    host.warm_component_cache();
+    g.bench_function("cold_activation", |b| {
+        b.iter(|| {
+            host.tick();
+            // Fails for want of an editor, after activating and running.
+            let r = host.run_command("bench.hello0", "word-count", None, Invocation::default());
+            black_box(r.is_err())
+        })
+    });
+
+    let provider = host.syntax_provider();
+    let lang = LanguageId::new("solidity0");
+    let unit = "contract Token {\n    uint256 public total;\n    mapping(address => uint256) balances;\n    event Sent(address to, uint256 v);\n    function send(address to, uint256 v) public returns (bool) {\n        // move funds\n        balances[to] += v;\n        emit Sent(to, v);\n        return true;\n    }\n}\n";
+    let text = unit.repeat(2000 / unit.lines().count());
+    assert!(provider.highlights(&lang, &text).is_some());
+    g.bench_function("syntax_highlights_2k_lines", |b| {
+        b.iter(|| black_box(provider.highlights(&lang, &text).map(|t| t.len())))
+    });
+    g.finish();
+}
+
+criterion_group!(benches, bench);
+criterion_main!(benches);

crates/ide-host/src/bin/openidea-plugin/main.rs

@@ -0,0 +1,624 @@
+//! `openidea-plugin`: scaffolds, builds, checks and links OpenIDEA plugins.
+//!
+//! ```text
+//! openidea-plugin new <dir> [--template command|theme|icon-theme|language] [--id ID] [--name NAME] [--sdk PATH]
+//! openidea-plugin build [dir] [--debug]   # cargo → dist/plugin.wasm, then `check`
+//! openidea-plugin check [dir]             # validate the package as the IDE would install it
+//! openidea-plugin link [dir]              # load the folder in the IDE without installing it
+//! openidea-plugin unlink [dir]
+//! openidea-plugin links                   # list linked folders
+//! openidea-plugin keygen <key-file>       # a publisher's Ed25519 key
+//! openidea-plugin pack [dir] [--key F --publisher ID] [--out FILE]   # <id>-<version>.oiplugin
+//! openidea-plugin index <dir> --publisher ID --name NAME --key F     # marketplace index.json
+//! ```
+//!
+//! `link` writes `links.json` in the IDE's plugins directory
+//! (`$OPENIDEA_PLUGINS_DIR`, or the app data directory); the IDE picks the
+//! change up when Settings › Plugins is opened or refreshed. Linked plugins
+//! are re-read from the folder, so `build` + refresh is the edit loop.
+
+mod templates;
+
+use ide_extension::{Manifest, validate_plugin_id};
+use ide_host::plugins::PluginHost;
+use ide_plugin::{Limits, PluginEngine};
+use std::path::{Path, PathBuf};
+use std::process::{Command, ExitCode};
+use std::sync::Arc;
+
+const USAGE: &str = "\
+usage: openidea-plugin <command> [options]
+
+commands:
+  new <dir> [--template T] [--id ID] [--name NAME] [--sdk PATH]
+        create a plugin; T = command (default), theme, icon-theme, language
+  build [dir] [--debug]   compile a Rust plugin to dist/plugin.wasm and check it
+  check [dir]             validate the package as the IDE would install it
+  link [dir]              load the folder in the IDE without installing it
+  unlink [dir]            stop loading a linked folder
+  links                   list linked folders
+  keygen <key-file>       create a publisher signing key (keep the file secret)
+  pack [dir] [--key F --publisher ID] [--out FILE]
+                          write <id>-<version>.oiplugin, signed with the key
+  index <dir> --publisher ID --name NAME --key F [--out FILE]
+                          write the marketplace index.json for the packages in dir
+
+environment:
+  OPENIDEA_PLUGINS_DIR    the IDE's plugins directory (default: the app data directory)";
+
+fn main() -> ExitCode {
+    let args: Vec<String> = std::env::args().skip(1).collect();
+    let result = match args.first().map(String::as_str) {
+        Some("new") => cmd_new(&args[1..]),
+        Some("build") => cmd_build(&args[1..]),
+        Some("check") => dir_arg(&args[1..]).and_then(|d| check(&d)),
+        Some("link") => dir_arg(&args[1..]).and_then(|d| link(&d, true)),
+        Some("unlink") => dir_arg(&args[1..]).and_then(|d| link(&d, false)),
+        Some("links") => list_links(),
+        Some("keygen") => cmd_keygen(&args[1..]),
+        Some("pack") => cmd_pack(&args[1..]),
+        Some("index") => cmd_index(&args[1..]),
+        Some("--version" | "-V") => {
+            println!("openidea-plugin {} (plugin API {})", env!("CARGO_PKG_VERSION"), ide_extension::ENGINE_VERSION);
+            Ok(())
+        }
+        Some("help" | "--help" | "-h") | None => {
+            println!("{USAGE}");
+            Ok(())
+        }
+        Some(other) => Err(format!("unknown command {other:?}\n\n{USAGE}")),
+    };
+    match result {
+        Ok(()) => ExitCode::SUCCESS,
+        Err(e) => {
+            eprintln!("error: {e}");
+            ExitCode::FAILURE
+        }
+    }
+}
+
+/// Splits `args` into positionals and `--flag value` / `--switch` options.
+struct Args {
+    positional: Vec<String>,
+    options: Vec<(String, Option<String>)>,
+}
+
+impl Args {
+    fn parse(args: &[String], switches: &[&str], valued: &[&str]) -> Result<Self, String> {
+        let mut out = Args { positional: Vec::new(), options: Vec::new() };
+        let mut it = args.iter();
+        while let Some(a) = it.next() {
+            if let Some(name) = a.strip_prefix("--") {
+                let (name, inline) = match name.split_once('=') {
+                    Some((n, v)) => (n, Some(v.to_owned())),
+                    None => (name, None),
+                };
+                if switches.contains(&name) && inline.is_none() {
+                    out.options.push((name.into(), None));
+                } else if valued.contains(&name) {
+                    let v = inline.or_else(|| it.next().cloned()).ok_or_else(|| format!("--{name} needs a value"))?;
+                    out.options.push((name.into(), Some(v)));
+                } else {
+                    return Err(format!("unknown option --{name}"));
+                }
+            } else {
+                out.positional.push(a.clone());
+            }
+        }
+        Ok(out)
+    }
+
+    fn value(&self, name: &str) -> Option<&str> {
+        self.options.iter().rev().find(|(n, _)| n == name).and_then(|(_, v)| v.as_deref())
+    }
+
+    fn has(&self, name: &str) -> bool {
+        self.options.iter().any(|(n, _)| n == name)
+    }
+
+    fn dir(&self) -> Result<PathBuf, String> {
+        match self.positional.as_slice() {
+            [] => Ok(PathBuf::from(".")),
+            [d] => Ok(PathBuf::from(d)),
+            _ => Err("expected at most one directory".into()),
+        }
+    }
+}
+
+fn dir_arg(args: &[String]) -> Result<PathBuf, String> {
+    Args::parse(args, &[], &[])?.dir()
+}
+
+fn canonical(dir: &Path) -> Result<PathBuf, String> {
+    dunce::canonicalize(dir).map_err(|e| format!("{}: {e}", dir.display()))
+}
+
+// ---------------------------------------------------------------- new
+
+fn cmd_new(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &[], &["template", "id", "name", "sdk"])?;
+    let [dir] = a.positional.as_slice() else {
+        return Err("usage: openidea-plugin new <dir> [--template T] [--id ID] [--name NAME]".into());
+    };
+    let dir = PathBuf::from(dir);
+    let template = templates::Template::parse(a.value("template").unwrap_or("command"))?;
+    let base = dir.file_name().and_then(|n| n.to_str()).ok_or("the directory needs a name")?;
+    let id = match a.value("id") {
+        Some(id) => id.to_owned(),
+        None => slugify(base),
+    };
+    validate_plugin_id(&id)?;
+    let name = match a.value("name") {
+        Some(n) => n.to_owned(),
+        None => title_case(id.rsplit('.').next().unwrap_or(&id)),
+    };
+    if name.trim().is_empty() || name.contains(['"', '\\', '\n']) {
+        return Err("--name must not be empty or contain quotes, backslashes or newlines".into());
+    }
+    if dir.exists() && std::fs::read_dir(&dir).map_err(|e| e.to_string())?.next().is_some() {
+        return Err(format!("{} already exists and is not empty", dir.display()));
+    }
+    std::fs::create_dir_all(&dir).map_err(|e| format!("{}: {e}", dir.display()))?;
+    let dir = canonical(&dir)?;
+    let sdk = match template {
+        templates::Template::Command => Some(sdk_path(a.value("sdk"), &dir)?),
+        _ => None,
+    };
+    let vars = templates::Vars { id: &id, name: &name, sdk: sdk.as_deref() };
+    let files = templates::render(template, &vars);
+    for (rel, content) in &files {
+        let path = dir.join(rel);
+        if let Some(parent) = path.parent() {
+            std::fs::create_dir_all(parent).map_err(|e| format!("{}: {e}", parent.display()))?;
+        }
+        std::fs::write(&path, content).map_err(|e| format!("{}: {e}", path.display()))?;
+    }
+    // Generated packages must be valid as written.
+    Manifest::load(&dir).map_err(|e| format!("internal error: the template is invalid: {e}"))?;
+    println!("created {} ({id}) in {}", template.label(), dir.display());
+    let shown = std::env::current_dir().ok().and_then(|cwd| dir.strip_prefix(cwd).ok().map(Path::to_path_buf));
+    let shown = shown.as_deref().unwrap_or(&dir).display().to_string();
+    println!();
+    println!("next:");
+    if template == templates::Template::Command {
+        println!("  cargo test --manifest-path {shown}/Cargo.toml   # unit tests against the mock host");
+        println!("  openidea-plugin build {shown}");
+    } else {
+        println!("  openidea-plugin check {shown}");
+    }
+    println!("  openidea-plugin link {shown}                  # then Settings › Plugins");
+    Ok(())
+}
+
+/// `My Cool_Plugin` → `my-cool-plugin`.
+fn slugify(s: &str) -> String {
+    let mut out = String::new();
+    for c in s.chars() {
+        match c {
+            'a'..='z' | '0'..='9' | '.' => out.push(c),
+            'A'..='Z' => out.push(c.to_ascii_lowercase()),
+            _ if !out.ends_with('-') && !out.is_empty() => out.push('-'),
+            _ => {}
+        }
+    }
+    out.trim_matches(['-', '.']).to_owned()
+}
+
+/// `my-cool_plugin` → `My Cool Plugin`.
+fn title_case(s: &str) -> String {
+    s.split(['-', '_'])
+        .filter(|w| !w.is_empty())
+        .map(|w| {
+            let mut c = w.chars();
+            c.next().map(|f| f.to_uppercase().chain(c).collect::<String>()).unwrap_or_default()
+        })
+        .collect::<Vec<_>>()
+        .join(" ")
+}
+
+/// The SDK dependency path written into a new plugin's Cargo.toml: `--sdk`,
+/// or the SDK of the source tree this tool was built from.
+fn sdk_path(explicit: Option<&str>, plugin_dir: &Path) -> Result<String, String> {
+    let sdk = match explicit {
+        Some(p) => PathBuf::from(p),
+        None => PathBuf::from(concat!(env!("CARGO_MANIFEST_DIR"), "/../../sdk/rust/openidea-plugin")),
+    };
+    let sdk = dunce::canonicalize(&sdk).map_err(|_| {
+        format!("the plugin SDK was not found at {}; pass --sdk <path to sdk/rust/openidea-plugin>", sdk.display())
+    })?;
+    if !sdk.join("Cargo.toml").is_file() {
+        return Err(format!("{} is not the openidea-plugin SDK (no Cargo.toml)", sdk.display()));
+    }
+    let path = relative(plugin_dir, &sdk).unwrap_or(sdk);
+    Ok(path.to_string_lossy().replace('\\', "/"))
+}
+
+/// `to` relative to `from` when they share a root (keeps packages in a repo movable).
+fn relative(from: &Path, to: &Path) -> Option<PathBuf> {
+    let (f, t): (Vec<_>, Vec<_>) = (from.components().collect(), to.components().collect());
+    let common = f.iter().zip(&t).take_while(|(a, b)| a == b).count();
+    if common <= 1 {
+        return None;
+    }
+    let mut out = PathBuf::new();
+    for _ in common..f.len() {
+        out.push("..");
+    }
+    for c in &t[common..] {
+        out.push(c);
+    }
+    Some(out)
+}
+
+// ---------------------------------------------------------------- build / check
+
+fn cmd_build(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &["debug"], &[])?;
+    let dir = canonical(&a.dir()?)?;
+    let manifest = Manifest::load(&dir)?;
+    let cargo_toml = dir.join("Cargo.toml");
+    if !cargo_toml.is_file() {
+        if manifest.wasm.is_some() {
+            return Err(format!(
+                "{} has no Cargo.toml: build the component with your toolchain, then run `check`",
+                dir.display()
+            ));
+        }
+        println!("{} has no code to build", manifest.id);
+        return check(&dir);
+    }
+    let wasm_rel = manifest.wasm.clone().ok_or("plugin.toml has no `wasm = \"dist/plugin.wasm\"`")?;
+    let crate_name = crate_name(&cargo_toml)?;
+    ensure_wasm_target();
+    let release = !a.has("debug");
+    let target_dir = std::env::var_os("CARGO_TARGET_DIR").map(PathBuf::from).unwrap_or_else(|| dir.join("target"));
+    let mut cmd = Command::new(std::env::var_os("CARGO").unwrap_or_else(|| "cargo".into()));
+    cmd.arg("build").arg("--manifest-path").arg(&cargo_toml).args(["--target", "wasm32-wasip2"]);
+    if release {
+        cmd.arg("--release");
+    }
+    cmd.env("CARGO_TARGET_DIR", &target_dir);
+    println!("building {crate_name} for wasm32-wasip2 ({})", if release { "release" } else { "debug" });
+    let status = cmd.status().map_err(|e| format!("cannot run cargo: {e}"))?;
+    if !status.success() {
+        return Err("cargo build failed".into());
+    }
+    let built = target_dir
+        .join("wasm32-wasip2")
+        .join(if release { "release" } else { "debug" })
+        .join(format!("{}.wasm", crate_name.replace('-', "_")));
+    if !built.is_file() {
+        return Err(format!("{} was not produced: is `crate-type = [\"cdylib\"]` set in Cargo.toml?", built.display()));
+    }
+    let out = dir.join(&wasm_rel);
+    if let Some(parent) = out.parent() {
+        std::fs::create_dir_all(parent).map_err(|e| format!("{}: {e}", parent.display()))?;
+    }
+    std::fs::copy(&built, &out).map_err(|e| format!("{}: {e}", out.display()))?;
+    let size = std::fs::metadata(&out).map(|m| m.len()).unwrap_or(0);
+    println!("  -> {} ({})", wasm_rel.display(), human_size(size));
+    check(&dir)
+}
+
+fn crate_name(cargo_toml: &Path) -> Result<String, String> {
+    let src = std::fs::read_to_string(cargo_toml).map_err(|e| format!("{}: {e}", cargo_toml.display()))?;
+    let doc: toml::Table = src.parse().map_err(|e| format!("{}: {e}", cargo_toml.display()))?;
+    let package = doc.get("package").and_then(|p| p.as_table());
+    let lib_name = doc.get("lib").and_then(|l| l.get("name")).and_then(|n| n.as_str());
+    lib_name
+        .or_else(|| package.and_then(|p| p.get("name")).and_then(|n| n.as_str()))
+        .map(str::to_owned)
+        .ok_or_else(|| format!("{}: no [package] name", cargo_toml.display()))
+}
+
+/// Installs the target through rustup when it is missing (no-op without rustup).
+fn ensure_wasm_target() {
+    let Ok(out) = Command::new("rustup").args(["target", "list", "--installed"]).output() else { return };
+    if String::from_utf8_lossy(&out.stdout).lines().any(|l| l.trim() == "wasm32-wasip2") {
+        return;
+    }
+    println!("installing the wasm32-wasip2 target");
+    let _ = Command::new("rustup").args(["target", "add", "wasm32-wasip2"]).status();
+}
+
+/// Validates `dir` exactly as Install from Disk would, and checks the
+/// component imports only the plugin API.
+fn check(dir: &Path) -> Result<(), String> {
+    let dir = canonical(dir)?;
+    let scratch = std::env::temp_dir().join(format!("openidea-plugin-check-{}", std::process::id()));
+    let result = (|| {
+        let host = PluginHost::new(scratch.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default())
+            .map_err(|e| e.to_string())?;
+        let preview = host.preview_install(&dir).map_err(|e| e.to_string())?;
+        let manifest = Manifest::load(&dir)?;
+        println!("{} {} — {}", preview.id, preview.version, preview.name);
+        if manifest.legacy {
+            println!("  note: plugin.toml uses the 0.1 format (`openidea-api`); see plugins/README.md to move to 0.2");
+        }
+        if let Some(wasm) = &manifest.wasm {
+            let engine = PluginEngine::new()?;
+            let component = engine.compile(&dir.join(wasm))?;
+            let built_for = engine.check_component(&component)?;
+            let size = std::fs::metadata(dir.join(wasm)).map(|m| m.len()).unwrap_or(0);
+            let api = built_for.map(|v| format!(", plugin API {}.{}", v.major, v.minor)).unwrap_or_default();
+            println!("  code: {} ({}{api})", wasm.display(), human_size(size));
+        } else {
+            println!("  code: none (contributions only)");
+        }
+        if !manifest.activation.is_empty() {
+            let events: Vec<String> = manifest.activation.iter().map(ToString::to_string).collect();
+            println!("  activation: {}", events.join(", "));
+        }
+        for c in &preview.contributions {
+            println!("  contributes {} × {}", c.count, c.point);
+        }
+        for c in &preview.capabilities {
+            let kind = if c.optional { "optional" } else { "required" };
+            println!("  capability {} ({kind}, {:?} risk): {}", c.id, c.risk, c.description);
+        }
+        for w in &preview.warnings {
+            println!("  warning: {w}");
+        }
+        println!("ok");
+        Ok(())
+    })();
+    let _ = std::fs::remove_dir_all(&scratch);
+    result
+}
+
+fn human_size(bytes: u64) -> String {
+    match bytes {
+        b if b >= 1 << 20 => format!("{:.1} MiB", b as f64 / (1 << 20) as f64),
+        b if b >= 1 << 10 => format!("{:.1} KiB", b as f64 / 1024.0),
+        b => format!("{b} B"),
+    }
+}
+
+// ---------------------------------------------------------------- link
+
+fn plugins_dir() -> Result<PathBuf, String> {
+    if let Some(dir) = std::env::var_os("OPENIDEA_PLUGINS_DIR") {
+        return Ok(PathBuf::from(dir));
+    }
+    dirs::data_dir()
+        .map(|d| d.join("ai.l0ng.openidea").join("plugins"))
+        .ok_or_else(|| "cannot find the app data directory; set OPENIDEA_PLUGINS_DIR".into())
+}
+
+#[derive(Default, serde::Serialize, serde::Deserialize)]
+struct Links {
+    #[serde(default)]
+    paths: Vec<PathBuf>,
+}
+
+fn read_links(file: &Path) -> Result<Links, String> {
+    match std::fs::read_to_string(file) {
+        Ok(s) => serde_json::from_str(&s).map_err(|e| format!("{}: {e}", file.display())),
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(Links::default()),
+        Err(e) => Err(format!("{}: {e}", file.display())),
+    }
+}
+
+fn link(dir: &Path, add: bool) -> Result<(), String> {
+    let plugins = plugins_dir()?;
+    let file = plugins.join("links.json");
+    let mut links = read_links(&file)?;
+    let dir = if add {
+        let dir = canonical(dir)?;
+        let m = Manifest::load(&dir)?;
+        if let Some(wasm) = &m.wasm
+            && !dir.join(wasm).is_file()
+        {
+            println!("note: {} does not exist yet; run `openidea-plugin build` first", wasm.display());
+        }
+        if links.paths.contains(&dir) {
+            println!("{} is already linked", dir.display());
+            return Ok(());
+        }
+        println!("linked {} ({})", m.id, dir.display());
+        links.paths.push(dir.clone());
+        dir
+    } else {
+        let dir = dunce::canonicalize(dir).unwrap_or_else(|_| dir.to_path_buf());
+        let before = links.paths.len();
+        links.paths.retain(|p| p != &dir);
+        if links.paths.len() == before {
+            return Err(format!("{} is not linked", dir.display()));
+        }
+        println!("unlinked {}", dir.display());
+        dir
+    };
+    let _ = dir;
+    std::fs::create_dir_all(&plugins).map_err(|e| format!("{}: {e}", plugins.display()))?;
+    let json = serde_json::to_string_pretty(&links).map_err(|e| e.to_string())?;
+    let tmp = file.with_extension("json.tmp");
+    std::fs::write(&tmp, json)
+        .and_then(|()| std::fs::rename(&tmp, &file))
+        .map_err(|e| format!("{}: {e}", file.display()))?;
+    println!("open Settings › Plugins in OpenIDEA to load the change");
+    Ok(())
+}
+
+fn list_links() -> Result<(), String> {
+    let links = read_links(&plugins_dir()?.join("links.json"))?;
+    if links.paths.is_empty() {
+        println!("no linked plugins");
+    }
+    for p in links.paths {
+        let id = Manifest::load(&p).map(|m| m.id).unwrap_or_else(|e| format!("invalid: {e}"));
+        println!("{id}\t{}", p.display());
+    }
+    Ok(())
+}
+
+// ---------------------------------------------------------------- distribution
+
+use ide_extension::package::{self, Index, IndexEntry, KeyEntry, PublisherKey};
+
+fn read_key(path: &str) -> Result<PublisherKey, String> {
+    PublisherKey::from_base64(&std::fs::read_to_string(path).map_err(|e| format!("{path}: {e}"))?)
+}
+
+fn cmd_keygen(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &[], &[])?;
+    let [file] = a.positional.as_slice() else { return Err("usage: openidea-plugin keygen <key-file>".into()) };
+    if Path::new(file).exists() {
+        return Err(format!("{file} exists; not overwriting a key"));
+    }
+    let mut seed = [0u8; 32];
+    getrandom::fill(&mut seed).map_err(|e| format!("random: {e}"))?;
+    let key = PublisherKey::from_seed(seed);
+    std::fs::write(file, key.seed_base64()).map_err(|e| format!("{file}: {e}"))?;
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        let _ = std::fs::set_permissions(file, std::fs::Permissions::from_mode(0o600));
+    }
+    println!("public key: {}", key.public_base64());
+    println!("register it with your publisher id in the marketplace index; keep {file} secret");
+    Ok(())
+}
+
+/// A scratch host to list a package's files as the IDE would.
+fn with_scratch_host<T>(f: impl FnOnce(&PluginHost) -> Result<T, String>) -> Result<T, String> {
+    let scratch = std::env::temp_dir().join(format!("openidea-plugin-pack-{}", std::process::id()));
+    let result = PluginHost::new(scratch.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default())
+        .map_err(|e| e.to_string())
+        .and_then(|h| f(&h));
+    let _ = std::fs::remove_dir_all(&scratch);
+    result
+}
+
+fn cmd_pack(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &[], &["key", "publisher", "out"])?;
+    let dir = canonical(&a.dir()?)?;
+    check(&dir)?;
+    let manifest = Manifest::load(&dir)?;
+    let mut files = with_scratch_host(|h| h.package_files_of(&dir).map_err(|e| e.to_string()))?;
+    let digest = package::package_digest(&dir, &files).map_err(|e| e.to_string())?;
+    let signature = match (a.value("key"), a.value("publisher")) {
+        (Some(key), Some(publisher)) => {
+            if !manifest.id.starts_with(&format!("{publisher}.")) {
+                return Err(format!("publisher {publisher:?} may only sign plugins named {publisher}.*"));
+            }
+            Some(read_key(key)?.sign(publisher, &manifest.id, &manifest.version, &digest))
+        }
+        (None, None) => None,
+        _ => return Err("--key and --publisher go together".into()),
+    };
+    for lic in ["LICENSE", "LICENSE.md", "LICENSE.txt", "NOTICE", "NOTICE.md", "COPYING", "README.md"] {
+        if dir.join(lic).is_file() {
+            files.push(PathBuf::from(lic));
+        }
+    }
+    let out = a.value("out").map(PathBuf::from).unwrap_or_else(|| {
+        PathBuf::from(format!("{}-{}.{}", manifest.id, manifest.version, package::PACKAGE_EXTENSION))
+    });
+    package::pack(&dir, &files, &out, signature.as_ref())?;
+    let size = std::fs::metadata(&out).map(|m| m.len()).unwrap_or(0);
+    let signed = signature.as_ref().map_or("unsigned".to_owned(), |s| format!("signed by {}", s.publisher));
+    println!("-> {} ({}, {signed})", out.display(), human_size(size));
+    Ok(())
+}
+
+fn cmd_index(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &[], &["publisher", "name", "key", "out"])?;
+    let dir = canonical(&a.dir()?)?;
+    let publisher = a.value("publisher").ok_or("--publisher is required")?;
+    let name = a.value("name").unwrap_or(publisher);
+    let key = read_key(a.value("key").ok_or("--key is required")?)?;
+    let out = a.value("out").map(PathBuf::from).unwrap_or_else(|| dir.join("index.json"));
+    // Revocations and other publishers of an existing index are kept.
+    let mut index = match std::fs::read_to_string(&out) {
+        Ok(text) => Index::parse(&text)?,
+        Err(_) => Index { format: package::INDEX_FORMAT, ..Index::default() },
+    };
+    // Earlier keys of the publisher stay listed (packages they signed remain valid until revoked).
+    let current = key.public_base64();
+    let earlier: Vec<KeyEntry> = index
+        .publishers
+        .iter()
+        .filter(|p| p.id == publisher)
+        .flat_map(|p| p.keys.iter().filter(|k| k.key != current).cloned())
+        .collect();
+    index.publishers.retain(|p| p.id != publisher);
+    let keys: Vec<KeyEntry> = std::iter::once(KeyEntry { key: current, revoked: false }).chain(earlier).collect();
+    index.publishers.push(package::Publisher { id: publisher.into(), name: name.into(), keys });
+    index.plugins.clear();
+    let mut packages: Vec<PathBuf> = std::fs::read_dir(&dir)
+        .map_err(|e| e.to_string())?
+        .flatten()
+        .map(|e| e.path())
+        .filter(|p| p.extension().is_some_and(|e| e == package::PACKAGE_EXTENSION))
+        .collect();
+    packages.sort();
+    for path in packages {
+        let scratch = std::env::temp_dir().join(format!("openidea-plugin-index-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&scratch);
+        let unpacked = package::unpack(&path, &scratch)?;
+        let entry = (|| {
+            let m = Manifest::load(&scratch)?;
+            let files = with_scratch_host(|h| h.package_files_of(&scratch).map_err(|e| e.to_string()))?;
+            let digest = package::package_digest(&scratch, &files).map_err(|e| e.to_string())?;
+            let sig = unpacked.signature.as_ref().ok_or_else(|| format!("{}: not signed", path.display()))?;
+            sig.check(&m.id, &m.version, &digest).map_err(|e| format!("{}: {e}", path.display()))?;
+            Ok::<_, String>(IndexEntry {
+                id: m.id.clone(),
+                name: m.name.clone(),
+                version: m.version.clone(),
+                description: m.description.clone(),
+                authors: m.authors.clone(),
+                publisher: sig.publisher.clone(),
+                download: path.file_name().map(|n| n.to_string_lossy().into_owned()).unwrap_or_default(),
+                digest,
+                capabilities: m.capabilities.all().map(|c| c.to_string()).collect(),
+            })
+        })();
+        let _ = std::fs::remove_dir_all(&scratch);
+        let entry = entry?;
+        println!("  {} {}", entry.id, entry.version);
+        index.plugins.push(entry);
+    }
+    let json = serde_json::to_string_pretty(&index).map_err(|e| e.to_string())?;
+    std::fs::write(&out, json).map_err(|e| format!("{}: {e}", out.display()))?;
+    println!("-> {} ({} plugins)", out.display(), index.plugins.len());
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn names() {
+        assert_eq!(slugify("My Cool_Plugin"), "my-cool-plugin");
+        assert_eq!(slugify("acme.Tools"), "acme.tools");
+        assert_eq!(title_case("material-icons"), "Material Icons");
+        assert_eq!(
+            relative(Path::new("/a/b/plugins/x"), Path::new("/a/b/sdk/rust/p")).unwrap(),
+            PathBuf::from("../../sdk/rust/p")
+        );
+        assert_eq!(relative(Path::new("/x/y"), Path::new("/z")), None);
+    }
+
+    #[test]
+    fn every_template_is_a_valid_package() {
+        for t in templates::Template::ALL {
+            let dir =
+                std::env::temp_dir().join(format!("openidea-plugin-template-{}-{}", t.label(), std::process::id()));
+            let _ = std::fs::remove_dir_all(&dir);
+            let vars = templates::Vars { id: "acme.sample", name: "Sample", sdk: Some("../sdk") };
+            for (rel, content) in templates::render(t, &vars) {
+                let path = dir.join(rel);
+                std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+                std::fs::write(path, content).unwrap();
+            }
+            let m = Manifest::load(&dir).unwrap_or_else(|e| panic!("{}: {e}", t.label()));
+            assert_eq!(m.id, "acme.sample");
+            if m.wasm.is_none() {
+                check(&dir).unwrap_or_else(|e| panic!("{}: {e}", t.label()));
+            }
+            std::fs::remove_dir_all(&dir).unwrap();
+        }
+    }
+}

crates/ide-host/src/bin/openidea-plugin/templates.rs

@@ -0,0 +1,278 @@
+//! The files of `openidea-plugin new`. Placeholders: `__ID__` (plugin id),
+//! `__SLUG__` (last id segment), `__NAME__`, `__CRATE__`, `__SDK__`.
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Template {
+    Command,
+    Theme,
+    IconTheme,
+    Language,
+}
+
+impl Template {
+    pub const ALL: [Template; 4] = [Self::Command, Self::Theme, Self::IconTheme, Self::Language];
+
+    pub fn parse(s: &str) -> Result<Self, String> {
+        Self::ALL
+            .into_iter()
+            .find(|t| t.label() == s)
+            .ok_or_else(|| format!("unknown template {s:?} (command, theme, icon-theme, language)"))
+    }
+
+    pub fn label(self) -> &'static str {
+        match self {
+            Self::Command => "command",
+            Self::Theme => "theme",
+            Self::IconTheme => "icon-theme",
+            Self::Language => "language",
+        }
+    }
+}
+
+pub struct Vars<'a> {
+    pub id: &'a str,
+    pub name: &'a str,
+    pub sdk: Option<&'a str>,
+}
+
+/// `(relative path, contents)` of every file of the template.
+pub fn render(template: Template, vars: &Vars) -> Vec<(String, String)> {
+    let slug = vars.id.rsplit('.').next().unwrap_or(vars.id).to_owned();
+    let crate_name = format!("openidea-plugin-{}", vars.id.replace('.', "-"));
+    let fill = |s: &str| {
+        s.replace("__ID__", vars.id)
+            .replace("__SLUG__", &slug)
+            .replace("__NAME__", vars.name)
+            .replace("__CRATE__", &crate_name)
+            .replace("__SDK__", vars.sdk.unwrap_or(""))
+            // The theme files come from the Harbor Night plugin.
+            .replace("harbor-night", &slug)
+            .replace("Harbor Night", vars.name)
+    };
+    let files: Vec<(String, &str)> = match template {
+        Template::Command => vec![
+            ("plugin.toml".into(), COMMAND_MANIFEST),
+            ("Cargo.toml".into(), COMMAND_CARGO),
+            ("src/lib.rs".into(), COMMAND_LIB),
+            (".gitignore".into(), "/target\n"),
+            ("README.md".into(), COMMAND_README),
+        ],
+        Template::Theme => vec![
+            ("plugin.toml".into(), THEME_MANIFEST),
+            (format!("themes/{slug}.theme.json"), THEME_UI),
+            (format!("themes/{slug}.scheme.json"), THEME_SCHEME),
+        ],
+        Template::IconTheme => vec![
+            ("plugin.toml".into(), ICON_MANIFEST),
+            ("icons/theme.json".into(), ICON_THEME),
+            ("icons/file.svg".into(), ICON_FILE),
+            ("icons/folder.svg".into(), ICON_FOLDER),
+            ("icons/folder-open.svg".into(), ICON_FOLDER_OPEN),
+            ("icons/markdown.svg".into(), ICON_MARKDOWN),
+        ],
+        Template::Language => {
+            vec![("plugin.toml".into(), LANGUAGE_MANIFEST), (format!("languages/{slug}.toml"), LANGUAGE_DEF)]
+        }
+    };
+    files.into_iter().map(|(path, content)| (path, fill(content))).collect()
+}
+
+const COMMAND_MANIFEST: &str = r#"id = "__ID__"
+name = "__NAME__"
+version = "0.1.0"
+description = "Adds two sample commands."
+authors = []
+engines.openidea = "^1.0"
+# Built by `openidea-plugin build`. The code is loaded the first time one of
+# its commands runs; the commands below show in Find Action before that.
+wasm = "dist/plugin.wasm"
+
+# What the code may do. The user approves these when installing.
+[capabilities]
+required = ["editor.read"]
+
+[[contributes.commands]]
+id = "say-hello"
+title = "__NAME__: Say Hello"
+category = "__NAME__"
+
+[[contributes.commands]]
+id = "line-count"
+title = "__NAME__: Line Count of Active File"
+category = "__NAME__"
+"#;
+
+const COMMAND_CARGO: &str = r#"[package]
+name = "__CRATE__"
+version = "0.1.0"
+edition = "2024"
+publish = false
+
+# A plugin builds on its own (target wasm32-wasip2), outside any IDE workspace.
+[workspace]
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+openidea-plugin = { path = "__SDK__" }
+
+[profile.release]
+opt-level = "s"
+lto = true
+strip = true
+codegen-units = 1
+panic = "abort"
+"#;
+
+const COMMAND_LIB: &str = r#"//! __NAME__: an OpenIDEA plugin.
+
+use openidea_plugin::{Invocation, NotificationLevel, Plugin, host, register_plugin};
+
+#[derive(Default)]
+pub struct Main {
+    greetings: u32,
+}
+
+impl Plugin for Main {
+    fn run_command(&mut self, id: &str, ctx: &Invocation, _arg: Option<&str>) -> Result<Option<String>, String> {
+        match id {
+            "say-hello" => {
+                // Instance state lasts until the plugin is idle for a while;
+                // keep what must survive in `host::storage`.
+                self.greetings += 1;
+                let body = format!("Hello #{} from __NAME__!", self.greetings);
+                host::notify(NotificationLevel::Info, "__NAME__", &body);
+                Ok(None)
+            }
+            "line-count" => {
+                let editor = ctx.editor().ok_or("no file is open")?;
+                let text = editor.document()?.text;
+                Ok(Some(format!("{} lines in {}", text.lines().count(), editor.path())))
+            }
+            _ => Err(format!("unknown command {id}")),
+        }
+    }
+}
+
+register_plugin!(Main);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use openidea_plugin::mock::MockHost;
+
+    #[test]
+    fn says_hello() {
+        let host = MockHost::install();
+        let mut plugin = Main::default();
+        plugin.run_command("say-hello", &host.invocation(), None).unwrap();
+        plugin.run_command("say-hello", &host.invocation(), None).unwrap();
+        assert_eq!(host.notifications()[1].body, "Hello #2 from __NAME__!");
+    }
+
+    #[test]
+    fn counts_lines() {
+        let host = MockHost::install();
+        host.open_editor("/project/src/main.rs", "rust", "fn main() {\n}\n", &[]);
+        let out = Main::default().run_command("line-count", &host.invocation(), None).unwrap();
+        assert_eq!(out.as_deref(), Some("2 lines in /project/src/main.rs"));
+    }
+}
+"#;
+
+const COMMAND_README: &str = r#"# __NAME__
+
+An OpenIDEA plugin.
+
+```sh
+cargo test                       # logic, against the SDK's mock host
+openidea-plugin build            # → dist/plugin.wasm, validated like an install
+openidea-plugin link             # load this folder in the IDE (Settings › Plugins)
+```
+
+`plugin.toml` declares the commands, so they appear in Find Action before the
+code is loaded, and the capabilities the code needs. `src/lib.rs` implements
+them with the `openidea-plugin` SDK.
+"#;
+
+const THEME_MANIFEST: &str = r#"id = "__ID__"
+name = "__NAME__"
+version = "0.1.0"
+description = "A dark theme."
+authors = []
+engines.openidea = "^1.0"
+
+# One entry per theme. `editor-scheme` is optional: its tokens are merged over
+# the theme's (IntelliJ's .theme.json + .icls pair). Reference: docs/plugins/themes.md.
+[[contributes.themes]]
+path = "themes/__SLUG__.theme.json"
+editor-scheme = "themes/__SLUG__.scheme.json"
+"#;
+
+const THEME_UI: &str = include_str!("../../../../../plugins/official/harbor-night/themes/harbor-night.theme.json");
+const THEME_SCHEME: &str = include_str!("../../../../../plugins/official/harbor-night/themes/harbor-night.scheme.json");
+
+const ICON_MANIFEST: &str = r#"id = "__ID__"
+name = "__NAME__"
+version = "0.1.0"
+description = "File and folder icons."
+authors = []
+engines.openidea = "^1.0"
+
+# Apply it in Settings › Plugins › __NAME__. SVGs are sanitised on install:
+# no scripts, event handlers, external references or entities.
+[[contributes.iconThemes]]
+id = "__SLUG__"
+label = "__NAME__"
+path = "icons/theme.json"
+"#;
+
+const ICON_THEME: &str = r#"{
+  "iconDefinitions": {
+    "file": "icons/file.svg",
+    "folder": "icons/folder.svg",
+    "folder-open": "icons/folder-open.svg",
+    "markdown": "icons/markdown.svg"
+  },
+  "file": "file",
+  "folder": "folder",
+  "folderExpanded": "folder-open",
+  "fileExtensions": { "md": "markdown", "markdown": "markdown" },
+  "fileNames": { "readme": "markdown" },
+  "folderNames": {}
+}
+"#;
+
+const ICON_FILE: &str = r##"<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path fill="#90a4ae" d="M4 1.5h5.5L13 5v9.5H4z"/><path fill="#cfd8dc" d="M9.5 1.5V5H13z"/></svg>
+"##;
+
+const ICON_FOLDER: &str = r##"<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path fill="#90a4ae" d="M1.5 3h5l1.5 1.5h6.5v9h-13z"/></svg>
+"##;
+
+const ICON_FOLDER_OPEN: &str = r##"<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path fill="#90a4ae" d="M1.5 3h5l1.5 1.5h6v2h-10l-2 7h-.5z"/><path fill="#b0bec5" d="M4 7.5h11.5l-2 6H2z"/></svg>
+"##;
+
+const ICON_MARKDOWN: &str = r##"<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><rect x="1" y="3.5" width="14" height="9" rx="1.5" fill="#42a5f5"/><path fill="#fff" d="M3 10.5v-5h1.5L6 7.5l1.5-2H9v5H7.5V8L6 10 4.5 8v2.5zm8 0L9.5 8h1V5.5H12V8h1z"/></svg>
+"##;
+
+const LANGUAGE_MANIFEST: &str = r#"id = "__ID__"
+name = "__NAME__"
+version = "0.1.0"
+description = "Language support for .__SLUG__ files: detection, comments and indentation."
+authors = []
+engines.openidea = "^1.0"
+
+# Same format as languages/<id>.toml in the IDE repository.
+[[contributes.languages]]
+path = "languages/__SLUG__.toml"
+"#;
+
+const LANGUAGE_DEF: &str = r##"id = "__SLUG__"
+name = "__NAME__"
+extensions = ["__SLUG__"]
+line-comment = "#"
+indent = { tab-size = 2, insert-spaces = true }
+# Borrow an existing CodeMirror mode for instant highlighting.
+ui-mode = "Properties files"
+"##;

crates/ide-host/src/bin/server.rs

@@ -1,6 +1,8 @@
 //! `openidea-server --stdio`: the IDE backend for remote development, serving
 //! one desktop client over stdin / stdout (started by the client over SSH).
 
+use ide_host::plugins::remote::{RemotePluginLanguages, SYNC_COMMAND};
+use ide_host::plugins::remote_host::RemotePlugins;
 use ide_host::rpc::{self, Dispatcher};
 use ide_host::{Host, HostConfig};
 use ide_language::LanguageRegistry;
@@ -51,8 +53,12 @@ async fn run(base: PathBuf) -> i32 {
             return 1;
         }
     };
+    // The desktop's plugin languages (`plugin_sync_languages`); programs pinned on this machine.
+    let plugin_languages = RemotePluginLanguages::new(Some(&data_dir));
+    languages.attach_plugins(plugin_languages.store().clone());
     let peer = Arc::new(OnceLock::new());
     let sink_peer = peer.clone();
+    let plugins_data = data_dir.clone();
     let host = Arc::new(Host::new(HostConfig {
         config_dir,
         local_data_dir: data_dir.clone(),
@@ -64,8 +70,31 @@ async fn run(base: PathBuf) -> i32 {
         runtime: tokio::runtime::Handle::current(),
         project_environment: true,
     }));
+    // The desktop's code plugins run here, next to the project (`plugin_sync_packages`).
+    let plugins = match RemotePlugins::start(&plugins_data, &host, peer.clone()) {
+        Ok(p) => Some(p),
+        Err(e) => {
+            tracing::warn!("plugins are unavailable: {e}");
+            None
+        }
+    };
     tracing::info!("openidea-server {} ready", env!("CARGO_PKG_VERSION"));
-    rpc::serve(host.clone(), Dispatcher::standard(), peer, tokio::io::stdin(), tokio::io::stdout()).await;
+    let mut dispatcher = Dispatcher::standard();
+    if let Some(plugins) = &plugins {
+        plugins.register(&mut dispatcher);
+    }
+    dispatcher.add(SYNC_COMMAND, move |c| {
+        let remote = plugin_languages.clone();
+        async move {
+            let report = remote.sync(c.arg("languages")?);
+            c.host.plugin_languages_changed();
+            Ok(report)
+        }
+    });
+    rpc::serve(host.clone(), dispatcher, peer, tokio::io::stdin(), tokio::io::stdout()).await;
+    if let Some(plugins) = &plugins {
+        plugins.host().shutdown();
+    }
     // `process::exit` skips destructors: nothing started for the client may outlive it.
     if tokio::time::timeout(std::time::Duration::from_secs(10), host.shutdown()).await.is_err() {
         tracing::warn!("language servers did not shut down in time");

crates/ide-host/src/formatter.rs

@@ -2,26 +2,48 @@
 
 use crate::Host;
 use ide_core::event::NotifyLevel;
-use ide_core::settings::PrettierSettings;
+use ide_core::settings::{ExternalFormatter, LanguagesSettings};
 use ide_core::{DocId, IdeError, IdeEvent, IdeResult, Range, TextEdit};
-use ide_language::FormatterConfig;
+use ide_language::LanguageConfig;
 use ide_lsp::types::FormatOptions;
 use ide_tools::{Tools, formatter};
 use std::path::Path;
 
 const OXFMT_CONFIGS: [&str; 4] = [".oxfmtrc.json", ".oxfmtrc.jsonc", "oxfmt.config.ts", "oxfmt.config.mts"];
 
-/// oxfmt below an oxfmt configuration file, else Prettier. The Prettier
-/// settings (languages, preference, on save) apply to both.
-fn external_tool(file: &Path) -> &'static str {
-    let oxfmt = OXFMT_CONFIGS.iter().any(|name| formatter::find_up(file, Path::new(name)).is_some());
-    if oxfmt { "oxfmt" } else { "prettier" }
-}
-
-fn external_selected(config: Option<&FormatterConfig>, language: &str, settings: &PrettierSettings, lsp: bool) -> bool {
-    config.is_some_and(|c| c.tool == "prettier")
-        && settings.languages.iter().any(|l| l == language)
-        && (settings.prefer || !lsp)
+/// The external formatter of a file, for a language with an external formatter.
+/// `forced` names the tool (Reformat with Prettier/oxfmt). Otherwise oxfmt
+/// applies when it is enabled for the language and either an oxfmt
+/// configuration is found above the file or oxfmt is the selected provider;
+/// else Prettier, when it is enabled. Turning Prettier off for a language
+/// leaves it to the language server, not to oxfmt.
+fn external_tool(
+    forced: Option<ExternalFormatter>,
+    language: Option<&LanguageConfig>,
+    file: &Path,
+    settings: &LanguagesSettings,
+) -> IdeResult<Option<ExternalFormatter>> {
+    use ExternalFormatter::{Oxfmt, Prettier};
+    let Some(language) = language.filter(|l| l.formatter.as_ref().is_some_and(|f| f.tool == "prettier")) else {
+        return match forced {
+            Some(tool) => Err(IdeError::invalid(format!(
+                "{} cannot format {} files",
+                formatter::display_name(tool.name()),
+                language.map_or("these", |l| l.name.as_str())
+            ))),
+            None => Ok(None),
+        };
+    };
+    if forced.is_some() {
+        return Ok(forced);
+    }
+    let enabled = |tool| settings.formatter(tool).languages.iter().any(|l| l == language.id.as_str());
+    let oxfmt_config = || OXFMT_CONFIGS.iter().any(|name| formatter::find_up(file, Path::new(name)).is_some());
+    Ok(if enabled(Oxfmt) && (settings.oxfmt.prefer || oxfmt_config()) {
+        Some(Oxfmt)
+    } else {
+        enabled(Prettier).then_some(Prettier)
+    })
 }
 
 pub async fn format(
@@ -34,29 +56,33 @@ pub async fn format(
     let project = host.project(window)?;
     let snap = project.documents.snapshot(doc)?;
     let settings = project.settings.effective();
-    let prettier = &settings.languages.prettier;
     let language = project.languages.get(&snap.language);
-    let config = language.as_ref().and_then(|l| l.formatter.as_ref());
-    let candidate =
-        config.is_some_and(|c| c.tool == "prettier") && prettier.languages.iter().any(|l| l == snap.language.as_str());
-    let lsp = if candidate && !prettier.prefer { project.lsp.can_format(doc).await? } else { false };
-    if !external_selected(config, snap.language.as_str(), prettier, lsp) {
+    let mut selected = external_tool(options.tool, language.as_ref(), &snap.path, &settings.languages)?;
+    if let Some(tool) = selected
+        && options.tool.is_none()
+        && !settings.languages.formatter(tool).prefer
+        && project.lsp.can_format(doc).await?
+    {
+        selected = None;
+    }
+    let Some(selected) = selected else {
         if options.on_save && !settings.editor.format_on_save {
             return Ok(Vec::new());
         }
         return project.lsp.format(doc, range, options).await;
-    }
-    if options.on_save && !prettier.run_on_save {
+    };
+    let tool_settings = settings.languages.formatter(selected);
+    if options.on_save && !tool_settings.run_on_save {
         return Ok(Vec::new());
     }
     host.require_trust(window)?;
     if snap.read_only {
         return Err(IdeError::invalid("The file is read-only"));
     }
-    let config = config.unwrap().clone();
-    let tool = external_tool(&snap.path);
+    let config = language.and_then(|l| l.formatter).expect("external_tool selects languages with a formatter");
+    let tool = selected.name();
     let name = formatter::display_name(tool);
-    let custom = ide_sdk::apply::setting_path(&project.root, &prettier.path).filter(|_| tool == "prettier");
+    let custom = ide_sdk::apply::setting_path(&project.root, &tool_settings.path);
     let tools = Tools::new(&host.local_data_dir);
     let whole_selection = range.is_some() && !formatter::supports_range(tool, &config);
     let edits: IdeResult<Vec<TextEdit>> = tokio::task::spawn_blocking(move || {
@@ -94,42 +120,76 @@ pub async fn format(
 #[cfg(test)]
 mod tests {
     use super::*;
+    use ExternalFormatter::{Oxfmt, Prettier};
+    use ide_core::LanguageId;
+    use ide_language::LanguageRegistry;
 
-    #[test]
-    fn language_enablement_and_preference_preserve_lsp_formatters() {
-        let languages = ide_language::LanguageRegistry::load(None).unwrap();
-        let mut settings = PrettierSettings::default();
-        for lang in languages.all() {
-            for lsp in [false, true] {
-                let configured = lang.formatter.as_ref().is_some_and(|f| f.tool == "prettier");
-                assert_eq!(
-                    external_selected(lang.formatter.as_ref(), lang.id.as_str(), &settings, lsp),
-                    configured && !lsp,
-                    "{}",
-                    lang.id
-                );
-            }
-        }
-        let ts = languages.get(&ide_core::LanguageId::new("typescript")).unwrap();
-        settings.prefer = true;
-        assert!(external_selected(ts.formatter.as_ref(), "typescript", &settings, true));
-        settings.languages.clear();
-        assert!(!external_selected(ts.formatter.as_ref(), "typescript", &settings, false));
-        assert!(!external_selected(None, "rust", &settings, false));
+    fn tool(
+        forced: Option<ExternalFormatter>,
+        language: &str,
+        file: &Path,
+        settings: &LanguagesSettings,
+    ) -> IdeResult<Option<ExternalFormatter>> {
+        let language = LanguageRegistry::load(None).unwrap().get(&LanguageId::new(language));
+        external_tool(forced, language.as_ref(), file, settings)
     }
 
     #[test]
-    fn oxfmt_config_selects_oxfmt_over_prettier() {
+    fn default_settings_give_every_external_formatter_language_to_prettier() {
+        let settings = LanguagesSettings::default();
+        let file = Path::new("/project/file");
+        for lang in LanguageRegistry::load(None).unwrap().all() {
+            let configured = lang.formatter.as_ref().is_some_and(|f| f.tool == "prettier");
+            let selected = external_tool(None, Some(&lang), file, &settings).unwrap();
+            assert_eq!(selected, configured.then_some(Prettier), "{}", lang.id);
+        }
+        assert_eq!(external_tool(None, None, file, &settings).unwrap(), None);
+    }
+
+    #[test]
+    fn oxfmt_config_selects_oxfmt_for_its_enabled_languages() {
         let dir = tempfile::tempdir().unwrap();
         let root = dir.path();
         std::fs::create_dir_all(root.join("web/src")).unwrap();
         let (web, api) = (root.join("web/src/app.ts"), root.join("api/main.ts"));
-        assert_eq!(external_tool(&web), "prettier");
+        let mut settings = LanguagesSettings::default();
+        assert_eq!(tool(None, "typescript", &web, &settings).unwrap(), Some(Prettier));
         for config in OXFMT_CONFIGS {
             std::fs::write(root.join("web").join(config), "{}").unwrap();
-            assert_eq!(external_tool(&web), "oxfmt", "{config}");
-            assert_eq!(external_tool(&api), "prettier", "{config}");
+            assert_eq!(tool(None, "typescript", &web, &settings).unwrap(), Some(Oxfmt), "{config}");
+            assert_eq!(tool(None, "typescript", &api, &settings).unwrap(), Some(Prettier), "{config}");
             std::fs::remove_file(root.join("web").join(config)).unwrap();
         }
+        std::fs::write(root.join("web/.oxfmtrc.json"), "{}").unwrap();
+        settings.oxfmt.languages.retain(|l| l != "markdown");
+        assert_eq!(tool(None, "markdown", &web, &settings).unwrap(), Some(Prettier));
+        assert_eq!(tool(None, "typescript", &web, &settings).unwrap(), Some(Oxfmt));
+    }
+
+    #[test]
+    fn oxfmt_provider_selects_oxfmt_without_a_config_and_prettier_off_leaves_the_language_server() {
+        let file = Path::new("/project/src/app.ts");
+        let mut settings = LanguagesSettings::default();
+        settings.oxfmt.prefer = true;
+        assert_eq!(tool(None, "typescript", file, &settings).unwrap(), Some(Oxfmt));
+        settings.oxfmt.prefer = false;
+        settings.prettier.languages.clear();
+        assert_eq!(tool(None, "typescript", file, &settings).unwrap(), None);
+        settings.oxfmt.prefer = true;
+        settings.oxfmt.languages.clear();
+        assert_eq!(tool(None, "typescript", file, &settings).unwrap(), None);
+    }
+
+    #[test]
+    fn forced_tool_runs_that_formatter_or_reports_why_not() {
+        let dir = tempfile::tempdir().unwrap();
+        std::fs::write(dir.path().join(".oxfmtrc.json"), "{}").unwrap();
+        let file = dir.path().join("app.ts");
+        let mut settings = LanguagesSettings::default();
+        settings.oxfmt.languages.clear();
+        assert_eq!(tool(Some(Prettier), "typescript", &file, &settings).unwrap(), Some(Prettier));
+        assert_eq!(tool(Some(Oxfmt), "typescript", &file, &settings).unwrap(), Some(Oxfmt));
+        let rust = tool(Some(Oxfmt), "rust", &dir.path().join("main.rs"), &settings).unwrap_err();
+        assert_eq!(rust.message, "oxfmt cannot format Rust files");
     }
 }

crates/ide-host/src/lib.rs

@@ -1,6 +1,6 @@
 //! The IDE backend without a UI toolkit: open projects per window, terminals,
 //! processes, settings and the remote services. The desktop shell (`src-tauri`)
-//! wraps one [`Host`] and adds windows, menus and plugins; `openidea-server`
+//! wraps one [`Host`] and adds windows and menus; `openidea-server`
 //! runs one on a remote machine and serves it over JSON-RPC ([`rpc`]).
 
 pub mod data_dirs;
@@ -10,6 +10,7 @@ mod java_runtime;
 mod kotlin_bridge;
 pub mod notebook;
 pub mod ops;
+pub mod plugins;
 mod project;
 mod proxy;
 mod requests;
@@ -133,6 +134,17 @@ impl Host {
         self.syntax.get_or_init(|| Arc::new(Syntax::new())).clone()
     }
 
+    /// Plugin languages or the servers they may start changed (they are part
+    /// of [`Self::languages`] and every project's fork): open documents are
+    /// detected again and language servers follow their new configuration.
+    pub fn plugin_languages_changed(&self) {
+        for project in self.projects() {
+            project.documents.redetect_languages();
+            let lsp = project.lsp.clone();
+            self.runtime.spawn(async move { lsp.reconfigure().await });
+        }
+    }
+
     /// Every open project (all windows).
     pub fn projects(&self) -> Vec<Arc<Project>> {
         self.projects.read().values().cloned().collect()

crates/ide-host/src/ops/agent.rs

@@ -23,6 +23,13 @@ pub fn providers(host: &Host, window: &str) -> IdeResult<Vec<AgentProvider>> {
     Ok(providers)
 }
 
+/// Overrides built-in agent `id`'s command with `command` (its agent file keeps the
+/// built-in's driver and arguments), or returns it to auto-detection with `None`.
+pub fn set_command(host: &Host, window: &str, id: String, command: Option<String>) -> IdeResult<()> {
+    host.require_trust(window)?;
+    host.project(window)?.agents.set_builtin_command(&id, command)
+}
+
 /// Where ACP Registry agents are saved (`<config>/agents`, like the user's own) and installed.
 pub(crate) fn registry_paths(host: &Host) -> RegistryPaths {
     RegistryPaths::new(&host.config_dir, &host.local_data_dir)
@@ -187,6 +194,7 @@ pub async fn base_text(host: &Host, window: &str, task: String, path: IpcPath) -
 pub(crate) fn register(d: &mut Dispatcher) {
     d.add("agent_subscribe", |c| async move { subscribe(&c.host, &c.window, c.channel("onEvent")?) });
     d.add("agent_providers", |c| async move { providers(&c.host, &c.window) });
+    d.add("agent_set_command", |c| async move { set_command(&c.host, &c.window, c.arg("id")?, c.arg("command")?) });
     d.add("agent_registry_list", |c| async move { registry_list(&c.host, &c.window, c.arg("request")?).await });
     d.add("agent_registry_install", |c| async move {
         registry_install(&c.host, &c.window, c.arg("id")?, c.arg("request")?, c.sender("onEvent")?).await

crates/ide-host/src/ops/build.rs

@@ -74,6 +74,18 @@ pub fn load(root: &Path, cache: &Path, settings: &Settings) -> BuildModel {
     model
 }
 
+/// `model` building with the Maven profiles of the last sync (`-P`), as Maven runs from
+/// the tool window do.
+fn with_profiles(mut model: BuildModel, cache: &Path) -> BuildModel {
+    let profiles = ide_build::maven_profiles(cache);
+    if let (Some(m), false) = (&mut model.maven, profiles.is_empty()) {
+        for p in &mut m.projects {
+            p.options.push(format!("-P{}", profiles.join(",")));
+        }
+    }
+    model
+}
+
 /// Maven and Gradle projects of the window's project, from the build files plus the last sync.
 pub async fn build_model(host: &Host, window: &str) -> IdeResult<BuildModel> {
     host.require_trust(window)?;
@@ -98,6 +110,12 @@ pub async fn build_sync(
     let project = host.project(window)?;
     let (root, cache, settings) = (project.root.clone(), project.build_cache_dir(), project.settings.effective());
     let bridge_profiles = profiles.clone();
+    // What the Java language server and Build Project resolve the project with from now on.
+    let profiles_changed = tool == BuildTool::Maven
+        && ide_build::save_maven_profiles(&cache, &profiles).unwrap_or_else(|e| {
+            tracing::warn!("Maven profiles not saved: {e}");
+            false
+        });
     let token = host.begin_project_request(window, request);
     let result = tokio::task::spawn_blocking(move || {
         let current = load(&root, &cache, &settings);
@@ -132,6 +150,13 @@ pub async fn build_sync(
     .map_err(join_err);
     host.end_request(request);
     let model = result??;
+    if tool == BuildTool::Gradle {
+        // The sync may report project folders outside the project (`includeFlat`): index and list them.
+        project.refresh_index_scope();
+        project.sink.emit(ide_core::IdeEvent::ProjectRootsChanged { root: project.root.clone().into() });
+        let p = project.clone();
+        tokio::task::spawn_blocking(move || p.refresh_repositories());
+    }
     if tool == BuildTool::Maven
         && model.maven.is_some()
         && let Some(bridge) = &project.kotlin_bridge
@@ -150,8 +175,21 @@ pub async fn build_sync(
         }
     };
     let lsp = project.lsp.clone();
-    let uris = build_files.iter().map(|f| ide_lsp::path_to_uri_string(&project.root.join(f))).collect();
+    // With a module of a reactor unlinked, jdtls imports the other modules one by one and
+    // not the reactor: naming the reactor here would import it again, all modules included.
+    let imported = match tool {
+        BuildTool::Maven => crate::project::jdtls_maven_import(&project.root, &project.settings.effective()).1,
+        BuildTool::Gradle => None,
+    };
+    let uris = match imported {
+        Some(files) => files.into_iter().filter(|f| f.ends_with("/pom.xml")).collect(),
+        None => build_files.iter().map(|f| ide_lsp::path_to_uri_string(&project.root.join(f))).collect(),
+    };
     tokio::spawn(async move {
+        if profiles_changed {
+            // jdtls takes the profiles from its Maven settings (see `ide_sdk::maven_profiles`).
+            lsp.reconfigure().await;
+        }
         if let Err(e) = lsp.java_update_project_configs(&project.root, uris).await {
             tracing::debug!("java/projectConfigurationsUpdate: {e}");
         }
@@ -257,7 +295,8 @@ pub async fn build_run(
             for member in workspace.projects.iter().filter(|p| file.as_ref().is_none_or(|f| f.starts_with(p))) {
                 let settings = ide_workspace::SettingsStore::load(&config_dir, Some(member)).effective();
                 let member_cache = cache.join(crate::project::project_key(member));
-                let plan = compile::plan(member, &load(member, &member_cache, &settings), kind, file.as_deref())?;
+                let model = with_profiles(load(member, &member_cache, &settings), &member_cache);
+                let plan = compile::plan(member, &model, kind, file.as_deref())?;
                 match &mut combined {
                     Some(combined) => combined.steps.extend(plan.steps),
                     None => combined = Some(plan),
@@ -267,7 +306,7 @@ pub async fn build_run(
             plan.title = workspace.name;
             plan
         } else {
-            compile::plan(&root, &load(&root, &cache, &settings), kind, file.as_deref())?
+            compile::plan(&root, &with_profiles(load(&root, &cache, &settings), &cache), kind, file.as_deref())?
         };
         let result = compile::run(&root, &plan, &token, &|e| {
             let _ = on_event.send(e);

crates/ide-host/src/ops/db.rs

@@ -0,0 +1,422 @@
+//! Database commands shared by the desktop shell's IPC commands and the
+//! remote server ([`crate::rpc`]). `db_export_file` stays in the desktop
+//! shell: its path comes from a local save dialog, so the export must land
+//! on the user's machine, not the side the project runs on.
+use crate::Host;
+use crate::rpc::Dispatcher;
+use ide_core::{IdeError, IdeResult, IpcPath, RequestId};
+use ide_db::split::SqlStatement;
+use ide_db::{
+    CompletionModel, DataSource, Databases, DbObjectKind, DbRowEdit, HistoryEntry, PlanNode, QueryResult,
+    SchemaObjects, SortKey, TableDetails, TableInfo, TablePage,
+};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+
+/// One statement of a console run.
+#[derive(Clone, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+#[serde(rename = "DbStatementOutcome")]
+pub struct StatementOutcome {
+    pub statement: SqlStatement,
+    pub result: Option<QueryResult>,
+    pub error: Option<String>,
+}
+
+pub(crate) fn register(d: &mut Dispatcher) {
+    d.add("db_sources", |c| async move { sources(&c.host, &c.window) });
+    d.add("db_save_sources", |c| async move {
+        let sources = c.arg("sources")?;
+        save_sources(&c.host, &c.window, sources).await
+    });
+    d.add("db_set_password", |c| async move {
+        let (id, password, save) =
+            (c.arg::<String>("id")?, c.arg::<Option<String>>("password")?, c.arg::<bool>("save")?);
+        set_password(&c.host, &c.window, &id, password, save).await
+    });
+    d.add("db_test", |c| async move {
+        let (source, password, ssh_secret) = (
+            c.arg::<DataSource>("source")?,
+            c.arg::<Option<String>>("password")?,
+            c.arg::<Option<String>>("sshSecret")?,
+        );
+        test(&c.host, &c.window, source, password, ssh_secret).await
+    });
+    d.add("db_set_ssh_secret", |c| async move {
+        let (id, secret, save) = (c.arg::<String>("id")?, c.arg::<Option<String>>("secret")?, c.arg::<bool>("save")?);
+        set_ssh_secret(&c.host, &c.window, &id, secret, save).await
+    });
+    d.add("db_trust_ssh_host", |c| async move {
+        let id = c.arg::<String>("id")?;
+        trust_ssh_host(&c.host, &c.window, &id).await
+    });
+    d.add("db_connected", |c| async move { connected(&c.host, &c.window) });
+    d.add("db_connect", |c| async move {
+        let id = c.arg::<String>("id")?;
+        connect(&c.host, &c.window, &id).await
+    });
+    d.add("db_set_manual_commit", |c| async move {
+        let (id, manual) = (c.arg::<String>("id")?, c.arg::<bool>("manual")?);
+        set_manual_commit(&c.host, &c.window, &id, manual).await
+    });
+    d.add("db_finish_transaction", |c| async move {
+        let (id, commit) = (c.arg::<String>("id")?, c.arg::<bool>("commit")?);
+        finish_transaction(&c.host, &c.window, &id, commit).await
+    });
+    d.add("db_disconnect", |c| async move {
+        let id = c.arg::<String>("id")?;
+        disconnect(&c.host, &c.window, &id).await
+    });
+    d.add("db_databases", |c| async move {
+        let id = c.arg::<String>("id")?;
+        databases(&c.host, &c.window, &id).await
+    });
+    d.add("db_schemas", |c| async move {
+        let id = c.arg::<String>("id")?;
+        schemas(&c.host, &c.window, &id).await
+    });
+    d.add("db_tables", |c| async move {
+        let (id, schema) = (c.arg::<String>("id")?, c.arg::<String>("schema")?);
+        tables(&c.host, &c.window, &id, &schema).await
+    });
+    d.add("db_table_details", |c| async move {
+        let (id, schema, table) = (c.arg::<String>("id")?, c.arg::<String>("schema")?, c.arg::<String>("table")?);
+        table_details(&c.host, &c.window, &id, &schema, &table).await
+    });
+    d.add("db_ddl", |c| async move {
+        let (id, schema, table) = (c.arg::<String>("id")?, c.arg::<String>("schema")?, c.arg::<String>("table")?);
+        ddl(&c.host, &c.window, &id, &schema, &table).await
+    });
+    d.add("db_schema_objects", |c| async move {
+        let (id, schema) = (c.arg::<String>("id")?, c.arg::<String>("schema")?);
+        schema_objects(&c.host, &c.window, &id, &schema).await
+    });
+    d.add("db_object_ddl", |c| async move {
+        let (id, schema, kind, name) = (
+            c.arg::<String>("id")?,
+            c.arg::<String>("schema")?,
+            c.arg::<DbObjectKind>("kind")?,
+            c.arg::<String>("name")?,
+        );
+        object_ddl(&c.host, &c.window, &id, &schema, kind, &name).await
+    });
+    d.add("db_explain", |c| async move {
+        let (request, id, statement) =
+            (c.arg::<RequestId>("request")?, c.arg::<String>("id")?, c.arg::<String>("statement")?);
+        explain(&c.host, &c.window, request, &id, &statement).await
+    });
+    d.add("db_history", |c| async move {
+        let id = c.arg::<String>("id")?;
+        history(&c.host, &c.window, &id).await
+    });
+    d.add("db_remove_history", |c| async move {
+        let (id, texts) = (c.arg::<String>("id")?, c.arg::<Option<Vec<String>>>("texts")?);
+        remove_history(&c.host, &c.window, &id, texts).await
+    });
+    d.add("db_completion", |c| async move {
+        let id = c.arg::<String>("id")?;
+        completion(&c.host, &c.window, &id).await
+    });
+    d.add("db_statements", |c| async move {
+        let (id, text, from, to) =
+            (c.arg::<String>("id")?, c.arg::<String>("text")?, c.arg::<u32>("from")?, c.arg::<u32>("to")?);
+        statements(&c.host, &c.window, &id, &text, from, to)
+    });
+    d.add("db_execute", |c| async move {
+        let (request, id, statements, max_rows) = (
+            c.arg::<RequestId>("request")?,
+            c.arg::<String>("id")?,
+            c.arg::<Vec<SqlStatement>>("statements")?,
+            c.arg::<u32>("maxRows")?,
+        );
+        execute(&c.host, &c.window, request, &id, statements, max_rows).await
+    });
+    d.add("db_table_page", |c| async move {
+        let (request, id, schema, table) = (
+            c.arg::<RequestId>("request")?,
+            c.arg::<String>("id")?,
+            c.arg::<String>("schema")?,
+            c.arg::<String>("table")?,
+        );
+        let (filter, sort, offset, limit) = (
+            c.arg::<Option<String>>("filter")?,
+            c.arg::<Vec<SortKey>>("sort")?,
+            c.arg::<u32>("offset")?,
+            c.arg::<u32>("limit")?,
+        );
+        table_page(&c.host, &c.window, request, &id, &schema, &table, filter, sort, offset, limit).await
+    });
+    d.add("db_apply_edits", |c| async move {
+        let (id, schema, table, edits) = (
+            c.arg::<String>("id")?,
+            c.arg::<String>("schema")?,
+            c.arg::<String>("table")?,
+            c.arg::<Vec<DbRowEdit>>("edits")?,
+        );
+        apply_edits(&c.host, &c.window, &id, &schema, &table, edits).await
+    });
+    d.add("db_console_path", |c| async move { console_path(&c.host, &c.arg::<String>("id")?) });
+}
+
+/// The data sources configured for the project (the tree's roots).
+pub fn sources(host: &Host, window: &str) -> IdeResult<Vec<DataSource>> {
+    host.project(window)?.db.sources()
+}
+
+/// Replaces the project's data sources with `sources`.
+pub async fn save_sources(host: &Host, window: &str, sources: Vec<DataSource>) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.save_sources(sources).await
+}
+
+/// Remembers the password of data source `id` for the session, and in the OS
+/// saved passwords when `save` (`None` forgets it).
+pub async fn set_password(host: &Host, window: &str, id: &str, password: Option<String>, save: bool) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.set_password(id, password, save).await
+}
+
+/// Test Connection: connects with unsaved settings and returns the server version.
+pub async fn test(
+    host: &Host,
+    window: &str,
+    source: DataSource,
+    password: Option<String>,
+    ssh_secret: Option<String>,
+) -> IdeResult<String> {
+    let db = host.project(window)?.db.clone();
+    db.test(&source, password, ssh_secret).await
+}
+
+/// Remembers the SSH password / key passphrase of a data source (see `set_password`).
+pub async fn set_ssh_secret(host: &Host, window: &str, id: &str, secret: Option<String>, save: bool) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.set_ssh_secret(id, secret, save).await
+}
+
+/// Trusts the SSH host key that made the last connection of `id` fail with
+/// "Unknown SSH host key" (records it in `~/.ssh/known_hosts`).
+pub async fn trust_ssh_host(host: &Host, window: &str, id: &str) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.trust_ssh_host(id).await
+}
+
+/// The data sources with an open connection.
+pub fn connected(host: &Host, window: &str) -> IdeResult<Vec<String>> {
+    Ok(host.project(window)?.db.connected())
+}
+
+/// Connects (fails with `permissionDenied` when the password is missing or wrong).
+pub async fn connect(host: &Host, window: &str, id: &str) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.pool(id).await.map(|_| ())
+}
+
+/// Switches a data source between auto-commit and manual commit (leaving
+/// manual mode rolls back what was not committed).
+pub async fn set_manual_commit(host: &Host, window: &str, id: &str, manual: bool) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.set_manual_commit(id, manual).await;
+    Ok(())
+}
+
+/// Commits or rolls back the open transaction of a manual-commit data source.
+pub async fn finish_transaction(host: &Host, window: &str, id: &str, commit: bool) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.finish_transaction(id, commit).await
+}
+
+/// Closes the connection of data source `id`.
+pub async fn disconnect(host: &Host, window: &str, id: &str) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.disconnect(id).await;
+    Ok(())
+}
+
+/// Databases of the server of data source `id` (PostgreSQL); connect to one as `<id>:<database>`.
+pub async fn databases(host: &Host, window: &str, id: &str) -> IdeResult<Databases> {
+    let db = host.project(window)?.db.clone();
+    db.databases(id).await
+}
+
+/// The schemas of data source `id`.
+pub async fn schemas(host: &Host, window: &str, id: &str) -> IdeResult<Vec<String>> {
+    let db = host.project(window)?.db.clone();
+    db.schemas(id).await
+}
+
+/// The tables and views of `schema`.
+pub async fn tables(host: &Host, window: &str, id: &str, schema: &str) -> IdeResult<Vec<TableInfo>> {
+    let db = host.project(window)?.db.clone();
+    db.tables(id, schema).await
+}
+
+/// Columns, keys and indexes of `table`.
+pub async fn table_details(host: &Host, window: &str, id: &str, schema: &str, table: &str) -> IdeResult<TableDetails> {
+    let db = host.project(window)?.db.clone();
+    db.table_details(id, schema, table).await
+}
+
+/// The DDL of table or view `table` (Go to DDL, Generate DDL).
+pub async fn ddl(host: &Host, window: &str, id: &str, schema: &str, table: &str) -> IdeResult<String> {
+    let db = host.project(window)?.db.clone();
+    db.ddl(id, schema, table).await
+}
+
+/// The routines and sequences of `schema` (the tree's `routines` / `sequences`).
+pub async fn schema_objects(host: &Host, window: &str, id: &str, schema: &str) -> IdeResult<SchemaObjects> {
+    let db = host.project(window)?.db.clone();
+    db.schema_objects(id, schema).await
+}
+
+/// The definition of a routine, trigger or sequence (Go to DDL, Quick Documentation).
+pub async fn object_ddl(
+    host: &Host,
+    window: &str,
+    id: &str,
+    schema: &str,
+    kind: DbObjectKind,
+    name: &str,
+) -> IdeResult<String> {
+    let db = host.project(window)?.db.clone();
+    db.object_ddl(id, schema, kind, name).await
+}
+
+/// Explain Plan: the execution plan of `statement` on `id`, without running it.
+pub async fn explain(
+    host: &Host,
+    window: &str,
+    request: RequestId,
+    id: &str,
+    statement: &str,
+) -> IdeResult<Vec<PlanNode>> {
+    let db = host.project(window)?.db.clone();
+    let cancel = host.begin_request(request);
+    let result = db.explain(id, statement, &cancel).await;
+    host.end_request(request);
+    result
+}
+
+/// The statements data source `id` ran, newest first (Browse Query History).
+pub async fn history(host: &Host, window: &str, id: &str) -> IdeResult<Vec<HistoryEntry>> {
+    let db = host.project(window)?.db.clone();
+    db.history(id).await
+}
+
+/// Removes statements from the query history of `id` (`None`: all of them).
+pub async fn remove_history(host: &Host, window: &str, id: &str, texts: Option<Vec<String>>) -> IdeResult<()> {
+    let db = host.project(window)?.db.clone();
+    db.remove_history(id, texts).await
+}
+
+/// Tables, columns and foreign keys for SQL completion.
+pub async fn completion(host: &Host, window: &str, id: &str) -> IdeResult<CompletionModel> {
+    let db = host.project(window)?.db.clone();
+    db.completion(id).await
+}
+
+/// Statements a console runs: the selection's (`from < to`) or the one at the caret (`from`).
+pub fn statements(host: &Host, window: &str, id: &str, text: &str, from: u32, to: u32) -> IdeResult<Vec<SqlStatement>> {
+    let driver = host.project(window)?.db.source(id)?.driver;
+    Ok(if from < to {
+        ide_db::split::statements_in(text, from, to, driver)
+    } else {
+        ide_db::split::statement_at(text, from, driver).into_iter().collect()
+    })
+}
+
+/// Runs `statements` in order on data source `id`, stopping at the first
+/// error. Cancel with `cancel_request(request)`.
+pub async fn execute(
+    host: &Host,
+    window: &str,
+    request: RequestId,
+    id: &str,
+    statements: Vec<SqlStatement>,
+    max_rows: u32,
+) -> IdeResult<Vec<StatementOutcome>> {
+    let db = host.project(window)?.db.clone();
+    let cancel = host.begin_request(request);
+    let mut out = Vec::new();
+    for statement in statements {
+        match db.execute(id, &statement.text, max_rows.max(1) as usize, &cancel).await {
+            Ok(result) => out.push(StatementOutcome { statement, result: Some(result), error: None }),
+            Err(e) if e.kind == ide_core::error::ErrorKind::Cancelled => {
+                host.end_request(request);
+                return Err(e);
+            }
+            Err(e) if e.kind == ide_core::error::ErrorKind::PermissionDenied && out.is_empty() => {
+                // Not connected for lack of a password: the UI asks and retries.
+                host.end_request(request);
+                return Err(e);
+            }
+            Err(e) => {
+                out.push(StatementOutcome { statement, result: None, error: Some(e.message) });
+                break;
+            }
+        }
+    }
+    host.end_request(request);
+    Ok(out)
+}
+
+/// One page of the rows of `table` (the table editor).
+#[allow(clippy::too_many_arguments)]
+pub async fn table_page(
+    host: &Host,
+    window: &str,
+    request: RequestId,
+    id: &str,
+    schema: &str,
+    table: &str,
+    filter: Option<String>,
+    sort: Vec<SortKey>,
+    offset: u32,
+    limit: u32,
+) -> IdeResult<TablePage> {
+    let db = host.project(window)?.db.clone();
+    let cancel = host.begin_request(request);
+    let result =
+        db.table_page(id, schema, table, filter.as_deref(), &sort, offset.into(), limit.max(1).into(), &cancel).await;
+    host.end_request(request);
+    result
+}
+
+/// Submits the table editor's changes in one transaction; returns the rows changed.
+pub async fn apply_edits(
+    host: &Host,
+    window: &str,
+    id: &str,
+    schema: &str,
+    table: &str,
+    edits: Vec<DbRowEdit>,
+) -> IdeResult<f64> {
+    let db = host.project(window)?.db.clone();
+    Ok(db.apply_edits(id, schema, table, &edits).await? as f64)
+}
+
+/// The query console file of data source `id` (`<dataDir>/consoles/db/<id>/console.sql`),
+/// created on first use. Consoles are files of the project, so a remote
+/// window resolves it on the host the project runs on.
+pub fn console_path(host: &Host, id: &str) -> IdeResult<IpcPath> {
+    let (source, database) = ide_db::split_target(id);
+    if source.is_empty() || !source.chars().all(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_') {
+        return Err(IdeError::invalid("invalid data source id"));
+    }
+    // One console per database: `<id>` for the default one, `<id>.<database>` for the others.
+    let name = match database {
+        Some(db) => {
+            let safe: String =
+                db.chars().map(|c| if c.is_alphanumeric() || c == '-' || c == '_' { c } else { '_' }).collect();
+            format!("{source}.{safe}")
+        }
+        None => source.to_owned(),
+    };
+    let dir = host.data_dir.join("consoles").join("db").join(&name);
+    std::fs::create_dir_all(&dir)?;
+    let file = dir.join("console.sql");
+    if !file.exists() {
+        std::fs::write(&file, "")?;
+    }
+    Ok(file.into())
+}

crates/ide-host/src/ops/dependencies.rs

@@ -91,7 +91,7 @@ mod tests {
         let host = Host::new(HostConfig {
             config_dir: base.join("config"),
             data_dir: base.join("data"),
-            local_data_dir: base.join("data"),
+            local_data_dir: base.join("local"),
             languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
             syntax: Arc::default(),
             sink_for: Box::new(|_| Arc::new(|_| {})),

crates/ide-host/src/ops/deploy.rs

@@ -1,6 +1,6 @@
 use crate::Host;
 use ide_core::{CancellationToken, IdeEvent, IdeResult, IpcPath, RequestId, SharedSink, TaskId};
-use ide_remote::{DeployedPath, DeploymentCoverage, SyncEntry, SyncStep, TransferReport};
+use ide_remote::{DeployedPath, DeploymentCoverage, DeploymentRoot, SyncEntry, SyncStep, TransferReport};
 use ide_ssh::{FsConnection, RemoteEntry};
 use std::path::PathBuf;
 
@@ -134,13 +134,12 @@ pub async fn deploy_info(
     state.remote.deployed(&project.settings.effective(), &project.root, server.as_deref(), &path).await
 }
 
-/// Remote Host tool window: the server root of `server`, resolved on the host.
-pub async fn deploy_server_root(window: &str, state: &Host, server: String) -> IdeResult<String> {
-    let settings = match state.project(window) {
-        Ok(p) => p.settings.effective(),
-        Err(_) => state.global_settings.effective(),
-    };
-    state.remote.server_root(&settings, &server).await
+/// Remote Host tool window: the resolved server root and project mappings.
+pub async fn deploy_server_root(window: &str, state: &Host, server: String) -> IdeResult<DeploymentRoot> {
+    let project = state.project(window).ok();
+    let settings =
+        project.as_ref().map(|p| p.settings.effective()).unwrap_or_else(|| state.global_settings.effective());
+    state.remote.server_info(&settings, project.as_ref().map(|p| p.root.as_path()), &server).await
 }
 
 /// Entries of a folder on the selected filesystem (`~`: its home directory).

crates/ide-host/src/ops/java.rs

@@ -86,7 +86,7 @@ async fn resolve_launch(
         };
         let mut class_paths: Vec<String> = built.iter().map(|p| p.to_string_lossy().into_owned()).collect();
         for p in std::mem::take(&mut info.class_paths) {
-            if !class_paths.contains(&p) {
+            if !class_paths.iter().any(|c| same_entry(c, &p, cfg!(windows))) {
                 class_paths.push(p);
             }
         }
@@ -96,7 +96,13 @@ async fn resolve_launch(
         let project_jdk = ide_sdk::apply::project_jdk(&project.root, &settings);
         let from_jdtls = info.java_home.as_deref().map(ide_sdk::java::java_executable).filter(|p| p.is_file());
         let java = project_jdk.map(|j| ide_sdk::java::java_executable(&j.home)).or(from_jdtls).or_else(|| {
-            let release = ide_sdk::java::project_java_version(&module);
+            // The build model's level includes what the module inherits from its parent POMs.
+            let release = model
+                .maven
+                .as_ref()
+                .and_then(|m| m.projects.iter().find(|p| project.root.join(&p.dir) == module))
+                .and_then(|p| p.java_version)
+                .or_else(|| ide_sdk::java::project_java_version(&module));
             let jdks = ide_sdk::java::installed_jdks();
             info.hints.extend(ide_sdk::java::missing_jdk_message(&jdks, release));
             ide_sdk::java::pick_jdk(&jdks, release).map(|j| ide_sdk::java::java_executable(&j.home))
@@ -131,15 +137,44 @@ async fn resolve_launch(
     .map_err(|e| IdeError::internal(e.to_string()))?
 }
 
+/// A classpath entry as a comparable key. Entries come from JDT LS and from our own
+/// build model, which spell one directory differently on Windows (`\\?\` prefix,
+/// `/` or `\\`, drive-letter case); compared as text, a module output stayed on the
+/// classpath next to its launch snapshot and every resource was found twice.
+fn entry_key(path: &str, windows: bool) -> String {
+    let path = match path.strip_prefix(r"\\?\UNC\") {
+        Some(share) => format!(r"\\{share}"),
+        None => path.strip_prefix(r"\\?\").unwrap_or(path).to_owned(),
+    };
+    let mut key = if windows { path.replace('\\', "/") } else { path };
+    while key.len() > 1 && key.ends_with('/') {
+        key.pop();
+    }
+    if windows { key.to_lowercase() } else { key }
+}
+
+fn same_entry(a: &str, b: &str, windows: bool) -> bool {
+    a == b || entry_key(a, windows) == entry_key(b, windows)
+}
+
 fn use_snapshot(info: &mut JavaLaunchInfo, built: &[PathBuf], snapshot: &std::path::Path) -> Vec<PathBuf> {
+    use_snapshot_on(info, built, snapshot, cfg!(windows))
+}
+
+fn use_snapshot_on(
+    info: &mut JavaLaunchInfo,
+    built: &[PathBuf],
+    snapshot: &std::path::Path,
+    windows: bool,
+) -> Vec<PathBuf> {
     let mut copies = Vec::new();
     for (index, source) in built.iter().enumerate() {
         let dest = snapshot.join(index.to_string());
         let original = source.to_string_lossy();
-        info.class_paths.retain(|p| p != original.as_ref());
+        info.class_paths.retain(|p| !same_entry(p, &original, windows));
         let mut modular = false;
         for path in &mut info.module_paths {
-            if path == original.as_ref() {
+            if same_entry(path, &original, windows) {
                 *path = dest.to_string_lossy().into_owned();
                 modular = true;
             }
@@ -185,6 +220,39 @@ pub(crate) fn register(d: &mut Dispatcher) {
 mod tests {
     use super::*;
 
+    /// JDT LS and our build model spell a module output differently on Windows; the
+    /// snapshot must still replace it, or resources (MyBatis mapper XML) load twice.
+    #[test]
+    fn snapshots_replace_outputs_however_windows_spells_them() {
+        let built = PathBuf::from(r"D:\workspace\arm\arm-web\target/classes");
+        let jdtls = [
+            r"D:\workspace\arm\arm-web\target\classes",
+            r"d:\workspace\arm\arm-web\target\classes",
+            r"D:/workspace/arm/arm-web/target/classes/",
+            r"\\?\D:\workspace\arm\arm-web\target\classes",
+        ];
+        for spelled in jdtls {
+            let mut info = JavaLaunchInfo {
+                class_paths: vec![spelled.into(), r"D:\m2\mybatis.jar".into()],
+                module_paths: vec![spelled.into()],
+                ..Default::default()
+            };
+            use_snapshot_on(&mut info, std::slice::from_ref(&built), std::path::Path::new(r"C:\cache\launch-x"), true);
+            assert_eq!(info.class_paths, [r"D:\m2\mybatis.jar"], "{spelled}");
+            assert_eq!(
+                info.module_paths,
+                [std::path::Path::new(r"C:\cache\launch-x").join("0").to_string_lossy()],
+                "{spelled}"
+            );
+        }
+        assert!(same_entry(r"\\?\UNC\server\share\app\target\classes", r"\\server\share\app\target/classes", true));
+        // Different directories stay different, and other platforms keep case and `\`.
+        assert!(!same_entry(r"D:\a\target\classes", r"D:\a\target\test-classes", true));
+        assert!(!same_entry("/work/App/target/classes", "/work/app/target/classes", false));
+        assert!(!same_entry(r"/work/a\b", "/work/a/b", false));
+        assert!(same_entry("/work/app/target/classes/", "/work/app/target/classes", false));
+    }
+
     #[test]
     fn launch_snapshots_survive_jdt_overwrites_and_replace_module_outputs() {
         let root = tempfile::tempdir().unwrap();

crates/ide-host/src/ops/jvm_icons.rs

@@ -1,7 +1,7 @@
 //! Bounded, read-only JVM presentation for visible files, also served remotely.
 use crate::Host;
 use ide_core::{CancellationToken, IdeError, IdeResult, LanguageId};
-use ide_syntax::{JvmPresentation, Snapshot};
+use ide_syntax::{JvmPresentation, Snapshot, StructureService, jvm_type_header};
 use serde::{Deserialize, Serialize};
 use specta::Type;
 use std::{
@@ -38,6 +38,27 @@ fn prefix(path: &PathBuf) -> std::io::Result<String> {
     Ok(String::from_utf8_lossy(&bytes).into_owned())
 }
 
+/// The presentation of the file at `path` from its first [`PREFIX_BYTES`].
+fn read_presentation(
+    structure: &StructureService,
+    path: &PathBuf,
+    language: &LanguageId,
+) -> IdeResult<JvmPresentation> {
+    let source = prefix(path)?;
+    let stem = path.file_stem().and_then(|s| s.to_str()).unwrap_or_default();
+    let present =
+        |source: &str| structure.jvm_presentation(&Snapshot::text(language, source), stem, &CancellationToken::new());
+    let presentation = present(&source)?;
+    // Cut off inside its body, a large file doesn't parse as a declaration: its header does.
+    if presentation.kind.is_none()
+        && source.len() as u64 >= PREFIX_BYTES
+        && let Some(header) = jvm_type_header(&source)
+    {
+        return Ok(present(&format!("{header}}}"))?);
+    }
+    Ok(presentation)
+}
+
 pub async fn jvm_file_presentations(
     host: &Host,
     window: &str,
@@ -67,13 +88,7 @@ pub async fn jvm_file_presentations(
             let presentation = if let Some(hit) = hit {
                 hit.presentation
             } else {
-                let Ok(source) = prefix(&path) else { continue };
-                let stem = path.file_stem().and_then(|s| s.to_str()).unwrap_or_default();
-                let presentation = project.structure.jvm_presentation(
-                    &Snapshot::text(&language, &source),
-                    stem,
-                    &CancellationToken::new(),
-                )?;
+                let Ok(presentation) = read_presentation(&project.structure, &path, &language) else { continue };
                 let mut cache = cache.lock().unwrap();
                 if cache.len() >= MAX_CACHE {
                     cache.clear();
@@ -99,4 +114,21 @@ mod tests {
         assert_eq!(prefix(&path).unwrap().len(), PREFIX_BYTES as usize);
         std::fs::remove_file(path).unwrap();
     }
+
+    #[test]
+    fn large_files_cut_off_in_their_body_keep_their_kind() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("Foo.java");
+        let mut text = String::from("package a;\n\n@Service\npublic class Foo implements IFoo {\n");
+        while text.len() < PREFIX_BYTES as usize + 1024 {
+            // The prefix ends inside one of these comments.
+            text.push_str("    /**\n     * Does something.\n     */\n    public void m() { call(\"x\"); }\n");
+        }
+        std::fs::write(&path, &text).unwrap();
+        let syntax = std::sync::Arc::new(ide_language::Syntax::new());
+        let structure = StructureService::new(std::sync::Arc::new(ide_language::SyntaxCache::new(syntax)));
+        let java = LanguageId::new("java");
+        let presentation = read_presentation(&structure, &path, &java).unwrap();
+        assert_eq!(presentation.kind, Some(ide_syntax::JvmTypeKind::Class));
+    }
 }

crates/ide-host/src/ops/lsp.rs

@@ -1,9 +1,11 @@
 use super::doc::blocking;
 use crate::Host;
 use crate::apply_workspace_edit as apply_edit;
+use crate::plugins::{ProviderKind, editor_providers_for as editor_providers};
 use crate::rpc::Dispatcher;
 use ide_core::{DocId, IdeResult, Location, Pos, Range, RequestId, ServerId, TextEdit, WorkspaceEdit};
 use ide_lsp::types::*;
+use ide_plugin::ProviderDocument;
 
 async fn prepare_actions(
     project: std::sync::Arc<crate::Project>,
@@ -38,9 +40,99 @@ pub async fn lsp_completion(
 ) -> IdeResult<CompletionList> {
     let lsp = host.project(window)?.lsp.clone();
     let cancel = host.begin_request(request);
-    let result = lsp.completion(doc, pos, trigger, cancel).await;
+    let result = lsp.completion(doc, pos, trigger.clone(), cancel).await;
     host.end_request(request);
-    result
+    // Plugin providers (`[[contributes.providers]]`) add theirs.
+    let Some((plugins, d)) = plugin_providers(host, window, doc, ProviderKind::Completion) else { return result };
+    let items = plugin_call(move || plugins.provide_completion(&d, pos, trigger.as_deref())).await.unwrap_or_default();
+    if items.is_empty() {
+        return result;
+    }
+    let mut list = result.unwrap_or(CompletionList { is_incomplete: false, items: Vec::new() });
+    list.items.extend(items.into_iter().map(|(_, item)| plugin_completion(item)));
+    Ok(list)
+}
+
+/// The plugin host and the document, when some plugin provides `kind`.
+fn plugin_providers(
+    host: &Host,
+    window: &str,
+    doc: DocId,
+    kind: ProviderKind,
+) -> Option<(std::sync::Arc<crate::plugins::PluginHost>, ProviderDocument)> {
+    let plugins = editor_providers(kind)?;
+    let snap = host.project(window).ok()?.documents.snapshot(doc).ok()?;
+    let d = ProviderDocument {
+        path: snap.path.0,
+        language: snap.language.0,
+        version: u64::from(snap.version),
+        text: snap.text,
+    };
+    Some((plugins, d))
+}
+
+/// Plugin calls block (the plugin's actor thread does the work).
+async fn plugin_call<T: Send + 'static>(f: impl FnOnce() -> T + Send + 'static) -> Option<T> {
+    tokio::task::spawn_blocking(f).await.ok()
+}
+
+/// Items from plugins carry no server (resolve and commands don't apply).
+const PLUGIN_SERVER: ServerId = ServerId(0);
+
+/// A plugin's `completion-item.kind` (wit/providers.wit lists them).
+fn plugin_completion_kind(kind: &str) -> Option<CompletionKind> {
+    Some(match kind {
+        "text" => CompletionKind::Text,
+        "method" => CompletionKind::Method,
+        "function" => CompletionKind::Function,
+        "constructor" => CompletionKind::Constructor,
+        "field" => CompletionKind::Field,
+        "variable" => CompletionKind::Variable,
+        "class" => CompletionKind::Class,
+        "interface" => CompletionKind::Interface,
+        "module" => CompletionKind::Module,
+        "property" => CompletionKind::Property,
+        "unit" => CompletionKind::Unit,
+        "value" => CompletionKind::Value,
+        "enum" => CompletionKind::Enum,
+        "keyword" => CompletionKind::Keyword,
+        "snippet" => CompletionKind::Snippet,
+        "color" => CompletionKind::Color,
+        "file" => CompletionKind::File,
+        "reference" => CompletionKind::Reference,
+        "folder" => CompletionKind::Folder,
+        "enum-member" => CompletionKind::EnumMember,
+        "constant" => CompletionKind::Constant,
+        "struct" => CompletionKind::Struct,
+        "event" => CompletionKind::Event,
+        "operator" => CompletionKind::Operator,
+        "type-parameter" => CompletionKind::TypeParameter,
+        _ => return None,
+    })
+}
+
+fn plugin_completion(item: ide_plugin::CompletionItem) -> CompletionItem {
+    let kind = item.kind.as_deref().and_then(plugin_completion_kind);
+    CompletionItem {
+        label: item.label,
+        label_detail: None,
+        detail: item.detail,
+        kind,
+        documentation: item.documentation.map(|value| Markup { kind: "markdown".into(), value }),
+        sort_text: item.sort_text,
+        filter_text: None,
+        preselect: false,
+        deprecated: false,
+        insert_text: item.insert_text,
+        is_snippet: false,
+        replace_range: item.replace,
+        replace_range_tab: None,
+        additional_edits: Vec::new(),
+        commit_characters: Vec::new(),
+        command: None,
+        data: None,
+        server: PLUGIN_SERVER,
+    }
 }
 
 /// Inline (ghost text) suggestions at `pos`; `automatic` when triggered by typing.
@@ -54,9 +146,26 @@ pub async fn lsp_inline_completion(
 ) -> IdeResult<Vec<InlineCompletionItem>> {
     let lsp = host.project(window)?.lsp.clone();
     let cancel = host.begin_request(request);
-    let result = lsp.inline_completion(doc, pos, automatic, cancel).await;
+    let result = lsp.inline_completion(doc, pos, automatic, cancel.clone()).await;
+    // Plugins: cancelled (cooperatively) when the editor cancels the request.
+    let plugin = match plugin_providers(host, window, doc, ProviderKind::InlineCompletion) {
+        Some((plugins, d)) if !matches!(&result, Ok(items) if !items.is_empty()) => {
+            let cancel = cancel.clone();
+            plugin_call(move || plugins.provide_inline_completion(&d, pos, &cancel)).await.flatten()
+        }
+        _ => None,
+    };
     host.end_request(request);
-    result
+    match plugin {
+        Some((_, s)) => Ok(vec![InlineCompletionItem {
+            insert_text: s.insert_text,
+            range: s.replace,
+            filter_text: None,
+            command: None,
+            server: PLUGIN_SERVER,
+        }]),
+        None => result,
+    }
 }
 
 pub async fn lsp_resolve_completion(
@@ -87,7 +196,40 @@ pub async fn lsp_signature_help(host: &Host, window: &str, doc: DocId, pos: Pos)
 }
 
 pub async fn lsp_goto(host: &Host, window: &str, doc: DocId, pos: Pos, kind: GotoKind) -> IdeResult<Vec<Location>> {
-    host.project(window)?.lsp.goto(doc, pos, kind).await
+    let result = host.project(window)?.lsp.goto(doc, pos, kind).await;
+    if kind != GotoKind::Definition {
+        return result;
+    }
+    let Some((plugins, d)) = plugin_providers(host, window, doc, ProviderKind::Definition) else { return result };
+    let found = plugin_call(move || plugins.provide_definition(&d, pos)).await.unwrap_or_default();
+    if found.is_empty() {
+        return result;
+    }
+    let mut out = result.unwrap_or_default();
+    out.extend(found.into_iter().map(|l| Location { path: l.path.into(), range: l.range, uri: None }));
+    Ok(out)
+}
+
+/// Gutter markers from plugins (`line-markers` providers) for `doc`.
+pub async fn plugin_line_markers(
+    host: &Host,
+    window: &str,
+    doc: DocId,
+) -> IdeResult<Vec<crate::plugins::LineMarkerInfo>> {
+    let Some((plugins, d)) = plugin_providers(host, window, doc, ProviderKind::LineMarkers) else {
+        return Ok(Vec::new());
+    };
+    let markers = plugin_call(move || plugins.provide_line_markers(&d)).await.unwrap_or_default();
+    Ok(markers
+        .into_iter()
+        .map(|(plugin_id, m)| crate::plugins::LineMarkerInfo {
+            plugin_id,
+            line: m.line,
+            icon: m.icon,
+            tooltip: m.tooltip,
+            target: m.target.map(|l| Location { path: l.path.into(), range: l.range, uri: None }),
+        })
+        .collect())
 }
 
 /// Implementations of the symbols at `positions`, one list per position (the
@@ -165,10 +307,47 @@ pub async fn lsp_code_actions(
     let project = host.project(window)?;
     let documents = project.documents.clone();
     let version = blocking(move || documents.version(doc)).await?;
-    let actions = project.lsp.code_actions(doc, range, only).await?;
+    let result = project.lsp.code_actions(doc, range, only.clone()).await;
+    let plugin_actions = match plugin_providers(host, window, doc, ProviderKind::CodeActions) {
+        Some((plugins, d)) => plugin_call(move || plugins.provide_code_actions(&d, range)).await.unwrap_or_default(),
+        None => Vec::new(),
+    };
+    let plugin_actions: Vec<CodeAction> = plugin_actions
+        .into_iter()
+        .map(|(_, a)| plugin_code_action(a))
+        .filter(|a| {
+            only.is_empty()
+                || a.kind.as_ref().is_some_and(|k| only.iter().any(|o| k == o || k.starts_with(&format!("{o}."))))
+        })
+        .collect();
+    let actions = if plugin_actions.is_empty() {
+        result?
+    } else {
+        let mut out = result.unwrap_or_default();
+        out.extend(plugin_actions);
+        out
+    };
     prepare_actions(project, doc, version, actions).await
 }
 
+fn plugin_code_action(a: ide_plugin::CodeAction) -> CodeAction {
+    let files = a
+        .edits
+        .into_iter()
+        .map(|(path, edits)| ide_core::FileEdit::Edit { path: path.into(), edits, version: None })
+        .collect();
+    CodeAction {
+        title: a.title,
+        kind: a.kind,
+        is_preferred: a.preferred,
+        disabled_reason: None,
+        edit: Some(WorkspaceEdit { files, preconditions: Vec::new() }),
+        command: None,
+        data: None,
+        server: PLUGIN_SERVER,
+    }
+}
+
 /// Cancellable code actions with the kinds the servers advertise (Refactor This, refactoring availability).
 pub async fn lsp_code_action_query(
     host: &Host,
@@ -551,3 +730,28 @@ pub(crate) fn register(d: &mut Dispatcher) {
         lsp_execute_command(&c.host, &c.window, c.arg("doc")?, c.arg("command")?).await
     });
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn every_completion_kind_the_plugin_api_documents_is_understood() {
+        let wit = include_str!("../../../../wit/providers.wit");
+        let doc: String = wit
+            .lines()
+            .map(|l| l.trim().trim_start_matches("///").trim())
+            .skip_while(|l| !l.starts_with("Icon and sort group:"))
+            .take_while(|l| !l.starts_with("kind:"))
+            .collect::<Vec<_>>()
+            .join(" ");
+        let list = doc.strip_prefix("Icon and sort group:").unwrap().split(". Unknown").next().unwrap();
+        let list = list.replace(" or ", ", ");
+        let kinds: Vec<&str> = list.split(',').map(str::trim).filter(|k| !k.is_empty()).collect();
+        assert_eq!(kinds.len(), 25, "{kinds:?}");
+        for k in kinds {
+            assert!(plugin_completion_kind(k).is_some(), "{k:?}");
+        }
+        assert_eq!(plugin_completion_kind("nonsense"), None);
+    }
+}

crates/ide-host/src/ops/mod.rs

@@ -7,6 +7,7 @@ pub mod analysis;
 pub mod build;
 pub mod bytes;
 pub mod coverage;
+pub mod db;
 pub mod debug;
 pub mod dependencies;
 pub mod deploy;
@@ -86,6 +87,7 @@ pub fn register_all(d: &mut crate::rpc::Dispatcher) {
     run::register(d);
     env::register(d);
     deploy::register(d);
+    db::register(d);
 }
 
 impl Host {

crates/ide-host/src/ops/run/commands.rs

@@ -4,6 +4,7 @@ use crate::Host;
 use crate::rpc::Dispatcher;
 use ide_core::{IdeError, IdeResult};
 use ide_run::RunConfig;
+use ide_run::import::{RunImport, RunImportSource};
 
 pub async fn run_dotnet_resolve(host: &Host, window: &str, config: RunConfig, debug: bool) -> IdeResult<RunConfig> {
     host.require_trust(window)?;
@@ -105,6 +106,25 @@ pub fn run_save_templates(host: &Host, window: &str, templates: Vec<RunConfig>)
     ide_run::save_templates(&root, &templates)
 }
 
+/// Project files run configurations can be imported from (`.vscode/launch.json`).
+pub fn run_import_sources(host: &Host, window: &str) -> IdeResult<Vec<RunImportSource>> {
+    let root = host.project(window)?.root.clone();
+    Ok(ide_run::import::available(&root))
+}
+
+/// Configurations read from `source`, not saved; names already in `existing` (the
+/// configurations being edited) are skipped.
+pub fn run_import_configs(
+    host: &Host,
+    window: &str,
+    source: RunImportSource,
+    existing: Vec<RunConfig>,
+) -> IdeResult<RunImport> {
+    host.require_trust(window)?;
+    let root = host.project(window)?.root.clone();
+    ide_run::import_configs(&root, source, &existing)
+}
+
 /// The environment runs inherit when "Include system environment variables" is on.
 pub fn run_system_env(_host: &Host, _window: &str) -> std::collections::BTreeMap<String, String> {
     ide_run::system_env()
@@ -240,6 +260,10 @@ pub(crate) fn register(d: &mut Dispatcher) {
     });
     d.add("run_templates", |c| async move { run_templates(&c.host, &c.window) });
     d.add("run_save_templates", |c| async move { run_save_templates(&c.host, &c.window, c.arg("templates")?) });
+    d.add("run_import_sources", |c| async move { run_import_sources(&c.host, &c.window) });
+    d.add("run_import_configs", |c| async move {
+        run_import_configs(&c.host, &c.window, c.arg("source")?, c.arg("existing")?)
+    });
     d.add("run_system_env", |c| async move { Ok(run_system_env(&c.host, &c.window)) });
     d.add("run_gradle_jvm_args_script", |c| async move {
         run_gradle_jvm_args_script(&c.host, &c.window, c.arg("jvmArgs")?).await

crates/ide-host/src/ops/sdk.rs

@@ -122,6 +122,7 @@ pub async fn sdk_python_pip(
     on_output: Channel<String>,
 ) -> IdeResult<()> {
     host.require_trust(window)?;
+    let project_root = host.project(window).ok().map(|p| p.root.clone());
     let cancel = host.begin_project_request(window, request);
     let result = tokio::task::spawn_blocking(move || {
         let send = |line: String| {
@@ -130,7 +131,7 @@ pub async fn sdk_python_pip(
         if uninstall {
             ide_sdk::python::uninstall_package(&python, &requirement, &cancel, &send)
         } else {
-            ide_sdk::python::install_package(&python, &requirement, upgrade, &cancel, &send)
+            ide_sdk::python::install_package(&python, &requirement, upgrade, project_root.as_deref(), &cancel, &send)
         }
     })
     .await

crates/ide-host/src/ops/vcs/commands.rs

@@ -552,12 +552,13 @@ pub async fn vcs_clone(
     request: RequestId,
     url: String,
     dest: PathBuf,
+    depth: Option<u32>,
     on_output: Channel<String>,
 ) -> IdeResult<()> {
     apply_git_executable(&host.global_settings.effective());
     let cancel = host.begin_request(request);
     let result = tokio::task::spawn_blocking(move || {
-        ide_vcs::clone(&url, &dest, &cancel, &|line| {
+        ide_vcs::clone(&url, &dest, depth, &cancel, &|line| {
             let _ = on_output.send(line);
         })
     })
@@ -1070,7 +1071,16 @@ pub(crate) fn register(d: &mut Dispatcher) {
         |c| async move { vcs_stage_hunks(&c.host, &c.window, c.arg("path")?, c.arg("hunks")?).await },
     );
     d.add("vcs_clone", |c| async move {
-        vcs_clone(&c.host, &c.window, c.arg("request")?, c.arg("url")?, c.arg("dest")?, c.sender("onOutput")?).await
+        vcs_clone(
+            &c.host,
+            &c.window,
+            c.arg("request")?,
+            c.arg("url")?,
+            c.arg("dest")?,
+            c.arg("depth")?,
+            c.sender("onOutput")?,
+        )
+        .await
     });
     d.add("vcs_init", |c| async move { vcs_init(&c.host, &c.window, c.arg("dir")?).await });
     d.add("vcs_git_version", |c| async move { vcs_git_version(&c.host, &c.window, c.arg("path")?).await });

crates/ide-host/src/plugins/api.rs

@@ -0,0 +1,803 @@
+//! [`HostApi`] for one plugin's code: what its imports reach in the IDE.
+//! Capabilities were checked by the runtime before any of this runs.
+
+use super::{PluginEvent, PluginEventSink};
+use ide_core::{CancellationToken, TextEdit};
+use ide_extension::Package;
+use ide_language::ProgramPin;
+use ide_plugin::{
+    EventKind, HostApi, HostError, HttpRequest, HttpResponse, NotificationLevel, ProcessOutput, RepositoryStatus,
+    StatusItem,
+};
+use parking_lot::{Mutex, RwLock};
+use std::collections::{BTreeMap, BTreeSet, HashMap};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::time::{Duration, Instant};
+
+/// Largest storage of one plugin (keys + values).
+const MAX_STORAGE: usize = 1 << 20;
+const MAX_KEY: usize = 256;
+/// Most status bar items per plugin.
+const MAX_STATUS_ITEMS: usize = 8;
+
+/// What plugins see of the open projects; provided by the app
+/// ([`super::PluginHost::set_workspace`]), over [`crate::Host`] on the desktop.
+pub trait PluginWorkspace: Send + Sync {
+    /// Roots of the open projects.
+    fn projects(&self) -> Vec<PathBuf>;
+    /// Unsaved text of the open document at `path`.
+    fn buffer_text(&self, path: &Path) -> Option<String>;
+    /// Version and text of the open document at `path`.
+    fn document(&self, path: &Path) -> Option<(u64, String)>;
+    /// Applies `edits` to the open document at `path` if it is still at
+    /// `version`, as one change (one undo step in the editor).
+    fn apply_edits(&self, path: &Path, version: u64, edits: &[TextEdit]) -> Result<u64, HostError>;
+    /// Code from the project may run (git hooks and config on fetch).
+    fn trusted(&self, root: &Path) -> bool;
+    /// Root of the project open in `window`.
+    fn project_of(&self, window: &str) -> Option<PathBuf>;
+    /// Shows `items` as producer `source`'s diagnostics of `path` (replacing earlier ones).
+    fn publish_diagnostics(&self, source: &str, path: &Path, items: Vec<ide_core::Diagnostic>)
+    -> Result<(), HostError>;
+    /// The user's values of `plugin`'s settings: the project's at `root`
+    /// (over global), or global.
+    fn plugin_settings(&self, _plugin: &str, _root: Option<&Path>) -> serde_json::Map<String, serde_json::Value> {
+        serde_json::Map::new()
+    }
+}
+
+/// Where plugin secrets live (the OS keychain on the desktop). Plugins can
+/// only ask whether one is set; values go out only inside `net` requests.
+pub trait SecretStore: Send + Sync {
+    fn get(&self, plugin: &str, name: &str) -> Option<String>;
+    /// Sets, or (`None`) deletes.
+    fn set(&self, plugin: &str, name: &str, value: Option<&str>) -> Result<(), String>;
+}
+
+/// Fallback [`SecretStore`]: one file per plugin, readable only by the user.
+pub struct FileSecretStore {
+    pub dir: PathBuf,
+}
+
+impl FileSecretStore {
+    fn file(&self, plugin: &str) -> PathBuf {
+        self.dir.join(plugin).join("secrets.json")
+    }
+
+    fn load(&self, plugin: &str) -> BTreeMap<String, String> {
+        std::fs::read(self.file(plugin)).ok().and_then(|b| serde_json::from_slice(&b).ok()).unwrap_or_default()
+    }
+}
+
+impl SecretStore for FileSecretStore {
+    fn get(&self, plugin: &str, name: &str) -> Option<String> {
+        self.load(plugin).remove(name)
+    }
+
+    fn set(&self, plugin: &str, name: &str, value: Option<&str>) -> Result<(), String> {
+        let mut map = self.load(plugin);
+        match value {
+            Some(v) => map.insert(name.to_owned(), v.to_owned()),
+            None => map.remove(name),
+        };
+        let file = self.file(plugin);
+        std::fs::create_dir_all(file.parent().expect("has parent")).map_err(|e| e.to_string())?;
+        let bytes = serde_json::to_vec(&map).map_err(|e| e.to_string())?;
+        let tmp = file.with_extension("tmp");
+        std::fs::write(&tmp, bytes).map_err(|e| e.to_string())?;
+        #[cfg(unix)]
+        {
+            use std::os::unix::fs::PermissionsExt;
+            let _ = std::fs::set_permissions(&tmp, std::fs::Permissions::from_mode(0o600));
+        }
+        std::fs::rename(&tmp, &file).map_err(|e| e.to_string())
+    }
+}
+
+/// Largest response body a plugin receives.
+const MAX_RESPONSE: usize = 8 << 20;
+/// Largest stdout / stderr kept from a process.
+const MAX_OUTPUT: usize = 4 << 20;
+/// Most files `find-files` walks before giving up.
+const MAX_WALK: usize = 200_000;
+
+/// Runtime for plugin HTTP requests (actor threads block on it).
+pub(super) fn net_runtime() -> &'static tokio::runtime::Runtime {
+    static RT: std::sync::OnceLock<tokio::runtime::Runtime> = std::sync::OnceLock::new();
+    RT.get_or_init(|| {
+        tokio::runtime::Builder::new_multi_thread()
+            .worker_threads(2)
+            .thread_name("plugin-net")
+            .enable_all()
+            .build()
+            .expect("plugin network runtime")
+    })
+}
+
+/// Replaces `{{secret:<name>}}` in `value` with the plugin's secrets.
+fn fill_secrets(value: &str, lookup: impl Fn(&str) -> Option<String>) -> Result<String, HostError> {
+    let mut out = String::with_capacity(value.len());
+    let mut rest = value;
+    while let Some(i) = rest.find("{{secret:") {
+        out.push_str(&rest[..i]);
+        let after = &rest[i + "{{secret:".len()..];
+        let end = after.find("}}").ok_or_else(|| HostError::Invalid("unterminated {{secret:…}}".into()))?;
+        let name = &after[..end];
+        let secret = lookup(name).ok_or_else(|| HostError::NotFound(format!("secret {name:?} is not set")))?;
+        out.push_str(&secret);
+        rest = &after[end + 2..];
+    }
+    out.push_str(rest);
+    Ok(out)
+}
+
+/// A plugin task shown in the UI.
+struct TaskEntry {
+    plugin: String,
+    cancel: CancellationToken,
+    cancelled: bool,
+}
+
+/// State shared by the host and every plugin's [`PluginApi`].
+pub(super) struct Shared {
+    pub sink: Arc<dyn PluginEventSink>,
+    pub workspace: RwLock<Option<Arc<dyn PluginWorkspace>>>,
+    /// `<plugins>/.data`: one directory per plugin id.
+    pub data_dir: PathBuf,
+    tasks: Mutex<HashMap<u64, TaskEntry>>,
+    next_task: AtomicU64,
+    /// (plugin, item id) → item, for windows opened later.
+    status: Mutex<BTreeMap<(String, String), StatusItem>>,
+    /// plugin → kinds subscribed at run time (kept across idle reclaim).
+    pub subscriptions: Mutex<HashMap<String, BTreeSet<EventKind>>>,
+    /// plugin → files it shows problems for, withdrawn when it stops.
+    diagnostics: Mutex<HashMap<String, BTreeSet<PathBuf>>>,
+    pub secrets: RwLock<Arc<dyn SecretStore>>,
+    /// (plugin, `process:` capability) → the approved program.
+    pub pins: Arc<RwLock<HashMap<(String, String), ProgramPin>>>,
+    /// Validated UI declarations (settings schemas, declared views).
+    pub ui: Arc<ide_extension::UiStore>,
+}
+
+impl Shared {
+    pub fn new(
+        sink: Arc<dyn PluginEventSink>,
+        data_dir: PathBuf,
+        pins: Arc<RwLock<HashMap<(String, String), ProgramPin>>>,
+        ui: Arc<ide_extension::UiStore>,
+    ) -> Arc<Self> {
+        Arc::new(Self {
+            ui,
+            sink,
+            workspace: RwLock::new(None),
+            secrets: RwLock::new(Arc::new(FileSecretStore { dir: data_dir.clone() })),
+            pins,
+            data_dir,
+            tasks: Mutex::default(),
+            next_task: AtomicU64::new(1),
+            status: Mutex::default(),
+            subscriptions: Mutex::default(),
+            diagnostics: Mutex::default(),
+        })
+    }
+
+    fn workspace(&self) -> Option<Arc<dyn PluginWorkspace>> {
+        self.workspace.read().clone()
+    }
+
+    pub fn project_of(&self, window: &str) -> Option<PathBuf> {
+        self.workspace()?.project_of(window)
+    }
+
+    /// Shows `plugin`'s problems of `path`, remembering the file until they are
+    /// cleared (by the plugin, or when it stops).
+    fn publish_diagnostics(
+        &self,
+        plugin: &str,
+        path: &Path,
+        items: Vec<ide_core::Diagnostic>,
+    ) -> Result<(), HostError> {
+        let workspace = self.workspace().ok_or_else(|| HostError::NotFound("no project is open".into()))?;
+        let empty = items.is_empty();
+        workspace.publish_diagnostics(plugin, path, items)?;
+        let mut published = self.diagnostics.lock();
+        if empty {
+            if let Some(paths) = published.get_mut(plugin) {
+                paths.remove(path);
+                if paths.is_empty() {
+                    published.remove(plugin);
+                }
+            }
+        } else {
+            published.entry(plugin.to_owned()).or_default().insert(path.to_path_buf());
+        }
+        Ok(())
+    }
+
+    pub fn status_items(&self) -> Vec<(String, String, StatusItem)> {
+        self.status.lock().iter().map(|((p, id), item)| (p.clone(), id.clone(), item.clone())).collect()
+    }
+
+    /// Withdraws a plugin's run-time state (it stopped or failed). Its
+    /// subscriptions go only with `subscriptions`, as they survive restarts.
+    pub fn clear_plugin(&self, plugin: &str, subscriptions: bool) {
+        let removed: Vec<String> = {
+            let mut status = self.status.lock();
+            let ids: Vec<String> = status.keys().filter(|(p, _)| p == plugin).map(|(_, id)| id.clone()).collect();
+            for id in &ids {
+                status.remove(&(plugin.to_owned(), id.clone()));
+            }
+            ids
+        };
+        for id in removed {
+            self.sink.emit(None, PluginEvent::StatusItemChanged { plugin_id: plugin.to_owned(), id, item: None });
+        }
+        let tasks: Vec<u64> = self.tasks.lock().iter().filter(|(_, t)| t.plugin == plugin).map(|(id, _)| *id).collect();
+        for id in tasks {
+            self.end_task(id);
+        }
+        // Its problems go with it (an idle reclaim keeps them: it isn't cleared then).
+        let paths = self.diagnostics.lock().remove(plugin).unwrap_or_default();
+        if let Some(workspace) = self.workspace() {
+            for path in paths {
+                let _ = workspace.publish_diagnostics(plugin, &path, Vec::new());
+            }
+        }
+        if subscriptions && self.subscriptions.lock().remove(plugin).is_some() {
+            self.sink.emit(None, PluginEvent::SubscriptionsChanged);
+        }
+    }
+
+    /// The user cancelled a task in the UI.
+    pub fn cancel_task(&self, id: u64) -> bool {
+        let mut tasks = self.tasks.lock();
+        let Some(t) = tasks.get_mut(&id) else { return false };
+        t.cancelled = true;
+        t.cancel.cancel();
+        true
+    }
+
+    fn end_task(&self, id: u64) {
+        if let Some(t) = self.tasks.lock().remove(&id) {
+            self.sink.emit(None, PluginEvent::TaskEnded { plugin_id: t.plugin, task_id: id.to_string() });
+        }
+    }
+
+    pub fn storage_file(&self, plugin: &str) -> PathBuf {
+        self.data_dir.join(plugin).join("storage.json")
+    }
+}
+
+pub(super) struct PluginApi {
+    pub pkg: Package,
+    pub shared: Arc<Shared>,
+}
+
+impl PluginApi {
+    fn id(&self) -> &str {
+        self.pkg.id()
+    }
+
+    fn load_storage(&self) -> Result<BTreeMap<String, String>, HostError> {
+        match std::fs::read(self.shared.storage_file(self.id())) {
+            Ok(bytes) => serde_json::from_slice(&bytes).map_err(|e| HostError::Failed(format!("storage: {e}"))),
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(BTreeMap::new()),
+            Err(e) => Err(HostError::Failed(format!("storage: {e}"))),
+        }
+    }
+
+    fn save_storage(&self, map: &BTreeMap<String, String>) -> Result<(), HostError> {
+        let file = self.shared.storage_file(self.id());
+        let bytes = serde_json::to_vec(map).map_err(|e| HostError::Failed(e.to_string()))?;
+        let io = |e: std::io::Error| HostError::Failed(format!("storage: {e}"));
+        std::fs::create_dir_all(file.parent().expect("has parent")).map_err(io)?;
+        let tmp = file.with_extension("tmp");
+        std::fs::write(&tmp, bytes).and_then(|()| std::fs::rename(&tmp, &file)).map_err(io)
+    }
+
+    /// The program approved for the (already checked) `process:` grant,
+    /// verified right before it starts.
+    fn approved_program(&self, program: &str) -> Result<PathBuf, HostError> {
+        let cap = format!("process:{program}");
+        // Granted without a pinned file: the program wasn't found when it was
+        // allowed, and installing it later approves nothing by itself.
+        let pin = self.shared.pins.read().get(&(self.id().to_owned(), cap.clone())).cloned().ok_or_else(|| {
+            HostError::Failed(format!(
+                "{cap}: `{program}` was not found when this permission was allowed; \
+                 install it, then allow {cap} again in Settings › Plugins"
+            ))
+        })?;
+        pin.verify().map(Path::to_path_buf).map_err(|e| HostError::Denied(format!("{cap}: {e}")))
+    }
+}
+
+fn failed(e: impl std::fmt::Display) -> HostError {
+    HostError::Failed(e.to_string())
+}
+
+impl HostApi for PluginApi {
+    fn notify(&self, client: Option<&str>, level: NotificationLevel, title: String, body: String) {
+        self.shared
+            .sink
+            .emit(client, PluginEvent::Notification { plugin_id: self.id().to_owned(), level, title, body });
+    }
+
+    fn status_item(&self, id: &str, item: Option<StatusItem>) {
+        let key = (self.id().to_owned(), id.to_owned());
+        {
+            let mut status = self.shared.status.lock();
+            match &item {
+                Some(item) => {
+                    let count = status.keys().filter(|(p, _)| p == self.id()).count();
+                    if !status.contains_key(&key) && count >= MAX_STATUS_ITEMS {
+                        tracing::warn!(plugin = %self.id(), "more than {MAX_STATUS_ITEMS} status items; {id:?} ignored");
+                        return;
+                    }
+                    if status.get(&key) == Some(item) {
+                        return;
+                    }
+                    status.insert(key, item.clone());
+                }
+                None => {
+                    if status.remove(&key).is_none() {
+                        return;
+                    }
+                }
+            }
+        }
+        self.shared
+            .sink
+            .emit(None, PluginEvent::StatusItemChanged { plugin_id: self.id().to_owned(), id: id.to_owned(), item });
+    }
+
+    fn projects(&self) -> Vec<PathBuf> {
+        self.shared.workspace().map(|w| w.projects()).unwrap_or_default()
+    }
+
+    fn buffer_text(&self, path: &Path) -> Option<String> {
+        self.shared.workspace()?.buffer_text(path)
+    }
+
+    fn document(&self, path: &Path) -> Option<(u64, String)> {
+        self.shared.workspace()?.document(path)
+    }
+
+    fn apply_edits(
+        &self,
+        _client: Option<&str>,
+        path: &Path,
+        version: u64,
+        edits: Vec<TextEdit>,
+    ) -> Result<u64, HostError> {
+        let workspace = self.shared.workspace().ok_or_else(|| HostError::NotFound("no project is open".into()))?;
+        workspace.apply_edits(path, version, &edits)
+    }
+
+    fn storage_get(&self, key: &str) -> Result<Option<String>, HostError> {
+        Ok(self.load_storage()?.get(key).cloned())
+    }
+
+    fn storage_set(&self, key: &str, value: Option<String>) -> Result<(), HostError> {
+        if key.is_empty() || key.len() > MAX_KEY {
+            return Err(HostError::Invalid(format!("keys are 1–{MAX_KEY} bytes")));
+        }
+        let mut map = self.load_storage()?;
+        let changed = match value {
+            Some(v) => map.insert(key.to_owned(), v.clone()).as_ref() != Some(&v),
+            None => map.remove(key).is_some(),
+        };
+        if !changed {
+            return Ok(());
+        }
+        let size: usize = map.iter().map(|(k, v)| k.len() + v.len()).sum();
+        if size > MAX_STORAGE {
+            return Err(HostError::Invalid(format!("storage is limited to {} KiB", MAX_STORAGE >> 10)));
+        }
+        self.save_storage(&map)
+    }
+
+    fn storage_keys(&self, prefix: &str) -> Result<Vec<String>, HostError> {
+        Ok(self.load_storage()?.into_keys().filter(|k| k.starts_with(prefix)).collect())
+    }
+
+    fn vcs_status(&self, root: &Path) -> Result<Option<RepositoryStatus>, HostError> {
+        let Some(repo) = ide_vcs::Repo::discover(root).map_err(failed)? else { return Ok(None) };
+        let info = repo.branch_info().map_err(failed)?;
+        let changed = repo.status().map_err(failed)?.len();
+        Ok(Some(RepositoryStatus {
+            root: repo.root().to_string_lossy().into_owned(),
+            branch: info.head,
+            commit: info.head_commit,
+            upstream: info.upstream,
+            ahead: info.ahead,
+            behind: info.behind,
+            operation: info.operation,
+            changed_files: u32::try_from(changed).unwrap_or(u32::MAX),
+        }))
+    }
+
+    fn vcs_fetch(&self, root: &Path, cancel: &CancellationToken) -> Result<(), HostError> {
+        let workspace = self.shared.workspace();
+        if !workspace.is_some_and(|w| w.trusted(root)) {
+            return Err(HostError::Failed("the project is in Restricted Mode: git does not run there".into()));
+        }
+        let Some(repo) = ide_vcs::Repo::discover(root).map_err(failed)? else {
+            return Err(HostError::NotFound("the project is not in a git repository".into()));
+        };
+        match repo.fetch(cancel, &|_| {}) {
+            Ok(()) => Ok(()),
+            Err(_) if cancel.is_cancelled() => Err(HostError::Cancelled),
+            Err(e) => Err(failed(e.message)),
+        }
+    }
+
+    fn find_files(&self, root: &Path, glob: &str, limit: usize) -> Result<Vec<String>, HostError> {
+        let matcher = globset::GlobBuilder::new(glob)
+            .literal_separator(true)
+            .build()
+            .map_err(|e| HostError::Invalid(format!("{glob:?}: {e}")))?
+            .compile_matcher();
+        let mut out = Vec::new();
+        for (n, entry) in ignore::WalkBuilder::new(root).hidden(true).build().flatten().enumerate() {
+            if n >= MAX_WALK || out.len() >= limit {
+                break;
+            }
+            if !entry.file_type().is_some_and(|t| t.is_file()) {
+                continue;
+            }
+            let Ok(rel) = entry.path().strip_prefix(root) else { continue };
+            if matcher.is_match(rel) {
+                out.push(entry.path().to_string_lossy().into_owned());
+            }
+        }
+        out.sort();
+        Ok(out)
+    }
+
+    fn publish_diagnostics(&self, path: &Path, items: Vec<ide_core::Diagnostic>) -> Result<(), HostError> {
+        self.shared.publish_diagnostics(self.id(), path, items)
+    }
+
+    fn fetch(&self, request: HttpRequest, cancel: &CancellationToken) -> Result<HttpResponse, HostError> {
+        let secrets = self.shared.secrets.read().clone();
+        let id = self.id().to_owned();
+        let mut headers = reqwest::header::HeaderMap::new();
+        for (name, value) in &request.headers {
+            let value = fill_secrets(value, |n| secrets.get(&id, n))?;
+            let name = reqwest::header::HeaderName::from_bytes(name.as_bytes())
+                .map_err(|e| HostError::Invalid(format!("header {name:?}: {e}")))?;
+            let mut value = reqwest::header::HeaderValue::from_str(&value)
+                .map_err(|e| HostError::Invalid(format!("header {name}: {e}")))?;
+            value.set_sensitive(true);
+            headers.append(name, value);
+        }
+        let method = reqwest::Method::from_bytes(request.method.to_ascii_uppercase().as_bytes())
+            .map_err(|_| HostError::Invalid(format!("method {:?}", request.method)))?;
+        let client = ide_http::client::shared().map_err(|e| HostError::Failed(e.message))?;
+        // A redirect to another host is refused after the fact (the shared
+        // client follows redirects).
+        let builder = client.request(method, &request.url).headers(headers).timeout(request.timeout);
+        let builder = match request.body {
+            Some(body) => builder.body(body),
+            None => builder,
+        };
+        let cancel = cancel.clone();
+        let host = ide_plugin::net_host(&request.url).map_err(HostError::Invalid)?;
+        net_runtime().block_on(async move {
+            let send = async {
+                let response = builder.send().await.map_err(|e| HostError::Failed(e.to_string()))?;
+                if ide_plugin::net_host(response.url().as_str()).ok().as_deref() != Some(host.as_str()) {
+                    return Err(HostError::Denied(format!(
+                        "net:{} (redirected)",
+                        response.url().host_str().unwrap_or("?")
+                    )));
+                }
+                let status = response.status().as_u16();
+                let headers = response
+                    .headers()
+                    .iter()
+                    .map(|(k, v)| (k.as_str().to_owned(), String::from_utf8_lossy(v.as_bytes()).into_owned()))
+                    .collect();
+                let mut body = Vec::new();
+                let mut response = response;
+                while let Some(chunk) = response.chunk().await.map_err(|e| HostError::Failed(e.to_string()))? {
+                    if body.len() + chunk.len() > MAX_RESPONSE {
+                        return Err(HostError::Failed("response larger than 8 MiB".into()));
+                    }
+                    body.extend_from_slice(&chunk);
+                }
+                Ok(HttpResponse { status, headers, body })
+            };
+            tokio::select! {
+                r = send => r,
+                () = cancel.cancelled() => Err(HostError::Cancelled),
+            }
+        })
+    }
+
+    fn secret_is_set(&self, name: &str) -> bool {
+        self.shared.secrets.read().get(self.id(), name).is_some()
+    }
+
+    fn run_process(
+        &self,
+        program: &str,
+        args: Vec<String>,
+        cwd: Option<&Path>,
+        stdin: Option<String>,
+        cancel: &CancellationToken,
+        timeout: Duration,
+    ) -> Result<ProcessOutput, HostError> {
+        let binary = self.approved_program(program)?;
+        let cwd = cwd.map(Path::to_path_buf).unwrap_or_else(|| self.shared.data_dir.join(self.id()));
+        let _ = std::fs::create_dir_all(&cwd);
+        let mut child = std::process::Command::new(&binary)
+            .args(&args)
+            .current_dir(&cwd)
+            .stdin(if stdin.is_some() { std::process::Stdio::piped() } else { std::process::Stdio::null() })
+            .stdout(std::process::Stdio::piped())
+            .stderr(std::process::Stdio::piped())
+            .spawn()
+            .map_err(|e| HostError::Failed(format!("{}: {e}", binary.display())))?;
+        if let (Some(input), Some(mut pipe)) = (stdin, child.stdin.take()) {
+            std::thread::spawn(move || {
+                use std::io::Write;
+                let _ = pipe.write_all(input.as_bytes());
+            });
+        }
+        let read = |pipe: Option<Box<dyn std::io::Read + Send>>| {
+            std::thread::spawn(move || {
+                use std::io::Read;
+                let mut out = Vec::new();
+                if let Some(p) = pipe {
+                    let _ = p.take(MAX_OUTPUT as u64).read_to_end(&mut out);
+                }
+                String::from_utf8_lossy(&out).into_owned()
+            })
+        };
+        let stdout = read(child.stdout.take().map(|p| Box::new(p) as Box<dyn std::io::Read + Send>));
+        let stderr = read(child.stderr.take().map(|p| Box::new(p) as Box<dyn std::io::Read + Send>));
+        let deadline = Instant::now() + timeout;
+        let status = loop {
+            if let Some(status) = child.try_wait().map_err(|e| HostError::Failed(e.to_string()))? {
+                break status;
+            }
+            if cancel.is_cancelled() || Instant::now() >= deadline {
+                let _ = child.kill();
+                let _ = child.wait();
+                return Err(if cancel.is_cancelled() {
+                    HostError::Cancelled
+                } else {
+                    HostError::Failed(format!("{program} timed out after {timeout:?}"))
+                });
+            }
+            std::thread::sleep(Duration::from_millis(10));
+        };
+        Ok(ProcessOutput {
+            status: status.code(),
+            stdout: stdout.join().unwrap_or_default(),
+            stderr: stderr.join().unwrap_or_default(),
+        })
+    }
+
+    fn subscribe(&self, kind: EventKind, on: bool) {
+        let changed = {
+            let mut subs = self.shared.subscriptions.lock();
+            let set = subs.entry(self.id().to_owned()).or_default();
+            if on { set.insert(kind) } else { set.remove(&kind) }
+        };
+        if changed {
+            self.shared.sink.emit(None, PluginEvent::SubscriptionsChanged);
+        }
+    }
+
+    fn task_begin(&self, client: Option<&str>, title: String, cancellable: bool, cancel: CancellationToken) -> u64 {
+        let id = self.shared.next_task.fetch_add(1, Ordering::Relaxed);
+        self.shared.tasks.lock().insert(id, TaskEntry { plugin: self.id().to_owned(), cancel, cancelled: false });
+        self.shared.sink.emit(
+            client,
+            PluginEvent::TaskStarted { plugin_id: self.id().to_owned(), task_id: id.to_string(), title, cancellable },
+        );
+        id
+    }
+
+    fn task_report(&self, id: u64, done: u32, total: Option<u32>, message: Option<String>) {
+        if !self.shared.tasks.lock().contains_key(&id) {
+            return;
+        }
+        self.shared.sink.emit(
+            None,
+            PluginEvent::TaskProgress {
+                plugin_id: self.id().to_owned(),
+                task_id: id.to_string(),
+                done,
+                total,
+                message,
+            },
+        );
+    }
+
+    fn task_cancelled(&self, id: u64) -> bool {
+        self.shared.tasks.lock().get(&id).is_some_and(|t| t.cancelled)
+    }
+
+    fn task_end(&self, id: u64) {
+        self.shared.end_task(id);
+    }
+
+    fn refresh_view(&self, view: &str) {
+        self.shared
+            .sink
+            .emit(None, PluginEvent::ViewChanged { plugin_id: self.id().to_owned(), view: view.to_owned() });
+    }
+
+    fn post_view_message(&self, view: &str, message: String) -> Result<(), HostError> {
+        let declared = [super::ui_points::VIEWS, super::ui_points::CUSTOM_EDITORS]
+            .iter()
+            .any(|point| self.shared.ui.items(point, Some(self.id())).iter().any(|i| i.key == view));
+        if !declared {
+            return Err(HostError::NotFound(format!("the plugin declares no view {view:?}")));
+        }
+        let event = PluginEvent::ViewMessage { plugin_id: self.id().to_owned(), view: view.to_owned(), message };
+        self.shared.sink.emit(None, event);
+        Ok(())
+    }
+
+    fn open_terminal(
+        &self,
+        client: Option<&str>,
+        title: String,
+        program: &str,
+        args: Vec<String>,
+        cwd: Option<&Path>,
+    ) -> Result<(), HostError> {
+        let binary = self.approved_program(program)?;
+        let cwd = cwd.map(Path::to_path_buf).unwrap_or_else(|| self.shared.data_dir.join(self.id()));
+        let _ = std::fs::create_dir_all(&cwd);
+        let event = PluginEvent::OpenTerminal {
+            plugin_id: self.id().to_owned(),
+            title,
+            program: binary.into(),
+            args,
+            cwd: cwd.into(),
+        };
+        self.shared.sink.emit(client, event);
+        Ok(())
+    }
+
+    fn setting(&self, root: Option<&Path>, key: &str) -> Option<String> {
+        let schema: Vec<super::ui_points::SettingSchema> = self
+            .shared
+            .ui
+            .items(super::ui_points::SETTINGS, Some(self.id()))
+            .into_iter()
+            .find_map(|i| serde_json::from_value(i.decl.get("properties")?.clone()).ok())?;
+        let setting = schema.into_iter().find(|s| s.key == key)?;
+        let user = self.shared.workspace().map(|w| w.plugin_settings(self.id(), root)).unwrap_or_default();
+        let value = user.get(key).filter(|v| setting.accepts(v)).cloned().unwrap_or(setting.default);
+        serde_json::to_string(&value).ok()
+    }
+}
+
+/// [`PluginWorkspace`] over the desktop host's open projects.
+pub struct HostWorkspace(pub std::sync::Weak<crate::Host>);
+
+impl HostWorkspace {
+    fn projects(&self) -> Vec<Arc<crate::project::Project>> {
+        self.0.upgrade().map(|h| h.projects()).unwrap_or_default()
+    }
+
+    /// The project holding an open document at `path`, and its id.
+    fn open_document(&self, path: &Path) -> Option<(Arc<crate::project::Project>, ide_core::DocId)> {
+        self.projects().into_iter().find_map(|p| p.documents.by_path(path).map(|doc| (p, doc)))
+    }
+}
+
+impl PluginWorkspace for HostWorkspace {
+    fn projects(&self) -> Vec<PathBuf> {
+        let mut roots: Vec<PathBuf> = HostWorkspace::projects(self).iter().map(|p| p.root.clone()).collect();
+        roots.sort();
+        roots.dedup();
+        roots
+    }
+
+    fn buffer_text(&self, path: &Path) -> Option<String> {
+        HostWorkspace::projects(self).iter().find_map(|p| p.documents.text_of(path))
+    }
+
+    fn document(&self, path: &Path) -> Option<(u64, String)> {
+        let (project, doc) = self.open_document(path)?;
+        let snap = project.documents.snapshot(doc).ok()?;
+        Some((u64::from(snap.version), snap.text))
+    }
+
+    fn apply_edits(&self, path: &Path, version: u64, edits: &[TextEdit]) -> Result<u64, HostError> {
+        let (project, doc) =
+            self.open_document(path).ok_or_else(|| HostError::NotFound(format!("{} is not open", path.display())))?;
+        let version = u32::try_from(version).map_err(|_| HostError::Stale)?;
+        match project.documents.apply_edits_at(doc, version, edits) {
+            Ok(Some(v)) => Ok(u64::from(v)),
+            Ok(None) => Err(HostError::Stale),
+            Err(e) if e.kind == ide_core::error::ErrorKind::InvalidInput => Err(HostError::Invalid(e.message)),
+            Err(e) => Err(HostError::Failed(e.message)),
+        }
+    }
+
+    fn trusted(&self, root: &Path) -> bool {
+        HostWorkspace::projects(self).iter().any(|p| p.root == root && p.is_trusted())
+    }
+
+    fn project_of(&self, window: &str) -> Option<PathBuf> {
+        self.0.upgrade()?.project(window).ok().map(|p| p.root.clone())
+    }
+
+    fn publish_diagnostics(
+        &self,
+        source: &str,
+        path: &Path,
+        items: Vec<ide_core::Diagnostic>,
+    ) -> Result<(), HostError> {
+        let projects = HostWorkspace::projects(self);
+        let project = projects
+            .iter()
+            .filter(|p| path.starts_with(&p.root))
+            .max_by_key(|p| p.root.as_os_str().len())
+            .ok_or_else(|| HostError::Invalid(format!("{} is not in an open project", path.display())))?;
+        project.sink.emit(ide_core::IdeEvent::Diagnostics {
+            path: path.to_path_buf().into(),
+            source: format!("plugin:{source}"),
+            items,
+        });
+        Ok(())
+    }
+
+    fn plugin_settings(&self, plugin: &str, root: Option<&Path>) -> serde_json::Map<String, serde_json::Value> {
+        let Some(host) = self.0.upgrade() else { return serde_json::Map::new() };
+        let settings = match root.and_then(|r| host.projects().into_iter().find(|p| p.root == r)) {
+            Some(p) => p.settings.effective(),
+            None => host.global_settings.effective(),
+        };
+        settings.plugins.get(plugin).cloned().unwrap_or_default()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn api(dir: &Path, pins: Arc<RwLock<HashMap<(String, String), ProgramPin>>>) -> PluginApi {
+        let manifest = ide_extension::Manifest::parse(
+            "id = \"acme.lint\"\nname = \"Lint\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n",
+        )
+        .unwrap();
+        let sink: Arc<dyn PluginEventSink> = Arc::new(|_: Option<&str>, _: PluginEvent| {});
+        let shared = Shared::new(sink, dir.join(".data"), pins, ide_extension::UiStore::new());
+        PluginApi { pkg: Package::new(manifest, dir.to_path_buf()), shared }
+    }
+
+    #[test]
+    fn programs_run_only_as_approved() {
+        let tmp = tempfile::tempdir().unwrap();
+        let bin = tmp.path().join("lint");
+        std::fs::write(&bin, "#!/bin/sh\n").unwrap();
+        let pins: Arc<RwLock<HashMap<(String, String), ProgramPin>>> = Arc::default();
+        let api = api(tmp.path(), pins.clone());
+
+        // Allowed while the program was missing: say how to fix it rather than "not granted".
+        let err = api.approved_program("lint").unwrap_err().to_string();
+        assert!(
+            err.contains("was not found when this permission was allowed") && err.contains("allow process:lint again"),
+            "{err}"
+        );
+
+        pins.write().insert(("acme.lint".into(), "process:lint".into()), ProgramPin::approve(&bin).unwrap());
+        assert_eq!(api.approved_program("lint").unwrap(), bin);
+
+        std::fs::write(&bin, "#!/bin/sh\necho replaced\n").unwrap();
+        assert!(
+            matches!(api.approved_program("lint"), Err(HostError::Denied(e)) if e.contains("changed since it was approved"))
+        );
+    }
+}

crates/ide-host/src/plugins/icons.rs

@@ -0,0 +1,615 @@
+//! The `iconThemes` extension point: file and folder icons.
+//!
+//! ```toml
+//! [[contributes.iconThemes]]
+//! id = "material"
+//! label = "Material Icons"
+//! path = "icons/theme.json"
+//! ```
+//!
+//! `theme.json` (paths relative to the package):
+//!
+//! ```json
+//! {
+//!   "iconDefinitions": { "rust": "icons/rust.svg", "folder-src": "icons/folder-src.svg" },
+//!   "file": "file", "folder": "folder", "folderExpanded": "folder-open",
+//!   "fileExtensions": { "rs": "rust" },
+//!   "fileNames": { "cargo.toml": "cargo" },
+//!   "folderNames": { "src": "folder-src" }
+//! }
+//! ```
+//!
+//! Every SVG is sanitised here (allow-listed elements and attributes, no
+//! scripts, event handlers, external references or entities) and stored as an
+//! asset; the client fetches the mapping and the icons only when the theme is
+//! selected, so installed icon themes cost nothing at start-up.
+
+use ide_extension::{Package, UiDecl, check_relative, decode, validate_item_id};
+use serde::Deserialize;
+use std::collections::{BTreeMap, BTreeSet};
+use std::path::PathBuf;
+
+pub const POINT_ID: &str = "iconThemes";
+const MAX_ICONS: usize = 5000;
+const MAX_SVG: usize = 64 << 10;
+const MAX_MAPPINGS: usize = 20_000;
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Decl {
+    id: String,
+    label: String,
+    path: PathBuf,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+struct ThemeFile {
+    icon_definitions: BTreeMap<String, PathBuf>,
+    #[serde(default)]
+    file: Option<String>,
+    #[serde(default)]
+    folder: Option<String>,
+    #[serde(default)]
+    folder_expanded: Option<String>,
+    #[serde(default)]
+    file_extensions: BTreeMap<String, String>,
+    #[serde(default)]
+    file_names: BTreeMap<String, String>,
+    #[serde(default)]
+    folder_names: BTreeMap<String, String>,
+}
+
+/// Asset id of a theme's mapping (JSON).
+pub fn map_asset(theme: &str) -> String {
+    format!("iconTheme/{theme}/map")
+}
+
+/// Asset id prefix of a theme's SVGs (`…/svg/<icon id>`).
+pub fn svg_prefix(theme: &str) -> String {
+    format!("iconTheme/{theme}/svg/")
+}
+
+/// An SVG icon of the package, size-checked and sanitised.
+pub(super) fn read_icon(pkg: &Package, path: &std::path::Path) -> Result<String, String> {
+    check_relative(path, "icon")?;
+    let svg = pkg.read_text(path)?;
+    if svg.len() > MAX_SVG {
+        return Err(format!("{}: larger than {} KiB", path.display(), MAX_SVG >> 10));
+    }
+    sanitize_svg(&svg).map_err(|e| format!("{}: {e}", path.display()))
+}
+
+pub(super) fn icon_theme(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: Decl = decode(POINT_ID, decl)?;
+    validate_item_id(&d.id, "icon theme id")?;
+    if d.label.trim().is_empty() {
+        return Err(format!("icon theme {:?} has an empty label", d.id));
+    }
+    let src = pkg.read_text(&d.path)?;
+    let theme: ThemeFile = serde_json::from_str(&src).map_err(|e| format!("{}: {e}", d.path.display()))?;
+    let at = |what: &str| format!("{} ({what})", d.path.display());
+    if theme.icon_definitions.len() > MAX_ICONS {
+        return Err(format!("{}: more than {MAX_ICONS} icons", d.path.display()));
+    }
+    let mappings = theme.file_extensions.len() + theme.file_names.len() + theme.folder_names.len();
+    if mappings > MAX_MAPPINGS {
+        return Err(format!("{}: more than {MAX_MAPPINGS} mappings", d.path.display()));
+    }
+    let defined: BTreeSet<&str> = theme.icon_definitions.keys().map(String::as_str).collect();
+    let check_ref = |icon: &str, what: &str| -> Result<(), String> {
+        if defined.contains(icon) { Ok(()) } else { Err(format!("{}: unknown icon {icon:?}", at(what))) }
+    };
+    for (what, icon) in [("file", &theme.file), ("folder", &theme.folder), ("folderExpanded", &theme.folder_expanded)] {
+        if let Some(icon) = icon {
+            check_ref(icon, what)?;
+        }
+    }
+    // Extensions may be written with their dot (`.rs`); names keep theirs (`.github`, `.gitignore`).
+    let lower = |map: &BTreeMap<String, String>, what: &str| -> Result<BTreeMap<String, String>, String> {
+        let mut out = BTreeMap::new();
+        for (k, icon) in map {
+            check_ref(icon, what)?;
+            let key = k.trim();
+            let key = if what == "fileExtensions" { key.trim_start_matches('.') } else { key }.to_lowercase();
+            if key.is_empty() || key.contains(['/', '\\']) {
+                return Err(format!("{}: invalid key {k:?}", at(what)));
+            }
+            out.insert(key, icon.clone());
+        }
+        Ok(out)
+    };
+    let file_extensions = lower(&theme.file_extensions, "fileExtensions")?;
+    let file_names = lower(&theme.file_names, "fileNames")?;
+    let folder_names = lower(&theme.folder_names, "folderNames")?;
+
+    let mut assets = Vec::with_capacity(theme.icon_definitions.len() + 1);
+    let mut files = vec![d.path.clone()];
+    for (icon, path) in &theme.icon_definitions {
+        validate_item_id(icon, "icon id")?;
+        let clean = read_icon(pkg, path)?;
+        assets.push((format!("{}{icon}", svg_prefix(&d.id)), clean));
+        files.push(path.clone());
+    }
+    let map = serde_json::json!({
+        "file": theme.file,
+        "folder": theme.folder,
+        "folderExpanded": theme.folder_expanded,
+        "fileExtensions": file_extensions,
+        "fileNames": file_names,
+        "folderNames": folder_names,
+    });
+    assets.push((map_asset(&d.id), map.to_string()));
+    let json = serde_json::json!({ "id": d.id, "label": d.label, "icons": theme.icon_definitions.len() });
+    let mut out = UiDecl::new(d.id.clone(), d.label, json);
+    out.files = files;
+    out.assets = assets;
+    Ok(out)
+}
+
+// ---------------------------------------------------------------------------
+// SVG sanitiser
+
+const ELEMENTS: &[&str] = &[
+    "svg",
+    "g",
+    "path",
+    "circle",
+    "ellipse",
+    "line",
+    "polyline",
+    "polygon",
+    "rect",
+    "defs",
+    "lineargradient",
+    "radialgradient",
+    "stop",
+    "clippath",
+    "mask",
+    "use",
+    "symbol",
+    "pattern",
+    "text",
+    "tspan",
+    "filter",
+    "fegaussianblur",
+    "feoffset",
+    "feblend",
+    "fecolormatrix",
+    "feflood",
+    "fecomposite",
+    "femerge",
+    "femergenode",
+    "fedropshadow",
+];
+
+/// Dropped with their content: harmless metadata.
+const STRIPPED: &[&str] = &["title", "desc", "metadata"];
+
+const ATTRIBUTES: &[&str] = &[
+    "id",
+    "class",
+    "viewbox",
+    "width",
+    "height",
+    "x",
+    "y",
+    "x1",
+    "y1",
+    "x2",
+    "y2",
+    "cx",
+    "cy",
+    "r",
+    "rx",
+    "ry",
+    "fx",
+    "fy",
+    "d",
+    "points",
+    "transform",
+    "fill",
+    "fill-opacity",
+    "fill-rule",
+    "clip-rule",
+    "clip-path",
+    "mask",
+    "stroke",
+    "stroke-width",
+    "stroke-linecap",
+    "stroke-linejoin",
+    "stroke-miterlimit",
+    "stroke-dasharray",
+    "stroke-dashoffset",
+    "stroke-opacity",
+    "opacity",
+    "offset",
+    "stop-color",
+    "stop-opacity",
+    "gradientunits",
+    "gradienttransform",
+    "spreadmethod",
+    "patternunits",
+    "patterncontentunits",
+    "patterntransform",
+    "clippathunits",
+    "maskunits",
+    "maskcontentunits",
+    "preserveaspectratio",
+    "style",
+    "href",
+    "xlink:href",
+    "xmlns",
+    "xmlns:xlink",
+    "version",
+    "font-family",
+    "font-size",
+    "font-weight",
+    "text-anchor",
+    "dominant-baseline",
+    "letter-spacing",
+    "display",
+    "visibility",
+    "color",
+    "filter",
+    "in",
+    "in2",
+    "result",
+    "stddeviation",
+    "dx",
+    "dy",
+    "mode",
+    "operator",
+    "values",
+    "type",
+    "flood-color",
+    "flood-opacity",
+    "k1",
+    "k2",
+    "k3",
+    "k4",
+    "filterunits",
+    "primitiveunits",
+    "vector-effect",
+    "shape-rendering",
+    "isolation",
+    "mix-blend-mode",
+];
+
+/// Parses `src` and re-serialises the allow-listed subset. Fails on anything
+/// that could execute, fetch or escape (scripts, `foreignObject`, event
+/// handlers, external `href`s, `url()` to anything but a local fragment,
+/// DTDs, entities, CDATA).
+pub fn sanitize_svg(src: &str) -> Result<String, String> {
+    let mut out = String::with_capacity(src.len());
+    let mut stack: Vec<String> = Vec::new();
+    // Depth inside a stripped element (its content is skipped).
+    let mut skip_depth = 0usize;
+    let mut seen_root = false;
+    let mut rest = src;
+    while !rest.is_empty() {
+        let Some(lt) = rest.find('<') else {
+            if skip_depth == 0 && !stack.is_empty() {
+                out.push_str(&text(rest)?);
+            } else if !rest.trim().is_empty() && stack.is_empty() {
+                return Err("text outside the <svg> element".into());
+            }
+            break;
+        };
+        if lt > 0 {
+            let t = &rest[..lt];
+            if skip_depth == 0 && !stack.is_empty() {
+                out.push_str(&text(t)?);
+            } else if stack.is_empty() && !t.trim().is_empty() {
+                return Err("text outside the <svg> element".into());
+            }
+        }
+        rest = &rest[lt..];
+        if let Some(after) = rest.strip_prefix("<!--") {
+            let end = after.find("-->").ok_or("unterminated comment")?;
+            rest = &after[end + 3..];
+            continue;
+        }
+        if rest.starts_with("<?") {
+            let end = rest.find("?>").ok_or("unterminated processing instruction")?;
+            rest = &rest[end + 2..];
+            continue;
+        }
+        if rest.starts_with("<!") {
+            return Err("DTDs, entities and CDATA are not allowed".into());
+        }
+        if let Some(after) = rest.strip_prefix("</") {
+            let end = after.find('>').ok_or("unterminated closing tag")?;
+            let name = after[..end].trim().to_ascii_lowercase();
+            rest = &after[end + 1..];
+            let open = stack.pop().ok_or_else(|| format!("unexpected </{name}>"))?;
+            if open != name {
+                return Err(format!("</{name}> does not close <{open}>"));
+            }
+            if skip_depth > 0 {
+                skip_depth -= 1;
+            } else {
+                out.push_str(&format!("</{name}>"));
+            }
+            continue;
+        }
+        // Start tag.
+        let end = tag_end(rest).ok_or("unterminated tag")?;
+        let inner = &rest[1..end];
+        rest = &rest[end + 1..];
+        let self_closing = inner.trim_end().ends_with('/');
+        let inner = inner.trim_end().trim_end_matches('/');
+        let name_end = inner.find(|c: char| c.is_whitespace()).unwrap_or(inner.len());
+        let raw_name = &inner[..name_end];
+        let name = raw_name.to_ascii_lowercase();
+        if name.is_empty() {
+            return Err("empty tag".into());
+        }
+        if stack.is_empty() {
+            if seen_root || name != "svg" {
+                return Err("the file must contain exactly one <svg> element".into());
+            }
+            seen_root = true;
+        }
+        if !self_closing {
+            stack.push(name.clone());
+        }
+        if skip_depth > 0 {
+            if !self_closing {
+                skip_depth += 1;
+            }
+            continue;
+        }
+        if STRIPPED.contains(&name.as_str()) || name.contains(':') {
+            // Editor metadata (sodipodi:namedview) or descriptive text.
+            if !self_closing {
+                skip_depth = 1;
+            }
+            continue;
+        }
+        if !ELEMENTS.contains(&name.as_str()) {
+            return Err(format!("<{raw_name}> is not allowed"));
+        }
+        out.push('<');
+        out.push_str(raw_name);
+        for (attr, value) in attributes(&inner[name_end..])? {
+            let key = attr.to_ascii_lowercase();
+            if key.starts_with("on") {
+                return Err(format!("event handler {attr} is not allowed"));
+            }
+            if key.contains(':') && !matches!(key.as_str(), "xlink:href" | "xmlns:xlink") {
+                continue; // inkscape:label, sodipodi:docname, …
+            }
+            if !ATTRIBUTES.contains(&key.as_str()) && !key.starts_with("data-") && !key.starts_with("aria-") {
+                return Err(format!("attribute {attr} is not allowed"));
+            }
+            check_value(&key, &value).map_err(|e| format!("{attr}: {e}"))?;
+            out.push(' ');
+            out.push_str(&attr);
+            out.push_str("=\"");
+            out.push_str(&escape(&value));
+            out.push('"');
+        }
+        out.push_str(if self_closing { "/>" } else { ">" });
+    }
+    if !stack.is_empty() {
+        return Err(format!("<{}> is not closed", stack.last().map(String::as_str).unwrap_or("?")));
+    }
+    if !seen_root {
+        return Err("no <svg> element".into());
+    }
+    Ok(out)
+}
+
+/// Index of the `>` ending the tag at the start of `s`, skipping quoted values.
+fn tag_end(s: &str) -> Option<usize> {
+    let mut quote: Option<char> = None;
+    for (i, c) in s.char_indices().skip(1) {
+        match (quote, c) {
+            (Some(q), c) if c == q => quote = None,
+            (Some(_), _) => {}
+            (None, '"' | '\'') => quote = Some(c),
+            (None, '>') => return Some(i),
+            (None, '<') => return None,
+            _ => {}
+        }
+    }
+    None
+}
+
+fn attributes(s: &str) -> Result<Vec<(String, String)>, String> {
+    let mut out = Vec::new();
+    let mut rest = s.trim_start();
+    while !rest.is_empty() {
+        let eq = rest.find('=').ok_or_else(|| format!("attribute without value near {:?}", clip(rest)))?;
+        let name = rest[..eq].trim();
+        if name.is_empty() || name.contains(|c: char| c.is_whitespace() || c == '"' || c == '\'') {
+            return Err(format!("malformed attribute near {:?}", clip(rest)));
+        }
+        let after = rest[eq + 1..].trim_start();
+        let quote = after.chars().next().filter(|c| *c == '"' || *c == '\'').ok_or("unquoted attribute value")?;
+        let close = after[1..].find(quote).ok_or("unterminated attribute value")?;
+        let value = decode_entities(&after[1..1 + close])?;
+        if out.iter().any(|(n, _): &(String, String)| n.eq_ignore_ascii_case(name)) {
+            return Err(format!("duplicate attribute {name}"));
+        }
+        out.push((name.to_owned(), value));
+        rest = after[close + 2..].trim_start();
+    }
+    Ok(out)
+}
+
+fn check_value(key: &str, value: &str) -> Result<(), String> {
+    let lower = value.to_ascii_lowercase();
+    if matches!(key, "href" | "xlink:href") {
+        return if value.starts_with('#') { Ok(()) } else { Err("only local references (#id) are allowed".into()) };
+    }
+    if key == "xmlns" || key == "xmlns:xlink" {
+        return Ok(());
+    }
+    if lower.contains("javascript:")
+        || lower.contains("expression(")
+        || lower.contains("@import")
+        || value.contains('\\')
+    {
+        return Err("unsafe value".into());
+    }
+    let mut rest = lower.as_str();
+    while let Some(i) = rest.find("url(") {
+        let inner = rest[i + 4..].trim_start().trim_start_matches(['"', '\'']);
+        if !inner.starts_with('#') {
+            return Err("url() may only reference a local fragment".into());
+        }
+        rest = &rest[i + 4..];
+    }
+    Ok(())
+}
+
+fn decode_entities(s: &str) -> Result<String, String> {
+    if !s.contains('&') {
+        return Ok(s.to_owned());
+    }
+    let mut out = String::with_capacity(s.len());
+    let mut rest = s;
+    while let Some(i) = rest.find('&') {
+        out.push_str(&rest[..i]);
+        let semi = rest[i..].find(';').ok_or("unterminated entity")?;
+        let ent = &rest[i + 1..i + semi];
+        let c = match ent {
+            "amp" => '&',
+            "lt" => '<',
+            "gt" => '>',
+            "quot" => '"',
+            "apos" => '\'',
+            _ => {
+                let code = if let Some(hex) = ent.strip_prefix("#x").or_else(|| ent.strip_prefix("#X")) {
+                    u32::from_str_radix(hex, 16).ok()
+                } else if let Some(dec) = ent.strip_prefix('#') {
+                    dec.parse().ok()
+                } else {
+                    None
+                };
+                code.and_then(char::from_u32).ok_or_else(|| format!("entity &{ent}; is not allowed"))?
+            }
+        };
+        out.push(c);
+        rest = &rest[i + semi + 1..];
+    }
+    out.push_str(rest);
+    Ok(out)
+}
+
+fn text(t: &str) -> Result<String, String> {
+    Ok(escape(&decode_entities(t)?))
+}
+
+fn escape(s: &str) -> String {
+    s.replace('&', "&amp;").replace('<', "&lt;").replace('>', "&gt;").replace('"', "&quot;")
+}
+
+fn clip(s: &str) -> &str {
+    let mut end = s.len().min(24);
+    while !s.is_char_boundary(end) {
+        end -= 1;
+    }
+    &s[..end]
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn keeps_ordinary_icons() {
+        let src = r##"<?xml version="1.0"?>
+<!-- Material icon -->
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:inkscape="x" viewBox="0 0 24 24" inkscape:version="1">
+  <title>rust</title>
+  <defs><linearGradient id="g"><stop offset="0" stop-color="#fff"/></linearGradient></defs>
+  <path fill="url(#g)" d="M1 2h3 &amp; 4" style="opacity:.5"/>
+  <use href="#g"/>
+</svg>"##;
+        let out = sanitize_svg(src).unwrap();
+        assert!(out.starts_with("<svg xmlns="), "{out}");
+        assert!(!out.contains("title") && !out.contains("inkscape") && !out.contains("<!--"));
+        assert!(out.contains(r#"fill="url(#g)""#));
+        assert!(out.contains(r#"d="M1 2h3 &amp; 4""#));
+        assert!(out.ends_with("</svg>"));
+    }
+
+    #[test]
+    fn rejects_active_content() {
+        let bad = [
+            r##"<svg><script>alert(1)</script></svg>"##,
+            r##"<svg onload="alert(1)"></svg>"##,
+            r##"<svg><foreignObject/></svg>"##,
+            r##"<svg><use href="https://evil/x.svg#a"/></svg>"##,
+            r##"<svg><use xlink:href="data:image/svg+xml,..."/></svg>"##,
+            r##"<svg><rect style="fill:url(https://evil)"/></svg>"##,
+            r##"<svg><rect fill="url( 'http://x' )"/></svg>"##,
+            r##"<!DOCTYPE svg [<!ENTITY x "y">]><svg/>"##,
+            r##"<svg><![CDATA[x]]></svg>"##,
+            r##"<svg><a href="#x"/></svg>"##,
+            r##"<svg><rect width="&xx;"/></svg>"##,
+            r##"<svg><rect width=10/></svg>"##,
+            r##"<svg><g></svg>"##,
+            r##"<svg/><svg/>"##,
+            r##"<g/>"##,
+            r##"hello"##,
+            r##"<svg><rect style="behavior:url(#x);x:expression(1)"/></svg>"##,
+        ];
+        for src in bad {
+            assert!(sanitize_svg(src).is_err(), "accepted: {src}");
+        }
+    }
+
+    #[test]
+    fn theme_files_validate_and_produce_assets() {
+        let tmp = tempfile::tempdir().unwrap();
+        let dir = tmp.path();
+        std::fs::create_dir_all(dir.join("icons")).unwrap();
+        std::fs::write(dir.join("icons/rust.svg"), r#"<svg viewBox="0 0 16 16"><path d="M0 0h16v16z"/></svg>"#)
+            .unwrap();
+        std::fs::write(dir.join("icons/file.svg"), r#"<svg viewBox="0 0 16 16"><rect width="16" height="16"/></svg>"#)
+            .unwrap();
+        std::fs::write(
+            dir.join("theme.json"),
+            r#"{"iconDefinitions":{"rust":"icons/rust.svg","file":"icons/file.svg"},"file":"file",
+                "fileExtensions":{".RS":"rust"},"fileNames":{"Cargo.toml":"rust",".gitignore":"file"},
+                "folderNames":{".GitHub":"file","src":"rust"}}"#,
+        )
+        .unwrap();
+        let manifest = ide_extension::Manifest::parse(
+            "id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"",
+        )
+        .unwrap();
+        let pkg = Package::new(manifest, dir.to_path_buf());
+        let decl = |path: &str| {
+            let mut t = toml::Table::new();
+            t.insert("id".into(), "m".into());
+            t.insert("label".into(), "M".into());
+            t.insert("path".into(), path.into());
+            toml::Value::Table(t)
+        };
+        let d = icon_theme(&pkg, decl("theme.json")).unwrap();
+        assert_eq!(d.json["icons"], 2);
+        assert_eq!(d.files.len(), 3);
+        let map: serde_json::Value =
+            serde_json::from_str(&d.assets.iter().find(|(k, _)| *k == map_asset("m")).unwrap().1).unwrap();
+        assert_eq!(map["fileExtensions"]["rs"], "rust");
+        assert_eq!(map["fileNames"]["cargo.toml"], "rust");
+        // Names keep their leading dot (only extensions drop it).
+        assert_eq!(map["fileNames"][".gitignore"], "file");
+        assert_eq!(map["folderNames"][".github"], "file");
+        assert_eq!(map["folderNames"]["src"], "rust");
+        assert!(map["folderNames"].get("github").is_none());
+        assert!(d.assets.iter().any(|(k, _)| *k == format!("{}rust", svg_prefix("m"))));
+
+        std::fs::write(dir.join("bad.json"), r#"{"iconDefinitions":{},"fileExtensions":{"rs":"nope"}}"#).unwrap();
+        assert!(icon_theme(&pkg, decl("bad.json")).unwrap_err().contains("unknown icon"));
+        std::fs::write(dir.join("icons/evil.svg"), r#"<svg><script/></svg>"#).unwrap();
+        std::fs::write(dir.join("evil.json"), r#"{"iconDefinitions":{"e":"icons/evil.svg"}}"#).unwrap();
+        assert!(icon_theme(&pkg, decl("evil.json")).unwrap_err().contains("evil.svg"));
+        assert!(icon_theme(&pkg, decl("../x.json")).is_err());
+    }
+}

crates/ide-host/src/plugins/install.rs

@@ -0,0 +1,288 @@
+//! Copying a package into the plugins directory without ever leaving the
+//! plugin missing. Installed plugins are versioned:
+//! `<plugins>/<id>/<version>/` plus an `active` pointer file (and `previous`,
+//! the version to roll back to). A new version is written to a staging
+//! directory, renamed into place, and only then made active by replacing the
+//! pointer; a swap interrupted by a crash is undone on the next start
+//! ([`recover`]). Older installs used `<plugins>/<id>/` directly; they are
+//! moved into the versioned layout on their next update.
+
+use std::io;
+use std::path::{Path, PathBuf};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+/// Top-level files copied with a package besides those its declarations reference.
+pub const LICENSE_FILES: &[&str] =
+    &["LICENSE", "LICENSE.md", "LICENSE.txt", "NOTICE", "NOTICE.md", "NOTICE.txt", "COPYING", "README.md"];
+/// Written into an installed package: the package hash the grant ledger compares.
+pub const HASH_FILE: &str = ".package-hash";
+
+const STAGING: &str = ".staging-";
+const OLD: &str = ".old-";
+/// `<root>/active`: the version in use.
+pub const ACTIVE_FILE: &str = "active";
+/// `<root>/previous`: the version an update replaced (for rollback).
+pub const PREVIOUS_FILE: &str = "previous";
+
+fn nonce() -> String {
+    let n = SystemTime::now().duration_since(UNIX_EPOCH).map(|d| d.as_nanos()).unwrap_or_default();
+    format!("{n:x}-{}", std::process::id())
+}
+
+/// Copies `files` (plus manifest and licence files) from `src` into `target`
+/// atomically, recording `hash`.
+pub fn install_package(src: &Path, target: &Path, files: &[PathBuf], hash: &str) -> io::Result<()> {
+    let parent = target.parent().ok_or_else(|| io::Error::other("plugin target has no parent"))?;
+    let name = target.file_name().and_then(|n| n.to_str()).ok_or_else(|| io::Error::other("bad target"))?;
+    std::fs::create_dir_all(parent)?;
+    let staging = parent.join(format!("{STAGING}{name}-{}", nonce()));
+    let result = (|| {
+        std::fs::create_dir_all(&staging)?;
+        std::fs::copy(src.join(ide_extension::MANIFEST_FILE), staging.join(ide_extension::MANIFEST_FILE))?;
+        for file in files {
+            let to = staging.join(file);
+            if let Some(dir) = to.parent() {
+                std::fs::create_dir_all(dir)?;
+            }
+            std::fs::copy(src.join(file), to)?;
+        }
+        for lic in LICENSE_FILES {
+            if src.join(lic).is_file() {
+                std::fs::copy(src.join(lic), staging.join(lic))?;
+            }
+        }
+        std::fs::write(staging.join(HASH_FILE), hash)?;
+        swap(&staging, target, |from, to| std::fs::rename(from, to))
+    })();
+    if result.is_err() {
+        let _ = std::fs::remove_dir_all(&staging);
+    }
+    result
+}
+
+/// A version as a directory name (semver: `[0-9A-Za-z.+-]`).
+fn version_dir(version: &str) -> io::Result<&str> {
+    let ok = !version.is_empty()
+        && version.len() <= 64
+        && !version.starts_with('.')
+        && version.chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '.' | '+' | '-'));
+    if ok { Ok(version) } else { Err(io::Error::other(format!("version {version:?} cannot name a directory"))) }
+}
+
+fn read_pointer(root: &Path, name: &str) -> Option<String> {
+    let v = std::fs::read_to_string(root.join(name)).ok()?;
+    let v = v.trim();
+    (!v.is_empty() && version_dir(v).is_ok()).then(|| v.to_owned())
+}
+
+/// Replaces the pointer file `name` atomically.
+fn write_pointer(root: &Path, name: &str, version: &str) -> io::Result<()> {
+    let tmp = root.join(format!(".{name}.tmp"));
+    std::fs::write(&tmp, version)?;
+    std::fs::rename(&tmp, root.join(name))
+}
+
+/// The directory of a plugin's active version under its `root`
+/// (`<plugins>/<id>`): `<root>/<active>`, or `root` itself in the flat layout.
+pub fn active_dir(root: &Path) -> Option<PathBuf> {
+    if let Some(v) = read_pointer(root, ACTIVE_FILE) {
+        let dir = root.join(v);
+        return dir.join(ide_extension::MANIFEST_FILE).is_file().then_some(dir);
+    }
+    root.join(ide_extension::MANIFEST_FILE).is_file().then(|| root.to_path_buf())
+}
+
+/// The version an update replaced, if it is still there.
+pub fn previous_version(root: &Path) -> Option<String> {
+    read_pointer(root, PREVIOUS_FILE).filter(|v| root.join(v).join(ide_extension::MANIFEST_FILE).is_file())
+}
+
+/// Moves a flat install (`<root>/plugin.toml`) to `<root>/<version>/`.
+fn migrate_flat(root: &Path, version_of: impl Fn(&Path) -> Option<String>) -> io::Result<()> {
+    if read_pointer(root, ACTIVE_FILE).is_some() || !root.join(ide_extension::MANIFEST_FILE).is_file() {
+        return Ok(());
+    }
+    let version = version_of(root).unwrap_or_else(|| "0.0.0".into());
+    let version = version_dir(&version).map(str::to_owned).unwrap_or_else(|_| "0.0.0".into());
+    let parent = root.parent().unwrap_or(Path::new("."));
+    let name = root.file_name().and_then(|n| n.to_str()).ok_or_else(|| io::Error::other("bad plugin directory"))?;
+    // `.old-<name>-…` is restored by `recover` if this is interrupted.
+    let old = parent.join(format!("{OLD}{name}-{}", nonce()));
+    std::fs::rename(root, &old)?;
+    std::fs::create_dir_all(root)?;
+    std::fs::rename(&old, root.join(&version))?;
+    write_pointer(root, ACTIVE_FILE, &version)
+}
+
+/// Installs `files` of `src` as `<root>/<version>` and makes it the active
+/// version. Returns the version it replaced (now `previous`).
+pub fn install_version(
+    src: &Path,
+    root: &Path,
+    version: &str,
+    files: &[PathBuf],
+    hash: &str,
+    version_of: impl Fn(&Path) -> Option<String>,
+) -> io::Result<Option<String>> {
+    let version = version_dir(version)?;
+    std::fs::create_dir_all(root)?;
+    migrate_flat(root, version_of)?;
+    install_package(src, &root.join(version), files, hash)?;
+    let previous = read_pointer(root, ACTIVE_FILE).filter(|v| v != version);
+    if let Some(p) = &previous {
+        write_pointer(root, PREVIOUS_FILE, p)?;
+    }
+    write_pointer(root, ACTIVE_FILE, version)?;
+    Ok(previous)
+}
+
+/// Makes `version` active again (rollback). The replaced version stays until [`prune`].
+pub fn activate_version(root: &Path, version: &str) -> io::Result<()> {
+    let version = version_dir(version)?;
+    if !root.join(version).join(ide_extension::MANIFEST_FILE).is_file() {
+        return Err(io::Error::other(format!("version {version} is not installed")));
+    }
+    let _ = std::fs::remove_file(root.join(PREVIOUS_FILE));
+    write_pointer(root, ACTIVE_FILE, version)
+}
+
+/// Removes versions other than the active and the previous one.
+pub fn prune(root: &Path) {
+    let keep: Vec<String> = [ACTIVE_FILE, PREVIOUS_FILE].iter().filter_map(|f| read_pointer(root, f)).collect();
+    if keep.is_empty() {
+        return;
+    }
+    let Ok(entries) = std::fs::read_dir(root) else { return };
+    for e in entries.flatten() {
+        let path = e.path();
+        let name = e.file_name().to_string_lossy().into_owned();
+        if path.is_dir() && !keep.contains(&name) {
+            let _ = std::fs::remove_dir_all(&path);
+        }
+    }
+}
+
+/// Moves `staging` to `target`, keeping the old `target` until the new one is in place.
+fn swap(staging: &Path, target: &Path, rename: impl Fn(&Path, &Path) -> io::Result<()>) -> io::Result<()> {
+    if !target.exists() {
+        return rename(staging, target);
+    }
+    let parent = target.parent().unwrap_or(Path::new("."));
+    let name = target.file_name().and_then(|n| n.to_str()).unwrap_or("plugin");
+    let old = parent.join(format!("{OLD}{name}-{}", nonce()));
+    rename(target, &old)?;
+    if let Err(e) = rename(staging, target) {
+        // Put the previous version back.
+        rename(&old, target)?;
+        return Err(e);
+    }
+    if let Err(e) = std::fs::remove_dir_all(&old) {
+        tracing::warn!("removing the previous version {}: {e}", old.display());
+    }
+    Ok(())
+}
+
+/// Undoes interrupted installs in `dir`: restores `.old-<name>-*` when
+/// `<name>` is missing, and removes leftover staging and old directories.
+pub fn recover(dir: &Path) {
+    let Ok(entries) = std::fs::read_dir(dir) else { return };
+    for entry in entries.flatten() {
+        let path = entry.path();
+        // Inside a versioned plugin: staging and old versions of a version swap.
+        if path.is_dir() && read_pointer(&path, ACTIVE_FILE).is_some() {
+            recover(&path);
+            continue;
+        }
+        let Some(file) = path.file_name().and_then(|n| n.to_str()).map(str::to_owned) else { continue };
+        if file.starts_with(STAGING) {
+            let _ = std::fs::remove_dir_all(&path);
+        } else if let Some(rest) = file.strip_prefix(OLD) {
+            // `<name>-<nonce>-<pid>`: the name is everything before the last two parts.
+            let parts: Vec<&str> = rest.rsplitn(3, '-').collect();
+            let name = parts.get(2).copied().unwrap_or_default();
+            let target = dir.join(name);
+            // A layout migration interrupted after creating the new root: it is still empty.
+            if !name.is_empty() && target.is_dir() && active_dir(&target).is_none() {
+                let _ = std::fs::remove_dir_all(&target);
+            }
+            if !name.is_empty() && !target.exists() {
+                tracing::warn!("restoring {} after an interrupted install", target.display());
+                let _ = std::fs::rename(&path, &target);
+            } else {
+                let _ = std::fs::remove_dir_all(&path);
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn failed_swap_keeps_the_old_version() {
+        let tmp = tempfile::tempdir().unwrap();
+        let target = tmp.path().join("p");
+        let staging = tmp.path().join(".staging-p-1");
+        std::fs::create_dir_all(&target).unwrap();
+        std::fs::write(target.join("v"), "1").unwrap();
+        std::fs::create_dir_all(&staging).unwrap();
+        std::fs::write(staging.join("v"), "2").unwrap();
+        let calls = std::cell::Cell::new(0);
+        let err = swap(&staging, &target, |a, b| {
+            calls.set(calls.get() + 1);
+            if calls.get() == 2 { Err(io::Error::other("disk full")) } else { std::fs::rename(a, b) }
+        });
+        assert!(err.is_err());
+        assert_eq!(std::fs::read_to_string(target.join("v")).unwrap(), "1");
+        swap(&staging, &target, |a, b| std::fs::rename(a, b)).unwrap();
+        assert_eq!(std::fs::read_to_string(target.join("v")).unwrap(), "2");
+        assert_eq!(std::fs::read_dir(tmp.path()).unwrap().count(), 1, "old version removed");
+    }
+
+    #[test]
+    fn versions_are_installed_side_by_side_and_rolled_back() {
+        let tmp = tempfile::tempdir().unwrap();
+        let src = tmp.path().join("src");
+        std::fs::create_dir_all(&src).unwrap();
+        let root = tmp.path().join("plugins/acme.tools");
+        let version_of = |_: &Path| Some("0.9.0".to_owned());
+        // A flat install from before versioning.
+        std::fs::create_dir_all(&root).unwrap();
+        std::fs::write(root.join(ide_extension::MANIFEST_FILE), "v0.9").unwrap();
+        assert_eq!(active_dir(&root), Some(root.clone()));
+
+        std::fs::write(src.join(ide_extension::MANIFEST_FILE), "v1").unwrap();
+        assert_eq!(install_version(&src, &root, "1.0.0", &[], "h1", version_of).unwrap().as_deref(), Some("0.9.0"));
+        assert_eq!(active_dir(&root), Some(root.join("1.0.0")));
+        std::fs::write(src.join(ide_extension::MANIFEST_FILE), "v2").unwrap();
+        assert_eq!(install_version(&src, &root, "2.0.0", &[], "h2", version_of).unwrap().as_deref(), Some("1.0.0"));
+        assert_eq!(previous_version(&root).as_deref(), Some("1.0.0"));
+        prune(&root);
+        assert!(!root.join("0.9.0").exists(), "older than previous: pruned");
+
+        activate_version(&root, "1.0.0").unwrap();
+        assert_eq!(
+            std::fs::read_to_string(active_dir(&root).unwrap().join(ide_extension::MANIFEST_FILE)).unwrap(),
+            "v1"
+        );
+        assert_eq!(previous_version(&root), None);
+        assert!(install_version(&src, &root, "../x", &[], "h", version_of).is_err());
+    }
+
+    #[test]
+    fn recover_restores_an_interrupted_swap() {
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::create_dir_all(tmp.path().join(".old-acme.tools-1a2b-77")).unwrap();
+        std::fs::write(tmp.path().join(".old-acme.tools-1a2b-77/v"), "1").unwrap();
+        std::fs::create_dir_all(tmp.path().join(".staging-acme.tools-1a2c-77")).unwrap();
+        std::fs::create_dir_all(tmp.path().join("x")).unwrap();
+        std::fs::create_dir_all(tmp.path().join(".old-x-1-2")).unwrap();
+        recover(tmp.path());
+        assert_eq!(std::fs::read_to_string(tmp.path().join("acme.tools/v")).unwrap(), "1");
+        let mut names: Vec<_> =
+            std::fs::read_dir(tmp.path()).unwrap().flatten().map(|e| e.file_name().into_string().unwrap()).collect();
+        names.sort();
+        assert_eq!(names, ["acme.tools", "x"]);
+    }
+}

crates/ide-host/src/plugins/market.rs

@@ -0,0 +1,314 @@
+//! The marketplace: a static index (`index.json` +
+//! packages, served from any URL or folder) lists publishers and their keys,
+//! plugins, and revocations. The host keeps the last index it read
+//! (`market-index.json`), checks signatures against it, and disables what it
+//! revokes — at start-up and on every refresh (the desktop refreshes daily).
+
+use super::{PluginHost, PluginSource, PluginStatus};
+use ide_core::{IdeError, IdeResult};
+use ide_extension::Manifest;
+use ide_extension::package::{self, Index, IndexEntry, PackageSignature, SIGNATURE_FILE};
+use serde::{Deserialize, Serialize};
+use std::path::{Path, PathBuf};
+
+/// The official marketplace: the index the release workflow publishes with
+/// the app, next to the signed packages of the official plugins.
+pub const OFFICIAL_INDEX: &str = "https://github.com/l0ng-ai/openidea/releases/latest/download/plugins-index.json";
+
+/// The last index read, in the plugins directory.
+pub const INDEX_FILE: &str = "market-index.json";
+const DOWNLOADS: &str = ".downloads";
+const MAX_INDEX: usize = 16 << 20;
+const MAX_PACKAGE: usize = 256 << 20;
+
+/// A marketplace entry with what is installed.
+#[derive(Clone, Debug, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct MarketPlugin {
+    #[serde(flatten)]
+    pub entry: IndexEntry,
+    /// Installed version, if any.
+    pub installed: Option<String>,
+}
+
+/// Reads `url`: `http(s)://…`, `file://…` or a local path.
+pub fn read_url(url: &str, max: usize) -> Result<Vec<u8>, String> {
+    if url.starts_with("https://") || url.starts_with("http://") {
+        let client = ide_http::client::shared().map_err(|e| e.message)?;
+        let url = url.to_owned();
+        return super::api::net_runtime().block_on(async move {
+            let response = client.get(&url).send().await.map_err(|e| format!("{url}: {e}"))?;
+            if !response.status().is_success() {
+                return Err(format!("{url}: HTTP {}", response.status()));
+            }
+            let bytes = response.bytes().await.map_err(|e| format!("{url}: {e}"))?;
+            if bytes.len() > max {
+                return Err(format!("{url}: larger than {} MiB", max >> 20));
+            }
+            Ok(bytes.to_vec())
+        });
+    }
+    let path = url.strip_prefix("file://").unwrap_or(url);
+    let bytes = std::fs::read(path).map_err(|e| format!("{path}: {e}"))?;
+    if bytes.len() > max {
+        return Err(format!("{path}: larger than {} MiB", max >> 20));
+    }
+    Ok(bytes)
+}
+
+/// `href` relative to the index at `base`: a URL, or a local path (with the
+/// platform's separators, e.g. `C:\\market\\index.json`).
+pub fn resolve(base: &str, href: &str) -> String {
+    if href.contains("://") || href.starts_with('/') || Path::new(href).is_absolute() {
+        return href.to_owned();
+    }
+    if base.contains("://") {
+        return match base.rfind('/') {
+            Some(i) => format!("{}/{href}", &base[..i]),
+            None => href.to_owned(),
+        };
+    }
+    match Path::new(base).parent() {
+        Some(dir) => dir.join(href).to_string_lossy().into_owned(),
+        None => href.to_owned(),
+    }
+}
+
+impl PluginHost {
+    pub(super) fn load_market_index(dir: &Path) -> Option<Index> {
+        let text = std::fs::read_to_string(dir.join(INDEX_FILE)).ok()?;
+        Index::parse(&text).map_err(|e| tracing::warn!("{INDEX_FILE}: {e}")).ok()
+    }
+
+    /// The marketplace index URL: the user's, else the default (none: no marketplace).
+    pub fn market_url(&self) -> Option<String> {
+        self.state.lock().market_url.clone().or_else(|| self.default_market_url.read().clone())
+    }
+
+    /// The marketplace used while the user has set none.
+    pub fn set_default_market_url(&self, url: Option<String>) {
+        *self.default_market_url.write() = url.filter(|u| !u.trim().is_empty());
+    }
+
+    pub fn set_market_url(&self, url: Option<String>) {
+        self.state.lock().market_url = url.filter(|u| !u.trim().is_empty());
+        self.save_state();
+    }
+
+    /// Reads the index again, keeps it, and applies its revocations.
+    pub fn refresh_market(&self) -> IdeResult<Vec<MarketPlugin>> {
+        let url = self.market_url().ok_or_else(|| IdeError::unavailable("no plugin marketplace is configured"))?;
+        let bytes = read_url(&url, MAX_INDEX).map_err(IdeError::unavailable)?;
+        let text = String::from_utf8(bytes).map_err(|_| IdeError::invalid("the index is not UTF-8"))?;
+        let index = Index::parse(&text).map_err(IdeError::invalid)?;
+        let _ = std::fs::write(self.plugins_dir.join(INDEX_FILE), &text);
+        *self.market.write() = Some(index);
+        // Trust may have changed: who signed what, what is revoked.
+        let installed: Vec<_> =
+            self.plugins.read().values().filter(|p| p.source == PluginSource::Installed).cloned().collect();
+        for plugin in installed {
+            let publisher = self.verified_publisher(plugin.dir());
+            plugin.meta.lock().publisher = publisher;
+        }
+        self.apply_revocations();
+        Ok(self.market_plugins())
+    }
+
+    /// The plugins of the last index read.
+    pub fn market_plugins(&self) -> Vec<MarketPlugin> {
+        let Some(index) = self.market.read().clone() else { return Vec::new() };
+        let plugins = self.plugins.read();
+        index
+            .plugins
+            .iter()
+            .filter(|e| index.revocation(&e.id, &e.version).is_none())
+            .cloned()
+            .map(|entry| {
+                let installed = plugins
+                    .get(&entry.id)
+                    .filter(|p| p.source == PluginSource::Installed)
+                    .map(|p| p.manifest().version.clone());
+                MarketPlugin { entry, installed }
+            })
+            .collect()
+    }
+
+    /// Downloads a marketplace plugin, checks it against the index (digest and
+    /// signature), and unpacks it for the install page. Returns the folder to
+    /// install from.
+    pub fn download_market_plugin(&self, id: &str) -> IdeResult<PathBuf> {
+        let url = self.market_url().ok_or_else(|| IdeError::unavailable("no plugin marketplace is configured"))?;
+        let index = self.market.read().clone().ok_or_else(|| IdeError::unavailable("refresh the marketplace first"))?;
+        let entry = index
+            .plugins
+            .iter()
+            .find(|e| e.id == id)
+            .cloned()
+            .ok_or_else(|| IdeError::not_found(format!("{id} is not in the marketplace")))?;
+        let bytes = read_url(&resolve(&url, &entry.download), MAX_PACKAGE).map_err(IdeError::unavailable)?;
+        let downloads = self.plugins_dir.join(DOWNLOADS);
+        std::fs::create_dir_all(&downloads)?;
+        let archive = downloads.join(format!("{}-{}.{}", entry.id, entry.version, package::PACKAGE_EXTENSION));
+        std::fs::write(&archive, bytes)?;
+        let dir = self.unpack_package(&archive)?;
+        let _ = std::fs::remove_file(&archive);
+        let manifest = Manifest::load(&dir).map_err(IdeError::invalid)?;
+        let files = self.package_files_in(&dir)?;
+        let digest = package::package_digest(&dir, &files)?;
+        if (manifest.id.as_str(), manifest.version.as_str(), digest.as_str())
+            != (&entry.id, &entry.version, &entry.digest)
+        {
+            let _ = std::fs::remove_dir_all(&dir);
+            return Err(IdeError::invalid("the download does not match the marketplace's entry"));
+        }
+        if self.verified_publisher(&dir).is_none() {
+            let _ = std::fs::remove_dir_all(&dir);
+            return Err(IdeError::invalid("the marketplace package is not signed by a trusted publisher"));
+        }
+        Ok(dir)
+    }
+
+    /// Unpacks a package file (`.oiplugin`, or a `.zip` of a package) next to the downloads; returns the folder.
+    pub fn unpack_package(&self, archive: &Path) -> IdeResult<PathBuf> {
+        let stem = archive.file_stem().and_then(|s| s.to_str()).unwrap_or("package");
+        let dir = self.plugins_dir.join(DOWNLOADS).join(format!("{stem}-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        let unpacked = package::unpack(archive, &dir).map_err(IdeError::invalid)?;
+        // Kept with the files: install checks it and keeps it with the installed copy.
+        if let Some(sig) = unpacked.signature {
+            let json = serde_json::to_string_pretty(&sig).map_err(|e| IdeError::internal(e.to_string()))?;
+            std::fs::write(dir.join(SIGNATURE_FILE), json)?;
+        }
+        Ok(dir)
+    }
+
+    /// Files of the package in `dir` (what its declarations reference, and
+    /// the component): what a package file holds besides the manifest.
+    pub fn package_files_of(&self, dir: &Path) -> IdeResult<Vec<PathBuf>> {
+        self.package_files_in(dir)
+    }
+
+    pub(super) fn package_files_in(&self, dir: &Path) -> IdeResult<Vec<PathBuf>> {
+        let manifest = Manifest::load(dir).map_err(IdeError::invalid)?;
+        let pkg = ide_extension::Package::new(manifest, dir.to_path_buf());
+        let set = self.registry.prepare(&pkg).map_err(IdeError::invalid)?;
+        Ok(set.files.into_iter().chain(pkg.manifest.wasm.clone()).collect())
+    }
+
+    /// The publisher whose valid, trusted signature the package in `dir` carries.
+    pub(super) fn verified_publisher(&self, dir: &Path) -> Option<String> {
+        let sig = read_signature(dir)?;
+        let index = self.market.read().clone()?;
+        let manifest = Manifest::load(dir).ok()?;
+        let files = self.package_files_in(dir).ok()?;
+        let digest = package::package_digest(dir, &files).ok()?;
+        index
+            .verify(&sig, &manifest.id, &manifest.version, &digest)
+            .map_err(|e| tracing::warn!("{}: {e}", dir.display()))
+            .ok()
+    }
+
+    /// A signature that is present but doesn't verify (tampered, foreign prefix,
+    /// revoked or unknown key): installing is refused.
+    pub(super) fn signature_problem(&self, dir: &Path) -> Option<String> {
+        let sig = read_signature(dir)?;
+        let manifest = Manifest::load(dir).ok()?;
+        let files = self.package_files_in(dir).ok()?;
+        let digest = package::package_digest(dir, &files).ok()?;
+        if let Err(e) = sig.check(&manifest.id, &manifest.version, &digest) {
+            return Some(e);
+        }
+        let index = self.market.read().clone()?;
+        index.verify(&sig, &manifest.id, &manifest.version, &digest).err()
+    }
+
+    /// Why an installed plugin must not run (index revocations, revoked signing key).
+    pub(super) fn revoked_reason(&self, id: &str, version: &str, dir: &Path) -> Option<String> {
+        let market = self.market.read();
+        let index = market.as_ref()?;
+        if let Some(r) = index.revocation(id, version) {
+            return Some(r.reason.clone());
+        }
+        let sig = read_signature(dir)?;
+        index.key_revoked(&sig.key).then(|| "its publisher's signing key was revoked".to_owned())
+    }
+
+    /// Disables installed plugins the index revokes (telling the user once),
+    /// and starts again those it no longer revokes.
+    pub(super) fn apply_revocations(&self) {
+        let installed: Vec<_> =
+            self.plugins.read().values().filter(|p| p.source == PluginSource::Installed).cloned().collect();
+        let mut changed = false;
+        for plugin in installed {
+            let reason = self.revoked_reason(plugin.id(), &plugin.manifest().version, plugin.dir());
+            let current = plugin.meta.lock().error.clone().filter(|e| e.starts_with("revoked: "));
+            match (reason, current) {
+                (Some(r), Some(c)) if c == format!("revoked: {r}") => {}
+                (Some(reason), was) => {
+                    self.stop(&plugin);
+                    {
+                        let mut meta = plugin.meta.lock();
+                        meta.status = PluginStatus::Failed;
+                        meta.error = Some(format!("revoked: {reason}"));
+                    }
+                    if was.is_none() {
+                        self.emit(
+                            None,
+                            super::PluginEvent::Notification {
+                                plugin_id: plugin.id().to_owned(),
+                                level: ide_plugin::NotificationLevel::Warning,
+                                title: format!("{} was disabled", plugin.manifest().name),
+                                body: format!("The marketplace revoked this plugin: {reason}"),
+                            },
+                        );
+                    }
+                    changed = true;
+                }
+                (None, Some(_)) => {
+                    {
+                        let mut meta = plugin.meta.lock();
+                        meta.status = PluginStatus::Inactive;
+                        meta.error = None;
+                    }
+                    if !self.state.lock().disabled.contains(plugin.id()) {
+                        self.start(&plugin);
+                    }
+                    changed = true;
+                }
+                (None, None) => {}
+            }
+        }
+        if changed {
+            self.changed();
+        }
+    }
+}
+
+pub(super) fn read_signature(dir: &Path) -> Option<PackageSignature> {
+    let text = std::fs::read_to_string(dir.join(SIGNATURE_FILE)).ok()?;
+    serde_json::from_str(&text).ok()
+}
+
+/// Keeps the signature of a package with its installed copy.
+pub(super) fn copy_signature(src: &Path, installed: &Path) {
+    if src.join(SIGNATURE_FILE).is_file() {
+        let _ = std::fs::copy(src.join(SIGNATURE_FILE), installed.join(SIGNATURE_FILE));
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn downloads_resolve_against_the_index() {
+        assert_eq!(resolve("https://x.dev/market/index.json", "p/a.oiplugin"), "https://x.dev/market/p/a.oiplugin");
+        assert_eq!(
+            Path::new(&resolve("/srv/market/index.json", "a.oiplugin")),
+            Path::new("/srv/market").join("a.oiplugin")
+        );
+        #[cfg(windows)]
+        assert_eq!(resolve(r"C:\market\index.json", "a.oiplugin"), r"C:\market\a.oiplugin");
+        assert_eq!(resolve("https://x.dev/index.json", "https://cdn.dev/a"), "https://cdn.dev/a");
+    }
+}

crates/ide-host/src/plugins/points.rs

@@ -0,0 +1,71 @@
+//! First-party extension points registered by the host, plus
+//! [`register_builtin_points`], the one place that lists them. Feature crates
+//! own their points (`ide_language::plugin_point`); adding a contribution type
+//! means adding a point here or in its crate, and a `defineUiPoint` projection
+//! on the client for `Ui` points — nothing else.
+
+use ide_extension::{ExtensionRegistry, Package, UiDecl, UiPoint, UiStore, decode, validate_item_id, validate_when};
+use ide_language::plugin_point::{LanguagesPoint, PluginLanguages};
+use serde::{Deserialize, Serialize};
+use std::sync::Arc;
+
+pub const COMMANDS: &str = "commands";
+const MAX_TITLE: usize = 256;
+
+/// `[[contributes.commands]]`: an action `plugin.<plugin-id>.<id>` in Search
+/// Everywhere and the keymap editor; shown before the plugin's code runs.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+pub struct CommandDecl {
+    pub id: String,
+    pub title: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub category: Option<String>,
+    /// Enablement, evaluated by the client against context keys (`editorLang == rust`).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub when: Option<String>,
+}
+
+fn command(_pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let c: CommandDecl = decode(COMMANDS, decl)?;
+    validate_item_id(&c.id, "command id")?;
+    if c.title.trim().is_empty() {
+        return Err(format!("command {:?} has an empty title", c.id));
+    }
+    if c.title.len() > MAX_TITLE || c.category.as_ref().is_some_and(|x| x.len() > MAX_TITLE) {
+        return Err(format!("command {:?}: title or category longer than {MAX_TITLE} bytes", c.id));
+    }
+    if let Some(when) = &c.when {
+        validate_when(when).map_err(|e| format!("command {:?}: {e}", c.id))?;
+    }
+    let c = CommandDecl { category: c.category.filter(|x| !x.trim().is_empty()), ..c };
+    let json = serde_json::to_value(&c).map_err(|e| e.to_string())?;
+    Ok(UiDecl::new(c.id.clone(), c.title, json))
+}
+
+/// Registers every first-party extension point.
+pub fn register_builtin_points(
+    registry: &ExtensionRegistry,
+    ui: &Arc<UiStore>,
+    languages: &Arc<PluginLanguages>,
+    run_detectors: &Arc<super::run_detectors::RunDetectors>,
+    providers: &Arc<super::providers::Providers>,
+) -> Result<(), String> {
+    registry.register(Arc::new(UiPoint::new(COMMANDS, ui.clone(), command)))?;
+    registry.register(Arc::new(super::theme::ThemesPoint::new(ui.clone())))?;
+    registry.register(Arc::new(LanguagesPoint::new(languages.clone())))?;
+    registry.register(Arc::new(UiPoint::new(super::icons::POINT_ID, ui.clone(), super::icons::icon_theme)))?;
+    registry.register(Arc::new(super::run_detectors::RunDetectorsPoint::new(run_detectors.clone())))?;
+    registry.register(Arc::new(super::providers::ProvidersPoint::new(providers.clone())))?;
+    registry.register(Arc::new(UiPoint::new(super::providers::SECRETS_POINT, ui.clone(), super::providers::secret)))?;
+    use super::ui_points as p;
+    registry.register(Arc::new(UiPoint::new(p::MENUS, ui.clone(), p::menu)))?;
+    registry.register(Arc::new(UiPoint::new(p::KEYMAPS, ui.clone(), p::keymap)))?;
+    registry.register(Arc::new(UiPoint::new(p::STATUS_BAR, ui.clone(), p::status_item)))?;
+    registry.register(Arc::new(UiPoint::new(p::SETTINGS, ui.clone(), p::settings)))?;
+    registry.register(Arc::new(UiPoint::new(p::VIEWS, ui.clone(), p::view)))?;
+    registry.register(Arc::new(UiPoint::new(p::CUSTOM_EDITORS, ui.clone(), p::custom_editor)))?;
+    registry.register(Arc::new(UiPoint::new(p::FILE_ICONS, ui.clone(), p::file_icon)))?;
+    registry.register(Arc::new(UiPoint::new(p::FILE_TEMPLATES, ui.clone(), p::file_template)))?;
+    Ok(())
+}

crates/ide-host/src/plugins/providers.rs

@@ -0,0 +1,342 @@
+//! Editor providers of plugins: completion, inline
+//! completion, code actions, go to definition and gutter line markers, for
+//! the languages a plugin declares. The host calls only plugins whose
+//! declaration matches, so the others stay unloaded.
+//!
+//! ```toml
+//! [[contributes.providers]]
+//! kinds = ["definition", "line-markers"]
+//! languages = ["java", "xml"]        # editor language ids; "*" for any
+//! ```
+//!
+//! And `[[contributes.secrets]]`: secrets the user can store for the plugin
+//! (shown in Settings › Plugins), used only through `net` request headers.
+//!
+//! ```toml
+//! [[contributes.secrets]]
+//! name = "api-key"
+//! label = "API key"
+//! description = "Create one at https://example.com/keys"
+//! ```
+
+use ide_extension::{Disposable, ExtensionPoint, Package, Placement, Prepared, UiDecl, decode, validate_item_id};
+use parking_lot::RwLock;
+use serde::{Deserialize, Serialize};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+pub const POINT_ID: &str = "providers";
+pub const SECRETS_POINT: &str = "secrets";
+
+/// What a plugin can provide in the editor.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "kebab-case")]
+pub enum ProviderKind {
+    Completion,
+    InlineCompletion,
+    CodeActions,
+    Definition,
+    LineMarkers,
+}
+
+#[derive(Clone, Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Decl {
+    kinds: Vec<ProviderKind>,
+    languages: Vec<String>,
+}
+
+/// (sequence, plugin, kinds, languages) of one declaration.
+type Declared = (u64, String, Vec<ProviderKind>, Vec<String>);
+
+/// Provider declarations of enabled plugins.
+#[derive(Default)]
+pub struct Providers {
+    items: RwLock<Vec<Declared>>,
+    seq: AtomicU64,
+}
+
+impl Providers {
+    fn add(self: &Arc<Self>, plugin: String, decl: Decl) -> Disposable {
+        let seq = self.seq.fetch_add(1, Ordering::Relaxed);
+        self.items.write().push((seq, plugin, decl.kinds, decl.languages));
+        let weak = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(this) = weak.upgrade() {
+                this.items.write().retain(|(s, ..)| *s != seq);
+            }
+        })
+    }
+
+    /// Plugins providing `kind` for `language`, in declaration order.
+    pub fn plugins_for(&self, kind: ProviderKind, language: &str) -> Vec<String> {
+        let mut out: Vec<String> = Vec::new();
+        for (_, plugin, kinds, languages) in self.items.read().iter() {
+            if kinds.contains(&kind) && languages.iter().any(|l| l == "*" || l == language) && !out.contains(plugin) {
+                out.push(plugin.clone());
+            }
+        }
+        out
+    }
+
+    /// Whether any plugin provides `kind` (for any language).
+    pub fn any(&self, kind: ProviderKind) -> bool {
+        self.items.read().iter().any(|(_, _, kinds, _)| kinds.contains(&kind))
+    }
+}
+
+pub struct ProvidersPoint {
+    store: Arc<Providers>,
+}
+
+impl ProvidersPoint {
+    pub fn new(store: Arc<Providers>) -> Self {
+        Self { store }
+    }
+}
+
+impl ExtensionPoint for ProvidersPoint {
+    fn id(&self) -> &'static str {
+        POINT_ID
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Workspace
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let d: Decl = decode(POINT_ID, decl)?;
+        if pkg.manifest.wasm.is_none() {
+            return Err("contributes.providers: providers need code (`wasm`)".into());
+        }
+        if d.kinds.is_empty() || d.languages.is_empty() || d.languages.len() > 64 {
+            return Err("contributes.providers: give `kinds` and 1–64 `languages`".into());
+        }
+        for l in &d.languages {
+            if l != "*"
+                && (l.is_empty()
+                    || l.len() > 64
+                    || !l.chars().all(|c| c.is_ascii_alphanumeric() || "-_.+#".contains(c)))
+            {
+                return Err(format!("contributes.providers: invalid language id {l:?}"));
+            }
+        }
+        let label = format!(
+            "{} for {}",
+            d.kinds
+                .iter()
+                .map(|k| serde_json::to_value(k).ok().and_then(|v| v.as_str().map(str::to_owned)).unwrap_or_default())
+                .collect::<Vec<_>>()
+                .join(", "),
+            d.languages.join(", ")
+        );
+        let (store, plugin) = (self.store.clone(), pkg.id().to_owned());
+        Ok(Prepared::new(label, move || Ok(store.add(plugin, d))))
+    }
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct SecretDecl {
+    name: String,
+    label: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    description: Option<String>,
+}
+
+/// `[[contributes.secrets]]` (a UI point: Settings › Plugins lists them).
+pub(super) fn secret(_pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: SecretDecl = decode(SECRETS_POINT, decl)?;
+    validate_item_id(&d.name, "secret name")?;
+    if d.label.trim().is_empty() || d.label.len() > 128 || d.description.as_ref().is_some_and(|x| x.len() > 1024) {
+        return Err(format!("secret {:?}: `label` 1–128 bytes, `description` up to 1 KiB", d.name));
+    }
+    let json = serde_json::to_value(&d).map_err(|e| e.to_string())?;
+    Ok(UiDecl::new(d.name.clone(), d.label, json))
+}
+
+// ---- dispatch ---------------------------------------------------------------
+
+use super::{LoadedPlugin, PluginHost, PluginStatus};
+use ide_core::CancellationToken;
+use ide_plugin::{
+    ActorError, CallError, CodeAction, CompletionItem, InlineSuggestion, LineMarker, Location, Pending,
+    ProviderDocument, Runtime,
+};
+use std::sync::Weak;
+use std::time::{Duration, Instant};
+
+/// How long a superseded inline completion may take to return after its
+/// request was cancelled before it is interrupted.
+const CANCEL_GRACE: Duration = Duration::from_millis(250);
+
+static EDITOR_PROVIDERS: RwLock<Option<Weak<PluginHost>>> = RwLock::new(None);
+
+/// Makes `host`'s plugin providers part of completion, code actions, go to
+/// definition and inline completion (`None` removes them).
+pub fn set_editor_providers(host: Option<&Arc<PluginHost>>) {
+    *EDITOR_PROVIDERS.write() = host.map(Arc::downgrade);
+}
+
+/// The plugin host whose providers take part, when any declares `kind`.
+pub(crate) fn editor_providers(kind: ProviderKind) -> Option<Arc<PluginHost>> {
+    let host = EDITOR_PROVIDERS.read().as_ref()?.upgrade()?;
+    host.providers.any(kind).then_some(host)
+}
+
+impl PluginHost {
+    /// Usable plugins declaring `kind` for `language`.
+    fn provider_plugins(&self, kind: ProviderKind, language: &str) -> Vec<Arc<LoadedPlugin>> {
+        self.providers
+            .plugins_for(kind, language)
+            .into_iter()
+            .filter_map(|id| self.get(&id).ok())
+            .filter(|p| {
+                let m = p.meta.lock();
+                matches!(m.status, PluginStatus::Active | PluginStatus::Inactive) && m.pending.is_empty()
+            })
+            .collect()
+    }
+
+    /// Edit-path calls (soft / hard deadline) to every usable plugin that
+    /// declares `kind` for `language`, in plugin order, leaving out those that
+    /// failed or were late. Each plugin runs on its own thread, so the calls
+    /// run at the same time: the wait is the slowest plugin's, not the sum.
+    fn edit_calls<R: Send + 'static>(
+        &self,
+        kind: ProviderKind,
+        language: &str,
+        f: impl FnOnce(&mut Runtime, Duration) -> Result<R, CallError> + Clone + Send + 'static,
+    ) -> Vec<(Arc<LoadedPlugin>, R)> {
+        let (soft, hard) = (self.limits.edit_soft, self.limits.edit_hard);
+        let queued: Vec<_> = self
+            .provider_plugins(kind, language)
+            .into_iter()
+            .filter_map(|plugin| {
+                let (actor, activated) = self.ensure_active(&plugin, None).ok()?;
+                if activated {
+                    self.changed();
+                }
+                let f = f.clone();
+                let started = Instant::now();
+                let call = actor.submit(Some(soft), move |rt| f(rt, hard));
+                Some((plugin, actor, started, call))
+            })
+            .collect();
+        queued
+            .into_iter()
+            .filter_map(|(plugin, actor, started, call)| {
+                let result = call.and_then(Pending::wait);
+                self.finish_provider_call(&plugin, &actor, started, result).map(|r| (plugin, r))
+            })
+            .collect()
+    }
+
+    pub(super) fn finish_provider_call<R>(
+        &self,
+        plugin: &Arc<LoadedPlugin>,
+        actor: &Arc<ide_plugin::Actor>,
+        started: Instant,
+        result: Result<R, ActorError>,
+    ) -> Option<R> {
+        let elapsed = started.elapsed();
+        match result {
+            Ok(r) => {
+                self.record_call(plugin, elapsed, true, true);
+                Some(r)
+            }
+            Err(ActorError::SoftTimeout) => {
+                plugin.meta.lock().stats.slow_calls += 1;
+                None
+            }
+            Err(ActorError::Cancelled) => None,
+            Err(ActorError::Call(CallError::Guest(e))) => {
+                self.record_call(plugin, elapsed, !e.is_failure(), true);
+                tracing::debug!(plugin = %plugin.id(), "provider: {e}");
+                None
+            }
+            Err(ActorError::Call(CallError::Trap(_)) | ActorError::Stopped) => {
+                self.record_call(plugin, elapsed, false, false);
+                self.reap(plugin, actor, None);
+                None
+            }
+        }
+    }
+
+    pub fn provide_completion(
+        &self,
+        doc: &ProviderDocument,
+        at: ide_core::Pos,
+        trigger: Option<&str>,
+    ) -> Vec<(String, CompletionItem)> {
+        let (d, t) = (Arc::new(doc.clone()), trigger.map(str::to_owned));
+        self.edit_calls(ProviderKind::Completion, &doc.language, move |rt, timeout| {
+            rt.provide_completion(&d, at, t.as_deref(), timeout)
+        })
+        .into_iter()
+        .flat_map(|(p, items)| items.into_iter().map(move |i| (p.id().to_owned(), i)))
+        .collect()
+    }
+
+    pub fn provide_code_actions(
+        &self,
+        doc: &ProviderDocument,
+        selection: ide_core::Range,
+    ) -> Vec<(String, CodeAction)> {
+        let d = Arc::new(doc.clone());
+        self.edit_calls(ProviderKind::CodeActions, &doc.language, move |rt, timeout| {
+            rt.provide_code_actions(&d, selection, timeout)
+        })
+        .into_iter()
+        .flat_map(|(p, actions)| actions.into_iter().map(move |a| (p.id().to_owned(), a)))
+        .collect()
+    }
+
+    pub fn provide_definition(&self, doc: &ProviderDocument, at: ide_core::Pos) -> Vec<Location> {
+        let d = Arc::new(doc.clone());
+        self.edit_calls(ProviderKind::Definition, &doc.language, move |rt, timeout| {
+            rt.provide_definition(&d, at, timeout)
+        })
+        .into_iter()
+        .flat_map(|(_, locations)| locations)
+        .collect()
+    }
+
+    pub fn provide_line_markers(&self, doc: &ProviderDocument) -> Vec<(String, LineMarker)> {
+        let d = Arc::new(doc.clone());
+        self.edit_calls(ProviderKind::LineMarkers, &doc.language, move |rt, timeout| {
+            rt.provide_line_markers(&d, timeout)
+        })
+        .into_iter()
+        .flat_map(|(p, markers)| markers.into_iter().map(move |m| (p.id().to_owned(), m)))
+        .collect()
+    }
+
+    /// Ghost text from the first plugin that has some. Not bound by the
+    /// edit-path soft deadline (it may need the network) but by `cancel`:
+    /// the editor cancels a request as soon as the user types on.
+    pub fn provide_inline_completion(
+        &self,
+        doc: &ProviderDocument,
+        at: ide_core::Pos,
+        cancel: &CancellationToken,
+    ) -> Option<(String, InlineSuggestion)> {
+        for p in self.provider_plugins(ProviderKind::InlineCompletion, &doc.language) {
+            if cancel.is_cancelled() {
+                return None;
+            }
+            let Ok((actor, activated)) = self.ensure_active(&p, None) else { continue };
+            if activated {
+                self.changed();
+            }
+            let (d, timeout) = (doc.clone(), self.limits.timeout);
+            let started = Instant::now();
+            let result =
+                actor.call_cancellable(cancel, CANCEL_GRACE, move |rt| rt.provide_inline_completion(&d, at, timeout));
+            if let Some(Some(s)) = self.finish_provider_call(&p, &actor, started, result) {
+                return Some((p.id().to_owned(), s));
+            }
+        }
+        None
+    }
+}

crates/ide-host/src/plugins/remote.rs

@@ -0,0 +1,222 @@
+//! Plugin languages of a remote project: `Workspace` contributions take effect where the project is, so the
+//! desktop pushes its plugins' language definitions to `openidea-server`
+//! (`plugin_sync_languages`) together with the `process:` programs the user
+//! granted. The server resolves each granted program on its own `PATH`, pins
+//! the file (path + hash, kept in `plugin-pins.json`) the first time and
+//! starts only that file afterwards; a program missing from a sync is revoked.
+//! Revoking and granting again on the desktop re-pins a replaced program.
+
+use ide_extension::Capability;
+use ide_extension::ledger::{self, BinaryGrant};
+use ide_language::plugin_point::{PluginLanguages, validate_definition};
+use ide_language::{LanguageConfig, ProgramPin};
+use parking_lot::Mutex;
+use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+pub const PINS_FILE: &str = "plugin-pins.json";
+/// The server command the desktop calls.
+pub const SYNC_COMMAND: &str = "plugin_sync_languages";
+
+/// One plugin language as the desktop sends it.
+#[derive(Clone, Debug, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct RemoteLanguage {
+    pub plugin: String,
+    pub language: LanguageConfig,
+    /// Program names of the plugin's granted `process:` capabilities.
+    #[serde(default)]
+    pub granted: Vec<String>,
+}
+
+/// What the server made of a sync.
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "camelCase")]
+pub struct SyncReport {
+    pub languages: usize,
+    /// `plugin: program` → the file it starts.
+    pub pinned: BTreeMap<String, PathBuf>,
+    /// Granted programs not found on this machine's `PATH`.
+    pub unresolved: Vec<String>,
+    /// Definitions that failed validation (not applied).
+    pub rejected: Vec<String>,
+}
+
+#[derive(Default, Serialize, Deserialize)]
+struct PinsFile {
+    /// `plugin\nprocess:program` → the approved file.
+    #[serde(default)]
+    pins: BTreeMap<String, BinaryGrant>,
+}
+
+type PathVar = Arc<dyn Fn() -> Option<std::ffi::OsString> + Send + Sync>;
+
+/// The server's side: an overlay for its language registry, filled by syncs.
+pub struct RemotePluginLanguages {
+    store: Arc<PluginLanguages>,
+    pins: Arc<Mutex<BTreeMap<String, BinaryGrant>>>,
+    file: Option<PathBuf>,
+    applied: Mutex<Vec<ide_extension::Disposable>>,
+    path_var: PathVar,
+}
+
+fn key(plugin: &str, cap: &Capability) -> String {
+    format!("{plugin}\n{cap}")
+}
+
+impl RemotePluginLanguages {
+    /// Pins persist in `data_dir` (none: in memory, for tests).
+    pub fn new(data_dir: Option<&std::path::Path>) -> Arc<Self> {
+        Self::with_path(data_dir, Arc::new(|| std::env::var_os("PATH")))
+    }
+
+    pub fn with_path(data_dir: Option<&std::path::Path>, path_var: PathVar) -> Arc<Self> {
+        let file = data_dir.map(|d| d.join(PINS_FILE));
+        let saved: PinsFile = file
+            .as_ref()
+            .and_then(|f| std::fs::read_to_string(f).ok())
+            .and_then(|s| serde_json::from_str(&s).ok())
+            .unwrap_or_default();
+        let pins = Arc::new(Mutex::new(saved.pins));
+        let store = PluginLanguages::new();
+        let policy_pins = pins.clone();
+        store.set_process_policy(Arc::new(move |plugin, cap| {
+            policy_pins.lock().get(&key(plugin, cap)).map(|b| ProgramPin { path: b.path.clone(), hash: b.hash.clone() })
+        }));
+        Arc::new(Self { store, pins, file, applied: Mutex::default(), path_var })
+    }
+
+    /// For [`ide_language::LanguageRegistry::attach_plugins`].
+    pub fn store(&self) -> &Arc<PluginLanguages> {
+        &self.store
+    }
+
+    /// Replaces every plugin language with `languages`.
+    pub fn sync(&self, languages: Vec<RemoteLanguage>) -> SyncReport {
+        let mut report = SyncReport::default();
+        let mut wanted: BTreeMap<String, (String, Capability)> = BTreeMap::new();
+        let mut accepted = Vec::new();
+        for l in languages {
+            if let Err(e) = validate_definition(&l.language) {
+                report.rejected.push(format!("{} ({}): {e}", l.language.id, l.plugin));
+                continue;
+            }
+            for program in &l.granted {
+                let cap = Capability::Process(program.clone());
+                // Only programs the definition starts: a grant is not a licence for anything else.
+                if ide_language::plugin_point::required_capabilities(&l.language).contains(&cap) {
+                    wanted.insert(key(&l.plugin, &cap), (program.clone(), cap));
+                }
+            }
+            accepted.push(l);
+        }
+        {
+            let mut pins = self.pins.lock();
+            pins.retain(|k, _| wanted.contains_key(k));
+            for (k, (program, _)) in &wanted {
+                if pins.contains_key(k) {
+                    continue;
+                }
+                let resolved = ledger::resolve_program(program, (self.path_var)().as_deref()).and_then(|path| {
+                    ledger::file_hash(&path).map(|hash| BinaryGrant { path, hash }).map_err(|e| e.to_string())
+                });
+                match resolved {
+                    Ok(bin) => {
+                        pins.insert(k.clone(), bin);
+                    }
+                    Err(e) => {
+                        tracing::info!("process:{program}: {e}");
+                        report.unresolved.push(program.clone());
+                    }
+                }
+            }
+            for (k, bin) in pins.iter() {
+                report.pinned.insert(k.replace("\nprocess:", ": "), bin.path.clone());
+            }
+            self.save(&pins);
+        }
+        let mut applied = self.applied.lock();
+        applied.clear(); // disposes the previous sync's languages
+        for l in accepted {
+            applied.push(self.store.add(l.plugin, l.language));
+        }
+        report.languages = applied.len();
+        self.store.invalidate();
+        report
+    }
+
+    fn save(&self, pins: &BTreeMap<String, BinaryGrant>) {
+        let Some(file) = &self.file else { return };
+        let json = serde_json::to_string_pretty(&PinsFile { pins: pins.clone() }).unwrap_or_default();
+        let tmp = file.with_extension("json.tmp");
+        if let Err(e) = std::fs::write(&tmp, json).and_then(|()| std::fs::rename(&tmp, file)) {
+            tracing::warn!("saving {}: {e}", file.display());
+        }
+    }
+}
+
+#[cfg(all(test, unix))]
+mod tests {
+    use super::*;
+    use ide_core::LanguageId;
+    use ide_language::LanguageRegistry;
+    use std::os::unix::fs::PermissionsExt;
+
+    fn toy(granted: &[&str]) -> RemoteLanguage {
+        let language = ide_language::plugin_point::parse_definition(
+            "id = \"toy\"\nname = \"Toy\"\nextensions = [\"toy\"]\n\
+             [[language-servers]]\nname = \"toylsp\"\ncommand = \"toylsp\"\n",
+        )
+        .unwrap();
+        RemoteLanguage {
+            plugin: "acme.toy".into(),
+            language,
+            granted: granted.iter().map(|s| (*s).to_owned()).collect(),
+        }
+    }
+
+    #[test]
+    fn syncs_languages_and_pins_granted_programs_on_this_machine() {
+        let tmp = tempfile::tempdir().unwrap();
+        let bin = tmp.path().join("bin");
+        std::fs::create_dir(&bin).unwrap();
+        std::fs::write(bin.join("toylsp"), "#!/bin/sh\n").unwrap();
+        std::fs::set_permissions(bin.join("toylsp"), std::fs::Permissions::from_mode(0o755)).unwrap();
+        let path = bin.clone().into_os_string();
+        let remote = RemotePluginLanguages::with_path(Some(tmp.path()), Arc::new(move || Some(path.clone())));
+        let registry = LanguageRegistry::load(None).unwrap();
+        registry.attach_plugins(remote.store().clone());
+        let project = registry.fork();
+        let id = LanguageId::new("toy");
+
+        // Not granted: the language, no server.
+        let report = remote.sync(vec![toy(&[])]);
+        assert_eq!(report.languages, 1);
+        assert_eq!(project.detect(std::path::Path::new("/r/a.toy"), None), id);
+        assert!(project.get(&id).unwrap().language_servers.is_empty());
+
+        // Granted: resolved here and pinned; persisted.
+        let report = remote.sync(vec![toy(&["toylsp", "rm"])]);
+        assert_eq!(report.pinned.len(), 1, "only programs the definition starts: {report:?}");
+        let pin = project.get(&id).unwrap().language_servers[0].pinned.clone().unwrap();
+        assert!(pin.verify().is_ok());
+        assert!(tmp.path().join(PINS_FILE).is_file());
+
+        // Replaced: refused at start until revoked and granted again.
+        std::fs::write(bin.join("toylsp"), "#!/bin/sh\necho x\n").unwrap();
+        remote.sync(vec![toy(&["toylsp"])]);
+        assert!(project.get(&id).unwrap().language_servers[0].pinned.as_ref().unwrap().verify().is_err());
+        remote.sync(vec![toy(&[])]);
+        remote.sync(vec![toy(&["toylsp"])]);
+        assert!(project.get(&id).unwrap().language_servers[0].pinned.as_ref().unwrap().verify().is_ok());
+
+        // Missing programs are reported; invalid definitions rejected; empty sync removes all.
+        let mut bad = toy(&[]);
+        bad.language.id = LanguageId::new("a b");
+        let report = remote.sync(vec![bad]);
+        assert_eq!(report.rejected.len(), 1);
+        assert_eq!(project.detect(std::path::Path::new("/r/a.toy"), None), LanguageId::plain_text());
+    }
+}

crates/ide-host/src/plugins/remote_host.rs

@@ -0,0 +1,504 @@
+//! Code plugins of remote projects:
+//! Wasm runs where the project is, so `openidea-server` hosts the desktop's
+//! code plugins and they read, search, run processes and publish diagnostics
+//! on the remote machine.
+//!
+//! The desktop stays the authority over what is installed and granted. It
+//! pushes its live code plugins with [`SYNC_PACKAGES`]: first their digests
+//! and grants, then the files of those the server doesn't have (one package
+//! per request); a package missing from a sync is uninstalled. The server
+//! installs them under `<data>/remote-plugins` and records the desktop's
+//! grants (a `process:` grant is pinned to the program on this machine's
+//! `PATH`).
+//!
+//! The commands a window needs at run time (`plugin_run_command`,
+//! `plugin_post_events`, `plugin_event_kinds`, `plugin_status_items`,
+//! `plugin_cancel_task`, `plugin_set_active_file`, `plugin_line_markers`,
+//! `plugin_view_render`, `plugin_view_event`)
+//! carry the desktop commands' names and arguments, so a remote window's UI
+//! routes them here unchanged. Plugin results come back as `plugin`
+//! notifications ([`PluginEventMessage`]); secrets stay in the desktop's
+//! keychain and are asked for with a `plugin_secret` request
+//! ([`SecretRequest`]) when a request header needs one (rule 4).
+
+use super::{
+    Consent, HostWorkspace, PluginEditor, PluginEvent, PluginHost, PluginSource, PluginStatusItem, SecretStore,
+};
+use crate::rpc::Dispatcher;
+use base64::Engine as _;
+use ide_core::{IdeError, IdeResult};
+use ide_extension::{MANIFEST_FILE, ledger};
+use ide_jsonrpc::Peer;
+use ide_plugin::{Invocation, Limits};
+use parking_lot::Mutex;
+use serde::{Deserialize, Serialize};
+use std::collections::{BTreeMap, BTreeSet};
+use std::path::{Component, Path, PathBuf};
+use std::sync::{Arc, OnceLock, Weak};
+use std::time::Duration;
+
+/// The server command the desktop calls with its packages.
+pub const SYNC_PACKAGES: &str = "plugin_sync_packages";
+/// Server → client notification carrying a [`PluginEventMessage`].
+pub const EVENT_NOTIFICATION: &str = "plugin";
+/// Server → client request ([`SecretRequest`] → `Option<String>`).
+pub const SECRET_REQUEST: &str = "plugin_secret";
+/// Under the server's data directory.
+pub const PLUGINS_DIR: &str = "remote-plugins";
+const INCOMING_DIR: &str = "remote-plugins.incoming";
+const SECRET_TIMEOUT: Duration = Duration::from_secs(10);
+const EVENT_FLUSH: Duration = Duration::from_millis(250);
+const TICKS_PER_SUPERVISION: u32 = 20;
+
+/// One live code plugin of the desktop.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct RemotePackage {
+    pub id: String,
+    /// [`package_digest`] of the package.
+    pub digest: String,
+    /// Capabilities the user granted on the desktop.
+    pub granted: Vec<String>,
+}
+
+/// One file of a package (`path` relative to the package, `data` base64).
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct PackageFile {
+    pub path: String,
+    pub data: String,
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PackageSyncReport {
+    /// Packages the server needs the files of (send them in another sync).
+    pub missing: Vec<String>,
+    pub installed: Vec<String>,
+    pub removed: Vec<String>,
+    /// `id: reason`.
+    pub failed: Vec<String>,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct PluginEventMessage {
+    /// The window that invoked the plugin (`None`: every window of the connection).
+    pub window: Option<String>,
+    pub event: PluginEvent,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct SecretRequest {
+    pub plugin: String,
+    pub name: String,
+}
+
+/// Identifies a package's content: the manifest, the files its declarations
+/// reference and the component.
+pub fn package_digest(dir: &Path, files: &[PathBuf]) -> IdeResult<String> {
+    let mut all = files.to_vec();
+    all.push(PathBuf::from(MANIFEST_FILE));
+    Ok(ledger::package_hash(dir, &all)?)
+}
+
+/// Whether a plugin event means something to a remote window (the desktop
+/// owns the plugin list, themes and consent).
+pub fn forwarded(event: &PluginEvent) -> bool {
+    matches!(
+        event,
+        PluginEvent::Notification { .. }
+            | PluginEvent::StatusItemChanged { .. }
+            | PluginEvent::TaskStarted { .. }
+            | PluginEvent::TaskProgress { .. }
+            | PluginEvent::TaskEnded { .. }
+            | PluginEvent::SubscriptionsChanged
+            | PluginEvent::ViewChanged { .. }
+            | PluginEvent::ViewMessage { .. }
+            | PluginEvent::OpenTerminal { .. }
+    )
+}
+
+// ---- desktop side -----------------------------------------------------------
+
+impl PluginHost {
+    fn package_files(&self, plugin: &super::LoadedPlugin) -> IdeResult<Vec<PathBuf>> {
+        let set = self.registry.prepare(&plugin.pkg).map_err(IdeError::invalid)?;
+        Ok(set.files.into_iter().chain(plugin.manifest().wasm.clone()).collect())
+    }
+
+    /// The live code plugins (installed or linked) for a remote project's server.
+    pub fn remote_packages(&self) -> Vec<RemotePackage> {
+        let plugins: Vec<_> = self.plugins.read().values().cloned().collect();
+        plugins
+            .iter()
+            .filter(|p| p.dev_root.is_none() && !p.invalid && p.manifest().wasm.is_some())
+            .filter(|p| matches!(p.status(), super::PluginStatus::Active | super::PluginStatus::Inactive))
+            .filter_map(|p| {
+                let files = self.package_files(p).ok()?;
+                let digest = package_digest(p.dir(), &files).ok()?;
+                let granted = p.meta.lock().granted.iter().map(ToString::to_string).collect();
+                Some(RemotePackage { id: p.id().to_owned(), digest, granted })
+            })
+            .collect()
+    }
+
+    /// The files of a package for [`SYNC_PACKAGES`], the manifest first.
+    pub fn remote_package_files(&self, id: &str) -> IdeResult<Vec<PackageFile>> {
+        let plugin = self.get(id)?;
+        let files = self.package_files(&plugin)?;
+        std::iter::once(PathBuf::from(MANIFEST_FILE))
+            .chain(files)
+            .map(|rel| {
+                let bytes = std::fs::read(plugin.dir().join(&rel))?;
+                let path = rel.to_str().ok_or_else(|| IdeError::invalid("non UTF-8 file name"))?.replace('\\', "/");
+                Ok(PackageFile { path, data: base64::engine::general_purpose::STANDARD.encode(bytes) })
+            })
+            .collect()
+    }
+
+    /// A secret a plugin declares, for its remote instance (`plugin_secret`).
+    pub fn declared_secret(&self, id: &str, name: &str) -> Option<String> {
+        let plugin = self.get(id).ok()?;
+        if !self.ui.items(super::providers::SECRETS_POINT, Some(plugin.id())).iter().any(|s| s.key == name) {
+            return None;
+        }
+        let store = self.shared.secrets.read().clone();
+        store.get(plugin.id(), name)
+    }
+}
+
+// ---- server side ------------------------------------------------------------
+
+/// The plugin host of `openidea-server`.
+pub struct RemotePlugins {
+    host: Arc<PluginHost>,
+    incoming: PathBuf,
+    sync: Mutex<()>,
+}
+
+/// Secrets from the desktop's keychain, asked for when used.
+struct ClientSecrets {
+    peer: Arc<OnceLock<Peer>>,
+    runtime: tokio::runtime::Handle,
+}
+
+impl SecretStore for ClientSecrets {
+    fn get(&self, plugin: &str, name: &str) -> Option<String> {
+        let peer = self.peer.get()?.clone();
+        let request = SecretRequest { plugin: plugin.to_owned(), name: name.to_owned() };
+        let ask = async move {
+            tokio::time::timeout(SECRET_TIMEOUT, peer.request::<_, Option<String>>(SECRET_REQUEST, request, None)).await
+        };
+        // Plugin threads block on the runtime; a runtime worker (a host
+        // command asking) must leave its thread to the other tasks first.
+        let answer = if tokio::runtime::Handle::try_current().is_ok() {
+            tokio::task::block_in_place(|| self.runtime.block_on(ask))
+        } else {
+            self.runtime.block_on(ask)
+        };
+        match answer {
+            Ok(Ok(value)) => value,
+            Ok(Err(e)) => {
+                tracing::warn!("plugin secret {plugin}/{name}: {e}");
+                None
+            }
+            Err(_) => None,
+        }
+    }
+
+    fn set(&self, _: &str, _: &str, _: Option<&str>) -> Result<(), String> {
+        Err("secrets are stored on the desktop".into())
+    }
+}
+
+impl RemotePlugins {
+    /// Creates the host over `<data_dir>/remote-plugins`, loads what earlier
+    /// sessions installed and starts event delivery and supervision.
+    pub fn start(data_dir: &Path, projects: &Arc<crate::Host>, peer: Arc<OnceLock<Peer>>) -> IdeResult<Arc<Self>> {
+        let sink_peer = peer.clone();
+        let sink = move |client: Option<&str>, event: PluginEvent| {
+            if forwarded(&event)
+                && let Some(p) = sink_peer.get()
+            {
+                let _ = p.notify(EVENT_NOTIFICATION, PluginEventMessage { window: client.map(str::to_owned), event });
+            }
+        };
+        let host = Arc::new(PluginHost::new(data_dir.join(PLUGINS_DIR), Arc::new(sink), Limits::default())?);
+        host.set_workspace(Some(Arc::new(HostWorkspace(Arc::downgrade(projects)))));
+        host.set_secret_store(Arc::new(ClientSecrets { peer, runtime: projects.runtime.clone() }));
+        let trust = Arc::downgrade(projects);
+        host.set_project_policy(Arc::new(move |root| {
+            trust.upgrade().is_some_and(|h| h.trust.trusted(root).unwrap_or(false))
+        }));
+        super::set_editor_providers(Some(&host));
+        ide_language::set_external_syntax(Some(host.syntax_provider()));
+        ide_run::set_external_detection(Some(host.run_detection()));
+        host.load_all();
+        host.startup_finished();
+        spawn_supervision(Arc::downgrade(&host))?;
+        Ok(Arc::new(Self { host, incoming: data_dir.join(INCOMING_DIR), sync: Mutex::new(()) }))
+    }
+
+    pub fn host(&self) -> &Arc<PluginHost> {
+        &self.host
+    }
+
+    /// Makes the installed packages match `packages`: uninstalls the others,
+    /// follows changed grants, installs those with `files` and reports the
+    /// rest as missing.
+    pub fn sync(
+        &self,
+        packages: Vec<RemotePackage>,
+        mut files: BTreeMap<String, Vec<PackageFile>>,
+    ) -> PackageSyncReport {
+        let _guard = self.sync.lock();
+        let mut report = PackageSyncReport::default();
+        let wanted: BTreeSet<&str> = packages.iter().map(|p| p.id.as_str()).collect();
+        let installed: Vec<String> = self
+            .host
+            .plugins
+            .read()
+            .values()
+            .filter(|p| p.source == PluginSource::Installed)
+            .map(|p| p.id().to_owned())
+            .collect();
+        for id in installed.iter().filter(|id| !wanted.contains(id.as_str())) {
+            match self.host.uninstall(id) {
+                Ok(()) => report.removed.push(id.clone()),
+                Err(e) => report.failed.push(format!("{id}: {e}")),
+            }
+        }
+        for pkg in packages {
+            if !valid_id(&pkg.id) {
+                report.failed.push(format!("{}: invalid plugin id", pkg.id));
+                continue;
+            }
+            let consent = Consent { optional: pkg.granted.clone() };
+            if self.current_digest(&pkg.id).as_deref() == Some(pkg.digest.as_str()) {
+                if let Err(e) = self.follow_grants(&pkg, &consent) {
+                    report.failed.push(format!("{}: {e}", pkg.id));
+                }
+                continue;
+            }
+            match files.remove(&pkg.id) {
+                None => report.missing.push(pkg.id),
+                Some(list) => match self.install(&pkg, list, &consent) {
+                    Ok(()) => report.installed.push(pkg.id),
+                    Err(e) => report.failed.push(format!("{}: {}", pkg.id, e.message)),
+                },
+            }
+        }
+        report
+    }
+
+    fn current_digest(&self, id: &str) -> Option<String> {
+        let plugin = self.host.plugins.read().get(id).cloned()?;
+        if plugin.source != PluginSource::Installed || plugin.invalid {
+            return None;
+        }
+        let files = self.host.package_files(&plugin).ok()?;
+        package_digest(plugin.dir(), &files).ok()
+    }
+
+    fn follow_grants(&self, pkg: &RemotePackage, consent: &Consent) -> IdeResult<()> {
+        let info = self.host.info_of(&pkg.id)?;
+        let have: BTreeSet<&str> = info.capabilities.iter().filter(|c| c.granted).map(|c| c.id.as_str()).collect();
+        let want: BTreeSet<&str> = pkg.granted.iter().map(String::as_str).collect();
+        if have != want || info.status == super::PluginStatus::NeedsConsent {
+            self.host.grant(&pkg.id, consent)?;
+        }
+        Ok(())
+    }
+
+    fn install(&self, pkg: &RemotePackage, files: Vec<PackageFile>, consent: &Consent) -> IdeResult<()> {
+        let dir = self.incoming.join(&pkg.id);
+        let _ = std::fs::remove_dir_all(&dir);
+        let result = (|| {
+            let mut rels = Vec::new();
+            for f in files {
+                let rel = safe_relative(&f.path)?;
+                let bytes = base64::engine::general_purpose::STANDARD
+                    .decode(f.data.as_bytes())
+                    .map_err(|e| IdeError::invalid(format!("{}: {e}", f.path)))?;
+                let to = dir.join(&rel);
+                if let Some(parent) = to.parent() {
+                    std::fs::create_dir_all(parent)?;
+                }
+                std::fs::write(&to, bytes)?;
+                if rel != Path::new(MANIFEST_FILE) {
+                    rels.push(rel);
+                }
+            }
+            if package_digest(&dir, &rels)? != pkg.digest {
+                return Err(IdeError::invalid("the package arrived incomplete or changed"));
+            }
+            let info = self.host.install_from_dir(&dir, consent)?;
+            if info.id != pkg.id {
+                let _ = self.host.uninstall(&info.id);
+                return Err(IdeError::invalid(format!("the package is plugin {:?}", info.id)));
+            }
+            Ok(())
+        })();
+        let _ = std::fs::remove_dir_all(&dir);
+        result
+    }
+
+    /// The run-time commands of remote windows plus [`SYNC_PACKAGES`].
+    pub fn register(self: &Arc<Self>, d: &mut Dispatcher) {
+        let this = self.clone();
+        d.add(SYNC_PACKAGES, move |c| {
+            let this = this.clone();
+            async move {
+                let packages: Vec<RemotePackage> = c.arg("packages")?;
+                let files: Option<BTreeMap<String, Vec<PackageFile>>> = c.arg("files")?;
+                blocking(move || Ok(this.sync(packages, files.unwrap_or_default()))).await
+            }
+        });
+        let host = Arc::downgrade(&self.host);
+        let h = host.clone();
+        d.add("plugin_run_command", move |c| {
+            let h = h.clone();
+            async move {
+                let host = alive(&h)?;
+                let plugin_id: String = c.arg("pluginId")?;
+                let command_id: String = c.arg("commandId")?;
+                let arg: Option<String> = c.arg("arg")?;
+                let editor: Option<PluginEditor> = c.arg("editor")?;
+                let invocation = Invocation {
+                    client: Some(c.window.clone()),
+                    workspace_root: c.host.project(&c.window).ok().map(|p| p.root.clone()),
+                    editor: editor.map(PluginEditor::context),
+                };
+                blocking(move || host.run_command(&plugin_id, &command_id, arg.as_deref(), invocation)).await
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_post_events", move |c| {
+            let h = h.clone();
+            async move {
+                alive(&h)?.post_events(Some(&c.window), c.arg("events")?);
+                Ok(())
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_event_kinds", move |_| {
+            let h = h.clone();
+            async move { Ok(alive(&h)?.event_kinds().into_iter().collect::<Vec<_>>()) }
+        });
+        let h = host.clone();
+        d.add("plugin_status_items", move |_| {
+            let h = h.clone();
+            async move {
+                Ok(alive(&h)?
+                    .status_items()
+                    .into_iter()
+                    .map(|(plugin_id, id, item)| PluginStatusItem { plugin_id, id, item })
+                    .collect::<Vec<_>>())
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_cancel_task", move |c| {
+            let h = h.clone();
+            async move { Ok(alive(&h)?.cancel_task(&c.arg::<String>("taskId")?)) }
+        });
+        let h = host.clone();
+        d.add("plugin_set_active_file", move |c| {
+            let h = h.clone();
+            async move {
+                alive(&h)?.set_active_file(&c.window, c.arg("path")?);
+                Ok(())
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_view_render", move |c| {
+            let h = h.clone();
+            async move {
+                let plugins = alive(&h)?;
+                super::views::render(
+                    &c.host,
+                    plugins,
+                    &c.window,
+                    c.arg("pluginId")?,
+                    c.arg("view")?,
+                    c.arg("viewport")?,
+                    c.arg("doc")?,
+                    c.arg("editor")?,
+                )
+                .await
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_view_event", move |c| {
+            let h = h.clone();
+            async move {
+                let plugins = alive(&h)?;
+                super::views::event(
+                    &c.host,
+                    plugins,
+                    &c.window,
+                    c.arg("pluginId")?,
+                    c.arg("view")?,
+                    c.arg("event")?,
+                    c.arg("doc")?,
+                    c.arg("editor")?,
+                )
+                .await
+            }
+        });
+        d.add("plugin_line_markers", |c| async move {
+            crate::ops::lsp::plugin_line_markers(&c.host, &c.window, c.arg("doc")?).await
+        });
+    }
+}
+
+fn alive(host: &Weak<PluginHost>) -> IdeResult<Arc<PluginHost>> {
+    host.upgrade().ok_or_else(|| IdeError::unavailable("the plugin host has shut down"))
+}
+
+async fn blocking<T: Send + 'static>(f: impl FnOnce() -> IdeResult<T> + Send + 'static) -> IdeResult<T> {
+    tokio::task::spawn_blocking(f).await.map_err(|e| IdeError::internal(e.to_string()))?
+}
+
+fn spawn_supervision(host: Weak<PluginHost>) -> IdeResult<()> {
+    std::thread::Builder::new().name("remote-plugins".into()).spawn(move || {
+        for n in 1u32.. {
+            std::thread::sleep(EVENT_FLUSH);
+            let Some(host) = host.upgrade() else { return };
+            host.flush_events();
+            if n % TICKS_PER_SUPERVISION == 0 {
+                host.tick();
+            }
+        }
+    })?;
+    Ok(())
+}
+
+fn valid_id(id: &str) -> bool {
+    !id.is_empty()
+        && id.len() <= 128
+        && !id.starts_with('.')
+        && id.chars().all(|c| c.is_ascii_alphanumeric() || "-_.".contains(c))
+}
+
+/// `path` as a relative path inside a package (no `..`, no root).
+fn safe_relative(path: &str) -> IdeResult<PathBuf> {
+    let p = Path::new(path);
+    if path.is_empty() || !p.components().all(|c| matches!(c, Component::Normal(_))) {
+        return Err(IdeError::invalid(format!("invalid file path {path:?} in package")));
+    }
+    Ok(p.to_path_buf())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn package_paths_stay_inside_the_package() {
+        assert!(safe_relative("dist/plugin.wasm").is_ok());
+        for bad in ["", "../x", "/etc/passwd", "a/../../b", "./x"] {
+            assert!(safe_relative(bad).is_err(), "{bad}");
+        }
+        assert!(valid_id("ai-completion"));
+        assert!(!valid_id("../x") && !valid_id(".data") && !valid_id(""));
+    }
+}

crates/ide-host/src/plugins/run_detectors.rs

@@ -0,0 +1,167 @@
+//! The `runDetectors` extension point: run configurations a plugin offers in
+//! projects that contain a marker file.
+//!
+//! ```toml
+//! [[contributes.runDetectors]]
+//! id = "forge-test"
+//! name = "forge test"
+//! files = ["foundry.toml"]       # any of these at the project root
+//! command = "forge"
+//! args = ["test"]
+//! test = true                    # results go to the test tree
+//! ```
+//!
+//! The command is a `process:` capability like a language server's: the
+//! configuration is offered only while it is granted, and starts the approved
+//! file (checked right before it starts).
+
+use ide_extension::{
+    Capability, Disposable, ExtensionPoint, Package, Placement, Prepared, check_relative, decode, validate_item_id,
+};
+use ide_language::ProgramPin;
+use ide_run::{EXTERNAL_PREFIX, ExternalDetection, RunConfig};
+use parking_lot::RwLock;
+use serde::Deserialize;
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+pub const POINT_ID: &str = "runDetectors";
+const MAX_FILES: usize = 16;
+const MAX_ARGS: usize = 64;
+
+#[derive(Clone, Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct Detector {
+    pub id: String,
+    pub name: String,
+    pub files: Vec<PathBuf>,
+    pub command: String,
+    #[serde(default)]
+    pub args: Vec<String>,
+    #[serde(default)]
+    pub test: bool,
+}
+
+/// Detectors of enabled plugins.
+#[derive(Default)]
+pub struct RunDetectors {
+    items: RwLock<Vec<(u64, String, Detector)>>,
+    seq: AtomicU64,
+}
+
+impl RunDetectors {
+    fn add(self: &Arc<Self>, plugin: String, detector: Detector) -> Disposable {
+        let seq = self.seq.fetch_add(1, Ordering::Relaxed);
+        self.items.write().push((seq, plugin, detector));
+        let weak = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(this) = weak.upgrade() {
+                this.items.write().retain(|(s, _, _)| *s != seq);
+            }
+        })
+    }
+}
+
+pub struct RunDetectorsPoint {
+    store: Arc<RunDetectors>,
+}
+
+impl RunDetectorsPoint {
+    pub fn new(store: Arc<RunDetectors>) -> Self {
+        Self { store }
+    }
+}
+
+impl ExtensionPoint for RunDetectorsPoint {
+    fn id(&self) -> &'static str {
+        POINT_ID
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Workspace
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let d: Detector = decode(POINT_ID, decl)?;
+        validate_item_id(&d.id, "run detector id")?;
+        if d.name.trim().is_empty() || d.name.len() > 128 {
+            return Err(format!("run detector {:?}: `name` must be 1–128 bytes", d.id));
+        }
+        if d.files.is_empty() || d.files.len() > MAX_FILES {
+            return Err(format!("run detector {:?}: give 1–{MAX_FILES} marker `files`", d.id));
+        }
+        for f in &d.files {
+            check_relative(f, "files")?;
+        }
+        let program = d.command.trim();
+        if program.is_empty() || program.contains(char::is_whitespace) {
+            return Err(format!("run detector {:?}: `command` is one program name (arguments go in `args`)", d.id));
+        }
+        if d.args.len() > MAX_ARGS {
+            return Err(format!("run detector {:?}: at most {MAX_ARGS} arguments", d.id));
+        }
+        let cap = Capability::Process(program.to_owned());
+        let (store, plugin, label) = (self.store.clone(), pkg.id().to_owned(), d.name.clone());
+        let key = d.id.clone();
+        Ok(Prepared::new(label, move || Ok(store.add(plugin, d))).key(key).capability(cap))
+    }
+}
+
+type Pins = Arc<RwLock<HashMap<(String, String), ProgramPin>>>;
+
+/// [`ExternalDetection`] over the detectors and the approved programs.
+pub struct PluginRunDetection {
+    pub(crate) store: Arc<RunDetectors>,
+    pub(crate) pins: Pins,
+}
+
+fn config_id(plugin: &str, detector: &str) -> String {
+    format!("{EXTERNAL_PREFIX}{plugin}:{detector}")
+}
+
+impl PluginRunDetection {
+    fn pin(&self, plugin: &str, d: &Detector) -> Option<ProgramPin> {
+        let cap = Capability::Process(d.command.trim().to_owned());
+        self.pins.read().get(&(plugin.to_owned(), cap.to_string())).cloned()
+    }
+}
+
+impl ExternalDetection for PluginRunDetection {
+    fn detect(&self, root: &Path) -> Vec<RunConfig> {
+        let items = self.store.items.read().clone();
+        items
+            .into_iter()
+            .filter(|(_, plugin, d)| self.pin(plugin, d).is_some() && d.files.iter().any(|f| root.join(f).exists()))
+            .map(|(_, plugin, d)| RunConfig {
+                id: config_id(&plugin, &d.id),
+                name: d.name.clone(),
+                kind: "plugin".into(),
+                command: d.command.trim().to_owned(),
+                args: d.args.clone(),
+                cwd: None,
+                env: Default::default(),
+                detected: true,
+                is_test: d.test,
+                debug_adapter: None,
+                allow_parallel: false,
+                extras: Default::default(),
+            })
+            .collect()
+    }
+
+    fn launch(&self, config: &RunConfig) -> Result<PathBuf, String> {
+        let items = self.store.items.read();
+        let (plugin, d) = items
+            .iter()
+            .find(|(_, plugin, d)| config_id(plugin, &d.id) == config.id)
+            .map(|(_, p, d)| (p.clone(), d.clone()))
+            .ok_or_else(|| "the plugin that detected this configuration is no longer enabled".to_owned())?;
+        drop(items);
+        let pin = self.pin(&plugin, &d).ok_or_else(|| {
+            format!("allow process:{} for plugin {plugin} in Settings › Plugins to run this configuration", d.command)
+        })?;
+        pin.verify().map(Path::to_path_buf)
+    }
+}

crates/ide-host/src/plugins/theme.rs

@@ -1,9 +1,21 @@
-//! Theme contributions: design-token overrides applied as CSS variables on `:root`.
-//! Theme and editor-scheme files are JSON that may contain `//` and `/* */` comments.
+//! The `themes` extension point: design-token overrides applied as CSS
+//! variables on `:root`. Theme and editor-scheme files are JSON that may
+//! contain `//` and `/* */` comments.
+//!
+//! ```toml
+//! [[contributes.themes]]
+//! path = "themes/harbor-night.json"
+//! editor-scheme = "themes/harbor-night.scheme.json"   # optional
+//! ```
 
+use ide_extension::{ExtensionPoint, Package, Placement, Prepared, UiContribution, UiStore, decode};
 use serde::{Deserialize, Serialize};
 use specta::Type;
 use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+pub const POINT_ID: &str = "themes";
 
 const MAX_TOKENS: usize = 512;
 const MAX_VALUE_LEN: usize = 256;
@@ -48,7 +60,7 @@ impl ThemeDef {
     }
 
     pub fn validate(&self) -> Result<(), String> {
-        crate::manifest::validate_command_id(&self.id).map_err(|e| e.replace("command id", "theme id"))?;
+        ide_extension::validate_item_id(&self.id, "theme id")?;
         if self.name.trim().is_empty() {
             return Err("theme name must not be empty".into());
         }
@@ -71,6 +83,55 @@ impl ThemeDef {
     }
 }
 
+pub struct ThemesPoint {
+    store: Arc<UiStore>,
+}
+
+impl ThemesPoint {
+    pub fn new(store: Arc<UiStore>) -> Self {
+        Self { store }
+    }
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case", deny_unknown_fields)]
+struct Decl {
+    path: PathBuf,
+    #[serde(default)]
+    editor_scheme: Option<PathBuf>,
+}
+
+impl ExtensionPoint for ThemesPoint {
+    fn id(&self) -> &'static str {
+        POINT_ID
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Ui
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let decl: Decl = decode(POINT_ID, decl)?;
+        let path = &decl.path;
+        let mut theme = ThemeDef::parse(&pkg.read_text(path)?).map_err(|e| format!("{}: {e}", path.display()))?;
+        let mut files = vec![path.clone()];
+        if let Some(scheme) = &decl.editor_scheme {
+            files.push(scheme.clone());
+            theme.merge_editor_scheme(&pkg.read_text(scheme)?).map_err(|e| format!("{}: {e}", scheme.display()))?;
+        }
+        let item = UiContribution {
+            plugin_id: pkg.id().to_owned(),
+            point: POINT_ID.into(),
+            key: theme.id.clone(),
+            decl: serde_json::to_value(&theme).map_err(|e| e.to_string())?,
+        };
+        let store = self.store.clone();
+        let mut prepared = Prepared::new(theme.name.clone(), move || Ok(store.insert(item))).key(theme.id);
+        prepared.files = files;
+        Ok(prepared)
+    }
+}
+
 /// Blanks out `//` and `/* */` comments outside strings, keeping newlines so
 /// parse errors still point at the right line.
 fn strip_json_comments(src: &str) -> String {

crates/ide-host/src/plugins/types.rs

@@ -0,0 +1,236 @@
+//! UI-facing plugin types and the event stream.
+
+use super::theme::ThemeDef;
+use ide_extension::{CapabilityInfo, ContributionInfo, UiContribution};
+pub use ide_plugin::{ActionPerformed, ActionSource, EventKind, NotificationLevel, StatusItem, WorkbenchEvent};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum PluginSource {
+    /// Installed under `<app-data>/plugins/<id>/`.
+    Installed,
+    /// Loaded from `<project>/.openidea/plugins/<dir>/` while that project is open.
+    Dev,
+    /// A development plugin linked from any folder (`openidea-plugin link`).
+    Linked,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum PluginStatus {
+    /// Code instantiated and activated.
+    Active,
+    /// Has code that has not been needed yet: contributions are live, no Wasm instance.
+    Inactive,
+    /// No code; contributions only.
+    Static,
+    Disabled,
+    /// Waiting for the user to confirm its permissions (project and new plugins).
+    NeedsConsent,
+    /// Failed to load, or failed repeatedly and was stopped for this session (see `error`).
+    Failed,
+}
+
+impl PluginStatus {
+    /// Contributions are in effect.
+    pub fn is_live(self) -> bool {
+        matches!(self, Self::Active | Self::Inactive | Self::Static)
+    }
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginInfo {
+    pub id: String,
+    pub name: String,
+    pub version: String,
+    pub description: String,
+    pub authors: Vec<String>,
+    pub homepage: Option<String>,
+    pub change_notes: Option<String>,
+    pub source: PluginSource,
+    /// Package directory.
+    pub path: ide_core::IpcPath,
+    pub enabled: bool,
+    pub status: PluginStatus,
+    pub error: Option<String>,
+    pub has_code: bool,
+    /// Declared capabilities with risk and grant state.
+    pub capabilities: Vec<CapabilityInfo>,
+    /// What it contributes while live (point + label).
+    pub contributions: Vec<ContributionInfo>,
+    /// `activation` events of the manifest.
+    pub activation: Vec<String>,
+    /// Non-fatal problems (unsupported contribution points).
+    pub warnings: Vec<String>,
+    /// Statistics of this session.
+    pub stats: PluginStats,
+    /// The marketplace publisher whose signature the package carries (none: unsigned or untrusted).
+    pub publisher: Option<String>,
+    /// The version an update replaced, to roll back to.
+    pub previous_version: Option<String>,
+}
+
+#[derive(Clone, Copy, Debug, Default, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginStats {
+    pub activations: u32,
+    /// Last activation (instantiate + `activate`), ms.
+    pub activation_ms: f64,
+    pub calls: u32,
+    pub errors: u32,
+    /// Slowest call, ms.
+    pub max_call_ms: f64,
+    /// 95th percentile of the recent calls, ms.
+    pub p95_call_ms: f64,
+    /// Edit-path calls whose result came too late and was dropped.
+    pub slow_calls: u32,
+    /// Traps (panics, budgets, permission violations); each drops the instance.
+    pub crashes: u32,
+    /// Instances reclaimed after being idle.
+    pub reclaims: u32,
+}
+
+/// Number of declarations of one extension point.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ContributionCount {
+    pub point: String,
+    pub count: u32,
+}
+
+/// A plugin package available for installation from a local catalog
+/// directory (the samples shipped with the IDE). Not installed by listing it.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct CatalogPlugin {
+    pub id: String,
+    pub name: String,
+    pub version: String,
+    pub description: String,
+    pub authors: Vec<String>,
+    pub homepage: Option<String>,
+    pub change_notes: Option<String>,
+    /// Package directory; install with `install_from_dir(path)`.
+    pub path: ide_core::IpcPath,
+    pub has_code: bool,
+    pub capabilities: Vec<CapabilityInfo>,
+    pub contributions: Vec<ContributionCount>,
+    /// Why the package cannot be installed as is (e.g. its WASM is not built).
+    pub problem: Option<String>,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ActiveTheme {
+    pub plugin_id: String,
+    pub theme: ThemeDef,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginsSnapshot {
+    pub plugins: Vec<PluginInfo>,
+    pub active_theme: Option<ActiveTheme>,
+    /// UI contributions of live plugins, projected by the client.
+    pub ui: Vec<UiContribution>,
+}
+
+/// Backend → UI notifications (Tauri event `ide://plugin`).
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(tag = "type", rename_all = "camelCase")]
+pub enum PluginEvent {
+    /// Plugins, their status or their contributions changed: re-fetch `plugin_list`.
+    CommandsChanged,
+    #[serde(rename_all = "camelCase")]
+    Notification { plugin_id: String, level: NotificationLevel, title: String, body: String },
+    /// A plugin's status bar item was set (`item`) or removed.
+    #[serde(rename_all = "camelCase")]
+    StatusItemChanged { plugin_id: String, id: String, item: Option<StatusItem> },
+    /// A plugin began a task: show it with the background tasks.
+    #[serde(rename_all = "camelCase")]
+    TaskStarted { plugin_id: String, task_id: String, title: String, cancellable: bool },
+    #[serde(rename_all = "camelCase")]
+    TaskProgress { plugin_id: String, task_id: String, done: u32, total: Option<u32>, message: Option<String> },
+    #[serde(rename_all = "camelCase")]
+    TaskEnded { plugin_id: String, task_id: String },
+    /// The kinds of workbench events plugins want changed: re-fetch
+    /// `plugin_event_kinds` (the UI reports only those).
+    SubscriptionsChanged,
+    #[serde(rename_all = "camelCase")]
+    ThemeChanged { theme: Option<ActiveTheme> },
+    /// A plugin needs capabilities the user has not granted yet (first use
+    /// after migrating from 0.1): show its consent dialog.
+    #[serde(rename_all = "camelCase")]
+    ConsentRequested { plugin_id: String, capabilities: Vec<CapabilityInfo> },
+    /// A view (or the custom editors) of a plugin must be rendered again.
+    #[serde(rename_all = "camelCase")]
+    ViewChanged { plugin_id: String, view: String },
+    /// For the script of a view's `html` body.
+    #[serde(rename_all = "camelCase")]
+    ViewMessage { plugin_id: String, view: String, message: String },
+    /// Open a terminal running `program` (already approved and verified).
+    #[serde(rename_all = "camelCase")]
+    OpenTerminal {
+        plugin_id: String,
+        title: String,
+        program: ide_core::IpcPath,
+        args: Vec<String>,
+        cwd: ide_core::IpcPath,
+    },
+    /// Plugin languages, or the servers they may start, changed: re-fetch
+    /// `languages` (the host re-detects open documents: [`crate::Host::plugin_languages_changed`]).
+    LanguagesChanged,
+}
+
+/// Delivers events to the UI. `client` is the window that invoked the plugin
+/// (`None` = broadcast, e.g. during activation).
+pub trait PluginEventSink: Send + Sync {
+    fn emit(&self, client: Option<&str>, event: PluginEvent);
+}
+
+impl<F: Fn(Option<&str>, PluginEvent) + Send + Sync> PluginEventSink for F {
+    fn emit(&self, client: Option<&str>, event: PluginEvent) {
+        self(client, event)
+    }
+}
+
+/// The focused editor when a plugin command is invoked.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginEditor {
+    pub path: String,
+    pub language: String,
+    pub selections: Vec<ide_core::Range>,
+}
+
+impl PluginEditor {
+    pub fn context(self) -> ide_plugin::EditorContext {
+        ide_plugin::EditorContext { path: self.path.into(), language: self.language, selections: self.selections }
+    }
+}
+
+/// A plugin's status bar item.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginStatusItem {
+    pub plugin_id: String,
+    pub id: String,
+    pub item: StatusItem,
+}
+
+/// A gutter marker from a plugin's `line-markers` provider.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct LineMarkerInfo {
+    pub plugin_id: String,
+    /// 0-based.
+    pub line: u32,
+    /// `navigate` (default), `implemented`, `implementing`, `run`.
+    pub icon: Option<String>,
+    pub tooltip: String,
+    /// Opened on click.
+    pub target: Option<ide_core::Location>,
+}

crates/ide-host/src/plugins/ui_points.rs

@@ -0,0 +1,544 @@
+//! Declarative UI contributions: menus, key
+//! bindings, status bar items and settings (L0, shown before any code runs),
+//! and the views and custom editors whose content plugin code renders (L2).
+//! Everything is validated here; the client only projects the JSON.
+//!
+//! ```toml
+//! [[contributes.menus]]
+//! menu = "editor.context"          # projectView.context, editorTab.context, tools
+//! command = "check"
+//! when = "editorLang == java"
+//!
+//! [[contributes.keymaps]]
+//! command = "check"
+//! key = "Ctrl+Alt+C"               # `mac` for a different binding on macOS (`Meta+Alt+C`)
+//!
+//! [[contributes.statusBar]]
+//! id = "branch"
+//! text = "…"                       # code replaces it with `set-status-item("branch", …)`
+//! command = "show"
+//!
+//! [contributes.settings]
+//! schema = "settings.schema.json"  # {"properties": {"key": {"type": "boolean", "default": true, …}}}
+//!
+//! [[contributes.views]]
+//! id = "jobs"
+//! title = "Jobs"
+//! icon = "server"
+//! location = "right"               # left, right, bottom
+//!
+//! [[contributes.customEditors]]
+//! id = "table"
+//! title = "Table"
+//! patterns = ["*.csv", "*.tsv"]
+//! priority = "default"             # or "option": only through Open With
+//! layout = "tab"                   # or "split" / "preview": beside the text editor
+//! web = "web/index.html"           # a web page from the package instead of rendered content
+//!
+//! [[contributes.fileIcons]]
+//! id = "drawing"
+//! patterns = ["*.excalidraw"]
+//! icon = "icons/drawing.svg"
+//! iconDark = "icons/drawing_dark.svg"
+//!
+//! [[contributes.fileTemplates]]
+//! id = "drawing"
+//! name = "Excalidraw Drawing"
+//! extension = "excalidraw"
+//! path = "templates/drawing.excalidraw"
+//! ```
+
+use ide_extension::{Package, UiDecl, decode, validate_item_id, validate_when};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use std::collections::BTreeSet;
+use std::path::PathBuf;
+
+pub const MENUS: &str = "menus";
+pub const KEYMAPS: &str = "keymaps";
+pub const STATUS_BAR: &str = "statusBar";
+pub const SETTINGS: &str = "settings";
+pub const VIEWS: &str = "views";
+pub const CUSTOM_EDITORS: &str = "customEditors";
+pub const FILE_ICONS: &str = "fileIcons";
+pub const FILE_TEMPLATES: &str = "fileTemplates";
+
+const MENU_IDS: [&str; 4] = ["editor.context", "projectView.context", "editorTab.context", "tools"];
+const MAX_TITLE: usize = 256;
+const MAX_SETTINGS: usize = 200;
+const MAX_PATTERNS: usize = 16;
+
+/// Command ids the package declares.
+fn commands(pkg: &Package) -> BTreeSet<String> {
+    pkg.manifest
+        .declarations(super::COMMANDS)
+        .iter()
+        .filter_map(|d| d.get("id").and_then(|v| v.as_str()).map(str::to_owned))
+        .collect()
+}
+
+fn declared_command(pkg: &Package, point: &str, command: &str) -> Result<(), String> {
+    if commands(pkg).contains(command) {
+        Ok(())
+    } else {
+        Err(format!("contributes.{point}: command {command:?} is not declared under [[contributes.commands]]"))
+    }
+}
+
+fn title(point: &str, t: &str) -> Result<(), String> {
+    if t.trim().is_empty() || t.len() > MAX_TITLE {
+        return Err(format!("contributes.{point}: titles are 1–{MAX_TITLE} bytes"));
+    }
+    Ok(())
+}
+
+fn json<T: Serialize>(v: &T) -> Result<Value, String> {
+    serde_json::to_value(v).map_err(|e| e.to_string())
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct MenuDecl {
+    menu: String,
+    command: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    when: Option<String>,
+}
+
+pub(super) fn menu(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: MenuDecl = decode(MENUS, decl)?;
+    if !MENU_IDS.contains(&d.menu.as_str()) {
+        return Err(format!("contributes.menus: unknown menu {:?} (one of {})", d.menu, MENU_IDS.join(", ")));
+    }
+    declared_command(pkg, MENUS, &d.command)?;
+    if let Some(w) = &d.when {
+        validate_when(w).map_err(|e| format!("contributes.menus: {e}"))?;
+    }
+    Ok(UiDecl::new(format!("{}/{}", d.menu, d.command), d.command.clone(), json(&d)?))
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct KeymapDecl {
+    command: String,
+    key: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    mac: Option<String>,
+}
+
+const MODIFIERS: [&str; 4] = ["Meta", "Ctrl", "Alt", "Shift"];
+const NAMED_KEYS: [&str; 22] = [
+    "Enter",
+    "Escape",
+    "Tab",
+    "Space",
+    "Backspace",
+    "Delete",
+    "Insert",
+    "Home",
+    "End",
+    "PageUp",
+    "PageDown",
+    "Up",
+    "Down",
+    "Left",
+    "Right",
+    "Minus",
+    "Equal",
+    "Comma",
+    "Period",
+    "Slash",
+    "Semicolon",
+    "Quote",
+];
+
+/// `Ctrl+Alt+C`, `Meta+K Meta+C` (a chord): at least one modifier per
+/// stroke but for function keys, so plugins can't take plain typing.
+pub fn validate_binding(binding: &str) -> Result<(), String> {
+    let strokes: Vec<&str> = binding.split(' ').collect();
+    if strokes.is_empty() || strokes.len() > 2 {
+        return Err(format!("{binding:?}: one stroke, or two for a chord"));
+    }
+    for stroke in strokes {
+        let parts: Vec<&str> = stroke.split('+').collect();
+        let (key, mods) = parts.split_last().ok_or_else(|| format!("{binding:?}: empty stroke"))?;
+        let mut seen = BTreeSet::new();
+        for m in mods {
+            if !MODIFIERS.contains(m) || !seen.insert(*m) {
+                return Err(format!("{binding:?}: unknown or repeated modifier {m:?}"));
+            }
+        }
+        let function = key.strip_prefix('F').and_then(|n| n.parse::<u8>().ok()).is_some_and(|n| (1..=24).contains(&n));
+        let plain = key.len() == 1 && key.chars().all(|c| c.is_ascii_uppercase() || c.is_ascii_digit());
+        if !(function || plain || NAMED_KEYS.contains(key)) {
+            return Err(format!("{binding:?}: unknown key {key:?}"));
+        }
+        if !function && seen.iter().all(|m| *m == "Shift") {
+            return Err(format!("{binding:?}: needs Ctrl, Alt or Meta (plain keys are for typing)"));
+        }
+    }
+    Ok(())
+}
+
+pub(super) fn keymap(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: KeymapDecl = decode(KEYMAPS, decl)?;
+    declared_command(pkg, KEYMAPS, &d.command)?;
+    validate_binding(&d.key).map_err(|e| format!("contributes.keymaps: {e}"))?;
+    if let Some(m) = &d.mac {
+        validate_binding(m).map_err(|e| format!("contributes.keymaps: {e}"))?;
+    }
+    Ok(UiDecl::new(d.command.clone(), d.key.clone(), json(&d)?))
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct StatusDecl {
+    id: String,
+    text: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    tooltip: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    command: Option<String>,
+    #[serde(default = "right")]
+    align: String,
+    #[serde(default)]
+    priority: u32,
+}
+
+fn right() -> String {
+    "right".into()
+}
+
+pub(super) fn status_item(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: StatusDecl = decode(STATUS_BAR, decl)?;
+    validate_item_id(&d.id, "status bar item id")?;
+    if d.text.is_empty() || d.text.len() > 128 || d.tooltip.as_ref().is_some_and(|t| t.len() > 1024) {
+        return Err(format!("status bar item {:?}: `text` 1–128 bytes, `tooltip` up to 1 KiB", d.id));
+    }
+    if d.align != "left" && d.align != "right" {
+        return Err(format!("status bar item {:?}: `align` is left or right", d.id));
+    }
+    if d.priority > 1000 {
+        return Err(format!("status bar item {:?}: `priority` is 0–1000", d.id));
+    }
+    if let Some(c) = &d.command {
+        declared_command(pkg, STATUS_BAR, c)?;
+    }
+    Ok(UiDecl::new(d.id.clone(), d.text.clone(), json(&d)?))
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct SettingsDecl {
+    #[serde(default)]
+    title: Option<String>,
+    schema: PathBuf,
+}
+
+#[derive(Debug, Deserialize)]
+struct SchemaFile {
+    properties: serde_json::Map<String, Value>,
+}
+
+/// One setting of a plugin.
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct SettingSchema {
+    pub key: String,
+    /// `boolean`, `string`, `number` or `integer`.
+    #[serde(rename = "type")]
+    pub kind: String,
+    pub title: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    pub default: Value,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub options: Option<Vec<String>>,
+    #[serde(default)]
+    pub multiline: bool,
+}
+
+impl SettingSchema {
+    /// Whether `v` is a valid value of this setting.
+    pub fn accepts(&self, v: &Value) -> bool {
+        match self.kind.as_str() {
+            "boolean" => v.is_boolean(),
+            "integer" => v.is_i64() || v.is_u64(),
+            "number" => v.is_number(),
+            _ => v
+                .as_str()
+                .is_some_and(|s| s.len() <= 64 << 10 && self.options.as_ref().is_none_or(|o| o.iter().any(|x| x == s))),
+        }
+    }
+}
+
+fn setting(key: &str, raw: &Value) -> Result<SettingSchema, String> {
+    if key.is_empty() || key.len() > 64 || !key.chars().all(|c| c.is_ascii_alphanumeric() || "-_.".contains(c)) {
+        return Err(format!("setting {key:?}: keys are 1–64 of [A-Za-z0-9._-]"));
+    }
+    let o = raw.as_object().ok_or_else(|| format!("setting {key:?}: expected an object"))?;
+    let kind = o.get("type").and_then(Value::as_str).unwrap_or("");
+    let default = match kind {
+        "boolean" => o.get("default").cloned().unwrap_or(Value::Bool(false)),
+        "string" => o.get("default").cloned().unwrap_or(Value::String(String::new())),
+        "number" | "integer" => o.get("default").cloned().unwrap_or(Value::from(0)),
+        _ => return Err(format!("setting {key:?}: `type` is boolean, string, number or integer")),
+    };
+    let options = match o.get("enum") {
+        None => None,
+        Some(Value::Array(a)) if kind == "string" && !a.is_empty() && a.len() <= 100 => Some(
+            a.iter()
+                .map(|v| v.as_str().map(str::to_owned).ok_or_else(|| format!("setting {key:?}: `enum` lists strings")))
+                .collect::<Result<Vec<_>, _>>()?,
+        ),
+        Some(_) => return Err(format!("setting {key:?}: `enum` is 1–100 strings of a string setting")),
+    };
+    let text = |name: &str, max: usize| -> Result<Option<String>, String> {
+        match o.get(name) {
+            None => Ok(None),
+            Some(Value::String(s)) if s.len() <= max => Ok(Some(s.clone())),
+            Some(_) => Err(format!("setting {key:?}: `{name}` is a string up to {max} bytes")),
+        }
+    };
+    let s = SettingSchema {
+        key: key.to_owned(),
+        kind: kind.to_owned(),
+        title: text("title", MAX_TITLE)?.unwrap_or_else(|| key.to_owned()),
+        description: text("description", 4096)?,
+        default,
+        options,
+        multiline: o.get("multiline").and_then(Value::as_bool).unwrap_or(false),
+    };
+    if !s.accepts(&s.default) {
+        return Err(format!("setting {key:?}: the default does not match its type"));
+    }
+    Ok(s)
+}
+
+/// The validated settings of a `[contributes.settings]` schema file.
+pub fn parse_settings_schema(text: &str) -> Result<Vec<SettingSchema>, String> {
+    let file: SchemaFile = serde_json::from_str(text).map_err(|e| e.to_string())?;
+    if file.properties.len() > MAX_SETTINGS {
+        return Err(format!("more than {MAX_SETTINGS} settings"));
+    }
+    file.properties.iter().map(|(k, v)| setting(k, v)).collect()
+}
+
+pub(super) fn settings(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: SettingsDecl = decode(SETTINGS, decl)?;
+    let text = pkg.read_text(&d.schema)?;
+    let properties = parse_settings_schema(&text).map_err(|e| format!("{}: {e}", d.schema.display()))?;
+    let title = d.title.unwrap_or_else(|| pkg.manifest.name.clone());
+    title_ok(&title)?;
+    let mut decl =
+        UiDecl::new("settings", title.clone(), serde_json::json!({ "title": title, "properties": properties }));
+    decl.files.push(d.schema);
+    Ok(decl)
+}
+
+fn title_ok(t: &str) -> Result<(), String> {
+    title(SETTINGS, t)
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct ViewDecl {
+    id: String,
+    title: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    icon: Option<String>,
+    #[serde(default = "right")]
+    location: String,
+    /// A web page of the package (`web/index.html`) instead of content the code renders.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    web: Option<String>,
+}
+
+/// The files of a `web` entry, or a check that the code renders the view.
+fn web_or_code(pkg: &Package, web: Option<&str>, what: &str) -> Result<Vec<PathBuf>, String> {
+    match web {
+        Some(entry) => super::web::web_files(pkg, entry, what),
+        None if pkg.manifest.wasm.is_none() => {
+            Err(format!("{what}: give a web page (`web`) or the code that renders it (`wasm`)"))
+        }
+        None => Ok(Vec::new()),
+    }
+}
+
+pub(super) fn view(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: ViewDecl = decode(VIEWS, decl)?;
+    validate_item_id(&d.id, "view id")?;
+    title(VIEWS, &d.title)?;
+    let files = web_or_code(pkg, d.web.as_deref(), &format!("view {:?}", d.id))?;
+    if !["left", "right", "bottom"].contains(&d.location.as_str()) {
+        return Err(format!("view {:?}: `location` is left, right or bottom", d.id));
+    }
+    if d.icon.as_ref().is_some_and(|i| i.len() > 64) {
+        return Err(format!("view {:?}: icon names are up to 64 bytes", d.id));
+    }
+    let mut out = UiDecl::new(d.id.clone(), d.title.clone(), json(&d)?);
+    out.files = files;
+    Ok(out)
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct CustomEditorDecl {
+    id: String,
+    title: String,
+    patterns: Vec<String>,
+    #[serde(default = "default_priority")]
+    priority: String,
+    /// `tab`: the file opens in this editor's own tab. `split` / `preview`:
+    /// the file opens in the text editor with this editor beside it (Editor /
+    /// Editor and Preview / Preview); the value is the layout files start in.
+    #[serde(default = "default_layout")]
+    layout: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    web: Option<String>,
+}
+
+fn default_priority() -> String {
+    "default".into()
+}
+
+fn default_layout() -> String {
+    "tab".into()
+}
+
+/// File name globs (`*.csv`, `{a,b}.json`): no directories.
+fn file_patterns(patterns: &[String], what: &str) -> Result<(), String> {
+    if patterns.is_empty() || patterns.len() > MAX_PATTERNS {
+        return Err(format!("{what}: 1–{MAX_PATTERNS} file name `patterns`"));
+    }
+    for p in patterns {
+        if p.is_empty() || p.len() > 128 || p.contains(['/', '\\']) || globset::Glob::new(p).is_err() {
+            return Err(format!("{what}: invalid file name pattern {p:?}"));
+        }
+    }
+    Ok(())
+}
+
+pub(super) fn custom_editor(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: CustomEditorDecl = decode(CUSTOM_EDITORS, decl)?;
+    validate_item_id(&d.id, "custom editor id")?;
+    title(CUSTOM_EDITORS, &d.title)?;
+    let what = format!("custom editor {:?}", d.id);
+    let files = web_or_code(pkg, d.web.as_deref(), &what)?;
+    file_patterns(&d.patterns, &what)?;
+    if d.priority != "default" && d.priority != "option" {
+        return Err(format!("{what}: `priority` is default or option"));
+    }
+    if !["tab", "split", "preview"].contains(&d.layout.as_str()) {
+        return Err(format!("{what}: `layout` is tab, split or preview"));
+    }
+    let mut out = UiDecl::new(d.id.clone(), d.title.clone(), json(&d)?);
+    out.files = files;
+    Ok(out)
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+struct FileIconDecl {
+    id: String,
+    patterns: Vec<String>,
+    icon: PathBuf,
+    #[serde(default)]
+    icon_dark: Option<PathBuf>,
+}
+
+/// Asset id of a file icon's SVG (`dark`: its dark-theme variant).
+pub fn file_icon_asset(id: &str, dark: bool) -> String {
+    format!("fileIcon/{id}/{}", if dark { "dark" } else { "light" })
+}
+
+/// `[[contributes.fileIcons]]`: an icon for the files matching `patterns`,
+/// whatever icon theme is in use (the user's own file type icons still win).
+pub(super) fn file_icon(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: FileIconDecl = decode(FILE_ICONS, decl)?;
+    validate_item_id(&d.id, "file icon id")?;
+    let what = format!("file icon {:?}", d.id);
+    file_patterns(&d.patterns, &what)?;
+    let mut files = Vec::new();
+    let mut assets = Vec::new();
+    for (path, dark) in [(Some(&d.icon), false), (d.icon_dark.as_ref(), true)] {
+        let Some(path) = path else { continue };
+        let svg = super::icons::read_icon(pkg, path)?;
+        assets.push((file_icon_asset(&d.id, dark), svg));
+        files.push(path.clone());
+    }
+    let json = serde_json::json!({ "id": d.id, "patterns": d.patterns, "dark": d.icon_dark.is_some() });
+    let mut out = UiDecl::new(d.id.clone(), d.patterns.join(", "), json);
+    out.files = files;
+    out.assets = assets;
+    Ok(out)
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+struct FileTemplateDecl {
+    id: String,
+    name: String,
+    /// Without the dot.
+    extension: String,
+    /// The new file's content (`$NAME$`, `$END$` and the other template variables work).
+    path: PathBuf,
+}
+
+const MAX_TEMPLATE: usize = 256 << 10;
+
+/// `[[contributes.fileTemplates]]`: an entry of the New menu.
+pub(super) fn file_template(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: FileTemplateDecl = decode(FILE_TEMPLATES, decl)?;
+    validate_item_id(&d.id, "file template id")?;
+    title(FILE_TEMPLATES, &d.name)?;
+    let what = format!("file template {:?}", d.id);
+    let ext = d.extension.trim_start_matches('.');
+    if ext.is_empty()
+        || ext.len() > 32
+        || !ext.chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '.' | '-' | '_'))
+    {
+        return Err(format!("{what}: `extension` is a file extension like \"md\" ({:?})", d.extension));
+    }
+    let body = pkg.read_text(&d.path)?;
+    if body.len() > MAX_TEMPLATE {
+        return Err(format!("{what}: {} is larger than {} KiB", d.path.display(), MAX_TEMPLATE >> 10));
+    }
+    let json = serde_json::json!({ "id": d.id, "name": d.name, "extension": ext, "body": body });
+    let mut out = UiDecl::new(d.id.clone(), d.name.clone(), json);
+    out.files = vec![d.path.clone()];
+    Ok(out)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn bindings_need_a_modifier() {
+        for ok in ["Ctrl+Alt+C", "Meta+Shift+K", "F5", "Shift+F6", "Meta+K Meta+C", "Alt+Enter"] {
+            assert!(validate_binding(ok).is_ok(), "{ok}");
+        }
+        for bad in ["C", "Shift+C", "Hyper+C", "Ctrl+Ctrl+C", "Ctrl+é", "Ctrl+A B C", ""] {
+            assert!(validate_binding(bad).is_err(), "{bad}");
+        }
+    }
+
+    #[test]
+    fn settings_schemas_are_typed() {
+        let s = parse_settings_schema(
+            r#"{"properties": {
+                "context": {"type": "string", "title": "Context", "default": ""},
+                "watch": {"type": "boolean", "default": true},
+                "mode": {"type": "string", "enum": ["a", "b"], "default": "b"},
+                "limit": {"type": "integer", "default": 100}
+            }}"#,
+        )
+        .unwrap();
+        assert_eq!(s.len(), 4);
+        assert!(s.iter().find(|x| x.key == "mode").unwrap().accepts(&Value::from("a")));
+        assert!(!s.iter().find(|x| x.key == "mode").unwrap().accepts(&Value::from("c")));
+        assert!(parse_settings_schema(r#"{"properties": {"x": {"type": "string", "default": 3}}}"#).is_err());
+        assert!(parse_settings_schema(r#"{"properties": {"x": {"type": "object"}}}"#).is_err());
+    }
+}

crates/ide-host/src/plugins/views.rs

@@ -0,0 +1,92 @@
+//! Declarative views and custom editors as the
+//! window commands `plugin_view_render` / `plugin_view_event` serve them —
+//! the desktop for local projects, `openidea-server` for remote ones.
+
+use super::{PluginEditor, PluginHost};
+use ide_core::{DocId, IdeError, IdeResult};
+use ide_plugin::{EditorContext, Invocation, View, ViewEvent, Viewport};
+use std::sync::Arc;
+
+/// The window's project, plus the editor the call is about: the document a
+/// custom editor shows, else (a tool window) the window's active editor, as
+/// a command gets it, so a view's buttons can act on what the user is editing.
+pub fn view_invocation(
+    host: &crate::Host,
+    window: &str,
+    doc: Option<DocId>,
+    editor: Option<PluginEditor>,
+) -> IdeResult<Invocation> {
+    let project = host.project(window).ok();
+    let editor = match doc {
+        None => editor.map(PluginEditor::context),
+        Some(doc) => {
+            let project = project.as_ref().ok_or_else(|| IdeError::not_found("no project is open in this window"))?;
+            let info = project.documents.snapshot(doc)?;
+            Some(EditorContext { path: info.path.0, language: info.language.0, selections: Vec::new() })
+        }
+    };
+    Ok(Invocation { client: Some(window.to_owned()), workspace_root: project.as_ref().map(|p| p.root.clone()), editor })
+}
+
+async fn blocking<T: Send + 'static>(f: impl FnOnce() -> IdeResult<T> + Send + 'static) -> IdeResult<T> {
+    tokio::task::spawn_blocking(f).await.map_err(|e| IdeError::internal(e.to_string()))?
+}
+
+#[allow(clippy::too_many_arguments)]
+pub async fn render(
+    host: &crate::Host,
+    plugins: Arc<PluginHost>,
+    window: &str,
+    plugin_id: String,
+    view: String,
+    viewport: Option<Viewport>,
+    doc: Option<DocId>,
+    editor: Option<PluginEditor>,
+) -> IdeResult<View> {
+    let invocation = view_invocation(host, window, doc, editor)?;
+    blocking(move || plugins.render_view(&plugin_id, &view, viewport, invocation)).await
+}
+
+#[allow(clippy::too_many_arguments)]
+pub async fn event(
+    host: &crate::Host,
+    plugins: Arc<PluginHost>,
+    window: &str,
+    plugin_id: String,
+    view: String,
+    event: ViewEvent,
+    doc: Option<DocId>,
+    editor: Option<PluginEditor>,
+) -> IdeResult<()> {
+    let invocation = view_invocation(host, window, doc, editor)?;
+    blocking(move || plugins.view_event(&plugin_id, &view, event, invocation)).await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{Host, HostConfig};
+
+    #[tokio::test]
+    async fn a_tool_window_call_carries_the_active_editor() {
+        let tmp = tempfile::tempdir().unwrap();
+        let host = Host::new(HostConfig {
+            config_dir: tmp.path().join("config"),
+            data_dir: tmp.path().join("data"),
+            local_data_dir: tmp.path().join("data"),
+            languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
+            syntax: Arc::default(),
+            sink_for: Box::new(|_| Arc::new(ide_core::NullSink)),
+            owner: |w| w,
+            runtime: tokio::runtime::Handle::current(),
+            project_environment: false,
+        });
+        let range = ide_core::Range::new(ide_core::Pos::new(1, 0), ide_core::Pos::new(1, 4));
+        let active = PluginEditor { path: "/p/a.rs".into(), language: "rust".into(), selections: vec![range] };
+        let inv = view_invocation(&host, "main", None, Some(active)).unwrap();
+        let editor = inv.editor.expect("the active editor");
+        assert_eq!((editor.path.to_string_lossy().as_ref(), editor.selections.as_slice()), ("/p/a.rs", &[range][..]));
+        assert_eq!(inv.client.as_deref(), Some("main"));
+        assert!(view_invocation(&host, "main", None, None).unwrap().editor.is_none());
+    }
+}

crates/ide-host/src/plugins/web.rs

@@ -0,0 +1,245 @@
+//! Web views: a view or custom editor whose UI is a web page shipped in the
+//! package (`web = "web/index.html"`) instead of content the plugin's code
+//! renders.
+//!
+//! The entry's directory is the page's root. Every file under it is part of
+//! the declaration: it is checked when the package is prepared (count, size,
+//! no links leaving the package), copied on install and covered by the
+//! package digest and signature. The client loads the page in a sandboxed
+//! frame (an opaque origin with no network and no IDE API) and fetches its
+//! files through [`PluginHost::web_file`] (the desktop's `openidea-plugin`
+//! URL scheme); the page talks to the IDE only through the frame bridge.
+
+use super::PluginHost;
+use ide_core::{IdeError, IdeResult};
+use ide_extension::{Package, check_relative};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+use std::path::{Component, Path, PathBuf};
+
+/// Most files under one web root.
+const MAX_FILES: usize = 4096;
+/// Most bytes under one web root.
+const MAX_BYTES: u64 = 256 << 20;
+/// Deepest directory nesting under a web root.
+const MAX_DEPTH: usize = 16;
+
+/// Checks a declaration's `web` entry: an `.html` file inside a directory of
+/// the package (the directory is what the page can load, so it can't be the
+/// package root), and everything under that directory. Returns those files,
+/// package-relative.
+pub(super) fn web_files(pkg: &Package, entry: &str, what: &str) -> Result<Vec<PathBuf>, String> {
+    let path = Path::new(entry);
+    check_relative(path, "web")?;
+    if entry.contains('\\') || !entry.to_ascii_lowercase().ends_with(".html") {
+        return Err(format!("{what}: `web` names an .html file, `/`-separated ({entry:?})"));
+    }
+    let dir = path.parent().filter(|d| !d.as_os_str().is_empty()).ok_or_else(|| {
+        format!("{what}: put the page in a directory of its own (`web/index.html`): the directory is what it can load")
+    })?;
+    let real_entry = pkg.resolve(path)?;
+    if !real_entry.is_file() {
+        return Err(format!("{what}: {entry} is not a file"));
+    }
+    let root = pkg.resolve(dir)?;
+    let mut files = Vec::new();
+    let mut total = 0u64;
+    let mut stack = vec![(root.clone(), dir.to_path_buf(), 0usize)];
+    while let Some((real, rel, depth)) = stack.pop() {
+        let mut entries: Vec<_> =
+            std::fs::read_dir(&real).map_err(|e| format!("{}: {e}", rel.display()))?.filter_map(Result::ok).collect();
+        entries.sort_by_key(|e| e.file_name());
+        for e in entries {
+            let name = e.file_name();
+            let rel = rel.join(&name);
+            // Links could point anywhere: only what is really in the package counts.
+            let ty = e.file_type().map_err(|err| format!("{}: {err}", rel.display()))?;
+            if ty.is_symlink() {
+                return Err(format!("{what}: {} is a link; web files must be real files", rel.display()));
+            }
+            if ty.is_dir() {
+                if depth + 1 > MAX_DEPTH {
+                    return Err(format!("{what}: {} is nested deeper than {MAX_DEPTH} directories", rel.display()));
+                }
+                stack.push((e.path(), rel, depth + 1));
+                continue;
+            }
+            if name.to_string_lossy() == ".DS_Store" {
+                continue;
+            }
+            let len = e.metadata().map_err(|err| format!("{}: {err}", rel.display()))?.len();
+            if len > ide_extension::MAX_PACKAGE_FILE {
+                return Err(format!(
+                    "{what}: {} is larger than {} MiB",
+                    rel.display(),
+                    ide_extension::MAX_PACKAGE_FILE >> 20
+                ));
+            }
+            total += len;
+            files.push(rel);
+            if files.len() > MAX_FILES || total > MAX_BYTES {
+                return Err(format!(
+                    "{what}: {} holds more than {MAX_FILES} files or {} MiB",
+                    dir.display(),
+                    MAX_BYTES >> 20
+                ));
+            }
+        }
+    }
+    files.sort();
+    Ok(files)
+}
+
+/// The page of a web view, for the client to load in its frame.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct WebPage {
+    /// `<plugin id>/<revision>/<entry>` under the `openidea-plugin` scheme. The
+    /// revision changes with the installed package, so a cached file is never
+    /// stale; relative URLs in the page resolve to the package's files.
+    pub path: String,
+}
+
+/// A file of a web view.
+pub struct WebFile {
+    pub bytes: Vec<u8>,
+    pub mime: &'static str,
+}
+
+impl PluginHost {
+    /// The web roots `plugin` declares (entry directories, package-relative, `/`-terminated).
+    fn web_dirs(&self, plugin: &str) -> Vec<String> {
+        [super::ui_points::VIEWS, super::ui_points::CUSTOM_EDITORS]
+            .iter()
+            .flat_map(|point| self.ui.items(point, Some(plugin)))
+            .filter_map(|item| item.decl.get("web").and_then(|w| w.as_str()).map(str::to_owned))
+            .filter_map(|entry| entry.rsplit_once('/').map(|(dir, _)| format!("{dir}/")))
+            .collect()
+    }
+
+    /// Changes whenever the installed package does (cache key of its web files).
+    fn web_revision(&self, plugin: &super::LoadedPlugin) -> String {
+        let digest = plugin.pkg.digest.as_deref().unwrap_or_default();
+        let short: String = digest.chars().filter(char::is_ascii_alphanumeric).take(16).collect();
+        if short.is_empty() { format!("v{}", plugin.pkg.manifest.version) } else { short }
+    }
+
+    /// The page of `plugin`'s view or custom editor `view`.
+    pub fn web_page(&self, plugin_id: &str, view: &str) -> IdeResult<WebPage> {
+        let plugin = self.get(plugin_id)?;
+        if !plugin.status().is_live() {
+            return Err(IdeError::unavailable(format!("plugin {plugin_id:?} is not enabled")));
+        }
+        let entry = [super::ui_points::VIEWS, super::ui_points::CUSTOM_EDITORS]
+            .iter()
+            .flat_map(|point| self.ui.items(point, Some(plugin_id)))
+            .find(|item| item.key == view)
+            .and_then(|item| item.decl.get("web").and_then(|w| w.as_str()).map(str::to_owned))
+            .ok_or_else(|| IdeError::not_found(format!("plugin {plugin_id:?} has no web view {view:?}")))?;
+        Ok(WebPage { path: format!("{plugin_id}/{}/{entry}", self.web_revision(&plugin)) })
+    }
+
+    /// A file of one of `plugin`'s web views: `path` is `<revision>/<package path>`
+    /// as [`WebPage::path`] makes them. Only files under a declared web root
+    /// of a live plugin are served; the revision must be the installed one.
+    pub fn web_file(&self, plugin_id: &str, path: &str) -> IdeResult<WebFile> {
+        let plugin = self.get(plugin_id)?;
+        if !plugin.status().is_live() {
+            return Err(IdeError::unavailable(format!("plugin {plugin_id:?} is not enabled")));
+        }
+        let (revision, rel) = path.split_once('/').ok_or_else(|| IdeError::not_found(path.to_owned()))?;
+        if revision != self.web_revision(&plugin) {
+            return Err(IdeError::not_found(format!("{path}: not the installed version")));
+        }
+        let rel_path = Path::new(rel);
+        if !rel_path.components().all(|c| matches!(c, Component::Normal(_))) {
+            return Err(IdeError::invalid(format!("{rel}: not a plain relative path")));
+        }
+        if !self.web_dirs(plugin_id).iter().any(|dir| rel.starts_with(dir.as_str())) {
+            return Err(IdeError::not_found(format!("{rel}: not part of a web view")));
+        }
+        let bytes = plugin.pkg.read_bytes(rel_path).map_err(IdeError::not_found)?;
+        Ok(WebFile { bytes, mime: mime(rel) })
+    }
+}
+
+/// Content type by extension; unknown files are opaque bytes (never sniffed as script).
+pub fn mime(path: &str) -> &'static str {
+    let ext = path.rsplit_once('.').map(|(_, e)| e.to_ascii_lowercase()).unwrap_or_default();
+    match ext.as_str() {
+        "html" | "htm" => "text/html; charset=utf-8",
+        "js" | "mjs" | "cjs" => "text/javascript; charset=utf-8",
+        "css" => "text/css; charset=utf-8",
+        "json" | "map" => "application/json",
+        "wasm" => "application/wasm",
+        "svg" => "image/svg+xml",
+        "png" => "image/png",
+        "jpg" | "jpeg" => "image/jpeg",
+        "gif" => "image/gif",
+        "webp" => "image/webp",
+        "avif" => "image/avif",
+        "ico" => "image/x-icon",
+        "woff2" => "font/woff2",
+        "woff" => "font/woff",
+        "ttf" => "font/ttf",
+        "otf" => "font/otf",
+        "txt" | "md" => "text/plain; charset=utf-8",
+        "mp3" => "audio/mpeg",
+        "mp4" => "video/mp4",
+        "webm" => "video/webm",
+        _ => "application/octet-stream",
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ide_extension::Manifest;
+
+    fn pkg(dir: &Path) -> Package {
+        let src = "id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n";
+        Package::new(Manifest::parse(src).unwrap(), dir.to_path_buf())
+    }
+
+    #[test]
+    fn a_web_root_is_its_directory_and_nothing_else() {
+        let tmp = tempfile::tempdir().unwrap();
+        let d = tmp.path();
+        std::fs::create_dir_all(d.join("web/assets/fonts")).unwrap();
+        std::fs::write(d.join("web/index.html"), "<p>hi</p>").unwrap();
+        std::fs::write(d.join("web/assets/app.js"), "1").unwrap();
+        std::fs::write(d.join("web/assets/fonts/a.woff2"), "f").unwrap();
+        std::fs::write(d.join("web/.DS_Store"), "x").unwrap();
+        std::fs::write(d.join("secret.txt"), "no").unwrap();
+        let files = web_files(&pkg(d), "web/index.html", "v").unwrap();
+        let files: Vec<String> = files.iter().map(|f| f.to_string_lossy().replace('\\', "/")).collect();
+        assert_eq!(files, ["web/assets/app.js", "web/assets/fonts/a.woff2", "web/index.html"]);
+
+        std::fs::write(d.join("index.html"), "x").unwrap();
+        let err = |entry: &str| web_files(&pkg(d), entry, "v").err().unwrap_or_default();
+        assert!(err("index.html").contains("directory of its own"), "{}", err("index.html"));
+        assert!(err("web/app.js").contains(".html"));
+        assert!(err("../web/index.html").contains("relative"));
+        assert!(err("web/missing.html").contains("no such file"));
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn links_out_of_a_web_root_are_refused() {
+        let tmp = tempfile::tempdir().unwrap();
+        let d = tmp.path();
+        std::fs::create_dir_all(d.join("web")).unwrap();
+        std::fs::write(d.join("web/index.html"), "x").unwrap();
+        std::os::unix::fs::symlink("/etc/hosts", d.join("web/hosts")).unwrap();
+        assert!(web_files(&pkg(d), "web/index.html", "v").unwrap_err().contains("is a link"));
+    }
+
+    #[test]
+    fn content_types_never_make_unknown_files_scripts() {
+        assert_eq!(mime("a/b.JS"), "text/javascript; charset=utf-8");
+        assert_eq!(mime("x.woff2"), "font/woff2");
+        assert_eq!(mime("x.wasm"), "application/wasm");
+        assert_eq!(mime("x.bin"), "application/octet-stream");
+        assert_eq!(mime("noext"), "application/octet-stream");
+    }
+}

crates/ide-host/src/project.rs

@@ -91,7 +91,8 @@ impl Host {
         let settings = SettingsStore::load(&self.config_dir, Some(&root));
         let detected_roots = Arc::new(RwLock::new(ide_workspace::roots::detect(&root)));
         let excludes = exclude_globs(&root, &settings.effective(), &detected_roots.read());
-        let extra_roots = content_roots(&settings.effective(), &root);
+        let build_cache = self.local_data_dir.join("cache").join(project_key(&root)).join("build");
+        let extra_roots = content_roots(&settings.effective(), &root, &build_cache);
         mark("roots");
 
         // The project's own registry: File Types associations may be project-scoped.
@@ -129,6 +130,7 @@ impl Host {
             let root = root.clone();
             let data_dir = self.local_data_dir.clone();
             let config_dir = self.config_dir.clone();
+            let build_cache = self.local_data_dir.join("cache").join(&project_key).join("build");
             let sink = sink.clone();
             let formatter_problem = std::sync::Mutex::new(None);
             lsp.set_config_hook(Box::new(move |cfg, server_root| {
@@ -142,6 +144,15 @@ impl Host {
                 let root = member.as_ref().unwrap_or(&root);
                 ide_sdk::apply::server_launch_overrides(cfg, &effective);
                 ide_sdk::apply::configure_server(cfg, root, server_root, &effective);
+                if cfg.name == "jdtls" {
+                    // A workspace member keeps its build model under its own key (Build Project).
+                    let cache = match &member {
+                        Some(member) => build_cache.join(crate::project::project_key(member)),
+                        None => build_cache.clone(),
+                    };
+                    let profiles = ide_build::maven_profiles(&cache);
+                    ide_sdk::maven_profiles::configure_jdtls(cfg, root, &effective, &profiles, &cache);
+                }
                 ide_sdk::java::cap_java_home(cfg, &ide_sdk::java::installed_jdks());
                 if cfg.name == "jdtls" {
                     let problem = ide_lsp::jdtls::configure_formatter(
@@ -207,8 +218,10 @@ impl Host {
                     ide_sdk::jdtls::launch_directly(cfg);
                 }
                 ide_sdk::apply::server_protocol_overrides(cfg, &effective);
-                let excluded_poms = unlinked_maven_poms(root, &effective);
-                ide_sdk::apply::configure_maven_import(cfg, root, &excluded_poms);
+                if cfg.name == "jdtls" {
+                    let (excluded_poms, build_files) = jdtls_maven_import(root, &effective);
+                    ide_sdk::apply::configure_maven_import(cfg, root, &excluded_poms, build_files.as_deref());
+                }
             }));
         }
         {
@@ -255,7 +268,7 @@ impl Host {
 
         let kotlin_bridge = crate::kotlin_bridge::KotlinBridge::new(
             root.clone(),
-            self.local_data_dir.join("cache").join(&project_key).join("build"),
+            build_cache.clone(),
             &self.local_data_dir,
             settings.clone(),
             lsp.clone(),
@@ -282,6 +295,7 @@ impl Host {
             let runtime = self.runtime.clone();
             let lsp = lsp.clone();
             let trusted = trusted.clone();
+            let build_cache = build_cache.clone();
             Watcher::start(
                 &root.clone(),
                 excludes.clone(),
@@ -318,7 +332,7 @@ impl Host {
                             // Detected excluded folders (`target`, `build`) leave the index too.
                             let effective = settings.effective();
                             index.set_scope(
-                                index_roots(&root, content_roots(&effective, &root)),
+                                index_roots(&root, content_roots(&effective, &root, &build_cache)),
                                 exclude_globs(&root, &effective, &fresh),
                             );
                             *detected_roots.write() = fresh;
@@ -356,7 +370,7 @@ impl Host {
                         matches!(rest.as_slice(), [first, ..] if first == "worktrees" && rest.len() <= 2)
                     });
                     if git_dirs {
-                        scan_repositories(&root, &repos, &settings, &sink);
+                        scan_repositories(&root, &repos, &settings, &sink, &build_cache);
                     }
                     let vcs_moved = batch.vcs.iter().any(|p| vcs_path_changed(p));
                     if git_dirs || vcs_moved {
@@ -403,9 +417,10 @@ impl Host {
         mark("watcher");
         {
             let (root, repos, settings, sink) = (root.clone(), repos.clone(), settings.clone(), sink.clone());
+            let build_cache = build_cache.clone();
             std::thread::Builder::new()
                 .name("openidea-vcs-roots".into())
-                .spawn(move || scan_repositories(&root, &repos, &settings, &sink))?;
+                .spawn(move || scan_repositories(&root, &repos, &settings, &sink, &build_cache))?;
         }
         mark("git");
         tracing::info!("opened {} in window {window} in {} ms {laps:?}", root.display(), started.elapsed().as_millis());
@@ -484,12 +499,14 @@ impl Host {
             ide_agent::AgentPaths {
                 project_root: root.to_path_buf(),
                 store_dir: self.data_dir.join("agents").join(project_key),
-                // Outside the app data dir: its path has spaces on macOS, which trips up build scripts.
-                worktrees_dir: dirs::home_dir()
-                    .unwrap_or_else(|| self.data_dir.clone())
-                    .join(".openidea")
-                    .join("worktrees")
-                    .join(project_key),
+                worktrees_dir: agent_worktrees_dir(root, || {
+                    // Outside the app data dir: its path has spaces on macOS, which trips up build scripts.
+                    dirs::home_dir()
+                        .unwrap_or_else(|| self.data_dir.clone())
+                        .join(".openidea")
+                        .join("worktrees")
+                        .join(project_key)
+                }),
                 models_file: self.data_dir.join("agents").join("models.json"),
                 custom_agents_dir: Some(self.config_dir.join("agents")),
                 home_dir: dirs::home_dir(),
@@ -638,11 +655,17 @@ fn light_watcher(
 
 /// Looks for repositories nested below the project (and the one containing it);
 /// emits `VcsChanged` when the set of roots changed.
-fn scan_repositories(root: &Path, repos: &RwLock<Repos>, settings: &SettingsStore, sink: &SharedSink) {
+fn scan_repositories(
+    root: &Path,
+    repos: &RwLock<Repos>,
+    settings: &SettingsStore,
+    sink: &SharedSink,
+    build_cache: &Path,
+) {
     let ignored = settings.effective().ignored_names();
     let skip = |p: &Path| p.file_name().is_some_and(|n| ignored.is_ignored_name(&n.to_string_lossy()));
     let mut roots = vec![root.to_path_buf()];
-    roots.extend(content_roots(&settings.effective(), root));
+    roots.extend(content_roots(&settings.effective(), root, build_cache));
     match Repos::discover_roots(&roots, &skip) {
         Ok(found) => {
             if found.roots() != repos.read().roots() {
@@ -656,7 +679,7 @@ fn scan_repositories(root: &Path, repos: &RwLock<Repos>, settings: &SettingsStor
 
 impl Project {
     pub fn refresh_repositories(&self) {
-        scan_repositories(&self.root, &self.repos, &self.settings, &self.sink);
+        scan_repositories(&self.root, &self.repos, &self.settings, &self.sink, &self.build_cache_dir());
     }
 
     /// The project's git repositories.
@@ -762,7 +785,8 @@ impl Project {
 
     /// Effective source / test / resource / excluded roots (detected + Project Structure marks).
     pub fn roots(&self) -> ProjectRoots {
-        linked_roots(&self.root, &self.settings.effective(), &self.detected_roots.read())
+        let detected = with_gradle_roots(&self.root, &self.build_cache_dir(), &self.detected_roots.read());
+        linked_roots(&self.root, &self.settings.effective(), &detected)
     }
 
     /// Where the Maven / Gradle tool windows cache what the build tools reported.
@@ -829,7 +853,7 @@ impl Project {
 
     /// Project Structure content roots besides the project folder (existing directories).
     pub fn content_roots(&self) -> Vec<PathBuf> {
-        content_roots(&self.settings.effective(), &self.root)
+        content_roots(&self.settings.effective(), &self.root, &self.build_cache_dir())
     }
 
     /// Applies Settings › File Types; open documents whose language changed are
@@ -948,14 +972,15 @@ fn index_roots(root: &Path, folders: Vec<PathBuf>) -> ide_index::IndexRoots {
     ide_index::IndexRoots { include_root: !root.join(ide_workspace::workspace::FILE).is_file(), folders }
 }
 
-/// Workspace members in manifest order, or extra Project Structure directories.
-fn content_roots(settings: &ide_core::settings::Settings, root: &Path) -> Vec<PathBuf> {
+/// Workspace members in manifest order, or extra Project Structure directories and the
+/// Gradle project folders outside the project as of the last sync (`build_cache`).
+fn content_roots(settings: &ide_core::settings::Settings, root: &Path, build_cache: &Path) -> Vec<PathBuf> {
     if let Ok(Some(workspace)) = ide_workspace::workspace::Workspace::load(root) {
         return workspace.projects;
     }
     let mut out: Vec<PathBuf> = Vec::new();
-    for r in &settings.project_structure.content_roots {
-        let p = PathBuf::from(r.trim());
+    let user = settings.project_structure.content_roots.iter().map(|r| PathBuf::from(r.trim()));
+    for p in user.chain(ide_build::gradle_external_roots(root, build_cache)) {
         if p.is_absolute() && p.is_dir() && !p.starts_with(root) && !out.contains(&p) {
             out.push(p);
         }
@@ -994,10 +1019,76 @@ fn content_root_watcher(
     .ok()
 }
 
+/// Where agent tasks create their worktrees: next to the project, `<parent>/<name>.worktrees`,
+/// so they sit on the project's drive and outside its tree (not indexed, watched or shown in
+/// its git status); `fallback` for a project at a filesystem root.
+fn agent_worktrees_dir(root: &Path, fallback: impl FnOnce() -> PathBuf) -> PathBuf {
+    match (root.parent(), root.file_name()) {
+        (Some(parent), Some(name)) => {
+            let mut dir = name.to_os_string();
+            dir.push(".worktrees");
+            parent.join(dir)
+        }
+        _ => fallback(),
+    }
+}
+
 pub(crate) fn unlinked_maven_poms(root: &Path, settings: &ide_core::settings::Settings) -> Vec<PathBuf> {
     ide_build::maven::UnlinkedProjects::load(root, &settings.languages.java.maven).poms().map(PathBuf::from).collect()
 }
 
+/// The unlinked Maven POMs jdtls leaves out, and the build files (`file:` URIs) it is to
+/// import when that takes more than exclusions: an unlinked module of a linked reactor.
+/// Those then include the Gradle build, which jdtls would otherwise find by itself.
+pub(crate) fn jdtls_maven_import(
+    root: &Path,
+    settings: &ide_core::settings::Settings,
+) -> (Vec<PathBuf>, Option<Vec<String>>) {
+    let maven = &settings.languages.java.maven;
+    if maven.unlinked_projects.is_empty() {
+        return (Vec::new(), None);
+    }
+    let model = ide_build::maven::load(root);
+    let unlinked = ide_build::maven::UnlinkedProjects::from_model(&model, maven);
+    let excluded = unlinked.poms().map(PathBuf::from).collect();
+    let build_files = unlinked.import_poms(&model).map(|poms| {
+        let gradle = ide_build::gradle::load(root).and_then(|g| {
+            let dir = root.join(&g.dir);
+            let names = ide_build::gradle::SETTINGS_FILES.iter().chain(ide_build::gradle::BUILD_FILES);
+            names.map(|n| dir.join(n)).find(|f| f.is_file())
+        });
+        poms.iter().map(|pom| root.join(pom)).chain(gradle).map(|f| ide_lsp::path_to_uri_string(&f)).collect()
+    });
+    (excluded, build_files)
+}
+
+/// The detected roots with the last Gradle sync's source sets first: Gradle evaluated what
+/// static detection guesses. Folders outside the project keep their absolute path, which
+/// `normalize` turns into the same form the UI compares (`Users/me/svc/src/main/java`).
+fn with_gradle_roots(root: &Path, build_cache: &Path, detected: &[SourceFolder]) -> Vec<SourceFolder> {
+    use ide_build::gradle::ReportedRoot;
+    use ide_workspace::roots::RootKind;
+    let mut out: Vec<SourceFolder> = Vec::new();
+    for (dir, kind) in ide_build::gradle_source_roots(build_cache) {
+        if !dir.is_dir() {
+            continue;
+        }
+        let path = ide_workspace::roots::normalize(&dir.strip_prefix(root).unwrap_or(&dir).to_string_lossy());
+        let kind = match kind {
+            ReportedRoot::Source => RootKind::Source,
+            ReportedRoot::Test => RootKind::Test,
+            ReportedRoot::Resources => RootKind::Resources,
+            ReportedRoot::TestResources => RootKind::TestResources,
+            ReportedRoot::Excluded => RootKind::Excluded,
+        };
+        if !out.iter().any(|f| f.path == path) {
+            out.push(SourceFolder { path, kind, detected_from: Some("Gradle".into()) });
+        }
+    }
+    out.extend(detected.iter().filter(|d| !out.iter().any(|o| o.path == d.path)).cloned().collect::<Vec<_>>());
+    out
+}
+
 fn linked_roots(root: &Path, settings: &ide_core::settings::Settings, detected: &[SourceFolder]) -> ProjectRoots {
     let unlinked = ide_build::maven::UnlinkedProjects::load(root, &settings.languages.java.maven);
     let detected = detected
@@ -1148,6 +1239,27 @@ pub fn apply_git_executable(settings: &ide_core::settings::Settings) {
 
 #[cfg(test)]
 mod maven_linkage_tests {
+    #[test]
+    fn jdtls_imports_the_linked_modules_and_the_gradle_build_once_a_reactor_module_is_unlinked() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        for (dir, body) in [("", "<modules><module>x</module><module>y</module></modules>"), ("x", ""), ("y", "")] {
+            std::fs::create_dir_all(root.join(dir)).unwrap();
+            std::fs::write(root.join(dir).join("pom.xml"), format!("<project>{body}</project>")).unwrap();
+        }
+        std::fs::write(root.join("settings.gradle"), "rootProject.name = 'g'").unwrap();
+        let mut settings = ide_core::settings::Settings::default();
+        assert_eq!(super::jdtls_maven_import(root, &settings), (Vec::new(), None));
+        settings.languages.java.maven.unlinked_projects.push("y/pom.xml".into());
+        let (excluded, files) = super::jdtls_maven_import(root, &settings);
+        assert_eq!(excluded, vec![std::path::PathBuf::from("y/pom.xml")]);
+        let uri = |f: &str| ide_lsp::path_to_uri_string(&root.join(f));
+        assert_eq!(files, Some(vec![uri("x/pom.xml"), uri("settings.gradle")]));
+        // The whole reactor unlinked: the import exclusions are enough.
+        settings.languages.java.maven.unlinked_projects = vec!["pom.xml".into()];
+        assert_eq!(super::jdtls_maven_import(root, &settings).1, None);
+    }
+
     #[test]
     fn unlinked_roots_remain_plain_files() {
         let tmp = tempfile::tempdir().unwrap();
@@ -1176,7 +1288,7 @@ mod maven_linkage_tests {
             serde_json::json!({"name": "jdtls", "command": "jdtls"}),
         )
         .unwrap();
-        ide_sdk::apply::configure_maven_import(&mut server, tmp.path(), &excluded_poms);
+        ide_sdk::apply::configure_maven_import(&mut server, tmp.path(), &excluded_poms, None);
         let options = serde_json::to_value(server.initialization_options).unwrap();
         let exclusions = options.pointer("/settings/java/import/exclusions").unwrap().as_array().unwrap();
         assert!(exclusions.contains(&serde_json::json!(tmp.path().join("a").to_string_lossy().replace('\\', "/"))));
@@ -1199,6 +1311,46 @@ fn vcs_path_changed(path: &Path) -> bool {
     !path.ends_with(".git/index") || !ide_vcs::is_own_index_write(path)
 }
 
+#[cfg(test)]
+mod gradle_roots_tests {
+    use super::*;
+    use ide_workspace::RootKind;
+
+    #[test]
+    fn gradle_sync_roots_win_and_reach_outside_the_project() {
+        let tmp = tempfile::tempdir().unwrap();
+        let ws = dunce::canonicalize(tmp.path()).unwrap();
+        let (root, svc, cache) = (ws.join("p"), ws.join("svc"), ws.join("cache"));
+        for d in [root.join("src/it/java"), svc.join("src/main/java"), svc.join("build")] {
+            std::fs::create_dir_all(d).unwrap();
+        }
+        let s = |p: PathBuf| p.to_string_lossy().into_owned();
+        let json = serde_json::json!({ "hash": "", "at_ms": 1.0, "error": null, "tasks": [], "projects": [
+            { "path": ":", "dir": s(root.clone()), "sourceSets": [
+                { "name": "integrationTest", "test": true, "src": [s(root.join("src/it/java"))], "res": [] } ] },
+            { "path": ":svc", "dir": s(svc.clone()), "buildDir": s(svc.join("build")), "sourceSets": [
+                { "name": "main", "test": false,
+                  "src": [s(svc.join("src/main/java")), s(svc.join("src/main/kotlin"))], "res": [] } ] },
+        ]});
+        std::fs::create_dir_all(&cache).unwrap();
+        std::fs::write(cache.join("gradle.json"), json.to_string()).unwrap();
+        let guessed = SourceFolder { path: "src/it/java".into(), kind: RootKind::Source, detected_from: None };
+        let other = SourceFolder { path: "web".into(), kind: RootKind::Source, detected_from: None };
+        let out = with_gradle_roots(&root, &cache, &[guessed, other.clone()]);
+        let abs = |p: PathBuf| ide_workspace::roots::normalize(&s(p));
+        let got: Vec<(String, RootKind)> = out.iter().map(|f| (f.path.clone(), f.kind)).collect();
+        assert_eq!(
+            got,
+            [
+                ("src/it/java".into(), RootKind::Test),
+                (abs(svc.join("src/main/java")), RootKind::Source),
+                (abs(svc.join("build")), RootKind::Excluded),
+                ("web".into(), RootKind::Source),
+            ]
+        );
+    }
+}
+
 #[cfg(test)]
 mod index_event_tests {
     use super::vcs_path_changed;
@@ -1269,3 +1421,17 @@ mod workspace_edit_tests {
         assert_eq!(documents.snapshot(doc.id).unwrap().text, "sum_values();\n");
     }
 }
+
+#[cfg(test)]
+mod agent_worktree_tests {
+    use super::agent_worktrees_dir;
+    use std::path::{Path, PathBuf};
+
+    #[test]
+    fn agent_worktrees_sit_next_to_the_project() {
+        let fallback = || PathBuf::from("/home/me/.openidea/worktrees/key");
+        let project = Path::new("/work").join("acme-api");
+        assert_eq!(agent_worktrees_dir(&project, fallback), Path::new("/work").join("acme-api.worktrees"));
+        assert_eq!(agent_worktrees_dir(Path::new("/"), fallback), fallback());
+    }
+}

crates/ide-host/src/rpc.rs

@@ -9,7 +9,10 @@
 //! * server → client notification `event` `{ window, event }` (an `IdeEvent`
 //!   for that window, or every window when `window` is null);
 //! * server → client notification `channel` `{ id, data }`: one value of a
-//!   streaming argument.
+//!   streaming argument;
+//! * server → client notification `plugin` `{ window, event }` and request
+//!   `plugin_secret` `{ plugin, name }` → `string | null`: code plugins of the
+//!   remote project (`plugins::remote_host`).
 
 use crate::Host;
 use crate::ops::{self, Emit};

crates/ide-host/src/trust.rs

@@ -273,6 +273,7 @@ pub fn restricted_command_allowed(cmd: &str) -> bool {
             | "plugin_set_theme"
             | "plugin_set_theme_frame"
             | "plugin_catalog"
+            | "plugin_assets"
             | "notebook_open"
             | "notebook_get"
             | "notebook_edit"

crates/ide-host/tests/distribution.rs

@@ -0,0 +1,262 @@
+//! Versioned installs with automatic rollback, signed packages from
+//! a static marketplace index, and revocation.
+
+use ide_extension::package::{self, Index, IndexEntry, KeyEntry, Publisher, PublisherKey, Revocation};
+use ide_host::plugins::*;
+use ide_plugin::{Invocation, Limits};
+use parking_lot::Mutex;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+type Events = Arc<Mutex<Vec<PluginEvent>>>;
+
+fn repo() -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../..")
+}
+
+fn copy_dir(from: &Path, to: &Path) {
+    std::fs::create_dir_all(to).unwrap();
+    for entry in std::fs::read_dir(from).unwrap().flatten() {
+        let (src, dst) = (entry.path(), to.join(entry.file_name()));
+        if entry.file_name() == "target" {
+            continue;
+        }
+        if src.is_dir() { copy_dir(&src, &dst) } else { std::fs::copy(&src, &dst).map(|_| ()).unwrap() }
+    }
+}
+
+/// A copy of `from` (under `dir/name`) whose manifest is rewritten by `f`.
+fn variant(from: &Path, dir: &Path, name: &str, f: impl Fn(&str) -> String) -> PathBuf {
+    let pkg = dir.join(name);
+    copy_dir(from, &pkg);
+    let manifest = pkg.join("plugin.toml");
+    std::fs::write(&manifest, f(&std::fs::read_to_string(&manifest).unwrap())).unwrap();
+    pkg
+}
+
+struct Fixture {
+    host: PluginHost,
+    plugins_dir: PathBuf,
+    events: Events,
+    _tmp: tempfile::TempDir,
+    work: PathBuf,
+}
+
+fn fixture() -> Fixture {
+    let tmp = tempfile::tempdir().unwrap();
+    let plugins_dir = tmp.path().join("plugins");
+    let events: Events = Arc::default();
+    let sink = {
+        let events = events.clone();
+        move |_: Option<&str>, e: PluginEvent| events.lock().push(e)
+    };
+    let host = PluginHost::new(plugins_dir.clone(), Arc::new(sink), Limits::default()).unwrap();
+    host.load_all();
+    let work = tmp.path().join("work");
+    std::fs::create_dir_all(&work).unwrap();
+    Fixture { host, plugins_dir, events, work, _tmp: tmp }
+}
+
+fn inv() -> Invocation {
+    Invocation { client: Some("main".into()), workspace_root: None, editor: None }
+}
+
+fn misbehave() -> PathBuf {
+    repo().join("crates/ide-plugin/tests/fixtures/misbehave")
+}
+
+/// P8 acceptance: an update that fails to start rolls back to the version it replaced.
+#[test]
+fn a_failing_update_rolls_back_automatically() {
+    let f = fixture();
+    let v1 = variant(&misbehave(), &f.work, "v1", |t| t.replace("version = \"0.0.2\"", "version = \"1.0.0\""));
+    f.host.install_from_dir(&v1, &Consent::all()).unwrap();
+    assert_eq!(f.host.run_command("misbehave", "echo", Some("hi"), inv()).unwrap().as_deref(), Some("hi"));
+
+    let broken =
+        variant(&misbehave(), &f.work, "v2", |t| t.replace("version = \"0.0.2\"", "version = \"2.0.0-broken\""));
+    let info = f.host.install_from_dir(&broken, &Consent::all()).unwrap();
+    assert_eq!((info.version.as_str(), info.previous_version.as_deref()), ("2.0.0-broken", Some("1.0.0")));
+    let root = f.plugins_dir.join("misbehave");
+    assert!(root.join("2.0.0-broken").is_dir() && root.join("1.0.0").is_dir(), "versions side by side");
+
+    // Its first start fails: back to 1.0.0, without the user doing anything.
+    f.events.lock().clear();
+    let err = f.host.run_command("misbehave", "echo", Some("x"), inv()).unwrap_err();
+    assert!(err.message.contains("version 1.0.0 was restored"), "{}", err.message);
+    let info = f.host.info_of("misbehave").unwrap();
+    assert_eq!((info.version.as_str(), info.status), ("1.0.0", PluginStatus::Inactive));
+    assert!(!root.join("2.0.0-broken").exists(), "the failed version is removed");
+    assert!(
+        f.events
+            .lock()
+            .iter()
+            .any(|e| matches!(e, PluginEvent::Notification { title, .. } if title.contains("rolled back")))
+    );
+    assert_eq!(f.host.run_command("misbehave", "echo", Some("ok"), inv()).unwrap().as_deref(), Some("ok"));
+
+    // A working update is confirmed by its first start; the user can still roll it back.
+    let v3 = variant(&misbehave(), &f.work, "v3", |t| t.replace("version = \"0.0.2\"", "version = \"3.0.0\""));
+    f.host.install_from_dir(&v3, &Consent::all()).unwrap();
+    f.host.run_command("misbehave", "echo", None, inv()).unwrap();
+    assert_eq!(f.host.info_of("misbehave").unwrap().version, "3.0.0");
+    let info = f.host.roll_back_update("misbehave").unwrap();
+    assert_eq!((info.version.as_str(), info.previous_version.as_deref()), ("1.0.0", None));
+    assert!(f.host.roll_back_update("misbehave").is_err(), "nothing older to go back to");
+
+    // A restart loads the active version.
+    let again = PluginHost::new(f.plugins_dir.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default()).unwrap();
+    again.load_all();
+    assert_eq!(again.info_of("misbehave").unwrap().version, "1.0.0");
+    f.host.uninstall("misbehave").unwrap();
+    assert!(!root.exists(), "every version goes");
+}
+
+#[test]
+fn installs_from_before_versioning_keep_working_and_move_on_update() {
+    let f = fixture();
+    // The flat layout of earlier releases.
+    copy_dir(&misbehave(), &f.plugins_dir.join("misbehave"));
+    let again = PluginHost::new(f.plugins_dir.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default()).unwrap();
+    again.load_all();
+    assert_eq!(again.info_of("misbehave").unwrap().version, "0.0.2");
+    let v1 = variant(&misbehave(), &f.work, "v1", |t| t.replace("version = \"0.0.2\"", "version = \"1.0.0\""));
+    let info = again.install_from_dir(&v1, &Consent::all()).unwrap();
+    assert_eq!((info.version.as_str(), info.previous_version.as_deref()), ("1.0.0", Some("0.0.2")));
+    assert!(f.plugins_dir.join("misbehave/0.0.2/plugin.toml").is_file());
+    assert!(f.plugins_dir.join("misbehave/1.0.0/plugin.toml").is_file());
+}
+
+// ---- marketplace ------------------------------------------------------------------
+
+/// `hello` as `acme.hello` at `version`, packed and signed with `key`.
+fn signed_hello(dir: &Path, version: &str, key: &PublisherKey, host: &PluginHost) -> (PathBuf, IndexEntry) {
+    let src = variant(&repo().join("crates/ide-plugin/tests/fixtures/hello"), dir, &format!("src-{version}"), |t| {
+        t.replace("id = \"hello\"", "id = \"acme.hello\"")
+            .replace("version = \"0.3.0\"", &format!("version = \"{version}\""))
+    });
+    let files = host.package_files_of(&src).unwrap();
+    let digest = package::package_digest(&src, &files).unwrap();
+    let sig = key.sign("acme", "acme.hello", version, &digest);
+    let out = dir.join(format!("acme.hello-{version}.oiplugin"));
+    package::pack(&src, &files, &out, Some(&sig)).unwrap();
+    let entry = IndexEntry {
+        id: "acme.hello".into(),
+        name: "Hello".into(),
+        version: version.into(),
+        description: String::new(),
+        authors: vec![],
+        publisher: "acme".into(),
+        download: out.file_name().unwrap().to_string_lossy().into_owned(),
+        digest,
+        capabilities: vec![],
+    };
+    (out, entry)
+}
+
+fn write_index(
+    dir: &Path,
+    key: &PublisherKey,
+    plugins: Vec<IndexEntry>,
+    revoked: Vec<Revocation>,
+    key_revoked: bool,
+) -> String {
+    let index = Index {
+        format: package::INDEX_FORMAT,
+        publishers: vec![Publisher {
+            id: "acme".into(),
+            name: "ACME".into(),
+            keys: vec![KeyEntry { key: key.public_base64(), revoked: key_revoked }],
+        }],
+        plugins,
+        revoked,
+    };
+    let path = dir.join("index.json");
+    std::fs::write(&path, serde_json::to_string(&index).unwrap()).unwrap();
+    path.to_string_lossy().into_owned()
+}
+
+#[test]
+fn signed_marketplace_plugins_install_and_revocations_disable_them() {
+    let f = fixture();
+    let market = f.work.join("market");
+    std::fs::create_dir_all(&market).unwrap();
+    let key = PublisherKey::from_seed([3; 32]);
+    let (_, entry) = signed_hello(&market, "1.0.0", &key, &f.host);
+    let url = write_index(&market, &key, vec![entry.clone()], vec![], false);
+
+    assert!(f.host.refresh_market().is_err(), "no marketplace configured yet");
+    f.host.set_market_url(Some(url.clone()));
+    let listed = f.host.refresh_market().unwrap();
+    assert_eq!((listed[0].entry.id.as_str(), listed[0].installed.as_deref()), ("acme.hello", None));
+
+    let dir = f.host.download_market_plugin("acme.hello").unwrap();
+    let preview = f.host.preview_install(&dir).unwrap();
+    assert_eq!((preview.unsigned, preview.publisher.as_deref()), (false, Some("acme")));
+    let info = f.host.install_from_dir(&dir, &Consent::all()).unwrap();
+    assert_eq!(info.publisher.as_deref(), Some("acme"));
+    assert_eq!(f.host.market_plugins()[0].installed.as_deref(), Some("1.0.0"));
+
+    // A changed file breaks the signature: refused.
+    let tampered = f.host.download_market_plugin("acme.hello").unwrap();
+    let manifest = std::fs::read_to_string(tampered.join("plugin.toml")).unwrap();
+    std::fs::write(tampered.join("plugin.toml"), manifest.replace("Sample plugin", "Totally safe plugin")).unwrap();
+    let err = f.host.preview_install(&tampered).unwrap_err();
+    assert!(err.message.contains("changed after signing"), "{}", err.message);
+
+    // Someone else's key, or another publisher's prefix: not trusted.
+    let stranger = PublisherKey::from_seed([4; 32]);
+    let (foreign, _) = signed_hello(&f.work, "1.0.1", &stranger, &f.host);
+    let unpacked = f.host.unpack_package(&foreign).unwrap();
+    assert!(f.host.preview_install(&unpacked).unwrap_err().message.contains("not one of"));
+
+    // The index revokes the installed version: disabled, the user told.
+    f.events.lock().clear();
+    let revoked =
+        vec![Revocation { id: "acme.hello".into(), versions: vec!["1.0.0".into()], reason: "steals tokens".into() }];
+    write_index(&market, &key, vec![entry.clone()], revoked, false);
+    f.host.refresh_market().unwrap();
+    let info = f.host.info_of("acme.hello").unwrap();
+    assert_eq!((info.status, info.error.as_deref()), (PluginStatus::Failed, Some("revoked: steals tokens")));
+    assert!(
+        f.events
+            .lock()
+            .iter()
+            .any(|e| matches!(e, PluginEvent::Notification { body, .. } if body.contains("steals tokens")))
+    );
+    assert!(f.host.market_plugins().is_empty(), "revoked versions are not offered");
+    assert!(f.host.install_from_dir(&dir, &Consent::all()).is_err(), "nor installable");
+    f.host.set_enabled("acme.hello", true).unwrap();
+    assert_eq!(f.host.info_of("acme.hello").unwrap().status, PluginStatus::Failed, "enabling doesn't bring it back");
+
+    // Revocations hold across restarts (the index is kept).
+    let again = PluginHost::new(f.plugins_dir.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default()).unwrap();
+    again.load_all();
+    assert_eq!(again.info_of("acme.hello").unwrap().status, PluginStatus::Failed);
+
+    // A revoked signing key disables what it signed.
+    write_index(&market, &key, vec![entry.clone()], vec![], true);
+    f.host.refresh_market().unwrap();
+    let info = f.host.info_of("acme.hello").unwrap();
+    assert!(info.error.as_deref().unwrap_or("").contains("signing key was revoked"), "{:?}", info.error);
+
+    // Lifted: it runs again.
+    write_index(&market, &key, vec![entry], vec![], false);
+    f.host.refresh_market().unwrap();
+    let info = f.host.info_of("acme.hello").unwrap();
+    assert_eq!((info.status, info.error), (PluginStatus::Inactive, None));
+}
+
+#[test]
+fn package_files_install_from_disk_unsigned() {
+    let f = fixture();
+    let src = variant(&misbehave(), &f.work, "pkg", |t| t.to_owned());
+    let files = f.host.package_files_of(&src).unwrap();
+    let out = f.work.join("misbehave-0.0.2.oiplugin");
+    package::pack(&src, &files, &out, None).unwrap();
+    let dir = f.host.unpack_package(&out).unwrap();
+    let preview = f.host.preview_install(&dir).unwrap();
+    assert_eq!((preview.unsigned, preview.publisher), (true, None));
+    let info = f.host.install_from_dir(&dir, &Consent::all()).unwrap();
+    assert_eq!((info.status, info.publisher), (PluginStatus::Inactive, None));
+}

crates/ide-host/tests/light_edit.rs

@@ -116,7 +116,7 @@ async fn light_windows_stay_restricted_when_folder_trust_changes() {
         "main",
         doc.id,
         None,
-        ide_lsp::types::FormatOptions { tab_size: 2, insert_spaces: true, on_save: false },
+        ide_lsp::types::FormatOptions { tab_size: 2, insert_spaces: true, on_save: false, tool: None },
     )
     .await
     .unwrap_err();

crates/ide-host/tests/remote_plugins.rs

@@ -0,0 +1,304 @@
+//! Code plugins of a remote project run on the
+//! server. The desktop's plugin host syncs its live
+//! code plugins over the remote protocol; Checkstyle then checks the file on
+//! the server's disk when it is saved, and secrets come from the desktop.
+
+#![cfg(unix)]
+
+use ide_core::IdeEvent;
+use ide_host::plugins::remote_host::{
+    EVENT_NOTIFICATION, PackageSyncReport, PluginEventMessage, RemotePlugins, SECRET_REQUEST, SYNC_PACKAGES,
+    SecretRequest,
+};
+use ide_host::plugins::{Consent, PluginEvent, PluginHost, PluginStatus, WorkbenchEvent};
+use ide_host::rpc::{self, Dispatcher, EventMessage, Invoke};
+use ide_host::{Host, HostConfig};
+use ide_jsonrpc::{Handler, Peer};
+use ide_plugin::Limits;
+use parking_lot::Mutex;
+use serde_json::{Value, json};
+use std::os::unix::fs::PermissionsExt;
+use std::path::{Path, PathBuf};
+use std::sync::{Arc, OnceLock};
+use std::time::Duration;
+
+#[derive(Default)]
+struct Client {
+    events: Mutex<Vec<EventMessage>>,
+    plugin_events: Mutex<Vec<PluginEventMessage>>,
+    secret_requests: Mutex<Vec<SecretRequest>>,
+}
+
+impl Handler for Client {
+    fn on_notification(&self, method: &str, params: Value) {
+        match method {
+            "event" => self.events.lock().push(serde_json::from_value(params).unwrap()),
+            EVENT_NOTIFICATION => self.plugin_events.lock().push(serde_json::from_value(params).unwrap()),
+            _ => {}
+        }
+    }
+
+    fn on_request(&self, method: &str, params: Value) -> Result<Value, (i64, String)> {
+        if method == SECRET_REQUEST {
+            let r: SecretRequest = serde_json::from_value(params).unwrap();
+            let value = (r.name == "api-key").then(|| "sk-desktop".to_owned());
+            self.secret_requests.lock().push(r);
+            return Ok(serde_json::to_value(value).unwrap());
+        }
+        Err((ide_jsonrpc::codes::METHOD_NOT_FOUND, method.to_owned()))
+    }
+}
+
+async fn invoke(peer: &Peer, cmd: &str, args: Value) -> Result<Value, ide_core::IdeError> {
+    let call = Invoke { window: "main".into(), cmd: cmd.into(), args };
+    peer.request::<_, Value>("invoke", call, None).await.map_err(rpc::error_from_reply)
+}
+
+async fn sync(peer: &Peer, desktop: &PluginHost, files: &[&str]) -> PackageSyncReport {
+    let files: serde_json::Map<String, Value> = files
+        .iter()
+        .map(|id| ((*id).to_owned(), serde_json::to_value(desktop.remote_package_files(id).unwrap()).unwrap()))
+        .collect();
+    let args = json!({ "packages": desktop.remote_packages(), "files": files });
+    serde_json::from_value(invoke(peer, SYNC_PACKAGES, args).await.unwrap()).unwrap()
+}
+
+fn official(name: &str) -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../../plugins/official").join(name)
+}
+
+/// A test fixture plugin (`crates/ide-plugin/tests/fixtures/<name>`).
+fn fixture(name: &str) -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../ide-plugin/tests/fixtures").join(name)
+}
+
+/// A `checkstyle` that reports a tab on line 2 of the file it is given.
+fn fake_checkstyle(bin: &Path) {
+    std::fs::create_dir_all(bin).unwrap();
+    std::fs::write(
+        bin.join("checkstyle"),
+        "#!/bin/sh\nfor a; do file=\"$a\"; done\ngrep -q '\t' \"$file\" || { echo '<checkstyle/>'; exit 0; }\n\
+         echo '<?xml version=\"1.0\"?><checkstyle><file name=\"'\"$file\"'\">'\n\
+         echo '<error line=\"2\" column=\"1\" severity=\"warning\" message=\"Line contains a tab character.\" source=\"com.puppycrawl.tools.checkstyle.checks.whitespace.FileTabCharacterCheck\"/>'\n\
+         echo '</file></checkstyle>'\nexit 1\n",
+    )
+    .unwrap();
+    std::fs::set_permissions(bin.join("checkstyle"), std::fs::Permissions::from_mode(0o755)).unwrap();
+}
+
+async fn until(what: &str, secs: u64, mut done: impl FnMut() -> bool) {
+    for _ in 0..secs * 50 {
+        if done() {
+            return;
+        }
+        tokio::time::sleep(Duration::from_millis(20)).await;
+    }
+    panic!("timed out waiting for {what}");
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+async fn remote_projects_run_the_desktops_code_plugins_on_the_server() {
+    let tmp = tempfile::tempdir().unwrap();
+    let bin = tmp.path().join("bin");
+    fake_checkstyle(&bin);
+    let path_var = {
+        let bin = bin.clone();
+        Arc::new(move || Some(bin.clone().into_os_string()))
+    };
+
+    // The desktop: Checkstyle and AI Completion installed and granted.
+    let desktop =
+        PluginHost::new(tmp.path().join("desktop/plugins"), Arc::new(|_: Option<&str>, _| {}), Limits::default())
+            .unwrap();
+    desktop.set_program_path(path_var.clone());
+    for name in ["checkstyle", "ai-completion"] {
+        let info = desktop.install_from_dir(&official(name), &Consent::all()).unwrap();
+        assert_eq!(info.status, PluginStatus::Inactive, "{:?}", info.error);
+    }
+
+    // The server, with the project on "its" disk.
+    // Canonical, as the UI reports paths (macOS: /var → /private/var).
+    let project = tmp.path().join("remote/demo");
+    std::fs::create_dir_all(project.join("src")).unwrap();
+    let project = std::fs::canonicalize(project).unwrap();
+    let base = tmp.path().join("server");
+    let peer_slot = Arc::new(OnceLock::new());
+    let sink_peer = peer_slot.clone();
+    let host = Arc::new(Host::new(HostConfig {
+        config_dir: base.join("config"),
+        data_dir: base.join("data"),
+        local_data_dir: base.join("data"),
+        languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
+        syntax: Arc::default(),
+        sink_for: Box::new(move |w| rpc::event_sink(sink_peer.clone(), Some(w.to_owned()))),
+        owner: |w| w,
+        runtime: tokio::runtime::Handle::current(),
+        project_environment: false,
+    }));
+    let plugins = RemotePlugins::start(&base.join("data"), &host, peer_slot.clone()).unwrap();
+    plugins.host().set_program_path(path_var);
+    let mut dispatcher = Dispatcher::standard();
+    plugins.register(&mut dispatcher);
+    let (client_io, server_io) = tokio::io::duplex(1 << 20);
+    let (sr, sw) = tokio::io::split(server_io);
+    tokio::spawn(rpc::serve(host.clone(), dispatcher, peer_slot, sr, sw));
+    let (cr, cw) = tokio::io::split(client_io);
+    let client = Arc::new(Client::default());
+    let peer = Peer::connect(cr, cw, client.clone());
+    let _: Value = peer.request("initialize", json!({ "version": rpc::PROTOCOL_VERSION }), None).await.unwrap();
+    invoke(&peer, "open_project", json!({ "path": project })).await.unwrap();
+    invoke(&peer, "project_trust_set", json!({ "path": project, "trusted": true, "folder": false })).await.unwrap();
+
+    // Digests first; then the files of what the server lacks; then nothing to do.
+    let first = sync(&peer, &desktop, &[]).await;
+    assert_eq!(first.missing, ["openidea.ai-completion", "openidea.checkstyle"], "{first:?}");
+    let second = sync(&peer, &desktop, &["openidea.ai-completion", "openidea.checkstyle"]).await;
+    assert_eq!(second.installed.len(), 2, "{second:?}");
+    assert!(second.failed.is_empty(), "{second:?}");
+    assert_eq!(sync(&peer, &desktop, &[]).await, PackageSyncReport::default());
+    let remote = plugins.host().info_of("openidea.checkstyle").unwrap();
+    assert_eq!(remote.status, PluginStatus::Inactive, "{:?}", remote.error);
+    assert!(remote.capabilities.iter().any(|c| c.id == "process:checkstyle" && c.granted));
+
+    // The remote window's UI routes the run-time commands to the server.
+    let kinds = invoke(&peer, "plugin_event_kinds", json!({})).await.unwrap();
+    assert!(kinds.as_array().unwrap().contains(&json!("file-saved")), "{kinds}");
+
+    // Saving a file that exists only on the server: Checkstyle reads that file.
+    let java = project.join("src/A.java");
+    std::fs::write(&java, "class A {\n\tint x;\n}\n").unwrap();
+    let saved = WorkbenchEvent::FileSaved(java.to_string_lossy().into_owned());
+    invoke(&peer, "plugin_post_events", json!({ "events": [saved] })).await.unwrap();
+    let published = || {
+        client.events.lock().iter().find_map(|m| match &m.event {
+            IdeEvent::Diagnostics { path, source, items } if source == "plugin:openidea.checkstyle" => {
+                Some((path.0.clone(), items.clone()))
+            }
+            _ => None,
+        })
+    };
+    until("remote checkstyle diagnostics", 20, || published().is_some()).await;
+    let (path, items) = published().unwrap();
+    assert_eq!(path, java);
+    assert_eq!((items.len(), items[0].range.start.line), (1, 1));
+
+    // Secrets stay on the desktop: the server asks for them when used.
+    let secrets = plugins.host().secrets("openidea.ai-completion").unwrap();
+    assert_eq!(secrets, [("api-key".to_owned(), true)]);
+    assert_eq!(client.secret_requests.lock()[0].plugin, "openidea.ai-completion");
+
+    // A command of a remote plugin, with this window as its client.
+    invoke(
+        &peer,
+        "plugin_run_command",
+        json!({ "pluginId": "openidea.ai-completion", "commandId": "toggle", "arg": null, "editor": null }),
+    )
+    .await
+    .unwrap();
+    until("the command's notification", 5, || {
+        client
+            .plugin_events
+            .lock()
+            .iter()
+            .any(|m| m.window.as_deref() == Some("main") && matches!(m.event, PluginEvent::Notification { .. }))
+    })
+    .await;
+
+    // Disabled on the desktop: gone from the server.
+    desktop.set_enabled("openidea.checkstyle", false).unwrap();
+    let removed = sync(&peer, &desktop, &[]).await;
+    assert_eq!(removed.removed, ["openidea.checkstyle"]);
+    assert!(plugins.host().info_of("openidea.checkstyle").is_err());
+    plugins.host().shutdown();
+}
+
+/// CSV Editor and a tool window with a terminal (the `jobs` fixture) in a
+/// remote project. The table edits the document on the server; the jobs are
+/// the server's `jobs` program's, and the terminal opens in the remote window.
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+async fn remote_projects_get_plugin_views_and_custom_editors() {
+    let tmp = tempfile::tempdir().unwrap();
+    let bin = tmp.path().join("bin");
+    std::fs::create_dir_all(&bin).unwrap();
+    std::fs::write(bin.join("jobs"), "#!/bin/sh\n[ \"$1\" = list ] && echo remote-job\n").unwrap();
+    std::fs::set_permissions(bin.join("jobs"), std::fs::Permissions::from_mode(0o755)).unwrap();
+    let path_var = {
+        let bin = bin.clone();
+        Arc::new(move || Some(bin.clone().into_os_string()))
+    };
+    let desktop =
+        PluginHost::new(tmp.path().join("desktop/plugins"), Arc::new(|_: Option<&str>, _| {}), Limits::default())
+            .unwrap();
+    desktop.set_program_path(path_var.clone());
+    for dir in [official("csv-editor"), fixture("jobs")] {
+        let info = desktop.install_from_dir(&dir, &Consent::all()).unwrap();
+        assert_eq!(info.status, PluginStatus::Inactive, "{:?}", info.error);
+    }
+
+    let project = tmp.path().join("remote/demo");
+    std::fs::create_dir_all(&project).unwrap();
+    let project = std::fs::canonicalize(project).unwrap();
+    std::fs::write(project.join("people.csv"), "name,city\nAda,London\n").unwrap();
+    let base = tmp.path().join("server");
+    let peer_slot = Arc::new(OnceLock::new());
+    let sink_peer = peer_slot.clone();
+    let host = Arc::new(Host::new(HostConfig {
+        config_dir: base.join("config"),
+        data_dir: base.join("data"),
+        local_data_dir: base.join("data"),
+        languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
+        syntax: Arc::default(),
+        sink_for: Box::new(move |w| rpc::event_sink(sink_peer.clone(), Some(w.to_owned()))),
+        owner: |w| w,
+        runtime: tokio::runtime::Handle::current(),
+        project_environment: false,
+    }));
+    let plugins = RemotePlugins::start(&base.join("data"), &host, peer_slot.clone()).unwrap();
+    plugins.host().set_program_path(path_var);
+    let mut dispatcher = Dispatcher::standard();
+    plugins.register(&mut dispatcher);
+    let (client_io, server_io) = tokio::io::duplex(1 << 20);
+    let (sr, sw) = tokio::io::split(server_io);
+    tokio::spawn(rpc::serve(host.clone(), dispatcher, peer_slot, sr, sw));
+    let (cr, cw) = tokio::io::split(client_io);
+    let client = Arc::new(Client::default());
+    let peer = Peer::connect(cr, cw, client.clone());
+    let _: Value = peer.request("initialize", json!({ "version": rpc::PROTOCOL_VERSION }), None).await.unwrap();
+    invoke(&peer, "open_project", json!({ "path": project })).await.unwrap();
+    invoke(&peer, "project_trust_set", json!({ "path": project, "trusted": true, "folder": false })).await.unwrap();
+    let report = sync(&peer, &desktop, &["openidea.csv-editor", "jobs"]).await;
+    assert_eq!(report.installed.len(), 2, "{report:?}");
+
+    // CSV Editor: the document is the server's.
+    let opened = invoke(&peer, "doc_open", json!({ "path": project.join("people.csv") })).await.unwrap();
+    let doc = opened["id"].as_u64().expect("doc id");
+    let args = |extra: Value| {
+        let mut a = json!({ "pluginId": "openidea.csv-editor", "view": "table", "doc": doc });
+        a.as_object_mut().unwrap().extend(extra.as_object().unwrap().clone());
+        a
+    };
+    let view =
+        invoke(&peer, "plugin_view_render", args(json!({ "viewport": { "firstRow": 0, "rows": 50 } }))).await.unwrap();
+    assert_eq!(view["body"]["kind"], "table");
+    assert_eq!(view["body"]["value"]["rows"], json!([["Ada", "London"]]));
+    let cell = json!({ "event": { "kind": "cell", "row": 0, "column": 1, "value": "Oslo" } });
+    invoke(&peer, "plugin_view_event", args(cell)).await.unwrap();
+    let snap = invoke(&peer, "doc_snapshot", json!({ "doc": doc })).await.unwrap();
+    assert_eq!(snap["text"], "name,city\nAda,Oslo\n");
+
+    // Jobs: the server's program; the terminal opens in this window.
+    let jobs = |event: Value| json!({ "pluginId": "jobs", "view": "jobs", "doc": null, "event": event });
+    let view =
+        invoke(&peer, "plugin_view_render", json!({ "pluginId": "jobs", "view": "jobs", "doc": null })).await.unwrap();
+    assert_eq!(view["body"]["value"][0]["label"], "remote-job", "{view}");
+    invoke(&peer, "plugin_view_event", jobs(json!({ "kind": "select", "key": "remote-job" }))).await.unwrap();
+    invoke(&peer, "plugin_view_event", jobs(json!({ "kind": "button", "id": "follow" }))).await.unwrap();
+    until("the job's terminal", 5, || {
+        client.plugin_events.lock().iter().any(|m| {
+            m.window.as_deref() == Some("main")
+                && matches!(&m.event, PluginEvent::OpenTerminal { program, .. } if program.0.starts_with(bin.canonicalize().unwrap()))
+        })
+    })
+    .await;
+    plugins.host().shutdown();
+}

crates/ide-host/tests/rpc.rs

@@ -321,6 +321,33 @@ async fn local_deployment_runs_on_the_project_host() {
         "remote_delete",
         "remote_mkdir",
         "remote_rename",
+        "db_sources",
+        "db_save_sources",
+        "db_set_password",
+        "db_test",
+        "db_set_ssh_secret",
+        "db_trust_ssh_host",
+        "db_connected",
+        "db_connect",
+        "db_set_manual_commit",
+        "db_finish_transaction",
+        "db_disconnect",
+        "db_databases",
+        "db_schemas",
+        "db_tables",
+        "db_table_details",
+        "db_ddl",
+        "db_schema_objects",
+        "db_object_ddl",
+        "db_explain",
+        "db_history",
+        "db_remove_history",
+        "db_completion",
+        "db_statements",
+        "db_execute",
+        "db_table_page",
+        "db_apply_edits",
+        "db_console_path",
     ] {
         assert!(dispatcher.commands().contains(&cmd), "missing host command {cmd}");
     }

crates/ide-http/src/client.rs

@@ -35,8 +35,16 @@ pub fn build(proxy: &ProxySettings) -> IdeResult<reqwest::Client> {
         .with_platform_verifier()
         .map_err(|e| fail(e.to_string()))?
         .with_no_client_auth();
+    // `localhost` is tried on IPv4 first: local servers (Ollama, dev servers)
+    // usually listen there, and on Windows a refused `::1` costs ~2 s before
+    // the system resolver's order falls back. Ports come from the URL.
+    let loopback = [
+        std::net::SocketAddr::from((std::net::Ipv4Addr::LOCALHOST, 0)),
+        std::net::SocketAddr::from((std::net::Ipv6Addr::LOCALHOST, 0)),
+    ];
     let builder = reqwest::Client::builder()
         .tls_backend_preconfigured(tls)
+        .resolve_to_addrs("localhost", &loopback)
         .connect_timeout(Duration::from_secs(30))
         .user_agent(concat!("OpenIDEA-HttpClient/", env!("CARGO_PKG_VERSION")));
     with_proxy(builder, proxy).build().map_err(|e| fail(e.to_string()))
@@ -113,7 +121,11 @@ mod tests {
 
     /// A one-shot HTTP server on loopback: answers `200` and hands back the request head.
     fn server() -> (u16, std::thread::JoinHandle<String>) {
-        let listener = TcpListener::bind("127.0.0.1:0").unwrap();
+        server_on("127.0.0.1:0")
+    }
+
+    fn server_on(addr: &str) -> (u16, std::thread::JoinHandle<String>) {
+        let listener = TcpListener::bind(addr).unwrap();
         let port = listener.local_addr().unwrap().port();
         let handle = std::thread::spawn(move || {
             let (stream, _) = listener.accept().unwrap();
@@ -141,6 +153,21 @@ mod tests {
         check_connection(proxy, url, &CancellationToken::new()).await
     }
 
+    /// `localhost` reaches a server on either loopback address.
+    #[tokio::test]
+    async fn localhost_reaches_ipv4_and_ipv6_servers() {
+        let direct = ProxySettings::default();
+        let (port, v4) = server();
+        assert_eq!(get(&direct, &format!("http://localhost:{port}/")).await.unwrap(), "200 OK");
+        v4.join().unwrap();
+        // Hosts without IPv6 loopback skip this half.
+        if TcpListener::bind("[::1]:0").is_ok() {
+            let (port, v6) = server_on("[::1]:0");
+            assert_eq!(get(&direct, &format!("http://localhost:{port}/")).await.unwrap(), "200 OK");
+            v6.join().unwrap();
+        }
+    }
+
     #[tokio::test]
     async fn builds_for_every_mode() {
         for mode in [ProxyMode::None, ProxyMode::Auto, ProxyMode::Manual] {

crates/ide-jsonrpc/src/lib.rs

@@ -384,6 +384,9 @@ impl Peer {
         let resolved = resolve_spawn_program(command, env);
         let mut cmd = tokio::process::Command::new(&resolved);
         ide_core::process::prepare(cmd.as_std_mut());
+        // Wrappers (`npx`, `codex.cmd`, launcher scripts) start the real server as a child:
+        // stopping the connection stops the whole tree.
+        ide_core::process::own_group(cmd.as_std_mut());
         cmd.args(args)
             .current_dir(cwd)
             .envs(ide_core::process::shell_env())
@@ -422,6 +425,9 @@ impl Peer {
             let (status, killed) = tokio::select! {
                 status = child.wait() => (status.ok(), false),
                 _ = inner.kill.cancelled() => {
+                    if let Some(pid) = child.id() {
+                        let _ = tokio::task::spawn_blocking(move || ide_core::process::kill_tree_of(pid)).await;
+                    }
                     let _ = child.start_kill();
                     (child.wait().await.ok(), true)
                 }

crates/ide-language/Cargo.toml

@@ -7,6 +7,7 @@ license.workspace = true
 
 [dependencies]
 ide-core.workspace = true
+ide-extension.workspace = true
 ide-text.workspace = true
 serde.workspace = true
 serde_json.workspace = true

crates/ide-language/src/lib.rs

@@ -8,16 +8,20 @@ use ide_core::{LanguageId, Range, SymbolKind};
 use serde::{Deserialize, Serialize};
 use specta::Type;
 use std::collections::BTreeMap;
+use std::path::{Path, PathBuf};
 
 mod markers;
+pub mod plugin_point;
 mod registry;
 mod syntax;
 pub use markers::marked_root;
+pub use plugin_point::PluginLanguages;
 pub use registry::{FileTypes, LanguageRegistry};
 pub use syntax::{
-    CSS_CLASS, CSS_ID, CSS_VARIABLE, ConfigurationKey, FileReference, Literal, LiteralKind, MAX_CACHED_TREES,
-    MAX_PARSE_BYTES, ParsedTree, SpellingKind, SpellingRegion, Syntax, SyntaxCache, SyntaxCacheStats,
-    SyntaxHighlightKind, SyntaxHighlights, TreeError, WebReference, WebReferenceKind, merge_visibility,
+    CSS_CLASS, CSS_ID, CSS_VARIABLE, ConfigurationKey, ExternalFold, ExternalSymbol, ExternalSyntax, ExternalToken,
+    FileReference, Literal, LiteralKind, MAX_CACHED_TREES, MAX_PARSE_BYTES, ParsedTree, SpellingKind, SpellingRegion,
+    Syntax, SyntaxCache, SyntaxCacheStats, SyntaxHighlightKind, SyntaxHighlights, TreeError, WebReference,
+    WebReferenceKind, merge_visibility, set_external_syntax,
 };
 
 /// Parsed form of `languages/<id>.toml`. Backend-only; the UI gets [`LanguageInfo`].
@@ -138,6 +142,9 @@ pub struct LanguageServerConfig {
     /// Register source files with tsserver when no project configuration exists.
     #[serde(default)]
     pub tsserver_project: bool,
+    /// Set on plugin languages: start exactly this approved program.
+    #[serde(skip)]
+    pub pinned: Option<ProgramPin>,
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -157,6 +164,41 @@ pub struct DebuggerConfig {
     pub connect: Option<String>,
     #[serde(default)]
     pub install_hint: Option<String>,
+    /// Set on plugin languages: start exactly this approved program.
+    #[serde(skip)]
+    pub pinned: Option<ProgramPin>,
+}
+
+/// The program a plugin's `process:` grant approved:
+/// a plugin language's server or debug adapter starts from this exact path,
+/// and only while the file still has the approved content. Set by the plugin
+/// host, never read from a definition.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ProgramPin {
+    pub path: PathBuf,
+    /// blake3 of the file when approved.
+    pub hash: String,
+}
+
+impl ProgramPin {
+    /// Approves `path` as it is now.
+    pub fn approve(path: impl Into<PathBuf>) -> std::io::Result<Self> {
+        let path = path.into();
+        let hash = ide_extension::ledger::file_hash(&path)?;
+        Ok(Self { path, hash })
+    }
+
+    /// Checks the file right before it is started; the error tells the user what to do.
+    pub fn verify(&self) -> Result<&Path, String> {
+        match ide_extension::ledger::file_hash(&self.path) {
+            Ok(hash) if hash == self.hash => Ok(&self.path),
+            Ok(_) => Err(format!(
+                "{} changed since it was approved; review the plugin's permissions in Settings › Plugins",
+                self.path.display()
+            )),
+            Err(e) => Err(format!("{}: {e}", self.path.display())),
+        }
+    }
 }
 
 fn default_transport() -> String {

crates/ide-language/src/plugin_point.rs

@@ -0,0 +1,294 @@
+//! The `languages` extension point: language definitions contributed by
+//! plugins, in the same format as `languages/<id>.toml`.
+//!
+//! ```toml
+//! [[contributes.languages]]
+//! path = "languages/solidity.toml"
+//! ```
+//!
+//! A definition that starts programs (`language-servers.command`,
+//! `debugger.command`) needs `process:<program>` for each: a declaration is a
+//! capability too, or registering languages would bypass the sandbox.
+//! Committed definitions live in [`PluginLanguages`], an overlay over the
+//! built-in registry (built-in definitions win on id clashes): see
+//! [`crate::LanguageRegistry::attach_plugins`]. A server or debugger whose
+//! program is not granted is left out; the language itself still works.
+
+use crate::{LanguageConfig, ProgramPin};
+use ide_extension::{Capability, Disposable, ExtensionPoint, Package, Placement, Prepared, decode};
+use parking_lot::RwLock;
+use serde::Deserialize;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+pub const POINT_ID: &str = "languages";
+
+/// Decides whether a plugin may start a program: the approved file for a
+/// granted `process:` capability, or `None`.
+pub type ProcessPolicy = dyn Fn(&str, &Capability) -> Option<ProgramPin> + Send + Sync;
+
+/// Languages of enabled plugins, in commit order.
+#[derive(Default)]
+pub struct PluginLanguages {
+    items: RwLock<Vec<(u64, String, LanguageConfig)>>,
+    seq: AtomicU64,
+    revision: AtomicU64,
+    policy: RwLock<Option<Arc<ProcessPolicy>>>,
+}
+
+impl PluginLanguages {
+    pub fn new() -> Arc<Self> {
+        Arc::new(Self::default())
+    }
+
+    pub fn all(&self) -> Vec<LanguageConfig> {
+        self.items.read().iter().map(|(_, _, c)| c.clone()).collect()
+    }
+
+    /// `(plugin id, definition)` pairs.
+    pub fn with_owners(&self) -> Vec<(String, LanguageConfig)> {
+        self.items.read().iter().map(|(_, p, c)| (p.clone(), c.clone())).collect()
+    }
+
+    /// The plugin that contributes language `id`.
+    pub fn owner_of(&self, id: &ide_core::LanguageId) -> Option<String> {
+        self.items.read().iter().find(|(_, _, c)| &c.id == id).map(|(_, p, _)| p.clone())
+    }
+
+    /// Changes whenever [`effective`](Self::effective) may give something else.
+    pub fn revision(&self) -> u64 {
+        self.revision.load(Ordering::Acquire)
+    }
+
+    /// Who may start what. Without a policy no plugin program starts.
+    pub fn set_process_policy(&self, policy: Arc<ProcessPolicy>) {
+        *self.policy.write() = Some(policy);
+        self.invalidate();
+    }
+
+    /// Grants changed: registries recompute [`effective`](Self::effective).
+    pub fn invalidate(&self) {
+        self.revision.fetch_add(1, Ordering::Release);
+    }
+
+    /// The definitions as they take effect: servers and the debugger whose
+    /// program is granted are pinned to the approved file, the others are
+    /// left out.
+    pub fn effective(&self) -> Vec<LanguageConfig> {
+        let policy = self.policy.read().clone();
+        let pin = |plugin: &str, program: &str| {
+            policy.as_ref().and_then(|p| p(plugin, &Capability::Process(program.to_owned())))
+        };
+        self.items
+            .read()
+            .iter()
+            .map(|(_, plugin, cfg)| {
+                let mut cfg = cfg.clone();
+                cfg.language_servers.retain_mut(|s| {
+                    s.pinned = pin(plugin, &s.command);
+                    s.pinned.is_some()
+                });
+                let debugger_pin = cfg.debugger.as_ref().and_then(|d| pin(plugin, &d.command));
+                match (&mut cfg.debugger, debugger_pin) {
+                    (Some(d), Some(p)) => d.pinned = Some(p),
+                    (debugger, _) => *debugger = None,
+                }
+                cfg
+            })
+            .collect()
+    }
+
+    /// Adds a definition until the returned handle is dropped.
+    pub fn add(self: &Arc<Self>, plugin: String, cfg: LanguageConfig) -> Disposable {
+        let seq = self.seq.fetch_add(1, Ordering::Relaxed);
+        self.items.write().push((seq, plugin, cfg));
+        self.revision.fetch_add(1, Ordering::Release);
+        let weak = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(this) = weak.upgrade() {
+                this.items.write().retain(|(s, _, _)| *s != seq);
+                this.revision.fetch_add(1, Ordering::Release);
+            }
+        })
+    }
+}
+
+pub struct LanguagesPoint {
+    store: Arc<PluginLanguages>,
+}
+
+impl LanguagesPoint {
+    pub fn new(store: Arc<PluginLanguages>) -> Self {
+        Self { store }
+    }
+}
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Decl {
+    /// A `languages/<id>.toml`-style file in the package.
+    path: PathBuf,
+}
+
+/// Parses and checks one language definition.
+pub fn parse_definition(src: &str) -> Result<LanguageConfig, String> {
+    let cfg: LanguageConfig = toml::from_str(src).map_err(|e| format!("invalid language definition: {e}"))?;
+    validate_definition(&cfg)?;
+    Ok(cfg)
+}
+
+/// Checks a definition that did not come from a package file (a remote sync).
+pub fn validate_definition(cfg: &LanguageConfig) -> Result<(), String> {
+    let id = cfg.id.as_str();
+    if id.is_empty() || cfg.name.trim().is_empty() {
+        return Err("language `id` and `name` must not be empty".into());
+    }
+    if !id.chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '-' | '_' | '.' | '+')) || id.len() > 64 {
+        return Err(format!("invalid language id {id:?}"));
+    }
+    if let Some(first) = &cfg.first_line {
+        regex_lite::Regex::new(first).map_err(|e| format!("invalid first-line pattern: {e}"))?;
+    }
+    Ok(())
+}
+
+/// The programs a definition starts, as `process:` capabilities.
+pub fn required_capabilities(cfg: &LanguageConfig) -> Vec<Capability> {
+    let mut caps: Vec<Capability> = Vec::new();
+    let servers = cfg.language_servers.iter().map(|s| s.command.as_str());
+    for program in servers.chain(cfg.debugger.iter().map(|d| d.command.as_str())) {
+        let cap = Capability::Process(program.to_owned());
+        if !program.trim().is_empty() && !caps.contains(&cap) {
+            caps.push(cap);
+        }
+    }
+    caps
+}
+
+impl ExtensionPoint for LanguagesPoint {
+    fn id(&self) -> &'static str {
+        POINT_ID
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Workspace
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let decl: Decl = decode(POINT_ID, decl)?;
+        let src = pkg.read_text(&decl.path)?;
+        let cfg = parse_definition(&src).map_err(|e| format!("{}: {e}", decl.path.display()))?;
+        let caps = required_capabilities(&cfg);
+        let (store, plugin, key, label) = (
+            self.store.clone(),
+            pkg.id().to_owned(),
+            cfg.id.to_string(),
+            format!("{} (.{})", cfg.name, cfg.extensions.join(", .")),
+        );
+        let mut prepared = Prepared::new(label, move || Ok(store.add(plugin, cfg))).key(key).file(decl.path);
+        for cap in caps {
+            prepared = prepared.capability(cap);
+        }
+        Ok(prepared)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ide_extension::{ExtensionRegistry, Manifest};
+
+    #[test]
+    fn languages_point_registers_and_requires_process_capabilities() {
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::create_dir(tmp.path().join("l")).unwrap();
+        std::fs::write(
+            tmp.path().join("l/sol.toml"),
+            "id = \"solidity\"\nname = \"Solidity\"\nextensions = [\"sol\"]\n\
+             [[language-servers]]\nname = \"solc\"\ncommand = \"solc\"\nargs = [\"--lsp\"]\n",
+        )
+        .unwrap();
+        let src = "id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n\
+                   [[contributes.languages]]\npath = \"l/sol.toml\"";
+        let pkg = Package::new(Manifest::parse(src).unwrap(), tmp.path().to_path_buf());
+        let store = PluginLanguages::new();
+        let reg = ExtensionRegistry::new();
+        reg.register(Arc::new(LanguagesPoint::new(store.clone()))).unwrap();
+        let set = reg.prepare(&pkg).unwrap();
+        assert_eq!(set.capabilities, [Capability::Process("solc".into())]);
+        assert_eq!(set.files, [PathBuf::from("l/sol.toml")]);
+        reg.commit(set).unwrap();
+        assert_eq!(store.all()[0].id.as_str(), "solidity");
+        reg.dispose_plugin("p");
+        assert!(store.all().is_empty());
+
+        let bad = |def: &str| parse_definition(def).unwrap_err();
+        assert!(bad("not toml [").contains("invalid language"));
+        assert!(bad("id = \"\"\nname = \"x\"").contains("must not be empty"));
+        assert!(bad("id = \"a b\"\nname = \"x\"").contains("invalid language id"));
+    }
+
+    #[test]
+    fn registry_overlay_follows_the_store_and_the_grants() {
+        use crate::LanguageRegistry;
+        use ide_core::LanguageId;
+        use std::path::Path;
+
+        let base = LanguageRegistry::load(None).unwrap();
+        let store = PluginLanguages::new();
+        base.attach_plugins(store.clone());
+        // Projects fork before plugins load: the fork follows the store anyway.
+        let project = base.fork();
+        assert_eq!(project.detect(Path::new("a.sol"), None), LanguageId::plain_text());
+
+        let sol = parse_definition(
+            "id = \"solidity\"\nname = \"Solidity\"\nextensions = [\"sol\"]\n\
+             [[language-servers]]\nname = \"solc\"\ncommand = \"solc\"\n\
+             [debugger]\nadapter = \"soldbg\"\ncommand = \"soldbg\"\n",
+        )
+        .unwrap();
+        let rust_clash = parse_definition("id = \"rust\"\nname = \"Evil Rust\"\nextensions = [\"rs\"]").unwrap();
+        let ext_clash = parse_definition(
+            "id = \"rusty\"\nname = \"Rusty\"\nextensions = [\"rs\", \"rsy\"]\nfilenames = [\"Cargo.lock\"]",
+        )
+        .unwrap();
+        let _sol = store.add("acme.sol".into(), sol);
+        let _clash = store.add("acme.evil".into(), rust_clash);
+        let _ext = store.add("acme.evil".into(), ext_clash);
+
+        assert_eq!(project.detect(Path::new("a.sol"), None).as_str(), "solidity");
+        let rust = project.get(&LanguageId::new("rust")).unwrap();
+        assert_eq!(rust.name, "Rust", "built-in definitions win on id clashes");
+        assert_eq!(project.detect(Path::new("main.rs"), None).as_str(), "rust", "and keep their extensions");
+        assert_ne!(project.detect(Path::new("Cargo.lock"), None).as_str(), "rusty", "and file names");
+        assert_eq!(project.detect(Path::new("x.rsy"), None).as_str(), "rusty");
+        // No policy: the language works, its programs do not start.
+        let cfg = project.get(&LanguageId::new("solidity")).unwrap();
+        assert!(cfg.language_servers.is_empty() && cfg.debugger.is_none());
+
+        let pin = ProgramPin { path: "/opt/solc".into(), hash: "h".into() };
+        let granted = pin.clone();
+        store.set_process_policy(Arc::new(move |plugin, cap| {
+            (plugin == "acme.sol" && *cap == Capability::Process("solc".into())).then(|| granted.clone())
+        }));
+        let cfg = project.get(&LanguageId::new("solidity")).unwrap();
+        assert_eq!(cfg.language_servers[0].pinned.as_ref(), Some(&pin));
+        assert!(cfg.debugger.is_none(), "soldbg was not granted");
+
+        drop(_sol);
+        assert_eq!(project.detect(Path::new("a.sol"), None), LanguageId::plain_text());
+        assert!(base.get(&LanguageId::new("solidity")).is_none());
+    }
+
+    #[test]
+    fn program_pins_check_the_file() {
+        let tmp = tempfile::tempdir().unwrap();
+        let bin = tmp.path().join("tool");
+        std::fs::write(&bin, "v1").unwrap();
+        let pin = ProgramPin { path: bin.clone(), hash: ide_extension::ledger::file_hash(&bin).unwrap() };
+        assert_eq!(pin.verify().unwrap(), bin);
+        std::fs::write(&bin, "v2").unwrap();
+        assert!(pin.verify().unwrap_err().contains("changed since it was approved"));
+    }
+}