Merge pull request #3578 from d3grando/fix-3432

🤖 Agent: proven on union/pt1-w3 by pr-triage-1: every vanilla harness this branch reaches passes (mob_ai and the equine ones included), clippy -D warnings and the horizon-client tests pass (the one failing test is main's own, fixed by #3851), and the last commit only reorders an import for rustfmt. Thank you!

.claude/skills/vanilla-parity/SKILL.md

@@ -0,0 +1,76 @@
+---
+name: vanilla-parity
+description: Fix a Horizon bug or gap so it behaves 1:1 like vanilla 26.3, starting from the port ledger (tools/port_ledger.py) instead of grepping. Use for any issue, Discord report or PR that makes Horizon match vanilla: "X doesn't work like in Java", a missing sound, particle, animation, mob behaviour, block rule, screen or packet.
+---
+
+# Vanilla parity with the port ledger
+
+The port ledger pairs every vanilla method with the Rust fn that ports it (or says it is missing, or needs
+no port) and lists where a port isn't wired like vanilla. Ask it first; grep only for what it can't answer.
+Full reference: `docs/port-ledger.md`.
+
+## 0. Have a fresh ledger
+
+```sh
+python3 tools/port_ledger.py build          # ~20 s; again after pulling main
+```
+
+It needs the vanilla jar (the launcher's `versions/26.3/26.3.jar`, or `--jar`) and/or the lab's decompiled
+sources (`python3 tools/lab.py decompile`, or `--sources DIR`). If `build` says it has no vanilla code, run
+the lab first; don't guess vanilla from memory.
+
+## 1. From the report to the code
+
+```sh
+python3 tools/port_ledger.py issue 3236                      # a GitHub issue number
+python3 tools/port_ledger.py issue "mooshroom stays red after lightning"   # or the report's text
+```
+
+It ranks the vanilla classes the report names and lists, per class, its Rust home files, where each method is
+ported, and the known gaps (`missing` rows from the verdict map, seam/client/drift gaps). Often the cause is
+already written there ("Type is not saved"). Then drill in:
+
+```sh
+python3 tools/port_ledger.py where MushroomCow.readAdditionalSaveData   # ports, callers, callees, gaps
+python3 tools/port_ledger.py class MushroomCow                          # every method: where, or missing
+python3 tools/port_ledger.py what crates/horizon-client/src/mobs/farm.rs:120   # which vanilla method a fn ports
+```
+
+A ledger answer is a lead, not a verdict: about 1 in 12 map rows is wrong. Read the vanilla method (path and
+line are in the output) and the Rust fn before changing anything.
+
+## 2. Port it the vanilla way
+
+- Translate the vanilla method, don't reinvent it: same order of operations, same constants, the same random
+  draws in the same order (`horizon_core::random`), Java `Math` through `horizon_core::jmath`.
+- Open the fn's doc with the vanilla method it ports: `` /// `MushroomCow.readAdditionalSaveData`: ... ``.
+  That one line is what makes the next agent find it.
+- Fix the path players run: single player is a client of the integrated server, so server logic lives in
+  `game/lan*.rs` and `src/lan/`, and what only the client's copy shows (particles, local sounds, hand
+  animation) must be reached from `game/remote*.rs`. A fix on the old in-frame path alone fixes nothing.
+- Look at the neighbours the ledger lists for the same class: a `client` or `seam` gap next to your fix is
+  usually the same bug on the other path.
+
+## 3. Before the PR
+
+```sh
+python3 tools/port_ledger.py check --base origin/main
+```
+
+It lists the ports your branch touches with their open gaps, citations to add, stale citations, and (against
+the base) the gaps the branch closes and opens. Close what belongs to your fix, cite what you ported, leave
+no new stale citation. If you ported a method the verdict map called `missing`, change its row in
+`tools/port_map/*.tsv` to `port` with the fn (`file.rs::Owner::fn`) and run
+`python3 tools/port_ledger.py map-check tools/port_map/<file>.tsv`.
+
+Then the usual: the harness for the area (`docs/architecture.md`), `cargo check`/tests per `AGENTS.md`, and
+a small PR that says which vanilla method it now matches.
+
+## Finding work
+
+```sh
+python3 tools/port_ledger.py gaps --kind seam      # ported on two paths, wired on one: the best leads
+python3 tools/port_ledger.py gaps --kind client    # client-only effects the server path never reaches
+python3 tools/port_ledger.py gaps --kind drift     # a port missing a sound, particle, item or constant
+rg -n "player:" tools/port_map/*.tsv               # missing behaviour a player would see
+```

.githooks/pre-commit

@@ -1,2 +1,11 @@
 #!/bin/sh
-exec python3 tools/check_public_tree.py
+# Git for Windows puts a `python3` on PATH that is only the Microsoft Store
+# stub: it prints "Python" and exits non-zero, so the hook fails with no other
+# output. Use the first name that actually runs Python 3.
+for py in python3 python py; do
+    if "$py" -c "import sys; sys.exit(sys.version_info < (3,))" >/dev/null 2>&1; then
+        exec "$py" tools/check_public_tree.py
+    fi
+done
+echo "check_public_tree: no working Python 3 found" >&2
+exit 1

.githooks/pre-push

@@ -1,2 +1,11 @@
 #!/bin/sh
-exec python3 tools/check_public_tree.py --pre-push
+# Git for Windows puts a `python3` on PATH that is only the Microsoft Store
+# stub: it prints "Python" and exits non-zero, so the hook fails with no other
+# output. Use the first name that actually runs Python 3.
+for py in python3 python py; do
+    if "$py" -c "import sys; sys.exit(sys.version_info < (3,))" >/dev/null 2>&1; then
+        exec "$py" tools/check_public_tree.py --pre-push
+    fi
+done
+echo "check_public_tree: no working Python 3 found" >&2
+exit 1

.github/pull_request_template.md

@@ -1,3 +1,5 @@
+<!-- Opened by an AI agent? First line: "> 🤖 Opened by <your GitHub login>'s AI agent (<tool, model>), not by <your GitHub login> personally." Use your own login, not someone else's. -->
+
 ## What and why
 
 <!-- What this changes, and why. Link the issue it fixes ("Fixes #123"). -->

.github/workflows/cancel-on-close.yml

@@ -16,12 +16,14 @@ jobs:
           GH_TOKEN: ${{ github.token }}
           REPO: ${{ github.repository }}
           BRANCH: ${{ github.event.pull_request.head.ref }}
-          SHA: ${{ github.event.pull_request.head.sha }}
+          HEAD_REPO: ${{ github.event.pull_request.head.repo.full_name }}
         run: |
+          # Every head the pull request had, not only its last: a run-parity label added on an older head left that
+          # run queued after the merge (#3104, 2026-10-29). Its branch in its own repository names its runs (another
+          # fork can have a branch of the same name).
           for status in queued in_progress waiting pending requested; do
-            gh run list -R "$REPO" --branch "$BRANCH" --status "$status" --limit 100 \
-              --json databaseId,event,headSha \
-              -q ".[] | select(.event == \"pull_request\" and .headSha == \"$SHA\") | .databaseId"
+            gh api -X GET "repos/$REPO/actions/runs" -f branch="$BRANCH" -f event=pull_request -f status="$status" \
+              -f per_page=100 --jq ".workflow_runs[] | select(.head_repository.full_name == \"$HEAD_REPO\") | .id"
           done | sort -u | while read -r id; do
             gh run cancel -R "$REPO" "$id" || true
           done

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
         run: |
           cargo +stable fmt --all -- --check
           # With the game's code mods (on in every release build, off by default).
-          cargo +stable clippy --workspace --all-targets --features horizon-client/mods -- -D warnings
+          cargo +stable clippy --workspace --all-targets -- -D warnings
           # The server build (released as horizon-engine): the game without sound or controllers.
           cargo +stable clippy -p horizon-client --all-targets --no-default-features -- -D warnings
       # Libraries, binaries and integration tests, then doc tests: not the ~275 examples, which clippy above already
@@ -71,11 +71,11 @@ jobs:
       - name: Test Rust core and voxel kernel correctness
         if: steps.rust.outputs.required != 'false'
         run: |
-          cargo +stable test --workspace --lib --bins --tests --features horizon-client/mods,horizon-mods/pack
+          cargo +stable test --workspace --lib --bins --tests --features horizon-mods/pack
           # The full content-root tests (#[ignore]d: minutes each on a laptop). The same build as above; they need the
           # prepared vanilla data, so without it they pass at once.
-          cargo +stable test --workspace --lib --features horizon-client/mods,horizon-mods/pack mod_content::tests:: -- --ignored
-          cargo +stable test --workspace --doc --features horizon-client/mods,horizon-mods/pack
+          cargo +stable test --workspace --lib --features horizon-mods/pack mod_content::tests:: -- --ignored
+          cargo +stable test --workspace --doc --features horizon-mods/pack
   # The launcher is its own workspace (launcher/Cargo.toml), so verify's cargo runs never build it. A pull request that
   # changes it or a crate it builds is checked here, and so is every push to main: two pull requests can each pass
   # alone and break it together (#2059 and the registry ratings did, 2026-10-26).

.github/workflows/game-build.yml

@@ -37,9 +37,10 @@ permissions:
 jobs:
   exporters:
     # This runner holds the maintainer's own pinned Minecraft jars. Only our classes leave it. An untrusted build
-    # goes to the Mac mini runner that already runs pull requests' parity jobs (macOS + horizon-game:
-    # ludovics-mac-mini), never the release runner (MAC_RUNNER: ludovics-mac-mini-release) nor parity-main's.
-    runs-on: ${{ inputs.trusted && vars.MAC_RUNNER || fromJSON('["self-hosted", "macOS", "horizon-game"]') }}
+    # goes to the Mac mini's nightly runner (macOS + horizon-nightly: ludovics-mac-mini-nightly, beside the one that
+    # runs pull requests' parity jobs, so a nightly never waits behind their queue), never the release runner
+    # (MAC_RUNNER: ludovics-mac-mini-release) nor parity-main's.
+    runs-on: ${{ inputs.trusted && vars.MAC_RUNNER || fromJSON('["self-hosted", "macOS", "horizon-nightly"]') }}
     # Three full preparations (two isolated, one batched) besides the compile.
     timeout-minutes: 60
     steps:
@@ -103,7 +104,7 @@ jobs:
             mac: true
             dir: horizon-macos-arm64
             asset: horizon-macos-arm64.zip
-    runs-on: ${{ matrix.mac && (inputs.trusted && vars.MAC_RUNNER || fromJSON('["self-hosted", "macOS", "horizon-game"]')) || matrix.os }}
+    runs-on: ${{ matrix.mac && (inputs.trusted && vars.MAC_RUNNER || fromJSON('["self-hosted", "macOS", "horizon-nightly"]')) || matrix.os }}
     # Notarizing the zip can take a few minutes.
     timeout-minutes: ${{ matrix.mac && 60 || 40 }}
     env:
@@ -137,8 +138,7 @@ jobs:
         if: runner.os == 'Linux'
         run: sudo apt-get update && sudo apt-get install -y --no-install-recommends libasound2-dev libudev-dev
       - name: Build the client, horizon-ctl, horizon-prepare and horizon-server
-        # `horizon-client/mods`: every released game runs code mods (the feature is off in dev builds).
-        run: cargo build --release --locked --features horizon-client/mods -p horizon-client --bin horizon-client --bin horizon-ctl -p horizon-prepare --bin horizon-prepare -p horizon-server --bin horizon-server
+        run: cargo build --release --locked -p horizon-client --bin horizon-client --bin horizon-ctl -p horizon-prepare --bin horizon-prepare -p horizon-server --bin horizon-server
       - name: Every program the release folder takes was built
         run: |
           for binary in horizon-client horizon-ctl horizon-prepare horizon-server; do
@@ -266,9 +266,8 @@ jobs:
         run: |
           set -euo pipefail
           # After the client is packaged: target/release/horizon-client is rebuilt without the audio and
-          # controllers features, so it needs neither libasound nor libudev (minimal server images lack them),
-          # and with code mods like the client.
-          cargo build --release --locked -p horizon-client --no-default-features --features mods --bin horizon-client
+          # controllers features, so it needs neither libasound nor libudev (minimal server images lack them).
+          cargo build --release --locked -p horizon-client --no-default-features --bin horizon-client
           cargo run --locked -p xtask -- package-server target/release/horizon-client "dist/${{ matrix.server_dir }}"
           folder="dist/${{ matrix.server_dir }}"
           python3 tools/check_imports.py --server "$folder/horizon-engine" "$folder/horizon-server" "$folder/horizon-prepare"

.github/workflows/launcher.yml

@@ -192,9 +192,11 @@ jobs:
           retry "$launcher" install latest
           "$launcher" versions --installed
           "$launcher" links --json
-          clients=("$HORIZON_LAUNCHER_HOME"/versions/v*/horizon-client*)
+          # `install latest` is the Nightly since #3342 (versions/nightly-<date>-<commit>), a vX.Y.Z before.
+          clients=("$HORIZON_LAUNCHER_HOME"/versions/*/horizon-client*)
           client="${clients[0]}"
           echo "installed client: $client"
+          [[ -f "$client" ]] || { echo "::error::no game installed under versions/"; exit 1; }
           # The game's Linux build is the game's to keep portable (release.yml checks it): a
           # release linked to a Nix store is a warning here, not a broken launcher.
           soft() { if [[ "$RUNNER_OS" == "Linux" ]]; then "$@" || echo "::warning::$* failed"; else "$@"; fi; }

.github/workflows/nightly-build.yml

@@ -1,11 +1,12 @@
 name: nightly build
 run-name: nightly build${{ inputs.request && format(' (request {0})', inputs.request) || '' }}
-# The opt-in Nightly channel (docs/release-flow.md "Nightly"; Ludovic, 2026-10-27). Once a night, and when a trusted
+# The Nightly, the only build Horizon ships since 2026-10-28 (docs/release-flow.md "Nightly"; Ludovic). When the batch
+# train decides (release.yml, with the commit as `base`), once a night, and when a trusted
 # reviewer asks (`/nightly 2640 2642`, nightly-command.yml), it builds main plus the pull requests the reviewers
-# picked, merged in order (tools/ci/nightly_set.py). With none picked, it builds the newest union branch on origin
-# (union/<agent>-<name>: main plus pull requests the contribution gate proved together), or main when no union is
-# newer. It publishes the result as the `nightly` pre-release. Launchers install it only for players who turn Nightly
-# on. The previous nightly stays a week as nightly-<date>.
+# picked, merged in order (tools/ci/nightly_set.py), or main alone with none picked. Main is its newest commit where
+# checks and parity-main passed (or the `base` input), as for a release, and no Nightly is published while a
+# release-blocker is open. It publishes the result as the `nightly` pre-release, which every launcher and
+# `horizon-server update` install. The previous nightly stays a week as nightly-<date>.
 #
 # Why the signing key never meets the pull requests' code:
 # - `pick` merges the picked heads onto main with `git merge-tree --write-tree`: git objects only, no working tree,
@@ -13,11 +14,11 @@ run-name: nightly build${{ inputs.request && format(' (request {0})', inputs.req
 #   request that changes a path CODEOWNERS gives to Ludovic (this folder, tools/ci/, the signing and update code),
 #   pushes the merge as nightly/build-<date>-<n> and saves the set on the nightly-state branch.
 # - This file, game-build.yml and every script below run from main's copy: a schedule runs the default branch, and
-#   `uses: ./…` takes the caller's commit. The union's own .github/ is never read.
+#   `uses: ./…` takes the caller's commit. A picked pull request's own .github/ is never read.
 # - `build` (game-build.yml, `trusted: false`) never reaches a release's tools: its macOS jobs run on the runner
 #   that already runs pull requests' parity jobs, never the release runner; its Rust cache has its own key and is
 #   never saved; and releases don't read the machine's shared sccache.
-# - `build` (game-build.yml) checks out and compiles the merge (or the union) with no secrets: its token reads contents only and
+# - `build` (game-build.yml) checks out and compiles the merge with no secrets: its token reads contents only and
 #   isn't kept in the checkout; the macOS programs are signed ad hoc (Developer ID needs the runner's keychain,
 #   which stays locked for nightlies).
 # - `sign` is the only job with RELEASE_SIGNING_KEY. It checks out nothing but main's tools/ci/sign_release.sh, which
@@ -25,6 +26,9 @@ run-name: nightly build${{ inputs.request && format(' (request {0})', inputs.req
 #   names the channel ("horizon release nightly"), so a nightly's signature can't pass for a release's.
 # - `publish` verifies the signature with main's horizon-release-sign, checks the smoke test, and only then moves
 #   the tag. Like sign, it never executes what build produced.
+# - The source ships with the build: `pick` writes horizon-source.tar.gz with `git archive` (git objects again, nothing
+#   run), `sign` signs it with the builds, and `publish` attaches it and tags the commit nightly-source/<date>-<short>
+#   for good (the dated release and the build branch go after 7 days; native mods pin the commit: docs/native-mods.md).
 #   gh workflow run "nightly build"                     # now (skips when the pick is the same commit as last night's)
 #   gh workflow run "nightly build" -f force=true       # build and publish even if unchanged
 #   gh workflow run "nightly build" -f dry_run=true     # build and sign with a throwaway key, publish nothing
@@ -53,6 +57,14 @@ on:
         description: A dry run's own set, `2640@<head> 2642@<head>` (the saved set stays)
         type: string
         default: ''
+      base:
+        description: The commit of main to build on (default main's newest with green checks and parity-main)
+        type: string
+        default: ''
+      urgent:
+        description: Past the day's cap of 12 builds (the train, for a release-now pull request or a forced run)
+        type: boolean
+        default: false
 permissions:
   contents: read
 concurrency:
@@ -68,6 +80,7 @@ jobs:
       contents: write       # nightly/build-<date>-<n> and the nightly-state branch (main is protected)
       issues: write         # says in the thread when the picked pull requests conflict
       pull-requests: write
+      actions: read         # main's newest green checks and parity-main runs (the base)
     outputs:
       build: ${{ steps.pick.outputs.build }}
       sha: ${{ steps.pick.outputs.sha }}
@@ -76,6 +89,7 @@ jobs:
       date: ${{ steps.pick.outputs.date }}
       version: ${{ steps.pick.outputs.version }}
       nightly: ${{ steps.pick.outputs.nightly }}
+      source_tag: ${{ steps.pick.outputs.source_tag }}
       dry_run: ${{ steps.mode.outputs.dry_run }}
     steps:
       - uses: actions/checkout@v4
@@ -92,6 +106,8 @@ jobs:
           DRY_RUN: ${{ steps.mode.outputs.dry_run }}
           NIGHTLY_ISSUE: ${{ inputs.issue }}
           NIGHTLY_PRS: ${{ inputs.prs }}
+          NIGHTLY_BASE: ${{ inputs.base }}
+          NIGHTLY_URGENT: ${{ inputs.urgent }}
         run: |
           python3 tools/ci/nightly.py pick ${FORCE:+--force} | tee -a "$GITHUB_STEP_SUMMARY"
           { echo; cat nightly-notes.md; } >> "$GITHUB_STEP_SUMMARY"
@@ -103,6 +119,18 @@ jobs:
           GH_TOKEN: ${{ github.token }}
         run: |
           { echo "### nightly/build-* branches"; python3 tools/ci/nightly.py prune-builds --days 7; } | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: The source of the build (horizon-source.tar.gz)
+        if: steps.pick.outputs.build == 'true'
+        env:
+          SHA: ${{ steps.pick.outputs.sha }}
+        run: git archive --format=tar.gz --prefix="horizon-${SHA:0:7}/" -o horizon-source.tar.gz "$SHA"
+      - uses: actions/upload-artifact@v4
+        if: steps.pick.outputs.build == 'true'
+        with:
+          name: horizon-source
+          path: horizon-source.tar.gz
+          if-no-files-found: error
+          retention-days: 3
       - uses: actions/upload-artifact@v4
         with:
           name: nightly-notes
@@ -144,7 +172,7 @@ jobs:
           EPHEMERAL: ${{ needs.pick.outputs.dry_run == 'true' && 'yes' || '' }}
         run: |
           bash tools/ci/sign_release.sh nightly dist/horizon-linux-x86_64.tar.gz dist/horizon-windows-x64.zip \
-            dist/horizon-macos-arm64.zip dist/horizon-server-linux-x86_64.tar.gz
+            dist/horizon-macos-arm64.zip dist/horizon-server-linux-x86_64.tar.gz dist/horizon-source.tar.gz
       - uses: actions/upload-artifact@v4
         with:
           name: signature
@@ -164,6 +192,7 @@ jobs:
     timeout-minutes: 15
     permissions:
       contents: write
+      issues: read          # the open release-blocker issues (gate)
     steps:
       - uses: actions/checkout@v4
         with:
@@ -178,27 +207,39 @@ jobs:
         run: |
           key=(); [[ -n "$EPHEMERAL" ]] && key=(--key "$(cat dist/ephemeral.pub)")
           cargo run --locked --quiet -p horizon-release-sign -- verify --tag nightly --publishing "${key[@]}" dist
-      - name: The smoke test drew a world
-        # No release-blocker check: a nightly is how blockers get tested.
-        run: python3 tools/release_train.py gate --kind game --smoke dist/smoke-test.json
+      - name: Ready to publish (the smoke test drew a world, no release-blocker is open)
+        # Right before publishing, as for a release: an issue labelled while the builds ran still holds it. A dry run
+        # only reports what a real run would do (that is how a blocker's fix is tried).
+        env:
+          GH_TOKEN: ${{ github.token }}
+          DRY_RUN: ${{ needs.pick.outputs.dry_run }}
+        run: |
+          if ! python3 tools/release_train.py gate --kind game --smoke dist/smoke-test.json --blockers; then
+            [[ "$DRY_RUN" == true ]] || { echo "::error::Nothing published"; exit 1; }
+            echo "::warning::A real run would publish nothing"
+          fi
       - name: Publish as the `nightly` pre-release
         if: needs.pick.outputs.dry_run != 'true'
         env:
           GH_TOKEN: ${{ github.token }}
           SHA: ${{ needs.pick.outputs.sha }}
           DATE: ${{ needs.pick.outputs.date }}
+          SOURCE_TAG: ${{ needs.pick.outputs.source_tag }}
         run: |
           set -euo pipefail
           python3 tools/ci/nightly.py rotate
           signature=(); [[ -f dist/SHA256SUMS.sig ]] && signature=(dist/SHA256SUMS.sig)
-          # A pre-release, never GitHub's latest: launchers on the release channel never see it.
+          # A pre-release, never GitHub's latest: the latest stays the last vX.Y.Z, which launchers and servers from
+          # before the Nightly-only switch keep (they don't read Nightlies).
           gh release create nightly --prerelease --latest=false --target "$SHA" \
             --title "Nightly $DATE · ${SHA:0:7}" --notes-file dist/nightly-notes.md \
             "dist/horizon-linux-x86_64.tar.gz#Nightly game files: Linux (horizon-linux-x86_64.tar.gz)" \
             "dist/horizon-windows-x64.zip#Nightly game files: Windows (horizon-windows-x64.zip)" \
             "dist/horizon-macos-arm64.zip#Nightly game files: macOS (horizon-macos-arm64.zip)" \
             "dist/horizon-server-linux-x86_64.tar.gz#Nightly dedicated server for Linux (horizon-server-linux-x86_64.tar.gz)" \
+            "dist/horizon-source.tar.gz#Source of this Nightly, commit ${SHA:0:7} (horizon-source.tar.gz; kept for good as the tag $SOURCE_TAG)" \
             dist/SHA256SUMS "${signature[@]}" dist/smoke-test.json
+          python3 tools/ci/nightly.py keep-source "$SHA" "$DATE"
           python3 tools/ci/nightly.py prune --days 7
       - name: Dry run, the nightly that would be published
         if: needs.pick.outputs.dry_run == 'true'
@@ -230,7 +271,7 @@ jobs:
           elif [[ "$PUBLISHED" == success && "$DRY_RUN" == true ]]; then
             text="the dry run built and signed $NAME; nothing was published. $RUN"
           elif [[ "$PUBLISHED" == success ]]; then
-            text="published $NAME: https://github.com/$GITHUB_REPOSITORY/releases/tag/nightly. Launchers with Nightly on install it at their next start."
+            text="published $NAME: https://github.com/$GITHUB_REPOSITORY/releases/tag/nightly. Launchers install it at their next check."
           else
             text="the build failed, nothing was published: $RUN"
           fi

.github/workflows/release.yml

@@ -1,22 +1,15 @@
 name: release
-# Automatic game releases (docs/release-flow.md). After every green `checks` run on main, every 10 minutes (so a
-# release waiting for merges to settle goes out without another merge) and by hand, tools/release_train.py decides,
-# for a commit whose checks and parity-main (the vanilla harnesses on main) both passed:
-# a release when 5 pull requests merged since the last one changed what players run and the newest merged 5 minutes
-# ago, or when the oldest has waited 6 hours, or at once for a pull request labelled release-now.
-# RELEASES_PAUSED=1 (repository variable) stops them; so does an open issue labelled release-blocker, forced runs too.
-# Builds Linux (an older Ubuntu, so the binary runs on any recent distribution and on NixOS through nix-ld) and
-# Windows on GitHub, macOS on the Mac mini's runner (MAC_RUNNER=macos-latest sends it to GitHub), then
-# publishes vX.Y.Z on the release line in .github/release-line.txt (docs/versioning.md; without it, the dated
-# vYYYY.MM.DD[.N] from before 0.2) with notes from the merged pull requests, as the release and GitHub's latest: one
-# channel, which launchers, `horizon-server update` and install.sh follow at once. So it is published only after the
-# checks that used to gate a promotion pass in this run: the Mac mini's smoke test drew a world, and no release-blocker
-# is open (tools/release_train.py gate); otherwise nothing is published. macOS: with the repository variable
-# MACOS_SIGN_IDENTITY set, the programs are signed with
-# Developer ID and the hardened runtime and the zip is notarized, from the runner's signing keychain
-# (packaging/macos/README.md); unset (forks), ad hoc.
-#   gh workflow run release --ref <branch>                       # dry run: builds and notes, publishes nothing
-#   gh workflow run release -f dry_run=false -f force=true       # on main: release now, whatever the rules say
+# Automatic game releases (docs/release-flow.md). Horizon ships only the Nightly since 2026-10-28 (Ludovic): this
+# workflow is the batch train that decides when a new Nightly goes out, and `nightly build` (nightly-build.yml) builds,
+# signs and publishes it. After every green `checks` run on main, every 10 minutes (so a batch waiting for merges to
+# settle goes out without another merge) and by hand, tools/release_train.py decides, for a commit whose checks and
+# parity-main (the vanilla harnesses on main) both passed: a Nightly when 5 pull requests merged since the published
+# Nightly changed what players run and the newest merged 5 minutes ago, or when the oldest has waited 6 hours, or at
+# once for a pull request labelled release-now. RELEASES_PAUSED=1 (repository variable) stops it; so does an open issue
+# labelled release-blocker, forced runs too (nightly-build.yml checks again before publishing). One Nightly build at a
+# time, at most 12 a day (release-now and force=true pass the cap). No `vX.Y.Z` game release is made any more.
+#   gh workflow run release --ref <branch>                       # dry run: decides, starts nothing
+#   gh workflow run release -f dry_run=false -f force=true       # on main: a Nightly now, whatever the rules say
 on:
   workflow_run:
     # A game release ships a commit both passed on (parity-main runs on batches: the newest commit it passed on).
@@ -28,17 +21,19 @@ on:
   workflow_dispatch:
     inputs:
       dry_run:
-        description: Build everything and write the notes, but publish nothing
+        description: Decide only; start no Nightly build
         type: boolean
         default: true
       force:
-        description: Release even without player-facing changes, before merges settle or while paused
+        description: A Nightly even without player-facing changes, before merges settle, while paused or past the day's cap
         type: boolean
         default: false
 permissions:
   contents: read
   # The open release-blocker issues (decide).
   issues: read
+  # The checks, parity-main and nightly build runs (decide).
+  actions: read
 concurrency:
   # One release at a time. A hand-started dry run publishes nothing, so it can't race a real release: it gets a
   # group of its own. In the shared group, a release queued behind it replaced it as the pending run and GitHub
@@ -54,9 +49,8 @@ jobs:
     timeout-minutes: 10
     outputs:
       release: ${{ steps.decide.outputs.release }}
-      tag: ${{ steps.decide.outputs.tag }}
-      version: ${{ steps.decide.outputs.version }}
       head: ${{ steps.decide.outputs.head }}
+      urgent: ${{ steps.decide.outputs.urgent }}
       dry_run: ${{ steps.mode.outputs.dry_run }}
     steps:
       - uses: actions/checkout@v4
@@ -76,127 +70,21 @@ jobs:
         run: |
           python3 tools/release_train.py decide --kind game ${HEAD_SHA:+--head "$HEAD_SHA"} ${FORCE:+--force} | tee decision.json
           echo "### $(jq -r '.reason' decision.json)" >> "$GITHUB_STEP_SUMMARY"
-          # The version the programs are built with (docs/versioning.md): the tag without its v.
-          tag=$(jq -r '.tag' decision.json)
-          echo "version=${tag#v}" >> "$GITHUB_OUTPUT"
-          # A dry run builds whatever the decision, to test the builds.
-          if [[ "${{ steps.mode.outputs.dry_run }}" == true ]]; then echo "release=true" >> "$GITHUB_OUTPUT"; fi
 
-  build:
+  nightly:
+    # The Nightly is the release: nightly-build.yml builds the decided commit plus the reviewers' picks, signs it for
+    # the Nightly channel and publishes it once its smoke test passed and no release-blocker is open.
     needs: decide
-    if: needs.decide.outputs.release == 'true'
-    # Every platform's archive, and macOS's smoke test (game-build.yml).
-    uses: ./.github/workflows/game-build.yml
-    with:
-      ref: ${{ needs.decide.outputs.head }}
-      version: ${{ needs.decide.outputs.version }}
-      trusted: true  # main: the release runner, the release cache, no shared sccache
-
-  sign:
-    needs: [decide, build]
+    if: needs.decide.outputs.release == 'true' && needs.decide.outputs.dry_run != 'true'
     runs-on: ubuntu-latest
-    timeout-minutes: 10
-    # The only job that holds the release signing key, a secret of the `release` environment, which only main's real
-    # releases enter (dry runs sign with a throwaway key). It runs no code from the repository but
-    # tools/ci/sign_release.sh, which calls only the runner's sha256sum and OpenSSL (docs/release-flow.md).
-    environment: ${{ needs.decide.outputs.dry_run != 'true' && 'release' || '' }}
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          sparse-checkout: tools/ci/sign_release.sh
-          sparse-checkout-cone-mode: false
-          persist-credentials: false
-      - uses: actions/download-artifact@v4
-        with:
-          path: dist
-          pattern: horizon-*
-          merge-multiple: true
-      - name: Sign the checksums (SHA256SUMS, SHA256SUMS.sig)
-        env:
-          RELEASE_SIGNING_KEY: ${{ secrets.RELEASE_SIGNING_KEY }}
-          RELEASE_SIGNING_KEY_NEXT: ${{ secrets.RELEASE_SIGNING_KEY_NEXT }}
-          EPHEMERAL: ${{ needs.decide.outputs.dry_run == 'true' && 'yes' || '' }}
-          TAG: ${{ needs.decide.outputs.tag }}
-        run: |
-          bash tools/ci/sign_release.sh "$TAG" dist/horizon-linux-x86_64.tar.gz dist/horizon-windows-x64.zip \
-            dist/horizon-macos-arm64.zip dist/horizon-server-linux-x86_64.tar.gz
-      - uses: actions/upload-artifact@v4
-        with:
-          name: signature
-          path: dist/SHA256SUMS*
-          if-no-files-found: error
-          retention-days: 3
-      - uses: actions/upload-artifact@v4
-        if: needs.decide.outputs.dry_run == 'true'
-        with:
-          name: ephemeral.pub
-          path: dist/ephemeral.pub
-          retention-days: 3
-
-  publish:
-    needs: [decide, build, sign]
-    runs-on: ubuntu-latest
-    timeout-minutes: 15
+    timeout-minutes: 5
     permissions:
-      contents: write
-      issues: read
+      actions: write  # starts `nightly build`
     steps:
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-      - name: Notes
-        env:
+      - env:
           GH_TOKEN: ${{ github.token }}
+          HEAD_SHA: ${{ needs.decide.outputs.head }}
+          URGENT: ${{ needs.decide.outputs.urgent }}
         run: |
-          python3 tools/release_train.py notes --kind game --tag "${{ needs.decide.outputs.tag }}" \
-            --head "${{ needs.decide.outputs.head }}" --out notes > /dev/null
-          { echo "## $(cat notes/title.txt)"; echo; cat notes/body.md; } >> "$GITHUB_STEP_SUMMARY"
-      - uses: actions/download-artifact@v4
-        with:
-          path: dist
-          merge-multiple: true
-      - name: The signature, checked as launchers check it
-        env:
-          TAG: ${{ needs.decide.outputs.tag }}
-          EPHEMERAL: ${{ needs.decide.outputs.dry_run == 'true' && 'yes' || '' }}
-        run: |
-          key=(); [[ -n "$EPHEMERAL" ]] && key=(--key "$(cat dist/ephemeral.pub)")
-          cargo run --locked --quiet -p horizon-release-sign -- verify --tag "$TAG" --publishing "${key[@]}" dist
-      - name: Ready to publish (the smoke test passed, no release-blocker is open)
-        # Right before publishing: an issue labelled while the builds ran still holds this release. A dry run only
-        # reports what a real run would do.
-        env:
-          GH_TOKEN: ${{ github.token }}
-          DRY_RUN: ${{ needs.decide.outputs.dry_run }}
-        run: |
-          if ! python3 tools/release_train.py gate --kind game --smoke dist/smoke-test.json --blockers; then
-            [[ "$DRY_RUN" == true ]] || { echo "::error::Nothing published"; exit 1; }
-            echo "::warning::A real run would publish nothing"
-          fi
-      - name: Publish ${{ needs.decide.outputs.tag }}
-        if: needs.decide.outputs.dry_run != 'true'
-        env:
-          GH_TOKEN: ${{ github.token }}
-          TAG: ${{ needs.decide.outputs.tag }}
-        run: |
-          signature=(); [[ -f dist/SHA256SUMS.sig ]] && signature=(dist/SHA256SUMS.sig)
-          # The release and the latest at once: there is one channel (docs/release-flow.md). Each archive gets a
-          # label (file#label), which GitHub's page shows instead of the file name, so nobody takes the game's
-          # files for the download (#1647). Launchers, servers and install.sh match the name, which stays.
-          gh release create "$TAG" --target "${{ needs.decide.outputs.head }}" --title "$(cat notes/title.txt)" \
-            --notes-file notes/body.md --latest \
-            "dist/horizon-linux-x86_64.tar.gz#Game files the launcher installs: Linux (horizon-linux-x86_64.tar.gz)" \
-            "dist/horizon-windows-x64.zip#Game files the launcher installs: Windows (horizon-windows-x64.zip)" \
-            "dist/horizon-macos-arm64.zip#Game files the launcher installs: macOS (horizon-macos-arm64.zip)" \
-            "dist/horizon-server-linux-x86_64.tar.gz#Dedicated server for Linux (horizon-server-linux-x86_64.tar.gz)" \
-            dist/SHA256SUMS "${signature[@]}" dist/smoke-test.json
-      - name: Dry run, the release that would be published
-        if: needs.decide.outputs.dry_run == 'true'
-        run: |
-          echo "Would publish ${{ needs.decide.outputs.tag }} at ${{ needs.decide.outputs.head }} as the release and latest: $(cat notes/title.txt)"
-          ls -l dist
-      - uses: actions/upload-artifact@v4
-        with:
-          name: release-notes
-          path: notes/
-          retention-days: 3
+          gh workflow run nightly-build.yml --repo "$GITHUB_REPOSITORY" --ref main -f base="$HEAD_SHA" -f urgent="$URGENT"
+          echo "### Started \`nightly build\` on ${HEAD_SHA:0:9}" >> "$GITHUB_STEP_SUMMARY"

.github/workflows/run-parity.yml

@@ -5,11 +5,15 @@ name: run-parity
 # skipped `verify`, and GitHub counts a skipped required check as passed.
 on:
   pull_request:
-    types: [labeled]
+    # A push starts a run only to cancel the old head's (see concurrency): the job runs on the label alone.
+    types: [labeled, synchronize]
 permissions:
   contents: read
 concurrency:
-  group: run-parity-${{ github.event.pull_request.number }}
+  # The run-parity label and pushes share one group per pull request, so the newest run cancels the one before: a
+  # pushed pull request's run tested a head the merge would no longer land. Any other label gets a group of its own:
+  # in the shared one, adding needs-proof cancelled the parity run queued seconds before (run 40766180150).
+  group: run-parity-${{ github.event.pull_request.number }}${{ github.event.action == 'labeled' && github.event.label.name != 'run-parity' && format('-{0}', github.run_id) || '' }}
   cancel-in-progress: true
 env:
   # Test runs never reach the telemetry server: no live-count ping, no uploads (docs/telemetry.md).

AGENTS.md

@@ -13,13 +13,15 @@ Feature → files → harness for the most-changed areas: [docs/architecture.md]
   `XDG_CONFIG_HOME`, plus `HORIZON_LAUNCHER_NO_SELF_UPDATE=1` and `HORIZON_NO_AUDIO=1`, and, for the
   launcher, `HORIZON_LAUNCHER_TRASH`, `HORIZON_LAUNCHER_CLIPBOARD` and `HORIZON_LAUNCHER_DESKTOP` pointing into the scratch home. Never write to
   `~/.local/share/{applications,horizon,horizon-launcher}` or `~/.local/bin`.
-- **Mark what an agent posts.** A PR body starts with a line naming whose agent opened it and with what.
-  Ludovic's agents write `> 🤖 Opened by Ludovic's AI agent (Claude), not by Ludovic himself.`, and a
-  contributor's agent names its own person and tool (issues: "Filed by", reviews: "Review by"). Every
-  comment starts with `🤖 Agent:`. Never write as Ludovic or as anyone else.
+- **Mark what an agent posts.** A PR body starts with a line naming the person whose agent opened it and
+  the tool: `> 🤖 Opened by <login>'s AI agent (<tool, model>), not by <login> personally.`, where `<login>`
+  is the GitHub account the PR is opened from (`gh api user --jq .login`). Issues say "Filed by", reviews
+  "Review by". Every comment starts with `🤖 Agent:`. Write only as the person you work for: the lines on
+  this page that name Ludovic are for his own agents (account `ludovic111`), never for anyone else's.
 - **Attribution.** Commits end with a `Co-Authored-By:` line for the agent that wrote them, and PR bodies
-  with that agent's own "Generated with" line. Ludovic's agents use
-  `Co-Authored-By: Claude <model> <[email protected]>` and
+  with that agent's own "Generated with" line. Example, Ludovic's agents (Claude Code on `ludovic111`):
+  first line `> 🤖 Opened by Ludovic's AI agent (Claude), not by Ludovic himself.`, commits
+  `Co-Authored-By: Claude <model> <[email protected]>`, last line
   `🤖 Generated with [Claude Code](https://claude.com/claude-code)`.
 - Everything players run is Rust. Python/Java only for dev tools and harness drivers in `tools/`.
 - Horizon-only features follow [docs/design-system.md](docs/design-system.md) and are off by default where
@@ -35,11 +37,12 @@ Game workspace (root `Cargo.toml`); `launcher/` and `crates/horizon-telemetry-se
 
 | Crate | Owns |
 |---|---|
-| `horizon-client` | The game: a lib (`src/lib.rs`, ~170 flat modules) and the bin (`src/main.rs` → `game.rs` + `game/`), plus `horizon-ctl` (`src/bin/horizon-ctl/`). Also the dedicated server (`--dedicated`) |
+| `horizon-client` | The game: a lib (`src/lib.rs`, ~100 flat modules: gameplay, networking, title screens) and the bin (`src/main.rs` → `game.rs` + `game/`), plus `horizon-ctl` (`src/bin/horizon-ctl/`). Also the dedicated server (`--dedicated`) |
 | `horizon-items` | Blocks and items below gameplay: `blocks.rs` (block facts), `items.rs`, `item_data.rs` (components), `enchant.rs`, `cooldowns.rs`, `bundle.rs`, `item_nbt.rs`. Re-exported as `horizon_client::items`... |
 | `horizon-command` | Command parsing (Brigadier): the vanilla tree, argument types, selectors, suggestions, the tree's network form. Re-exported as `horizon_client::command` |
 | `horizon-client-core` | The client lib's bottom layer: `text.rs`, `lang.rs`, `snbt.rs`, `nbt_path.rs`, `component.rs`, `scoreboard.rs`, `bossbar.rs`, `gamerules.rs`, `block_entity_nbt.rs`, registry/particle/sound tables. Re-exported under the old paths (`horizon_client::text`...) |
 | `horizon-client-input` | Key bindings and key names, toggle keys, mouse options, controller settings and glyphs, the clipboard, window options (`keybinds.rs`, `gamepad.rs`, `mouse.rs`, `window.rs`...). Re-exported under the old paths |
+| `horizon-client-render` | The client's world data, rendering and screens (chunks, meshing, light, streaming, `gfx`, HUD, menus, settings): ~80 modules that horizon-client re-exports under the same paths. Nothing in it reaches gameplay |
 | `horizon-world` | Vanilla world data with no gameplay loop: NBT, regions, chunks, `datafix/`, `worldgen/`, `level/` (server-side block behaviour, ticks, redstone), entity physics, items, effects, food, damage |
 | `horizon-core` | Simulation primitives: Java `Random`s, `jmath` (HotSpot-exact `Math`), positions, noise, density, paletted storage, `version.rs` (the pinned version) |
 | `horizon-protocol` | Network protocol 777: codecs, framing, encryption, `packets/{handshake,status,login,configuration,play}.rs`, `entity_data.rs` |
@@ -73,7 +76,7 @@ cargo build --profile fast -p horizon-client        # optimized, quick to link:
 python3 tools/parity.py --changed origin/main       # the harnesses your branch can affect (CI's parity job)
 python3 tools/parity.py --changed-files paths.txt --list   # which harnesses cover these files, without running them
 python3 tools/parity.py mob_ai sculk       # named harnesses
-python3 tools/lan_e2e.py --check chest     # two real games over LAN (server-thread host); --in-frame compares the fallback
+python3 tools/lan_e2e.py --check chest     # two real games over LAN (server-thread host)
 python3 tools/agent_control_e2e.py         # horizon-ctl / MCP end to end
 ```
 
@@ -99,6 +102,9 @@ python3 tools/agent_control_e2e.py         # horizon-ctl / MCP end to end
 
 ## Vanilla reference
 
+- Start parity work from the port ledger, not grep: `python3 tools/port_ledger.py issue N` (or `where
+  Class.method`, `what file:line`), and `check --base origin/main` before the PR. How:
+  [.claude/skills/vanilla-parity/SKILL.md](.claude/skills/vanilla-parity/SKILL.md), [docs/port-ledger.md](docs/port-ledger.md).
 - Decompiled sources: `.local/minecraft/26.3/sources/{client,server}/` (`python3 tools/lab.py decompile`).
 - Bytecode queries (callers through lambdas, every overload):
   `python3 tools/rea_vanilla.py method net.minecraft.world.level.block.DispenserBlock dispenseFrom`
@@ -110,7 +116,8 @@ python3 tools/agent_control_e2e.py         # horizon-ctl / MCP end to end
 
 ## horizon-client: where things live
 
-`L:` = lib (`crates/horizon-client/src/`), `G:` = bin (`crates/horizon-client/src/game/`). The lib can't see
+`L:` = lib (`crates/horizon-client/src/`, or `crates/horizon-client-render/src/` for the modules that crate holds, under
+the same `horizon_client::<module>` paths), `G:` = bin (`crates/horizon-client/src/game/`). The lib can't see
 `Game`; bin code reaches the lib as `horizon_client::<module>`.
 
 | Subsystem | Files |
@@ -162,17 +169,18 @@ python3 tools/agent_control_e2e.py         # horizon-ctl / MCP end to end
    "Server thread" with one level per dimension; the window joins it as a client through memory (`remote`),
    exactly as a LAN guest or a dedicated server's player does. This is what players run. Open
    `[server-thread]` issues list the gaps left.
-2. **In-frame (`--in-frame`, `--no-server-thread` or `HORIZON_SERVER_THREAD=0`):** the window's `Game` ticks
-   the world itself, one level that follows the player (`fn enter_dimension`). Deterministic rule fixtures still use this path; player-facing integration uses the default server thread.
+2. **In-frame (`--in-frame`, `--no-server-thread` or `HORIZON_SERVER_THREAD=0`): DEPRECATED, never use it, it
+   will be removed soon.** The window's `Game` ticks the world itself, one level that follows the player
+   (`fn enter_dimension`). Compatibility does not matter: don't add features or fixes for it, don't write new
+   tests against it, and move code off it when you touch it. The deterministic rule fixtures still run on it
+   until they are ported.
 
-LAN guests and dedicated servers always use the server code, so a fix there serves both. Test both paths
-when you touch player-facing gameplay:
+LAN guests and dedicated servers always use the server code, so a fix there serves both. Test the server
+thread when you touch player-facing gameplay:
 
 ```sh
 cargo run --profile fast -p horizon-client -- --resources .local/horizon-client/26.3 --world T               # server thread
-cargo run --profile fast -p horizon-client -- --resources .local/horizon-client/26.3 --world T --in-frame    # in-frame
 python3 tools/lan_e2e.py --check <name>                  # host on its server thread, guest is a server client
-python3 tools/lan_e2e.py --in-frame --check <name>       # comparison (portals, levels, distance, lava need server-thread mode)
 python3 tools/parity.py dedicated_server server_entities server_player_damage
 ```
 

Cargo.lock

@@ -876,6 +876,12 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d8b14ccef22fc6f5a8f4d7d768562a182c04ce9a3b3157b91390b52ddfdf1a76"
 
+[[package]]
+name = "dunce"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92773504d58c093f6de2459af4af33faa518c13451eb8f2b5698ed3d36e7c813"
+
 [[package]]
 name = "either"
 version = "1.19.0"
@@ -1372,7 +1378,6 @@ dependencies = [
  "ab_glyph",
  "bytemuck",
  "chrono",
- "cpal",
  "flate2",
  "gilrs",
  "glam",
@@ -1380,6 +1385,7 @@ dependencies = [
  "horizon-bench",
  "horizon-client-core",
  "horizon-client-input",
+ "horizon-client-render",
  "horizon-command",
  "horizon-core",
  "horizon-dualsense",
@@ -1398,6 +1404,7 @@ dependencies = [
  "log",
  "miniz_oxide 0.8.9",
  "naga",
+ "open",
  "png",
  "pollster",
  "rustix 1.1.5",
@@ -1405,7 +1412,6 @@ dependencies = [
  "serde_json",
  "sha1",
  "sha2",
- "symphonia",
  "unicode-bidi",
  "ureq",
  "wgpu",
@@ -1434,6 +1440,48 @@ dependencies = [
  "winit",
 ]
 
+[[package]]
+name = "horizon-client-render"
+version = "0.1.0"
+dependencies = [
+ "ab_glyph",
+ "bytemuck",
+ "chrono",
+ "cpal",
+ "flate2",
+ "glam",
+ "horizon-assets",
+ "horizon-bench",
+ "horizon-client-core",
+ "horizon-client-input",
+ "horizon-command",
+ "horizon-core",
+ "horizon-hdr",
+ "horizon-items",
+ "horizon-protocol",
+ "horizon-shader-api",
+ "horizon-shaders",
+ "horizon-telemetry",
+ "horizon-theme",
+ "horizon-threads",
+ "horizon-world",
+ "log",
+ "miniz_oxide 0.8.9",
+ "naga",
+ "png",
+ "pollster",
+ "rustix 1.1.5",
+ "serde",
+ "serde_json",
+ "sha2",
+ "symphonia",
+ "unicode-bidi",
+ "ureq",
+ "wgpu",
+ "winit",
+ "zip",
+]
+
 [[package]]
 name = "horizon-command"
 version = "0.1.0"
@@ -1479,6 +1527,9 @@ name = "horizon-hdr"
 version = "0.1.0"
 dependencies = [
  "ash",
+ "wayland-backend",
+ "wayland-client",
+ "wayland-protocols",
  "wgpu",
 ]
 
@@ -1877,6 +1928,25 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "is-docker"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "928bae27f42bc99b60d9ac7334e3a21d10ad8f1835a4e12ec3ec0464765ed1b3"
+dependencies = [
+ "once_cell",
+]
+
+[[package]]
+name = "is-wsl"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "173609498df190136aa7dea1a91db051746d339e18476eed5ca40521f02d7aa5"
+dependencies = [
+ "is-docker",
+ "once_cell",
+]
+
 [[package]]
 name = "itertools"
 version = "0.14.0"
@@ -2691,6 +2761,17 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c08d65885ee38876c4f86fa503fb49d7b507c2b62552df7c70b2fce627e06381"
 
+[[package]]
+name = "open"
+version = "5.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d8c8b8e725ad26404d6896eb2f064294a0a7b4f1d9120210d85544684c4ca95"
+dependencies = [
+ "dunce",
+ "is-wsl",
+ "libc",
+]
+
 [[package]]
 name = "orbclient"
 version = "0.3.55"

Cargo.toml

@@ -9,6 +9,7 @@ members = [
     "crates/horizon-client",
     "crates/horizon-client-core",
     "crates/horizon-client-input",
+    "crates/horizon-client-render",
     "crates/horizon-command",
     "crates/horizon-items",
     "crates/horizon-server-files",
@@ -61,8 +62,10 @@ large_enum_variant = "allow"
 # wgpu-hal 30.0.1 with gfx-rs/wgpu#10124: wgpu 30 creates a Vulkan descriptor
 # pool with no pool sizes while it creates the device, which Vulkan allows only
 # since 1.3.215, and Intel's Windows driver for 6th-10th gen iGPUs (HD 520/530,
-# UHD 620/630) crashes on it with an access violation (#746). Drop this and the
-# folder once a wgpu release has the fix.
+# UHD 620/630) crashes on it with an access violation (#746). It also fixes the
+# Metal backend's lookup of the CoreGraphics HDR colour space names, which handed
+# CoreGraphics a symbol's address as the string and crashed HDR output on macOS.
+# Drop this and the folder once a wgpu release has both fixes.
 [patch.crates-io]
 wgpu-hal = { path = "third_party/wgpu-hal" }
 

README.md

@@ -1,5 +1,5 @@
 <p align="center">
-  <img src="docs/media/banner.webp" alt="Horizon: Minecraft: Java Edition 26.3, rewritten in Rust and checked against vanilla by 281 differential harnesses" width="100%">
+  <img src="docs/media/banner.webp" alt="Horizon: Minecraft: Java Edition 26.3, rewritten in Rust and checked against vanilla by more than 300 differential harnesses" width="100%">
 </p>
 
 <p align="center">
@@ -23,15 +23,15 @@
 
 # Horizon
 
-Horizon is Minecraft: Java Edition 26.3 rewritten in Rust: a native game that reads the same worlds, follows the same rules and generates the same terrain as the Java game, and is checked against it by 281 differential harnesses. You play it through a small launcher, on the files from your own copy of Minecraft. It is free, open source and unofficial.
+Horizon is Minecraft: Java Edition 26.3 rewritten in Rust: a native game that reads the same worlds, follows the same rules and generates the same terrain as the Java game, and is checked against it by more than 300 differential harnesses. You play it through a small launcher, on the files from your own copy of Minecraft. It is free, open source and unofficial.
 
 > Not an official Minecraft product. Not approved by or associated with Mojang or Microsoft. Horizon contains no Minecraft code, assets or data: you need your own legally obtained copy of Minecraft: Java Edition 26.3.
 
 ## Download
 
-Horizon is installed through **the Horizon launcher**. Get it from [playhorizon.dev](https://playhorizon.dev) (the Download button picks your system) or from [the launcher releases](https://github.com/horizon-rust/horizon/releases?q=launcher-v&expanded=true), for Linux x86-64, macOS on Apple Silicon or Windows x64. The launcher installs and updates the game, prepares its files from your own copy of Minecraft, and updates itself.
+Horizon is installed through **the Horizon launcher**. Get it from [playhorizon.dev](https://playhorizon.dev) (the Download button picks your system) or from [the launcher releases](https://github.com/horizon-rust/horizon/releases?q=launcher-v&expanded=true), for Linux x86-64, macOS on Apple Silicon or Windows x64. The launcher installs the game and keeps it up to date with each new build (Horizon ships on one channel, the Nightly), prepares its files from your copy of Minecraft (your own install, or downloaded from Mojang for your account), and updates itself.
 
-**You need** a Microsoft account that owns Minecraft: Java Edition (the launcher signs in with it, as other launchers do; see [Microsoft account](docs/microsoft-account.md)); Minecraft: Java Edition 26.3, played once (the official launcher, Prism, MultiMC and other launchers all work); a Java 25 runtime, for the one-time preparation; and a GPU with Vulkan on Linux and Windows, or any Apple Silicon Mac. Step by step, with macOS's first-open prompt and the first launch: [Install and first launch](https://playhorizon.dev/docs/install).
+**You need** a Microsoft account that owns Minecraft: Java Edition (the launcher signs in with it, as other launchers do; see [Microsoft account](docs/microsoft-account.md)) and a GPU with Vulkan or OpenGL 3.3 on Linux, Vulkan or DirectX 12 on Windows, or any Apple Silicon Mac. Nothing else: with no Minecraft on your computer, Play downloads 26.3 and the Java it needs from Mojang for your account, as the official launcher does, then prepares it once. An install you already have (the official launcher, Prism, MultiMC and other launchers all work) is used instead. Step by step, with macOS's first-open prompt and the first launch: [Install and first launch](https://playhorizon.dev/docs/install).
 
 <table>
   <tr>
@@ -46,9 +46,9 @@ The [documentation](https://playhorizon.dev/docs/) covers each of these.
 
 - **The game:** singleplayer with vanilla's world generation, mobs, villagers, raids, redstone, every command, the HUD and the recipe book, on saves in vanilla's format. Worlds from 1.8 to 26.2 are upgraded as vanilla does. [Status table](#project-status).
 - **Horizon's own extras:** new menus (vanilla's are one setting away), graphics presets, distant terrain up to 1024 chunks, controller support, optional zoom, minimap and more, all off by default where they would change the vanilla look. See [Settings](https://playhorizon.dev/docs/settings).
-- **Resource packs and data packs:** resource packs work, and data packs load functions, predicates and item modifiers.
+- **Resource packs and data packs:** resource packs work, and data packs load functions, predicates, item modifiers and world generation (vanilla's heights and biomes for now).
 - **Playing with others:** invite friends from the pause menu's Friends button with a code, Open to LAN, and joining servers, online-mode ones with the Microsoft account the launcher signs in with. See [Multiplayer](https://playhorizon.dev/docs/multiplayer).
-- **Mods:** Horizon has its own mod system (Rust compiled to WebAssembly). Java mod jars do not run. See [Mods and data packs](https://playhorizon.dev/docs/mods).
+- **Mods:** Horizon has its own mods, installed from the launcher. The official ones (Zoom, FPS Counter, Keystrokes and Minimap) are native Rust that the launcher builds into your game, with no Rust to install; older WebAssembly mods still run while they move. Java mod jars do not run in Horizon. See [Mods and data packs](https://playhorizon.dev/docs/mods).
 
 Screenshots, captured in the Rust client itself with vanilla assets and no mods or shaders:
 
@@ -93,7 +93,7 @@ Commands block until the action is done and reply with what happened; errors are
 
 For developers. Requirements: Rust 1.90 or newer, Python 3.10 or newer, JDK 25, and on Linux the ALSA and udev development headers (`libasound2-dev libudev-dev` on Debian and Ubuntu). Development and the vanilla harnesses run on Linux.
 
-Horizon contains no game files and never downloads them. It builds its resources from **your own copy** of Minecraft: Java Edition 26.3, verified against the checksums in `research-lock.json`:
+Horizon contains no game files, and `horizon-prepare` never downloads them (the launcher downloads them from Mojang only for a signed-in account that owns the game). It builds its resources from **your own copy** of Minecraft: Java Edition 26.3, verified against the checksums in `research-lock.json`:
 
 1. **Client:** install Java Edition with the official launcher and play 26.3 once. Horizon reads `versions/26.3/`, `libraries/` and `assets/` from the launcher's game directory (`~/.minecraft` on Linux). If yours lives elsewhere, pass `--minecraft-dir` or set `HORIZON_MINECRAFT_DIR`.
 2. **Server jar:** the 26.3 server jar, from the `downloads.server.url` in your launcher's `versions/26.3/26.3.json` (or [minecraft.net/download/server](https://www.minecraft.net/en-us/download/server) while 26.3 is the current release). Pass it with `--server-jar` or set `HORIZON_SERVER_JAR`. It is only needed the first time.
@@ -139,6 +139,11 @@ average; `tests/test_parity.py` keeps it in sync with this table. Last audited
 rerun whenever one of its inputs changed, and the Mac mini now runs every one of
 them too (Rust uses Java's own float maths on each platform).
 
+The harnesses measure behaviour. A second measure is method by method: the [port ledger](tools/port_ledger.py)
+lists every method of vanilla 26.3 next to the Rust functions that port it, with a verdict for each one
+(ported, folded into another function, missing, or needing no port), and the untested ports. Run
+`python3 tools/port_ledger.py build`, then `coverage`, with the vanilla data in `.local/`.
+
 | Subsystem | Score | Main gaps |
 | --- | ---: | --- |
 | Window, input and game loop | 1 | None: the game loop, options, camera, auto-jump, toggle sprint/sneak, local input and the frame limiter match vanilla |

ROADMAP.md

@@ -16,7 +16,7 @@ Horizon is Minecraft: Java Edition 26.3 rewritten from scratch in Rust, so it ru
 - **Single player as a server: the last differences**: Single player now runs a small server in the background, as vanilla does. We are fixing what still behaves differently there; every fix also works for LAN and server players.
 - **Horizon's mod registry**: One place for mods, modpacks and resource packs made for Horizon: browse them on the website and install them from the launcher in one click.
 
-**Next**: Microsoft sign-in (coming soon); CurseForge in the mod browser (coming soon); Fresh benchmarks against vanilla; Pistons push players and mobs; Horizon on Intel Macs; Faster world creation and entry on small CPUs; Servers that hold 20 TPS with 50 to 100 players; Low-end computers: Steam Deck, old Macs, 8 GB; Native upscaling; A batch of targeted optimisations; A Convert to Rust button for what isn't rewritten yet; Mods with code: machines, magic, mobs; Data packs in the mod browser; Prepare a version without Java; Server console, bans and a full admin API; Hosting polish: Windows service, safe updates; Guided hosting with Tailscale and an invite button; An official Docker image for servers; One single-player path: remove the in-frame world; Villages and combat, exactly as in vanilla; Choose the audio output device; Mods that read and change the world; Machines and blocks with inventories (API 0.4); Lua and other languages for mods; Well-known shader looks, rewritten for Horizon; A visible beta label; Wayland and Hyprland polish; A versioned agent-control protocol; Port mods with your own AI agent; Horizon on X (coming soon); Pipeline protection and a GitHub App for agents; Signed updates everywhere, installers included; A server you install with one command.
+**Next**: A new launcher design; CurseForge in the mod browser (coming soon); Fresh benchmarks against vanilla; Pistons push players and mobs; Horizon on Intel Macs; Faster world creation and entry on small CPUs; Servers that hold 20 TPS with 50 to 100 players; Low-end computers: Steam Deck, old Macs, 8 GB; Native upscaling; A batch of targeted optimisations; A Convert to Rust button for what isn't rewritten yet; Mods with code: machines, magic, mobs; Data packs in the mod browser; Prepare a version without Java; Server console, bans and a full admin API; Hosting polish: Windows service, safe updates; Guided hosting with Tailscale and an invite button; An official Docker image for servers; One single-player path: remove the in-frame world; Villages and combat, exactly as in vanilla; Choose the audio output device; Mods that read and change the world; Machines and blocks with inventories (API 0.4); Well-known shader looks, rewritten for Horizon; A visible beta label; Wayland and Hyprland polish; A versioned agent-control protocol; Port mods with your own AI agent; Horizon on X (coming soon); Pipeline protection and a GitHub App for agents; Signed updates everywhere, installers included; A server you install with one command; Ready-made setups for hosting panels.
 
 **How to help**: Play it and tell us what differs from vanilla (Discord or GitHub), run the benchmark on your computer, vote for what you want next, or pick one of the Help wanted items.
 
@@ -104,37 +104,49 @@ More: [docs/mods.md](docs/mods.md)
 
 </details>
 
+#### Native mods, built by the launcher
+
+Horizon's own mods become native code that the launcher builds into your game, with no Rust to install: Zoom, FPS Counter, Keystrokes and Minimap already are, and Recipes is next.
+
+<details><summary>Technical</summary>
+
+Stable hook points in the game (game/native_hooks.rs, [#3345](https://github.com/horizon-rust/horizon/issues/3345), [#3346](https://github.com/horizon-rust/horizon/issues/3346); v2 with the item panel and recipe pages, [#3434](https://github.com/horizon-rust/horizon/issues/3434), [#3435](https://github.com/horizon-rust/horizon/issues/3435)), horizon-mixins applied by the launcher with its own portable Rust ([#3388](https://github.com/horizon-rust/horizon/issues/3388)), on/off in Options > Mods. The official mods live in horizon-mods/native/ and are in the registry as native mods. Next: Recipes, native mods on automatically when a player installs one (with a notice about the first build), then the WebAssembly runtime is removed ([#3350](https://github.com/horizon-rust/horizon/issues/3350), [#3351](https://github.com/horizon-rust/horizon/issues/3351), [#3353](https://github.com/horizon-rust/horizon/issues/3353), [#3371](https://github.com/horizon-rust/horizon/issues/3371)).
+
+More: [docs/native-mods.md](docs/native-mods.md)
+
+</details>
+
 #### Mods that run on the server
 
 Mods that run on the server side of a world, so a dedicated server or a LAN world can have mods that react to players joining, chat and blocks being broken or placed, and that add commands.
 
 <details><summary>Technical</summary>
 
-API 0.3, experimental first ([#1833](https://github.com/horizon-rust/horizon/issues/1833), in review): the same sandboxed component runs on the server thread and the dedicated server, with world events (block broken or placed, entity spawned or killed, player joined or left), game rules and server commands with typed arguments. The world, item and entity interfaces come after (see 'Mods that read and change the world'). [docs/api/mods.md](docs/api/mods.md), [docs/mods.md](docs/mods.md).
+The same hook points on the server thread and the dedicated server: world events (block broken or placed, entity spawned or killed, player joined or left), game rules and server commands with typed arguments. The earlier WebAssembly API 0.3 ([#1833](https://github.com/horizon-rust/horizon/issues/1833)) is the reference for what to cover.
+
+More: [docs/native-mods.md](docs/native-mods.md)
 
 </details>
 
 #### Screens, input and drawing for mods
 
-Mods will be able to open their own screens and settings pages and react to keys and item use, so bigger mods, such as the Orbital Laser, can run on the normal game.
+Mods will be able to open their own screens and settings pages, react to keys and item use, and draw, so bigger mods, such as the Orbital Laser, run on the normal game.
 
 <details><summary>Technical</summary>
 
-Capability `ui` is in review ([#1864](https://github.com/horizon-rust/horizon/issues/1864)): mod-owned screens and a settings page under Options > Mods, built from vanilla's widgets. Still to design: `input` (an item's use, key binds, the crosshair target), `render` (a budgeted draw list on the native shader API) and `world` (changing blocks). Orbital Laser is the acceptance test: it needs all four today through its author's fork (see 'Orbital Laser on the normal game').
-
-More: [docs/mods.md](docs/mods.md)
+On native hook points ([docs/native-mods.md](docs/native-mods.md)): settings pages under Options > Mods and the item panel are there ([#3346](https://github.com/horizon-rust/horizon/issues/3346), [#3435](https://github.com/horizon-rust/horizon/issues/3435)). Next: mod-owned screens built from vanilla's widgets, an item's use, key binds and the crosshair target, and a budgeted draw list on the native shader API. Orbital Laser is the acceptance test.
 
 </details>
 
 #### Tools for people who make mods
 
-Better tools for mod makers: a test runner that needs no game window, templates for each kind of mod, and clear promises about what keeps working from one version to the next.
+Better tools for mod makers: templates for each kind of mod, a test run with no game window, and clear promises about which hook points keep working from one version to the next.
 
 <details><summary>Technical</summary>
 
-`cargo horizon-mod test` runs a mod's test scripts against a fake game snapshot ([#1816](https://github.com/horizon-rust/horizon/issues/1816)) and, for server mods, scripted server events ([#1837](https://github.com/horizon-rust/horizon/issues/1837)); the content template and the guides are merged ([#1859](https://github.com/horizon-rust/horizon/issues/1859), [#1810](https://github.com/horizon-rust/horizon/issues/1810), [docs/api/stability.md](docs/api/stability.md)). Left: templates for hud, server and machine mods, typed wrappers in the SDK, a frozen 0.1 compatibility mod that every runtime must load, a CI check that fails when a stable reference entry is removed without a new major version, and the SDK on crates.io once the API is stable.
+Native mod template and the content mod template (horizon-mods), `native.py check` that applies mods on a chosen Horizon and builds them together, a weekly check of every official mod on the newest Nightly. Left: a versioned list of stable hook points (NATIVE_HOOKS_API), a test runner without a window, and docs on the site for native mods.
 
-More: [https://playhorizon.dev/docs/test-a-mod](https://playhorizon.dev/docs/test-a-mod)
+More: [#3388](https://github.com/horizon-rust/horizon/issues/3388) · [docs/native-mods.md](docs/native-mods.md)
 
 </details>
 
@@ -244,6 +256,20 @@ Horizon's own way to make shader packs, with tools to write and test them. Every
 
 </details>
 
+### Launcher
+
+#### Minecraft Java instances in the launcher
+
+Play the real Java game from the Horizon launcher too: vanilla and modded instances, any version, mods from Modrinth filtered to what fits, and your instances imported from other launchers.
+
+<details><summary>Technical</summary>
+
+For an account that owns the game: any version downloaded with the Java it needs ([#3406](https://github.com/horizon-rust/horizon/issues/3406)), Java instances, the version list and the CLI ([#3395](https://github.com/horizon-rust/horizon/issues/3395)), the start command read from the version JSON ([#3419](https://github.com/horizon-rust/horizon/issues/3419)). Next: Play for a Java instance, Fabric and Quilt, then NeoForge and Forge; Modrinth with compatibility filtering and dependencies; imports from Prism, MultiMC, the CurseForge app, the Modrinth App, ATLauncher and the official launcher, each from its documented on-disk format.
+
+More: [#3506](https://github.com/horizon-rust/horizon/issues/3506)
+
+</details>
+
 ### Horizon extras
 
 #### Discord Rich Presence
@@ -268,6 +294,16 @@ A review of the whole tree: dead code and stubs removed ([#1432](https://github.
 
 </details>
 
+#### Every vanilla method, tracked
+
+A public list of every method of the Java game and where Horizon does it, so anyone can see what is ported, what is missing and pick something to fix.
+
+<details><summary>Technical</summary>
+
+[tools/port_ledger.py](tools/port_ledger.py) and tools/port_map/ ([#3139](https://github.com/horizon-rust/horizon/issues/3139)): every 26.3 method outside the skipped packages has a verdict (port, inline, missing, skip, trivial), linked to the harnesses that cover it ([#3526](https://github.com/horizon-rust/horizon/issues/3526)), with one tracking issue per area. Bug fixes start from it (.claude/skills/vanilla-parity).
+
+</details>
+
 ## Next
 
 ### Performance
@@ -444,6 +480,16 @@ A player's idea (#horizon-ideas). `horizon-server` already runs headless; left:
 
 </details>
 
+#### Ready-made setups for hosting panels
+
+Install a Horizon server from the panels hosts use, such as Pterodactyl and AMP, the usual way for each panel.
+
+<details><summary>Technical</summary>
+
+Asked in the suggestion queue for Pterodactyl eggs and AMP templates. Builds on the one-command install ('A server you install with one command') and horizon-server's server.toml ([docs/hosting.md](docs/hosting.md)).
+
+</details>
+
 ### Mods and API
 
 #### Mods that read and change the world
@@ -452,9 +498,9 @@ Mods that can see and change blocks, read inventories and items, and find and af
 
 <details><summary>Technical</summary>
 
-After server mods: read blocks, states and biomes in loaded chunks and change them through the server's block log, so clients and the parity harnesses see vanilla's updates; the player's inventory, held item, open container and item stacks with components; entity queries near a position, a safe subset of entity data and data-driven mod entity types. Snapshots and batched calls per tick, never per-block host calls in hot paths. [docs/api/mods.md](docs/api/mods.md) ('Not there yet').
+Hook points for reading blocks, states and biomes and changing them through the server's block log, so clients and the parity harnesses see vanilla's updates; the player's inventory and item stacks with components; entity queries near a position. Batched per tick, never per-block calls in hot paths.
 
-More: [docs/modpacks.md](docs/modpacks.md)
+More: [docs/native-mods.md](docs/native-mods.md) · [docs/modpacks.md](docs/modpacks.md)
 
 </details>
 
@@ -468,16 +514,6 @@ Block entities and menus: ticking machines with slots, server menu logic and the
 
 </details>
 
-#### Lua and other languages for mods
-
-Write mods as Lua scripts, in the style of KubeJS, with no compiler, and later in other languages that pass the tests. Every language runs in the same sandbox.
-
-<details><summary>Technical</summary>
-
-Lua first: Horizon ships a Lua interpreter that is itself a WebAssembly mod, and a script mod's manifest names it and the capabilities it uses, so a script can do exactly what a compiled mod with the same manifest can, with hot reload of `main.lua`. Then C, C++, Zig, Go (TinyGo), AssemblyScript and JavaScript or TypeScript are measured against Rust on the same tick-heavy example, and each is supported only with a template, an example and a CI test. [docs/api/mods.md](docs/api/mods.md) ('Ways in').
-
-</details>
-
 ### Gameplay parity
 
 #### Pistons push players and mobs
@@ -536,15 +572,13 @@ More: [docs/shaders.md](docs/shaders.md)
 
 ### Launcher
 
-#### Microsoft sign-in (coming soon)
+#### A new launcher design
 
-Coming soon: sign in with your Microsoft account to play on online-mode servers. The code is ready; it waits for Microsoft's approval.
+A redesigned launcher: every button where you expect it, the fewest clicks to play, add an instance or add mods, smooth animations, and instant startup.
 
 <details><summary>Technical</summary>
 
-Device-code sign-in in the launcher and online-mode login in the client ([docs/microsoft-account.md](docs/microsoft-account.md)). It is turned on by setting the app's client id once Minecraft API access is approved; until then the launcher shows "Coming soon".
-
-More: [#1270](https://github.com/horizon-rust/horizon/issues/1270)
+Based on the site concept by the Team (Bricolage Grotesque, a night sky and an animated pixel sunset). Screens and flows are designed first, then small PRs; tokens in [crates/horizon-theme](crates/horizon-theme) and rules in [docs/design-system.md](docs/design-system.md), the game's vanilla look unchanged. Measured before and after: startup, frame time and idle CPU/GPU, reduced motion honoured. Mods screens separate Horizon native mods from Java mods; a running instance can be stopped from the launcher.
 
 </details>
 
@@ -708,6 +742,18 @@ Issue [#1270](https://github.com/horizon-rust/horizon/issues/1270) asks for Ely.
 
 </details>
 
+#### Join servers on older versions
+
+Join servers that run older Minecraft versions, such as 1.21 or 1.8 PvP servers, from Horizon.
+
+<details><summary>Technical</summary>
+
+Asked often in the suggestion queue. Horizon speaks 26.3's protocol; the path is a native protocol adapter in Rust that translates older versions' packets, not a downloaded Java proxy. Java instances in the launcher already play any version with the real game.
+
+More: [#3023](https://github.com/horizon-rust/horizon/issues/3023)
+
+</details>
+
 #### Online-mode checks for Play with Friends
 
 Friends who join through an invite code could prove who they are with their Microsoft account, as on online-mode servers.
@@ -720,6 +766,18 @@ Play with Friends joins over an encrypted tunnel with an invite code ([docs/play
 
 ### Mods and API
 
+#### Scripts for mods
+
+Small mods written as scripts, in the style of KubeJS, with no compiler.
+
+<details><summary>Technical</summary>
+
+Waits for native mods to settle: the earlier plan ran Lua inside the WebAssembly sandbox, which is being removed. A script layer over the native hook points is to be designed.
+
+More: [docs/native-mods.md](docs/native-mods.md)
+
+</details>
+
 #### Orbital Laser on the normal game
 
 The community mod Orbital Laser, made for a fork of Horizon, running on the normal game and listed in the registry as the showcase of the mod API.
@@ -732,13 +790,13 @@ A pull request on [https://github.com/Stink-O/orbital-laser](https://github.com/
 
 #### Native versions of popular client mods
 
-Built-in versions of the client mods players ask for: block info on hover, a recipe viewer like JEI, a world map and schematic overlays.
+Built-in versions of the client mods players ask for: block info on hover, a world map, inventory tweaks and schematic overlays.
 
 <details><summary>Technical</summary>
 
-Done as extras: a mod list and menu, a minimap and a zoom ([docs/extras.md](docs/extras.md)). Left: block info tooltips, a recipe viewer (a contributor offered to port JEI if it becomes a native feature), a world map and a schematic overlay. They need the read-only interfaces `inventory-read`, `recipes`, `world-read` and `render` in the mod API, or they go into the game directly.
+Done: a mod list and menu, minimap, zoom, keystrokes, an FPS counter and a recipe viewer, as native mods (horizon-mods/native/). Asked for: an angled world map that shows hills, overhangs and caves, inventory tweaks (drag and scroll to move items), block info tooltips and schematic overlays.
 
-More: [docs/mods.md](docs/mods.md)
+More: [docs/extras.md](docs/extras.md) · [docs/native-mods.md](docs/native-mods.md)
 
 </details>
 
@@ -784,6 +842,16 @@ The game side is merged ([docs/controllers.md](docs/controllers.md)): pads read
 
 </details>
 
+#### Splitscreen
+
+Play with a friend on the same screen, each with a controller.
+
+<details><summary>Technical</summary>
+
+Issue [#2054](https://github.com/horizon-rust/horizon/issues/2054); a contributor is working on it. Two local players on the same world, each with their own camera and HUD, built on the server thread's multiplayer.
+
+</details>
+
 #### The full debug screen
 
 Vanilla's complete F3 screen: debug options, a profiler chart, ten-second captures and an atlas dump.
@@ -834,7 +902,7 @@ More graphics options: multisample anti-aliasing, anisotropic filtering and an e
 
 <details><summary>Technical</summary>
 
-Not implemented ([docs/graphics.md](docs/graphics.md)). Anisotropic filtering needs linear magnification in wgpu, which blurs close blocks, so close-up sharpness has to be kept first; MSAA would sit beside FXAA; exclusive fullscreen where the backend supports it.
+Not implemented ([docs/graphics.md](docs/graphics.md)). Anisotropic filtering needs linear magnification in wgpu, which blurs close blocks, so close-up sharpness has to be kept first; MSAA would sit beside FXAA, and SMAA or TAA are asked for too; exclusive fullscreen where the backend supports it.
 
 </details>
 
@@ -862,6 +930,18 @@ Issue [#1709](https://github.com/horizon-rust/horizon/issues/1709): aarch64 buil
 
 </details>
 
+#### Horizon on Windows ARM64
+
+A native Horizon for Windows on ARM computers, such as Snapdragon laptops.
+
+<details><summary>Technical</summary>
+
+Releases are x64 for Windows and Linux and arm64 for macOS. Needs an aarch64-pc-windows-msvc build in the release workflow and a machine to test on.
+
+More: [docs/release-flow.md](docs/release-flow.md)
+
+</details>
+
 #### Android, iOS and the browser
 
 Versions of Horizon for Android, iOS and web browsers. Nothing official yet; contributors have started the first pieces.
@@ -968,6 +1048,7 @@ Armour and tools in End city chests should come enchanted, as in vanilla.
 
 ## Recently shipped
 
+- **Microsoft sign-in** (launcher@0.2.17): Sign in with your Microsoft account in the launcher to play on online-mode servers. [docs/microsoft-account.md](docs/microsoft-account.md) · [#2879](https://github.com/horizon-rust/horizon/issues/2879)
 - **OpenGL for old computers** (v0.2.63): Horizon now starts on old PCs whose graphics card has no Vulkan or DirectX 12 driver: it switches to OpenGL by itself, and Options > Graphics can pick OpenGL by hand. [#1917](https://github.com/horizon-rust/horizon/issues/1917) · [#1920](https://github.com/horizon-rust/horizon/issues/1920) · [#1936](https://github.com/horizon-rust/horizon/issues/1936)
 - **Server resource packs** (v0.2.48): Servers can send you their resource pack: Horizon asks, downloads it and applies it, like vanilla. [#1562](https://github.com/horizon-rust/horizon/issues/1562) · [#1569](https://github.com/horizon-rust/horizon/issues/1569) · [#1570](https://github.com/horizon-rust/horizon/issues/1570)
 - **Single player on its own server thread** (v0.2.39): Single player runs on a server thread, as vanilla does, so the world keeps ticking smoothly while the window draws. [#1514](https://github.com/horizon-rust/horizon/issues/1514) · [docs/server-levels.md](docs/server-levels.md)

crates/cargo-horizon-mod/src/check.rs

@@ -97,6 +97,9 @@ impl Report {
         for r in &f.requires {
             out += &format!("  needs {} {} ({})\n", r.id, r.version, &r.sha256[..12]);
         }
+        if self.kind == Kind::NativeMod {
+            out += "  native source: unsandboxed; not executed by the registry check. Compile and test against the exact pinned Horizon and Mixins revisions before review.\n";
+        }
         if self.kind == Kind::Mod && !self.code {
             out += "  no code: content only, nothing to run\n";
         } else if self.kind == Kind::Mod {
@@ -118,6 +121,7 @@ impl Report {
 pub fn kind_of(path: &Path) -> Option<Kind> {
     match path.extension()?.to_str()? {
         "hmod" => Some(Kind::Mod),
+        "hnmod" => Some(Kind::NativeMod),
         "hpack" => Some(Kind::Modpack),
         "zip" => Some(Kind::ResourcePack),
         "hshader" => Some(Kind::Shader),

crates/horizon-client-core/src/component.rs

@@ -1,6 +1,6 @@
 //! Text components from commands: `ComponentArgument` reads an SNBT (or JSON)
 //! value, `ComponentSerialization` turns it into styled text.
-use crate::text::{Style, Text, named_color};
+use crate::text::{InlineObject, Style, Text, named_color};
 use horizon_world::nbt::Tag;
 use serde_json::{Map, Value};
 
@@ -11,13 +11,18 @@ pub fn parse_snbt(input: &str) -> Result<(Value, usize), String> {
     let mut p = Parser {
         s: input.as_bytes(),
         i: 0,
+        depth: 0,
     };
     let v = p.value()?;
     Ok((v, p.i))
 }
+/// Nesting deeper than NBT's own limit (`NbtAccounter`'s 512) is refused
+/// rather than overflowing the stack.
+const SNBT_MAX_DEPTH: usize = 512;
 struct Parser<'a> {
     s: &'a [u8],
     i: usize,
+    depth: usize,
 }
 impl Parser<'_> {
     fn ws(&mut self) {
@@ -41,57 +46,22 @@ impl Parser<'_> {
         self.ws();
         match self.peek() {
             Some(b'{') => {
-                self.i += 1;
-                let mut map = Map::new();
-                self.ws();
-                if self.peek() == Some(b'}') {
-                    self.i += 1;
-                    return Ok(Value::Object(map));
-                }
-                loop {
-                    self.ws();
-                    let key = self.string()?;
-                    self.expect(b':')?;
-                    map.insert(key, self.value()?);
-                    self.ws();
-                    match self.peek() {
-                        Some(b',') => self.i += 1,
-                        Some(b'}') => {
-                            self.i += 1;
-                            return Ok(Value::Object(map));
-                        }
-                        _ => return Err("expected ',' or '}'".into()),
-                    }
+                if self.depth >= SNBT_MAX_DEPTH {
+                    return Err(format!("tag nesting too deep at {}", self.i));
                 }
+                self.depth += 1;
+                let v = self.object();
+                self.depth -= 1;
+                v
             }
             Some(b'[') => {
-                self.i += 1;
-                let mut list = Vec::new();
-                self.ws();
-                // Typed arrays [B;...], [I;...], [L;...].
-                if matches!(
-                    self.s.get(self.i..self.i + 2),
-                    Some([b'B' | b'I' | b'L', b';'])
-                ) {
-                    self.i += 2;
-                }
-                self.ws();
-                if self.peek() == Some(b']') {
-                    self.i += 1;
-                    return Ok(Value::Array(list));
-                }
-                loop {
-                    list.push(self.value()?);
-                    self.ws();
-                    match self.peek() {
-                        Some(b',') => self.i += 1,
-                        Some(b']') => {
-                            self.i += 1;
-                            return Ok(Value::Array(list));
-                        }
-                        _ => return Err("expected ',' or ']'".into()),
-                    }
+                if self.depth >= SNBT_MAX_DEPTH {
+                    return Err(format!("tag nesting too deep at {}", self.i));
                 }
+                self.depth += 1;
+                let v = self.array();
+                self.depth -= 1;
+                v
             }
             Some(b'"' | b'\'') => Ok(Value::String(self.string()?)),
             Some(_) => {
@@ -105,10 +75,20 @@ impl Parser<'_> {
                     _ => {
                         let digits = word
                             .trim_end_matches(['b', 'B', 's', 'S', 'l', 'L', 'f', 'F', 'd', 'D']);
-                        match (digits.parse::<i64>(), digits.parse::<f64>()) {
-                            (Ok(n), _) if digits.len() + 1 >= word.len() => Value::from(n),
-                            (_, Ok(f)) if digits.len() + 1 >= word.len() => Value::from(f),
-                            _ => Value::String(word),
+                        // Only digits (and an exponent) make a number: `nan`
+                        // or `Infinity`, which Rust's parse would take, stays
+                        // a string.
+                        if digits
+                            .bytes()
+                            .any(|c| c.is_ascii_alphabetic() && c != b'e' && c != b'E')
+                        {
+                            Value::String(word)
+                        } else {
+                            match (digits.parse::<i64>(), digits.parse::<f64>()) {
+                                (Ok(n), _) if digits.len() + 1 >= word.len() => Value::from(n),
+                                (_, Ok(f)) if digits.len() + 1 >= word.len() => Value::from(f),
+                                _ => Value::String(word),
+                            }
                         }
                     }
                 })
@@ -116,6 +96,59 @@ impl Parser<'_> {
             None => Err("expected a value".into()),
         }
     }
+    fn object(&mut self) -> Result<Value, String> {
+        self.i += 1;
+        let mut map = Map::new();
+        self.ws();
+        if self.peek() == Some(b'}') {
+            self.i += 1;
+            return Ok(Value::Object(map));
+        }
+        loop {
+            self.ws();
+            let key = self.string()?;
+            self.expect(b':')?;
+            map.insert(key, self.value()?);
+            self.ws();
+            match self.peek() {
+                Some(b',') => self.i += 1,
+                Some(b'}') => {
+                    self.i += 1;
+                    return Ok(Value::Object(map));
+                }
+                _ => return Err("expected ',' or '}'".into()),
+            }
+        }
+    }
+    fn array(&mut self) -> Result<Value, String> {
+        self.i += 1;
+        let mut list = Vec::new();
+        self.ws();
+        // Typed arrays [B;...], [I;...], [L;...].
+        if matches!(
+            self.s.get(self.i..self.i + 2),
+            Some([b'B' | b'I' | b'L', b';'])
+        ) {
+            self.i += 2;
+        }
+        self.ws();
+        if self.peek() == Some(b']') {
+            self.i += 1;
+            return Ok(Value::Array(list));
+        }
+        loop {
+            list.push(self.value()?);
+            self.ws();
+            match self.peek() {
+                Some(b',') => self.i += 1,
+                Some(b']') => {
+                    self.i += 1;
+                    return Ok(Value::Array(list));
+                }
+                _ => return Err("expected ',' or ']'".into()),
+            }
+        }
+    }
     fn unquoted(&mut self) -> String {
         let start = self.i;
         while let Some(c) = self.peek() {
@@ -195,6 +228,11 @@ fn object_style(o: &serde_json::Map<String, Value>) -> Style {
             Some("copy_to_clipboard") => {
                 text("value").map(crate::text::ClickEvent::CopyToClipboard)
             }
+            // ClickEvent.ShowDialog.CODEC: a `minecraft:dialog` registry id or
+            // the dialog itself; the server may send it (isAllowedFromServer).
+            Some("show_dialog") => e.get("dialog").map(|dialog| {
+                crate::text::ClickEvent::ShowDialog(crate::scoreboard::json_to_tag(dialog))
+            }),
             _ => None,
         };
     }
@@ -258,6 +296,10 @@ pub fn to_text_with(
             let style = object_style(o);
             let content = if let Some(t) = contents(o) {
                 t
+            } else if let Some(object) = inline_object(o, resolve, contents) {
+                let mut text = Text::literal("\u{fffc}");
+                text.spans[0].style.inline_object = Some(object);
+                text
             } else if let Some(t) = o.get("text") {
                 match t {
                     Value::String(s) => Text::literal(s.clone()),
@@ -294,12 +336,74 @@ pub fn to_text_with(
             {
                 out.push(to_text_with(extra, resolve, contents).with_style(&style));
             }
-            out
+            if o.contains_key("object") || o.contains_key("player") || o.contains_key("sprite") {
+                out.with_component(Value::Object(o.clone()))
+            } else {
+                out
+            }
         }
         Value::Null => Text::empty(),
     }
 }
 
+fn inline_object(
+    object: &serde_json::Map<String, Value>,
+    resolve: &mut dyn FnMut(&str) -> Text,
+    contents: &mut dyn FnMut(&serde_json::Map<String, Value>) -> Option<Text>,
+) -> Option<InlineObject> {
+    let kind = object.get("object").and_then(Value::as_str);
+    let fallback = object
+        .get("fallback")
+        .map(|value| to_text_with(value, resolve, contents).plain());
+    match kind {
+        Some("player") | None if object.contains_key("player") => {
+            let profile = object.get("player")?.clone();
+            // PlayerSprite.defaultFallback.
+            let fallback = fallback.unwrap_or_else(|| {
+                match profile
+                    .as_str()
+                    .or_else(|| profile.get("name").and_then(Value::as_str))
+                {
+                    Some(name) => format!("[{name} head]"),
+                    None => "[unknown player head]".to_owned(),
+                }
+            });
+            Some(InlineObject::Player {
+                profile,
+                hat: object.get("hat").and_then(Value::as_bool).unwrap_or(true),
+                fallback,
+            })
+        }
+        Some("atlas") | None if object.contains_key("sprite") => {
+            let atlas = object
+                .get("atlas")
+                .and_then(Value::as_str)
+                .unwrap_or("minecraft:blocks")
+                .to_owned();
+            let sprite = object.get("sprite")?.as_str()?.to_owned();
+            // AtlasSprite.defaultFallback: short names, the atlas unless blocks.
+            let fallback = fallback.unwrap_or_else(|| {
+                let short = |id: &str| match id.split_once(':') {
+                    Some(("minecraft", path)) => path.to_owned(),
+                    Some(_) => id.to_owned(),
+                    None => id.to_owned(),
+                };
+                if short(&atlas) == "blocks" {
+                    format!("[{}]", short(&sprite))
+                } else {
+                    format!("[{}@{}]", short(&sprite), short(&atlas))
+                }
+            });
+            Some(InlineObject::Atlas {
+                atlas,
+                sprite,
+                fallback,
+            })
+        }
+        _ => None,
+    }
+}
+
 /// `CustomName` as text: a string keeps its legacy formatting codes, anything
 /// else is a component (`ComponentSerialization`).
 pub fn name_text(tag: &Tag) -> Text {
@@ -313,6 +417,44 @@ pub fn name_text(tag: &Tag) -> Text {
 mod tests {
     use super::*;
 
+    #[test]
+    fn player_object_survives_text_parsing_and_keeps_its_siblings() {
+        let component = serde_json::json!({
+            "text": "<",
+            "extra": [
+                {"object": "player", "player": {"name": "elyapluggin"}, "hat": false,
+                 "fallback": "[head]"},
+                {"text": " >", "color": "gold"}
+            ]
+        });
+        let text = to_text(&component, &mut |_| Text::empty());
+        assert_eq!(text.plain(), "<[head] >");
+        assert!(matches!(
+            &text.spans[1].style.inline_object,
+            Some(InlineObject::Player { hat: false, .. })
+        ));
+        assert!(text.spans[2].style.inline_object.is_none());
+        assert_eq!(text.component(), component);
+        let sprite = serde_json::json!({"object": "atlas", "sprite": "minecraft:item/porkchop"});
+        let text = to_text(&sprite, &mut |_| Text::empty());
+        assert!(matches!(
+            &text.spans[0].style.inline_object,
+            Some(InlineObject::Atlas { sprite, .. }) if sprite == "minecraft:item/porkchop"
+        ));
+        // ObjectContents.visit without a fallback: the sprite's defaultFallback.
+        assert_eq!(text.plain(), "[item/porkchop]");
+        let head = serde_json::json!({"object": "player", "player": {"name": "Steve"}});
+        assert_eq!(
+            to_text(&head, &mut |_| Text::empty()).plain(),
+            "[Steve head]"
+        );
+        let gui = serde_json::json!({"atlas": "gui", "sprite": "hud/heart/full"});
+        assert_eq!(
+            to_text(&gui, &mut |_| Text::empty()).plain(),
+            "[hud/heart/full@gui]"
+        );
+    }
+
     #[test]
     fn snbt_and_json_components() {
         let input = "{text:'Hi ',color:red,extra:[{text:\"there\",bold:1b}]} rest";
@@ -346,4 +488,22 @@ mod tests {
         let t = to_text(&v, &mut |_| Text::empty());
         assert_eq!(t.spans[0].style.font, None);
     }
+
+    #[test]
+    fn snbt_nesting_is_bounded() {
+        let nest = |n: usize| format!("{}1{}", "[".repeat(n), "]".repeat(n));
+        assert!(parse_snbt(&nest(512)).is_ok());
+        assert!(parse_snbt(&nest(513)).is_err());
+        assert!(parse_snbt(&nest(100_000)).is_err());
+    }
+
+    #[test]
+    fn bare_words_that_look_numeric_stay_strings() {
+        let (v, _) = parse_snbt("{text:nan}").unwrap();
+        assert_eq!(v["text"], Value::String("nan".into()));
+        let (v, _) = parse_snbt("{text:Infinity}").unwrap();
+        assert_eq!(v["text"], Value::String("Infinity".into()));
+        let (v, _) = parse_snbt("{n:1.5}").unwrap();
+        assert_eq!(v["n"], Value::from(1.5));
+    }
 }

crates/horizon-client-core/src/lang.rs

@@ -40,6 +40,10 @@ static BIDIRECTIONAL: AtomicBool = AtomicBool::new(false);
 /// A source of resource files: the prepared root plus packs, highest priority last.
 pub trait ResourceSource {
     fn read(&self, path: &str) -> Option<Vec<u8>>;
+    /// Whether `path` is there, without reading it where the source can tell.
+    fn exists(&self, path: &str) -> bool {
+        self.read(path).is_some()
+    }
     /// The namespaces under `assets/` (resource packs may add their own).
     fn namespaces(&self) -> Vec<String> {
         vec!["minecraft".into()]
@@ -56,6 +60,9 @@ impl ResourceSource for Bundled {
             "assets/horizon/lang/ru_ru.json" => {
                 include_str!("../../horizon-client/assets/horizon/lang/ru_ru.json")
             }
+            "assets/horizon/lang/uk_ua.json" => {
+                include_str!("../../horizon-client/assets/horizon/lang/uk_ua.json")
+            }
             _ => return None,
         };
         Some(body.as_bytes().to_vec())
@@ -68,6 +75,9 @@ impl ResourceSource for std::path::PathBuf {
     fn read(&self, path: &str) -> Option<Vec<u8>> {
         std::fs::read(self.join(path)).ok()
     }
+    fn exists(&self, path: &str) -> bool {
+        self.join(path).is_file()
+    }
     fn namespaces(&self) -> Vec<String> {
         std::fs::read_dir(self.join("assets"))
             .into_iter()
@@ -190,7 +200,7 @@ pub fn available(sources: &[&dyn ResourceSource]) -> Vec<LanguageInfo> {
             for (code, info) in value["language"].as_object().into_iter().flatten() {
                 // Only languages whose file exists somewhere are selectable.
                 let file = format!("assets/minecraft/lang/{code}.json");
-                if code != DEFAULT && !sources.iter().any(|s| s.read(&file).is_some()) {
+                if code != DEFAULT && !sources.iter().any(|s| s.exists(&file)) {
                     continue;
                 }
                 found.insert(
@@ -259,6 +269,11 @@ mod tests {
         assert_eq!(en.get("horizon.options.controller"), Some("Controller"));
         let ru = Language::load(&[&empty], "ru_ru");
         assert_eq!(ru.get("horizon.options.controller"), Some("Геймпад"));
+        let uk = Language::load(&[&empty], "uk_ua");
+        assert_eq!(
+            uk.get("horizon.options.on_screen_keyboard"),
+            Some("Екранна клавіатура")
+        );
     }
 
     #[test]
@@ -284,4 +299,26 @@ mod tests {
         );
         assert_eq!(langs[1].label(), "Français (France)");
     }
+
+    #[test]
+    fn languages_are_listed_without_reading_their_files() {
+        struct NoLangReads;
+        impl ResourceSource for NoLangReads {
+            fn read(&self, path: &str) -> Option<Vec<u8>> {
+                assert!(!path.contains("/lang/"), "read {path}");
+                (path == "assets/pack.mcmeta").then(|| {
+                    br#"{"language":{"fr_fr":{"name":"French"},"de_de":{"name":"German"}}}"#
+                        .to_vec()
+                })
+            }
+            fn exists(&self, path: &str) -> bool {
+                path == "assets/minecraft/lang/fr_fr.json"
+            }
+        }
+        let langs = available(&[&NoLangReads]);
+        assert_eq!(
+            langs.iter().map(|l| l.code.as_str()).collect::<Vec<_>>(),
+            ["en_us", "fr_fr"]
+        );
+    }
 }

crates/horizon-client-core/src/potions.rs

@@ -91,6 +91,7 @@ pub fn effect(id: &str) -> Option<&'static EffectDef> {
 /// Namespaced effect ids for mob effect storage.
 pub fn namespaced(id: &'static str) -> &'static str {
     static IDS: OnceLock<HashMap<&'static str, &'static str>> = OnceLock::new();
+    let key = id.strip_prefix("minecraft:").unwrap_or(id);
     IDS.get_or_init(|| {
         EFFECTS
             .iter()
@@ -102,7 +103,7 @@ pub fn namespaced(id: &'static str) -> &'static str {
             })
             .collect()
     })
-    .get(id)
+    .get(key)
     .copied()
     .unwrap_or(id)
 }

crates/horizon-client-core/src/registries.rs

@@ -54,6 +54,12 @@ pub struct Registries {
     pub function_tags: Vec<String>,
     /// The block the source is looking at (relevant coordinates).
     pub target_block: Option<[i32; 3]>,
+    /// `ClientSuggestionProvider.getSelectedEntities`: the UUID of the
+    /// entity under the crosshair (`Entity.getStringUUID`), if any.
+    pub selected_entities: Vec<String>,
+    /// `ClientSuggestionProvider.getAbsoluteCoordinates`: the exact point of
+    /// that block hit, each coordinate as `%.2f` (`Locale.ROOT`).
+    pub target_point: Option<[String; 3]>,
     /// Every registry's element and tag ids (`minecraft:item` -> ...), as
     /// the server's registry access and reloadable registries hold them.
     pub by_registry: BTreeMap<String, RegistryIds>,

crates/horizon-client-core/src/scoreboard.rs

@@ -662,10 +662,22 @@ pub fn name_shown(own: Option<&Team>, viewer: Option<&Team>, v: NameView) -> boo
     }
     !v.hud_hidden && !v.is_camera && visible && !v.is_vehicle
 }
-/// `ServerPlayer.die`: whether a player's death message reaches the player
-/// themselves (the team broadcasts leave out the dying player).
-pub fn own_death_message_shown(team: Option<&Team>) -> bool {
-    team.is_none_or(|t| t.death_message_visibility == Visibility::Always)
+/// `ServerPlayer.die`: whether `other` hears the death message of `dying`
+/// (`broadcastSystemMessage`, `broadcastSystemToTeam` or
+/// `broadcastSystemToAllExceptTeam`, by the team's death message visibility).
+pub fn death_message_reaches(board: &Scoreboard, dying: &str, other: &str) -> bool {
+    let Some(team) = board.players_team(dying) else {
+        return true;
+    };
+    let same_team = board
+        .players_team(other)
+        .is_some_and(|t| t.name == team.name);
+    match team.death_message_visibility {
+        Visibility::Always => true,
+        Visibility::Never => false,
+        Visibility::HideForOtherTeams => same_team && other != dying,
+        Visibility::HideForOwnTeam => !same_team,
+    }
 }
 
 // ---- objectives and scores ---------------------------------------------

crates/horizon-client-core/src/text.rs

@@ -50,11 +50,36 @@ pub enum ClickEvent {
     /// `ClickEvent.RunCommand`: the command, with or without its `/`.
     RunCommand(String),
     CopyToClipboard(String),
+    /// `ClickEvent.ShowDialog`: a `minecraft:dialog` registry id, or the
+    /// dialog itself as the component carried it.
+    ShowDialog(horizon_world::nbt::Tag),
     /// A local file to open with the system handler.
     /// Only allow this in locally constructed messages, never server/LAN text.
     OpenFile(String),
 }
 
+/// A non-character `minecraft:object` embedded in a text component.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum InlineObject {
+    Player {
+        profile: Value,
+        hat: bool,
+        fallback: String,
+    },
+    Atlas {
+        atlas: String,
+        sprite: String,
+        fallback: String,
+    },
+}
+impl InlineObject {
+    pub fn fallback(&self) -> &str {
+        match self {
+            Self::Player { fallback, .. } | Self::Atlas { fallback, .. } => fallback,
+        }
+    }
+}
+
 /// Text style; `None` fields inherit from the enclosing style.
 #[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct Style {
@@ -74,6 +99,8 @@ pub struct Style {
     /// The font (`FontDescription.Resource`), a full id like
     /// `minecraft:alt`; the default font when unset.
     pub font: Option<String>,
+    /// Content metadata for a single U+FFFC object span; never inherited.
+    pub inline_object: Option<InlineObject>,
 }
 /// A style's `font` field: an identifier (`alt` is `minecraft:alt`).
 pub fn font_id(v: &Value) -> Option<String> {
@@ -334,7 +361,13 @@ impl Text {
     }
     /// Component.getString: the plain characters.
     pub fn plain(&self) -> String {
-        self.spans.iter().map(|s| s.text.as_str()).collect()
+        self.spans
+            .iter()
+            .map(|s| match &s.style.inline_object {
+                Some(object) if s.text == "\u{fffc}" => object.fallback(),
+                _ => s.text.as_str(),
+            })
+            .collect()
     }
     pub fn is_empty(&self) -> bool {
         self.spans.iter().all(|s| s.text.is_empty())
@@ -400,31 +433,7 @@ impl Text {
                     continue;
                 }
                 let Some(code) = chars.next() else { break };
-                let code = code.to_ascii_lowercase();
-                let next = if let Some(c) = COLORS.iter().find(|c| c.0 == code) {
-                    // Style.applyLegacyFormat: a colour clears the decorations.
-                    Style {
-                        color: Some(c.2),
-                        bold: Some(false),
-                        italic: Some(false),
-                        underlined: Some(false),
-                        strikethrough: Some(false),
-                        obfuscated: Some(false),
-                        ..style.clone()
-                    }
-                } else {
-                    let mut s = style.clone();
-                    match code {
-                        'k' => s.obfuscated = Some(true),
-                        'l' => s.bold = Some(true),
-                        'm' => s.strikethrough = Some(true),
-                        'n' => s.underlined = Some(true),
-                        'o' => s.italic = Some(true),
-                        'r' => s = span.style.clone(),
-                        _ => {}
-                    }
-                    s
-                };
+                let next = legacy_format(&style, code, &span.style);
                 if next != style {
                     if !current.is_empty() {
                         out.spans.push(Span {
@@ -557,6 +566,11 @@ fn style_json(style: &Style) -> Vec<(String, Value)> {
             ClickEvent::RunCommand(command) => {
                 json!({ "action": "run_command", "command": command })
             }
+            // ClickEvent.ShowDialog.CODEC: the dialog the server sent it with.
+            ClickEvent::ShowDialog(dialog) => json!({
+                "action": "show_dialog",
+                "dialog": crate::scoreboard::tag_to_json(dialog),
+            }),
             ClickEvent::OpenFile(path) => json!({ "action": "open_file", "path": path }),
         };
         out.push(("click_event".to_owned(), event));
@@ -580,6 +594,35 @@ fn style_json(style: &Style) -> Vec<(String, Value)> {
     out
 }
 
+/// `Style.applyLegacyFormat` for the code after a `§`, `§r` going back to
+/// `reset` (`StringDecomposer.iterateFormatted`); an unknown code changes nothing.
+pub fn legacy_format(style: &Style, code: char, reset: &Style) -> Style {
+    let code = code.to_ascii_lowercase();
+    if let Some(c) = COLORS.iter().find(|c| c.0 == code) {
+        // A colour clears the decorations.
+        return Style {
+            color: Some(c.2),
+            bold: Some(false),
+            italic: Some(false),
+            underlined: Some(false),
+            strikethrough: Some(false),
+            obfuscated: Some(false),
+            ..style.clone()
+        };
+    }
+    let mut s = style.clone();
+    match code {
+        'k' => s.obfuscated = Some(true),
+        'l' => s.bold = Some(true),
+        'm' => s.strikethrough = Some(true),
+        'n' => s.underlined = Some(true),
+        'o' => s.italic = Some(true),
+        'r' => s = reset.clone(),
+        _ => {}
+    }
+    s
+}
+
 /// TranslatableContents.decomposeTemplate: `%s` takes the next argument,
 /// `%n$s` a numbered one and `%%` is a percent sign. Malformed templates are
 /// shown verbatim.

crates/horizon-client-input/src/clipboard.rs

@@ -60,6 +60,19 @@ pub fn edit_shortcut(
     })
 }
 
+/// Windows reports AltGr as Ctrl plus Alt: the system presses a left Control
+/// in front of the right Alt.
+pub const ALTGR_IS_CTRL_ALT: bool = cfg!(windows);
+
+/// Whether a key's text reaches the screen (`KeyboardHandler.textInput`, then
+/// `charTyped` per code point). The edit modifier's shortcuts type nothing,
+/// but `textInput` takes no modifiers: with AltGr held (Ctrl plus Alt where
+/// `altgr_is_ctrl_alt`) the layout's third-level characters are text, as `/`
+/// on ABNT2, `@`, `{` and `[` on German or the Polish letters.
+pub fn types_text(edit_modifier: bool, alt: bool, altgr_is_ctrl_alt: bool) -> bool {
+    !edit_modifier || (altgr_is_ctrl_alt && alt)
+}
+
 /// `StringUtil.isAllowedChatCharacter`.
 pub fn is_allowed_chat_character(c: char) -> bool {
     c != '§' && c >= ' ' && c != '\u{7f}'
@@ -303,6 +316,22 @@ pub fn append_limited(value: &mut String, text: &str, max_chars: usize) -> bool
 mod tests {
     use super::*;
 
+    #[test]
+    fn altgr_types_text_where_it_is_ctrl_alt() {
+        // Plain keys and Shift type.
+        assert!(types_text(false, false, true));
+        assert!(types_text(false, false, false));
+        // Ctrl (Cmd) shortcuts do not.
+        assert!(!types_text(true, false, true));
+        assert!(!types_text(true, false, false));
+        // AltGr on Windows is Ctrl+Alt: ABNT2 `/`, German `@` type.
+        assert!(types_text(true, true, true));
+        // Where AltGr is its own modifier, Ctrl+Alt is a shortcut.
+        assert!(!types_text(true, true, false));
+        // Alt alone (macOS Option, Linux AltGr) types.
+        assert!(types_text(false, true, false));
+    }
+
     #[test]
     fn shortcuts_need_the_edit_modifier_alone() {
         let c = Some('c');

crates/horizon-client-input/src/keybinds.rs

@@ -300,9 +300,8 @@ impl Default for KeyBinds {
     }
 }
 /// Each default key once, in order: two mappings that share a default key
-/// (Advancements and the debug profiler both on L) are one press of it, not
-/// two (the second would close the screen the first opened). Vanilla clicks
-/// both mappings, but the profiler one only acts with F3 held.
+/// (Pick Block and the spectator hotbar both on the middle button) are one
+/// press of it, not two.
 fn distinct<T: PartialEq>(keys: Vec<T>) -> Vec<T> {
     let mut out = Vec::with_capacity(keys.len());
     for k in keys {
@@ -368,6 +367,25 @@ impl KeyBinds {
             .map(|m| m.0)
             .filter(move |n| self.get(n) == key)
     }
+    /// The mappings bound to `key` that [`KeyBinds::translate_all`] follows:
+    /// all but the debug keys. Those act only with F3 held
+    /// (`KeyboardHandler.handleDebugKeys`, `debug_keys.rs` reads the physical
+    /// key and the binding itself); their defaults (A, S, D, T, L, 1 to 4...)
+    /// would otherwise turn the key back into its old gameplay meaning.
+    fn translated_mappings<'a>(&'a self, key: &'a str) -> impl Iterator<Item = &'static str> + 'a {
+        MAPPINGS
+            .iter()
+            .filter(|m| m.2 != "debug")
+            .map(|m| m.0)
+            .filter(move |n| self.get(n) == key)
+    }
+    /// Whether a mapping (other than a debug key) whose default is `key` was
+    /// bound elsewhere.
+    fn default_moved(&self, key: &str) -> bool {
+        MAPPINGS
+            .iter()
+            .any(|(n, d, c)| *d == key && *c != "debug" && !self.is_default(n))
+    }
     /// Translate a physical key into the default key of the mapping it is
     /// bound to, so game code written against vanilla defaults follows the
     /// player's bindings. `None` means the key now does nothing; mouse
@@ -384,7 +402,7 @@ impl KeyBinds {
             return vec![Ok(key)];
         };
         let bound: Vec<_> = self
-            .mappings_for(name)
+            .translated_mappings(name)
             .filter_map(|mapping| {
                 let default = Self::default_of(mapping);
                 match key_code(default) {
@@ -397,10 +415,7 @@ impl KeyBinds {
             return distinct(bound);
         }
         // An unbound key whose default meaning was moved elsewhere is inert.
-        if MAPPINGS
-            .iter()
-            .any(|(n, d, _)| *d == name && !self.is_default(n))
-        {
+        if self.default_moved(name) {
             return Vec::new();
         }
         vec![Ok(key)]
@@ -413,7 +428,7 @@ impl KeyBinds {
     pub fn translate_mouse_all(&self, button: MouseButton) -> Vec<Result<KeyCode, MouseButton>> {
         let name = mouse_name(button);
         let bound: Vec<_> = self
-            .mappings_for(&name)
+            .translated_mappings(&name)
             .filter_map(|mapping| {
                 let default = Self::default_of(mapping);
                 match mouse_button(default) {
@@ -425,10 +440,7 @@ impl KeyBinds {
         if !bound.is_empty() {
             return distinct(bound);
         }
-        if MAPPINGS
-            .iter()
-            .any(|(n, d, _)| *d == name && !self.is_default(n))
-        {
+        if self.default_moved(&name) {
             return Vec::new();
         }
         vec![Err(button)]
@@ -508,6 +520,29 @@ mod tests {
         assert_eq!(k.conflicts("key.forward"), ["key.jump"]);
     }
     #[test]
+    fn a_moved_key_keeps_no_default_action() {
+        // #3158: the debug keys (F3+A, F3+1...) share these keys' defaults,
+        // and must not hand them back their gameplay meaning.
+        let mut k = KeyBinds::default();
+        k.set("key.hotbar.1", "key.keyboard.q");
+        assert_eq!(k.translate_all(KeyCode::Digit1), []);
+        assert_eq!(
+            k.translate_all(KeyCode::KeyQ),
+            [Ok(KeyCode::KeyQ), Ok(KeyCode::Digit1)]
+        );
+        k.set("key.inventory", "key.keyboard.a");
+        k.set("key.left", "key.keyboard.e");
+        assert_eq!(k.translate_all(KeyCode::KeyA), [Ok(KeyCode::KeyE)]);
+        assert_eq!(k.translate_all(KeyCode::KeyE), [Ok(KeyCode::KeyA)]);
+        k.set("key.back", "key.keyboard.down");
+        assert_eq!(k.translate_all(KeyCode::KeyS), []);
+        // Keys left alone still act, and a moved debug key changes nothing.
+        k.set("key.debug.fpsCharts", "key.keyboard.9");
+        assert_eq!(k.translate_all(KeyCode::Digit2), [Ok(KeyCode::Digit2)]);
+        assert_eq!(k.translate_all(KeyCode::Digit9), [Ok(KeyCode::Digit9)]);
+        assert_eq!(k.translate_all(KeyCode::F3), [Ok(KeyCode::F3)]);
+    }
+    #[test]
     fn display_names() {
         assert_eq!(display_name("key.keyboard.w").plain(), "W");
         assert_eq!(display_name("key.keyboard.slash").plain(), "/");

crates/horizon-client-input/src/mouse.rs

@@ -324,6 +324,24 @@ pub fn ease_in_out(t: f64) -> f64 {
     0.5 - 0.5 * (std::f64::consts::PI * t).cos()
 }
 
+/// `MouseHandler.grabMouse` / `releaseMouse`: the mouse position is the
+/// window's centre whenever the pointer's grab state changes, so a screen
+/// opened from gameplay starts with the cursor in the middle. A release of
+/// an already free pointer (or a grab of an already grabbed one) leaves the
+/// position where it is, as vanilla does.
+pub fn mouse_position_after_grab_change(
+    grab: bool,
+    was_grabbed: bool,
+    size: [u32; 2],
+    scale: f32,
+) -> Option<(f32, f32)> {
+    if grab == was_grabbed {
+        None
+    } else {
+        Some((size[0] as f32 / 2.0 / scale, size[1] as f32 / 2.0 / scale))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -485,4 +503,27 @@ mod tests {
         assert_eq!(look.on_scroll(0.0, 0.4, false, 1.0), None);
         assert_eq!(look.on_scroll(0.0, 0.7, false, 1.0), Some((1, (0, 1))));
     }
+    #[test]
+    fn the_mouse_position_is_the_centre_when_the_grab_changes() {
+        // A grab of a free pointer and a release of a grabbed one both put
+        // the position at the window's centre (`MouseHandler.grabMouse`,
+        // `MouseHandler.releaseMouse`).
+        assert_eq!(
+            mouse_position_after_grab_change(true, false, [1920, 1080], 1.0),
+            Some((960.0, 540.0))
+        );
+        assert_eq!(
+            mouse_position_after_grab_change(false, true, [1920, 1080], 2.0),
+            Some((480.0, 270.0))
+        );
+        // Without a change of the grab state the position stays where it is.
+        assert_eq!(
+            mouse_position_after_grab_change(false, false, [1920, 1080], 1.0),
+            None
+        );
+        assert_eq!(
+            mouse_position_after_grab_change(true, true, [1920, 1080], 1.0),
+            None
+        );
+    }
 }

crates/horizon-client-render/Cargo.toml

@@ -0,0 +1,67 @@
+[package]
+name = "horizon-client-render"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+rust-version = "1.90"
+description = "The client's world data, rendering and screens: chunks, meshing, light, streaming, the renderer, the HUD, menus and settings; no gameplay"
+
+[dependencies]
+horizon-assets = { path = "../horizon-assets" }
+horizon-bench = { path = "../horizon-bench" }
+horizon-client-core = { path = "../horizon-client-core" }
+horizon-client-input = { path = "../horizon-client-input" }
+horizon-command = { path = "../horizon-command" }
+horizon-core = { path = "../horizon-core" }
+horizon-hdr = { path = "../horizon-hdr" }
+horizon-items = { path = "../horizon-items" }
+horizon-protocol = { path = "../horizon-protocol" }
+horizon-shader-api = { path = "../horizon-shader-api" }
+horizon-shaders = { path = "../horizon-shaders" }
+horizon-telemetry = { path = "../horizon-telemetry", default-features = false, features = ["live"] }
+horizon-theme = { path = "../horizon-theme" }
+horizon-threads = { path = "../horizon-threads" }
+horizon-world = { path = "../horizon-world" }
+ab_glyph = "0.2.32"
+bytemuck = { version = "1.24", features = ["derive"] }
+# Sound (ALSA on Linux); the `audio` feature.
+cpal = { version = "0.16", optional = true }
+chrono = { version = "0.4.42", default-features = false, features = ["clock", "std"] }
+flate2 = { version = "1.1.10", default-features = false, features = ["zlib-rs", "runtime_detection"] }
+glam = "0.30"
+log = "0.4"
+miniz_oxide = "0.8"
+naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out"] }
+png = "0.18"
+pollster = "0.4"
+serde = { version = "1", features = ["derive"] }
+serde_json = { version = "1.0.151", features = ["raw_value"] }
+sha2 = "0.10.9"
+symphonia = { version = "0.5", default-features = false, features = ["ogg", "vorbis"] }
+unicode-bidi = "0.3.18"
+ureq = { version = "2", default-features = false, features = ["tls"] }
+wgpu = { version = "30.0.1", default-features = false, features = ["std", "parking_lot", "vulkan", "metal", "wgsl", "naga-ir"] }
+winit = "0.30.13"
+zip = { version = "2", default-features = false, features = ["deflate"] }
+
+[target.'cfg(unix)'.dependencies]
+rustix = { version = "1", default-features = false, features = ["std", "time"] }
+
+[target.'cfg(windows)'.dependencies]
+wgpu = { version = "30.0.1", default-features = false, features = ["dx12"] }
+
+[target.'cfg(not(target_os = "macos"))'.dependencies]
+wgpu = { version = "30.0.1", default-features = false, features = ["gles"] }
+
+[features]
+# Sound output: horizon-client's `audio` feature.
+audio = ["dep:cpal"]
+# Helpers horizon-client's tests build their fixtures with.
+test-support = []
+
+[lints]
+workspace = true
+
+[dev-dependencies]
+horizon-items = { path = "../horizon-items", features = ["test-support"] }
+naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out", "msl-out", "spv-out"] }

crates/horizon-client-render/examples/compositor.rs

@@ -0,0 +1,151 @@
+//! Two offscreen frames presented in one window, without game resources or player data.
+//! `cargo run --profile fast -p horizon-client-render --example compositor -- --smoke`
+use horizon_client_render::gfx::compositor::Compositor;
+use std::sync::Arc;
+use winit::{
+    application::ApplicationHandler,
+    event::WindowEvent,
+    event_loop::{ActiveEventLoop, EventLoop},
+    window::{Window, WindowId},
+};
+
+struct Frames {
+    window: Arc<Window>,
+    compositor: Compositor,
+    textures: [wgpu::Texture; 2],
+}
+
+impl Frames {
+    fn new(event_loop: &ActiveEventLoop) -> horizon_client_render::Result<Self> {
+        let window = Arc::new(
+            event_loop.create_window(
+                Window::default_attributes()
+                    .with_title("Compositor: red and blue views")
+                    .with_inner_size(winit::dpi::PhysicalSize::new(640, 360)),
+            )?,
+        );
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_with_display_handle(
+            Box::new(window.clone()),
+        ));
+        let surface = instance.create_surface(window.clone())?;
+        let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
+            compatible_surface: Some(&surface),
+            ..Default::default()
+        }))?;
+        let (device, queue) = pollster::block_on(adapter.request_device(&Default::default()))?;
+        let textures = [[0, 0, 255, 255], [255, 0, 0, 255]].map(|pixel| {
+            let size = wgpu::Extent3d {
+                width: 320,
+                height: 360,
+                depth_or_array_layers: 1,
+            };
+            let texture = device.create_texture(&wgpu::TextureDescriptor {
+                label: Some("Offscreen view"),
+                size,
+                mip_level_count: 1,
+                sample_count: 1,
+                dimension: wgpu::TextureDimension::D2,
+                format: wgpu::TextureFormat::Bgra8Unorm,
+                usage: wgpu::TextureUsages::COPY_SRC | wgpu::TextureUsages::COPY_DST,
+                view_formats: &[],
+            });
+            queue.write_texture(
+                texture.as_image_copy(),
+                &pixel.repeat(320 * 360),
+                wgpu::TexelCopyBufferLayout {
+                    offset: 0,
+                    bytes_per_row: Some(320 * 4),
+                    rows_per_image: Some(360),
+                },
+                size,
+            );
+            texture
+        });
+        let compositor = Compositor::new(
+            surface,
+            &adapter,
+            &device,
+            &queue,
+            window.inner_size().into(),
+        )?;
+        Ok(Self {
+            window,
+            compositor,
+            textures,
+        })
+    }
+}
+
+#[derive(Default)]
+struct Demo {
+    frames: Option<Frames>,
+    error: Option<String>,
+    presented: usize,
+    smoke: bool,
+}
+
+impl ApplicationHandler for Demo {
+    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
+        if self.frames.is_none() {
+            match Frames::new(event_loop) {
+                Ok(frames) => self.frames = Some(frames),
+                Err(error) => {
+                    self.error = Some(error.to_string());
+                    event_loop.exit();
+                }
+            }
+        }
+    }
+
+    fn window_event(&mut self, event_loop: &ActiveEventLoop, _: WindowId, event: WindowEvent) {
+        let Some(f) = &mut self.frames else { return };
+        match event {
+            WindowEvent::CloseRequested => event_loop.exit(),
+            WindowEvent::Resized(size) => f.compositor.resize(size.width, size.height),
+            // Uncovered pixels are black; resize smaller to exercise clipping.
+            WindowEvent::RedrawRequested
+                if f.compositor
+                    .present(&[(&f.textures[0], [0, 0]), (&f.textures[1], [320, 0])]) =>
+            {
+                self.presented += 1;
+                if self.smoke && self.presented == 10 {
+                    f.compositor.set_vsync(false);
+                    f.compositor.resize(0, 0);
+                    assert!(!f.compositor.present(&[]));
+                    f.compositor.resize(u32::MAX, u32::MAX);
+                    assert!(!f.compositor.present(&[]));
+                    f.compositor.resize(400, 240);
+                    let _ = f
+                        .window
+                        .request_inner_size(winit::dpi::PhysicalSize::new(400, 240));
+                }
+                if self.smoke && self.presented == 20 {
+                    println!("compositor: 20 frames, resize, suspension and clipping passed");
+                    event_loop.exit();
+                }
+            }
+            _ => {}
+        }
+    }
+
+    fn about_to_wait(&mut self, _: &ActiveEventLoop) {
+        if let Some(f) = &self.frames {
+            f.window.request_redraw();
+        }
+    }
+}
+
+fn main() -> horizon_client_render::Result<()> {
+    let mut demo = Demo {
+        smoke: std::env::args().any(|a| a == "--smoke"),
+        ..Default::default()
+    };
+    EventLoop::new()?.run_app(&mut demo)?;
+    if let Some(error) = demo.error {
+        return Err(error.into());
+    }
+    if demo.smoke && demo.presented < 20 {
+        return Err("smoke test closed early".into());
+    }
+    Ok(())
+}

crates/horizon-client-render/src/assets.rs

@@ -42,11 +42,11 @@ impl HeightmapState for StateFacts {
 }
 #[derive(Clone)]
 pub struct Properties(Arc<Vec<StateFacts>>);
-#[cfg(test)]
+#[cfg(any(test, feature = "test-support"))]
 impl Properties {
     /// Heightmap facts for tests, per state: (air, has a fluid, blocks
     /// motion, blocks motion but is not leaves). State 0 is minecraft:air.
-    pub(crate) fn for_tests(states: &[(bool, bool, bool, bool)]) -> Self {
+    pub fn for_tests(states: &[(bool, bool, bool, bool)]) -> Self {
         Self(Arc::new(
             states
                 .iter()
@@ -196,7 +196,7 @@ impl Assets {
 impl RenderAssets {
     pub fn load(root: &Path, assets: &Assets) -> Result<Self> {
         let registry = assets.registry;
-        let mut sprites = crate::sprites::Sprites::default();
+        let mut sprites = crate::sprites::Sprites::with_disk_cache(root);
         for name in MATERIALS {
             sprites.insert(root, &format!("minecraft:block/{name}"))?;
         }
@@ -217,6 +217,7 @@ impl RenderAssets {
         for stage in 0..10 {
             sprites.insert(root, &format!("minecraft:block/destroy_stage_{stage}"))?;
         }
+        sprites.save_disk_cache();
         sprites.finish();
         // `finish` grows the buffer by doubling: keep only the bytes in use.
         sprites.pixels.shrink_to_fit();

crates/horizon-client-render/src/atlas_sources.rs

@@ -187,7 +187,14 @@ pub fn list_textures(root: &Path) -> Vec<String> {
             };
             for e in entries.flatten() {
                 let p = e.path();
-                if p.is_dir() {
+                // `file_type` comes with the listing; `Path::is_dir` is a stat per
+                // entry, kept for links (which it follows).
+                let dir = match e.file_type() {
+                    Ok(t) if t.is_symlink() => p.is_dir(),
+                    Ok(t) => t.is_dir(),
+                    Err(_) => p.is_dir(),
+                };
+                if dir {
                     stack.push(p);
                 } else if p.extension().is_some_and(|x| x == "png")
                     && let Ok(rel) = p.strip_prefix(&base)

crates/horizon-client-render/src/audio.rs

@@ -144,6 +144,7 @@ type Stream = cpal::Stream;
 type Stream = std::convert::Infallible;
 pub struct Audio {
     _stream: Option<Stream>,
+    device_name: String,
     pub engine: SoundEngine,
     backend: MixerBackend,
     /// Record `Heard` sounds (the subtitle overlay is listening).
@@ -543,15 +544,48 @@ fn build_stream<T: cpal::SizedSample + cpal::FromSample<f32>>(
     )?;
     Ok(stream)
 }
+/// Available audio output device names.
+#[cfg(feature = "audio")]
+pub fn output_devices() -> Vec<String> {
+    if output_disabled(|name| std::env::var_os(name)).is_some() {
+        return Vec::new();
+    }
+    let host = cpal::default_host();
+    let mut names = Vec::new();
+    if let Ok(devices) = host.output_devices() {
+        for device in devices {
+            if let Ok(name) = device.name()
+                && !names.contains(&name)
+            {
+                names.push(name);
+            }
+        }
+    }
+    names
+}
+
+#[cfg(not(feature = "audio"))]
+pub fn output_devices() -> Vec<String> {
+    Vec::new()
+}
+
 impl Audio {
     pub fn new(root: &Path) -> Self {
-        Self::with_output(root, true)
+        Self::with_device(root, "")
+    }
+    pub fn with_device(root: &Path, device_name: &str) -> Self {
+        Self::with_output(root, true, device_name)
     }
     /// No output device: the dedicated server.
     pub fn silent(root: &Path) -> Self {
-        Self::with_output(root, false)
+        Self::with_output(root, false, "")
     }
-    fn with_output(root: &Path, output: bool) -> Self {
+    /// The output device asked for (`soundDevice`), empty for the system's default; the
+    /// default plays when that one can't be opened, as in vanilla.
+    pub fn device(&self) -> &str {
+        &self.device_name
+    }
+    fn with_output(root: &Path, output: bool, target_device: &str) -> Self {
         let registry = SoundRegistry::load(root);
         if output && registry.is_empty() {
             // The game then plays nothing on a working output (#1035, #1076).
@@ -564,7 +598,7 @@ impl Audio {
         }
         let mixer = Arc::new(Mutex::new(Mixer::default()));
         let opened = if output {
-            Self::open(mixer.clone())
+            Self::open_named(mixer.clone(), target_device)
         } else {
             Err("no output on a dedicated server".into())
         };
@@ -581,6 +615,7 @@ impl Audio {
         engine.loaded = live;
         Self {
             _stream: stream,
+            device_name: target_device.to_owned(),
             engine,
             backend: MixerBackend {
                 mixer,
@@ -602,10 +637,61 @@ impl Audio {
         }
     }
     #[cfg(not(feature = "audio"))]
-    fn open(_: Arc<Mutex<Mixer>>) -> Result<Stream> {
+    fn open_named(_: Arc<Mutex<Mixer>>, _: &str) -> Result<Stream> {
         Err("this build has no sound output (built without the `audio` feature)".into())
     }
     #[cfg(feature = "audio")]
+    fn open_named(mixer: Arc<Mutex<Mixer>>, target: &str) -> Result<Stream> {
+        if let Some(reason) = output_disabled(|name| std::env::var_os(name)) {
+            return Err(reason.into());
+        }
+        let host = cpal::default_host();
+        if !target.is_empty()
+            && let Ok(devices) = host.output_devices()
+        {
+            for device in devices {
+                let name = device.name().unwrap_or_else(|_| "unnamed device".into());
+                if name == target {
+                    match open_device(&device, mixer.clone()) {
+                        Ok((stream, config)) => {
+                            log::info!(
+                                "Horizon: audio output {name} ({} Hz, {} channels, {})",
+                                config.sample_rate().0,
+                                config.channels(),
+                                config.sample_format()
+                            );
+                            return Ok(stream);
+                        }
+                        Err(e) => {
+                            log::warn!(
+                                "Horizon: could not open audio device '{target}': {e}; falling back to default"
+                            );
+                        }
+                    }
+                    break;
+                }
+            }
+        }
+        Self::open(mixer)
+    }
+    #[cfg(feature = "audio")]
+    pub fn set_device(&mut self, name: &str) -> Result<()> {
+        if !self.backend.live && self._stream.is_none() && !self.engine.loaded {
+            self.device_name = name.to_owned();
+            return Ok(());
+        }
+        self._stream = Some(Self::open_named(self.backend.mixer.clone(), name)?);
+        self.device_name = name.to_owned();
+        self.backend.live = true;
+        self.engine.loaded = true;
+        Ok(())
+    }
+    #[cfg(not(feature = "audio"))]
+    pub fn set_device(&mut self, name: &str) -> Result<()> {
+        self.device_name = name.to_owned();
+        Ok(())
+    }
+    #[cfg(feature = "audio")]
     fn open(mixer: Arc<Mutex<Mixer>>) -> Result<Stream> {
         if let Some(reason) = output_disabled(|name| std::env::var_os(name)) {
             return Err(reason.into());

crates/horizon-client-render/src/biome.rs

@@ -20,12 +20,68 @@ pub struct SpawnEntry {
     /// A `ConstantInt` count (sampling draws nothing).
     pub constant: bool,
 }
+/// A `natural_mob_spawns` / `spawn_overrides` entry list.
+pub fn parse_entries(list: &Value) -> Vec<SpawnEntry> {
+    list.as_array()
+        .into_iter()
+        .flatten()
+        .filter_map(|e| {
+            let count = &e["count"];
+            let (min, max, constant) = match count {
+                Value::Number(n) => {
+                    let n = n.as_u64().unwrap_or(1) as u32;
+                    (n, n, true)
+                }
+                c if c["type"].as_str() == Some("minecraft:constant") => {
+                    let n = c["value"].as_u64().unwrap_or(1) as u32;
+                    (n, n, true)
+                }
+                c => (
+                    c["min_inclusive"].as_u64().unwrap_or(1) as u32,
+                    c["max_inclusive"].as_u64().unwrap_or(1) as u32,
+                    false,
+                ),
+            };
+            Some(SpawnEntry {
+                entity: e["type"].as_str()?.to_owned(),
+                weight: e["weight"].as_u64().unwrap_or(1) as u32,
+                min,
+                max,
+                constant,
+            })
+        })
+        .collect()
+}
+/// `MobSpawnSettings.MobSpawnCost`.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct SpawnCost {
+    pub energy_budget: f64,
+    pub charge: f64,
+}
+/// The `spawn_costs` of a `natural_mob_spawns` value.
+pub fn parse_costs(costs: &Value) -> HashMap<String, SpawnCost> {
+    costs
+        .as_object()
+        .into_iter()
+        .flatten()
+        .map(|(k, c)| {
+            (
+                k.clone(),
+                SpawnCost {
+                    energy_budget: c["energy_budget"].as_f64().unwrap_or(0.0),
+                    charge: c["charge"].as_f64().unwrap_or(0.0),
+                },
+            )
+        })
+        .collect()
+}
+
 #[derive(Clone, Debug)]
 pub struct BiomeInfo {
     /// `natural_mob_spawns` by category (creature, monster, ...).
     pub spawns: HashMap<String, Vec<SpawnEntry>>,
     /// `natural_mob_spawns` spawn costs by entity type.
-    pub spawn_costs: HashMap<String, crate::mobs::spawn_selection::SpawnCost>,
+    pub spawn_costs: HashMap<String, SpawnCost>,
     /// The `gameplay/creature_world_gen_spawn_probability` attribute.
     pub creature_probability: f32,
     /// The `gameplay/increased_fire_burnout` attribute (jungles, swamps, peaks,
@@ -150,12 +206,12 @@ impl Biomes {
             };
             let categories = &natural["spawns_by_category"];
             for (category, entries) in categories.as_object().into_iter().flatten() {
-                let list = crate::mobs::spawn_selection::parse_entries(entries);
+                let list = parse_entries(entries);
                 spawns.insert(category.clone(), list);
             }
             list.push(BiomeInfo {
                 spawns,
-                spawn_costs: crate::mobs::spawn_selection::parse_costs(&natural["spawn_costs"]),
+                spawn_costs: parse_costs(&natural["spawn_costs"]),
                 creature_probability:
                     attributes["minecraft:gameplay/creature_world_gen_spawn_probability"]
                         .as_f64()
@@ -200,6 +256,10 @@ impl Biomes {
             .copied()
             .unwrap_or(0)
     }
+    /// Whether the game has the biome `name`.
+    pub fn contains(&self, name: &str) -> bool {
+        self.index.contains_key(name)
+    }
     pub fn get(&self, id: u16) -> &BiomeInfo {
         &self.list[usize::from(id).min(self.list.len() - 1)]
     }

crates/horizon-client-render/src/block_entities.rs

@@ -26,6 +26,7 @@
 use crate::chunk::block_entity::BlockEntity;
 use crate::fast_hash::{FxHashMap, FxHashSet};
 use std::collections::HashMap;
+use std::sync::Arc;
 
 pub type Pos = (i32, i32, i32);
 
@@ -46,7 +47,7 @@ pub enum Ticking {
 pub struct BlockEntities {
     map: HashMap<Pos, BlockEntity>,
     /// `Level.blockEntityTickers`: positions and the slot each was given.
-    tickers: Vec<(Pos, u32)>,
+    tickers: Arc<Vec<(Pos, u32)>>,
     /// `LevelChunk.tickersInLevel`: the live slot of each ticking position.
     live: FxHashMap<Pos, u32>,
     /// Positions that may need a slot, in the order vanilla would have made
@@ -233,7 +234,7 @@ impl BlockEntities {
     }
     pub fn clear(&mut self) {
         self.map.clear();
-        self.tickers.clear();
+        self.tickers = Arc::default();
         self.live.clear();
         self.added.clear();
         self.pending.clear();
@@ -274,7 +275,7 @@ impl BlockEntities {
     /// and freed ones leave it. `state` reads the block state at a position.
     /// Returns the slots to tick, in order; check each with `is_live` before
     /// ticking it, as the ticks before it can free it.
-    pub fn tickers(&mut self, state: impl Fn(Pos) -> u32) -> Vec<(Pos, u32)> {
+    pub fn tickers(&mut self, state: impl Fn(Pos) -> u32) -> Arc<Vec<(Pos, u32)>> {
         for (pos, token) in std::mem::take(&mut self.added) {
             if self.pending.get(&pos) != Some(&token) {
                 continue;
@@ -288,21 +289,21 @@ impl BlockEntities {
             }
             let slot = self.next();
             self.live.insert(pos, slot);
-            self.tickers.push((pos, slot));
+            Arc::make_mut(&mut self.tickers).push((pos, slot));
         }
         if !std::mem::take(&mut self.freed) && self.out.is_empty() {
-            return self.tickers.clone();
+            return Arc::clone(&self.tickers);
         }
         self.out.clear();
         let (live, map) = (&mut self.live, &self.map);
-        self.tickers.retain(|(p, slot)| {
+        Arc::make_mut(&mut self.tickers).retain(|(p, slot)| {
             let mine = live.get(p) == Some(slot);
             if mine && !map.contains_key(p) {
                 live.remove(p);
             }
             mine && map.contains_key(p)
         });
-        self.tickers.clone()
+        Arc::clone(&self.tickers)
     }
     /// Whether a slot from `tickers` still ticks.
     pub fn is_live(&self, (pos, slot): (Pos, u32)) -> bool {
@@ -329,8 +330,8 @@ mod tests {
     }
     fn order(b: &mut BlockEntities, states: &HashMap<Pos, u32>) -> Vec<Pos> {
         b.tickers(|p| states.get(&p).copied().unwrap_or(0))
-            .into_iter()
-            .map(|(p, _)| p)
+            .iter()
+            .map(|(p, _)| *p)
             .collect()
     }
 

crates/horizon-client-render/src/block_entity_anim.rs

@@ -435,7 +435,8 @@ pub struct BellTick {
     pub ended: Option<(Vec<([f64; 3], i32)>, Vec<u64>)>,
 }
 
-fn closer_to_center_than(pos: [i32; 3], p: [f64; 3], distance: f64) -> bool {
+/// `Vec3i.closerToCenterThan`: `p` is within `distance` of the block's centre.
+pub fn closer_to_center_than(pos: [i32; 3], p: [f64; 3], distance: f64) -> bool {
     let dx = f64::from(pos[0]) + 0.5 - p[0];
     let dy = f64::from(pos[1]) + 0.5 - p[1];
     let dz = f64::from(pos[2]) + 0.5 - p[2];

crates/horizon-client-render/src/block_entity_render.rs

@@ -597,6 +597,18 @@ fn first_line(line: &str, max_width: f32, advance: &dyn Fn(char) -> f32) -> Stri
     line.to_owned()
 }
 
+/// `AbstractSignRenderer.isOutlineVisible`: the camera within 16 blocks of
+/// the sign's centre.
+fn sign_text_near(pos: [i32; 3], camera: DVec3) -> bool {
+    DVec3::new(
+        f64::from(pos[0]) + 0.5,
+        f64::from(pos[1]) + 0.5,
+        f64::from(pos[2]) + 0.5,
+    )
+    .distance_squared(camera)
+        < 256.0
+}
+
 /// `AbstractSignRenderer.submitSignText`: four centred lines, glowing text
 /// full-bright with an 8x outline in the dark colour.
 fn sign_text_calls(
@@ -642,10 +654,20 @@ fn sign_text_calls(
         .collect()
 }
 
+/// How far the text of an outlined call sits in front of its outline, in
+/// text units (`Font.DisplayMode.POLYGON_OFFSET`, see `draw_text`).
+const TEXT_OVER_OUTLINE: f32 = 0.05;
+
 /// Draws a text call with the font atlas: 8x8 glyph cells, the outline as
 /// eight one-pixel offsets under the text.
+///
+/// `TextFeatureRenderer.renderText` draws the outline glyphs NORMAL and the
+/// text over them POLYGON_OFFSET, so the coplanar text always wins the depth
+/// test. Here both share one mesh, so the text is lifted a hair towards the
+/// reader instead (a twentieth of a font pixel, invisible) rather than
+/// z-fighting with the outline under it.
 fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
-    let mut emit = |dx: f32, dy: f32, argb: u32| {
+    let mut emit = |dx: f32, dy: f32, z: f32, argb: u32| {
         let mut x = call.x + dx;
         let y0 = call.y + dy;
         for ch in call.text.chars() {
@@ -660,7 +682,7 @@ fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
                         normal: [0; 4],
                         pos: call
                             .matrix
-                            .transform_point3(Vec3::new(cx, cy, 0.0))
+                            .transform_point3(Vec3::new(cx, cy, z))
                             .to_array(),
                         uv,
                         layer: 0,
@@ -685,10 +707,15 @@ fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
             (0.0, 1.0),
             (1.0, 1.0),
         ] {
-            emit(dx, dy, call.outline);
+            emit(dx, dy, 0.0, call.outline);
         }
     }
-    emit(0.0, 0.0, call.color);
+    let z = if call.outline != 0 {
+        TEXT_OVER_OUTLINE
+    } else {
+        0.0
+    };
+    emit(0.0, 0.0, z, call.color);
 }
 
 /// Block-entity fields the level ticks, at one position (vanilla's own field
@@ -757,6 +784,9 @@ pub struct Scene<'a> {
     pub skull: &'a dyn Fn([i32; 3]) -> Option<String>,
     /// Font glyph cell (none for blank glyphs such as the space) and advance.
     pub glyph: &'a dyn Fn(char) -> (Option<Rect>, f32),
+    /// Changes whenever `glyph` may answer differently (`Font::epoch`): sign
+    /// text laid out under another value is laid out again.
+    pub glyphs: u64,
 }
 
 pub struct BlockEntityRenderer {
@@ -768,7 +798,30 @@ pub struct BlockEntityRenderer {
     pot_patterns: HashMap<String, String>,
     /// `Block.shouldRenderFace` for End gateway faces (its occlusion pair cache needs a lock).
     visibility: Option<Mutex<FaceVisibility>>,
+    sign_texts: Mutex<SignTexts>,
 }
+/// Laid-out sign text by position. `AbstractSignRenderer` lays the text out
+/// again each frame, glyph by glyph; its vertices only change with what is
+/// in the key, so they are kept relative to the block and moved to the camera.
+#[derive(Default)]
+struct SignTexts {
+    signs: crate::fast_hash::FxHashMap<[i32; 3], SignTextEntry>,
+    /// Game time of the last sweep of signs out of view.
+    swept: i64,
+}
+struct SignTextEntry {
+    state: u32,
+    data: crate::signs::SignData,
+    packed: u8,
+    /// Within the glowing text outline's distance (only kept for glowing text).
+    near: bool,
+    glyphs: u64,
+    /// Game time it was last drawn.
+    used: i64,
+    vertices: Vec<Vertex>,
+}
+/// Game ticks a sign's text is kept after it was last drawn.
+const SIGN_TEXT_KEEP: i64 = 100;
 const MODELS: [(&str, &str); 27] = [
     ("chest", "minecraft:chest#main"),
     ("double_chest_left", "minecraft:double_chest_left#main"),
@@ -898,6 +951,7 @@ impl BlockEntityRenderer {
             closed_chests,
             pot_patterns: HashMap::new(),
             visibility: None,
+            sign_texts: Mutex::default(),
         }
     }
     fn kind(&self, state: u32) -> &Kind {
@@ -932,11 +986,81 @@ impl BlockEntityRenderer {
             let origin = (DVec3::new(f64::from(pos[0]), f64::from(pos[1]), f64::from(pos[2]))
                 - scene.camera)
                 .as_vec3();
-            let base = Mat4::from_translation(origin);
             let packed = scene.world.light(pos[0], pos[1], pos[2]);
+            if matches!(kind, Kind::Sign { .. }) && scene.texts.is_none() {
+                self.sign_text(scene, *pos, *state, origin, packed, out);
+                continue;
+            }
+            let base = Mat4::from_translation(origin);
             self.render_one(scene, *pos, kind, base, packed, lights, false, true, out);
         }
     }
+    /// A sign's text from the cache, laid out again when its data, light,
+    /// state, outline or font changed.
+    fn sign_text(
+        &self,
+        scene: &Scene,
+        pos: [i32; 3],
+        state: u32,
+        origin: Vec3,
+        packed: u8,
+        out: &mut Vec<Vertex>,
+    ) {
+        let Some(data) = (scene.sign)(pos) else {
+            return;
+        };
+        let near = (data.front.glowing || data.back.glowing) && sign_text_near(pos, scene.camera);
+        let Ok(mut cache) = self.sign_texts.lock() else {
+            return;
+        };
+        let now = scene.game_time;
+        if (now - cache.swept).abs() >= SIGN_TEXT_KEEP {
+            cache.swept = now;
+            cache
+                .signs
+                .retain(|_, e| (now - SIGN_TEXT_KEEP..=now).contains(&e.used));
+        }
+        let glyphs = scene.glyphs;
+        let signs = &mut cache.signs;
+        if !signs.get(&pos).is_some_and(|e| {
+            (e.state, e.packed, e.near, e.glyphs) == (state, packed, near, glyphs)
+                && e.data == *data
+        }) {
+            let mut vertices = signs.remove(&pos).map_or_else(Vec::new, |e| e.vertices);
+            vertices.clear();
+            self.render_one(
+                scene,
+                pos,
+                self.kind(state),
+                Mat4::IDENTITY,
+                packed,
+                diffuse_lights(scene.nether),
+                false,
+                true,
+                &mut vertices,
+            );
+            signs.insert(
+                pos,
+                SignTextEntry {
+                    state,
+                    data: data.clone(),
+                    packed,
+                    near,
+                    glyphs,
+                    used: now,
+                    vertices,
+                },
+            );
+        }
+        let Some(entry) = signs.get_mut(&pos) else {
+            return;
+        };
+        entry.used = now;
+        out.extend(entry.vertices.iter().map(|v| Vertex {
+            pos: (Vec3::from_array(v.pos) + origin).to_array(),
+            ..*v
+        }));
+    }
     /// One block entity at `pos` drawn under `base` with the given packed light
     /// (the parity fixture's entry point).
     pub fn render_block(
@@ -1168,13 +1292,7 @@ impl BlockEntityRenderer {
                         m *= Mat4::from_translation(Vec3::new(0.0, 1.0 / 3.0, 0.046_666_667))
                             * Mat4::from_scale(s * 0.010_416_667);
                     }
-                    let near = DVec3::new(
-                        f64::from(pos[0]) + 0.5,
-                        f64::from(pos[1]) + 0.5,
-                        f64::from(pos[2]) + 0.5,
-                    )
-                    .distance_squared(scene.camera)
-                        < 256.0;
+                    let near = sign_text_near(pos, scene.camera);
                     let calls = sign_text_calls(scene, data, text, m, packed, near);
                     match scene.texts {
                         Some(sink) => sink.borrow_mut().extend(calls),
@@ -1954,6 +2072,7 @@ mod tests {
             banner: &|_| Vec::new(),
             skull: &|_| None,
             glyph: &|_| (None, 0.0),
+            glyphs: 0,
         };
         // Compare the cached world path with the original model renderer,
         // including atlas replacement, current light and animated fallback.
@@ -2154,6 +2273,191 @@ mod tests {
         assert_eq!(out[2].uv, [0.5, 0.5]);
     }
 
+    /// TextFeatureRenderer.renderText: an outlined call's text is drawn over
+    /// its outline (Font.DisplayMode.POLYGON_OFFSET), never level with it,
+    /// and plain text stays on the sign's plane.
+    #[test]
+    fn outlined_sign_text_sits_in_front_of_its_outline() {
+        let world = World::new(BlockStateId(0), 1);
+        let sprites = HashMap::new();
+        let glyph = |_: char| {
+            let rect = Rect {
+                u0: 0.0,
+                v0: 0.0,
+                u1: 0.0625,
+                v1: 0.0625,
+                w: 8,
+                h: 8,
+            };
+            (Some(rect), 6.0)
+        };
+        let scene = Scene {
+            camera: DVec3::ZERO,
+            orientation: Quat::IDENTITY,
+            anim: &|_| BlockAnim::default(),
+            texts: None,
+            partial: 0.0,
+            game_time: 0,
+            max_y: 320,
+            world: &world,
+            sprites: &sprites,
+            nether: false,
+            lid: &|_| 0.0,
+            sign: &|_| None,
+            banner: &|_| Vec::new(),
+            skull: &|_| None,
+            glyph: &glyph,
+            glyphs: 0,
+        };
+        let mut call = TextCall {
+            matrix: Mat4::IDENTITY,
+            x: 0.0,
+            y: 0.0,
+            text: "Hi".into(),
+            color: 0xFFFF_FF00,
+            outline: 0xFF33_3300,
+            light: 240 | 240 << 8,
+        };
+        let mut out = Vec::new();
+        draw_text(&scene, &call, &mut out);
+        // Eight outline copies, then the text, four corners a glyph.
+        assert_eq!(out.len(), 9 * 2 * 4);
+        let (outline, text) = out.split_at(8 * 2 * 4);
+        let front = outline.iter().map(|v| v.pos[2]).fold(f32::MIN, f32::max);
+        assert!(
+            text.iter().all(|v| v.pos[2] > front),
+            "text z {:?} not in front of the outline at {front}",
+            text.iter().map(|v| v.pos[2]).collect::<Vec<_>>()
+        );
+        call.outline = 0;
+        out.clear();
+        draw_text(&scene, &call, &mut out);
+        assert_eq!(out.len(), 2 * 4);
+        assert!(out.iter().all(|v| v.pos[2] == 0.0));
+    }
+
+    #[test]
+    fn cached_sign_text_matches_and_follows_changes() {
+        let renderer = BlockEntityRenderer {
+            models: HashMap::new(),
+            kinds: vec![
+                Kind::Sign {
+                    hanging: false,
+                    wall: false,
+                    angle: 180.0,
+                },
+                Kind::Sign {
+                    hanging: true,
+                    wall: true,
+                    angle: 90.0,
+                },
+            ],
+            closed_chests: Default::default(),
+            pot_patterns: HashMap::new(),
+            visibility: None,
+            sign_texts: Mutex::default(),
+        };
+        let world = World::new(BlockStateId(0), 1);
+        let sprites = HashMap::new();
+        let text = |line: &str, glowing| crate::signs::SignText {
+            lines: [line.into(), "two".into(), String::new(), "four".into()],
+            color: 3,
+            glowing,
+        };
+        let first_text = crate::signs::SignData {
+            front: text("one", false),
+            ..Default::default()
+        };
+        let changed = crate::signs::SignData {
+            front: text("changed", false),
+            ..Default::default()
+        };
+        let glowing = crate::signs::SignData {
+            back: text("glow", true),
+            ..changed.clone()
+        };
+        let wide = std::cell::Cell::new(6.0);
+        let glyph = |c: char| {
+            let u = f32::from(c as u8 % 16) / 16.0;
+            let rect = Rect {
+                u0: u,
+                v0: 0.0,
+                u1: u + 0.0625,
+                v1: 0.0625,
+                w: 8,
+                h: 8,
+            };
+            ((c != ' ').then_some(rect), wide.get())
+        };
+        let (first_sign, changed_sign, glowing_sign) = (
+            |_| Some(&first_text),
+            |_| Some(&changed),
+            |_| Some(&glowing),
+        );
+        let mut scene = Scene {
+            camera: DVec3::new(3.25, 70.5, -4.75),
+            orientation: Quat::IDENTITY,
+            anim: &|_| BlockAnim::default(),
+            texts: None,
+            partial: 0.0,
+            game_time: 0,
+            max_y: 320,
+            world: &world,
+            sprites: &sprites,
+            nether: false,
+            lid: &|_| 0.0,
+            sign: &first_sign,
+            banner: &|_| Vec::new(),
+            skull: &|_| None,
+            glyph: &glyph,
+            glyphs: 0,
+        };
+        let check = |scene: &Scene, pos: [i32; 3], state: u32| {
+            let mut cached = Vec::new();
+            renderer.render(scene, [(pos, state)].iter(), &mut cached);
+            let corner = DVec3::new(f64::from(pos[0]), f64::from(pos[1]), f64::from(pos[2]));
+            let mut original = Vec::new();
+            renderer.render_one(
+                scene,
+                pos,
+                renderer.kind(state),
+                Mat4::from_translation((corner - scene.camera).as_vec3()),
+                world.light(pos[0], pos[1], pos[2]),
+                diffuse_lights(false),
+                false,
+                true,
+                &mut original,
+            );
+            assert!(!cached.is_empty());
+            assert_eq!(cached.len(), original.len());
+            for (a, b) in cached.iter().zip(&original) {
+                assert!((Vec3::from_array(a.pos) - Vec3::from_array(b.pos)).length() < 1e-5);
+                assert_eq!((a.uv, a.color, a.light), (b.uv, b.color, b.light));
+            }
+            cached.len()
+        };
+        let (pos, other) = ([1, 70, 2], [-3, 64, 9]);
+        let first = check(&scene, pos, 0);
+        // The camera moves: the same text, moved.
+        scene.camera.x += 0.5;
+        check(&scene, pos, 0);
+        // New text, glowing text near and far, another state, other glyphs.
+        scene.sign = &changed_sign;
+        assert_ne!(check(&scene, pos, 0), first);
+        scene.sign = &glowing_sign;
+        check(&scene, pos, 0);
+        scene.camera.z -= 20.0;
+        check(&scene, pos, 0);
+        check(&scene, pos, 1);
+        check(&scene, other, 1);
+        wide.set(5.0);
+        scene.glyphs = 1;
+        check(&scene, pos, 1);
+        // Signs out of view for a while are dropped.
+        scene.game_time = 2 * SIGN_TEXT_KEEP;
+        check(&scene, pos, 0);
+        assert_eq!(renderer.sign_texts.lock().unwrap().signs.len(), 1);
+    }
     #[test]
     fn first_line_wraps_on_bytes_without_splitting_a_char() {
         let advance = |c: char| if c == ' ' { 4.0 } else { 6.0 };
@@ -2214,6 +2518,7 @@ mod tests {
             banner: &|_| Vec::new(),
             skull: &|_| None,
             glyph: &|_| (None, 0.0),
+            glyphs: 0,
         };
         let mut verts = Vec::new();
         renderer.render_block(&scene, [0; 3], state.0, Mat4::IDENTITY, 0xff, &mut verts);

crates/horizon-client-render/src/brewing.rs

@@ -14,14 +14,19 @@ pub use horizon_client_core::potions::{
     BASE_POTION_COLOR, Category, EFFECTS, EffectDef, POTIONS, PotionDef, effect, namespaced,
     potion, potion_color,
 };
-/// `MobEffectUtil.formatDuration` at 20 TPS: m:ss or h:mm:ss.
+/// `MobEffectUtil.formatDuration` at 20 TPS.
 pub fn format_duration(ticks: i32) -> String {
-    let secs = ticks / 20;
+    format_tick_duration(ticks, 20.0)
+}
+/// `StringUtil.formatTickDuration`: mm:ss, or hh:mm:ss from an hour up, every
+/// field two digits.
+pub fn format_tick_duration(ticks: i32, tick_rate: f32) -> String {
+    let secs = (ticks as f32 / tick_rate).floor() as i32;
     let (h, m, s) = (secs / 3600, secs / 60 % 60, secs % 60);
     if h > 0 {
-        format!("{h}:{m:02}:{s:02}")
+        format!("{h:02}:{m:02}:{s:02}")
     } else {
-        format!("{m}:{s:02}")
+        format!("{m:02}:{s:02}")
     }
 }
 /// `item.minecraft.potion.effect.<name>` style translation key for a potion item.
@@ -317,10 +322,14 @@ mod tests {
             potion_name_key("minecraft:splash_potion", Some("minecraft:long_swiftness")),
             "item.minecraft.splash_potion.effect.swiftness"
         );
-        assert_eq!(format_duration(9600), "8:00");
-        assert_eq!(format_duration(450), "0:22");
+        assert_eq!(format_duration(9600), "08:00");
+        assert_eq!(format_duration(450), "00:22");
+        assert_eq!(format_duration(140), "00:07");
+        assert_eq!(format_duration(1800), "01:30");
+        assert_eq!(format_duration(72000), "01:00:00");
+        assert_eq!(format_tick_duration(9600, 40.0), "04:00");
         let t = tooltip(Some("minecraft:strong_poison"), 1.0, &|_| None);
-        assert_eq!(t[0].0, "poison II (0:21)");
+        assert_eq!(t[0].0, "poison II (00:21)");
         assert_eq!(POTIONS.len(), 46);
     }
 
@@ -377,4 +386,23 @@ mod tests {
         stand.tick(&brewing, &items, &providers);
         assert_eq!(stand.brew_time, 0);
     }
+
+    /// #3312: `PotionContents.getPotionDescription` names the effects with
+    /// translatable components, so a Russian game reads them from ru_ru.json
+    /// (the prepared one; skipped without it), as the tooltip's other lines.
+    #[test]
+    fn effect_lines_read_the_selected_language() {
+        let root = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+            .join("../../.local/horizon-client")
+            .join(horizon_core::VANILLA_VERSION);
+        if !root.join("assets/minecraft/lang/ru_ru.json").exists() {
+            return;
+        }
+        let ru = crate::lang::Language::load(&[&root], "ru_ru");
+        let translate = |key: &str| ru.get(key).map(str::to_owned);
+        let lines = tooltip(Some("minecraft:turtle_master"), 0.125, &translate);
+        assert_eq!(lines.len(), 2);
+        assert!(lines[0].0.starts_with("Замедление IV ("), "{lines:?}");
+        assert!(lines[1].0.starts_with("Сопротивление III ("), "{lines:?}");
+    }
 }

crates/horizon-client-render/src/camera.rs

@@ -653,18 +653,57 @@ pub fn modify_fov_based_on_death_or_fluid(
     fov
 }
 
-/// `ClientAvatarState`: the walked distance and view bob of a player.
+/// `ClientAvatarState`: the walked distance, view bob and cloak of a player.
 #[derive(Clone, Copy, Debug, Default, PartialEq)]
 pub struct AvatarBob {
     pub walk_dist: f32,
     pub walk_dist_o: f32,
     pub bob: f32,
     pub bob_o: f32,
+    /// `xCloak`, `yCloak`, `zCloak`: a point trailing the player, which the cape leans from.
+    pub cloak: [f64; 3],
+    pub cloak_o: [f64; 3],
 }
 impl AvatarBob {
-    /// `ClientAvatarState.tick` (at the start of `AbstractClientPlayer.tick`).
-    pub fn tick(&mut self) {
+    /// `ClientAvatarState.tick` (at the start of `AbstractClientPlayer.tick`)
+    /// with the player's position then: `moveCloak` eases the cloak a quarter
+    /// of the way there, or puts it there from 10 blocks away.
+    pub fn tick(&mut self, position: [f64; 3]) {
         self.walk_dist_o = self.walk_dist;
+        self.cloak_o = self.cloak;
+        for i in 0..3 {
+            let d = position[i] - self.cloak[i];
+            if d > 10.0 || d < -10.0 {
+                self.cloak[i] = position[i];
+                self.cloak_o[i] = position[i];
+            } else {
+                self.cloak[i] += d * 0.25;
+            }
+        }
+    }
+    /// `AvatarRenderer.extractCapeState`: the cape's `capeFlap`, `capeLean`
+    /// and `capeLean2` (degrees) for the player at `position` (interpolated)
+    /// with its body turned `body_yaw` and its `fallFlyingScale`.
+    pub fn cape(
+        &self,
+        partial: f32,
+        position: [f64; 3],
+        body_yaw: f32,
+        fall_flying_scale: f32,
+    ) -> [f32; 3] {
+        let d: [f64; 3] = std::array::from_fn(|i| {
+            lerp_d(f64::from(partial), self.cloak_o[i], self.cloak[i]) - position[i]
+        });
+        let rad = f64::from(body_yaw * DEG_TO_RAD);
+        let (sin, cos) = (f64::from(trig::sin(rad)), f64::from(-trig::cos(rad)));
+        let mut flap = (d[1] as f32 * 10.0).clamp(-6.0, 32.0);
+        let lean = ((d[0] * sin + d[2] * cos) as f32 * 100.0 * (1.0 - fall_flying_scale))
+            .clamp(0.0, 150.0);
+        let lean2 = ((d[0] * cos - d[2] * sin) as f32 * 100.0).clamp(-20.0, 20.0);
+        let bob = self.interpolated_bob(partial);
+        let walk = lerp(partial, self.walk_dist_o, self.walk_dist);
+        flap += trig::sin(f64::from(walk * 6.0)) * 32.0 * bob;
+        [flap, lean, lean2]
     }
     /// `LocalPlayer.move`: `addWalkedDistance(Mth.length(dx, dz) * 0.6F)`
     /// with the float horizontal displacement.
@@ -795,6 +834,23 @@ pub fn spinning_effect_matrix(intensity: f32, angle_degrees: f32) -> glam::Mat4
 
 #[cfg(test)]
 mod tests {
+    /// `moveCloak` trails a quarter of the way, jumps from 10 blocks away; the
+    /// cape leans back as the player walks forward (south, body yaw 0).
+    #[test]
+    fn the_cloak_trails_the_player() {
+        let mut a = super::AvatarBob::default();
+        a.tick([0.0, 64.0, 0.0]);
+        assert_eq!((a.cloak, a.cloak_o), ([0.0, 64.0, 0.0], [0.0, 64.0, 0.0]));
+        a.tick([0.0, 64.0, 1.0]);
+        assert_eq!(a.cloak, [0.0, 64.0, 0.25]);
+        let [flap, lean, lean2] = a.cape(1.0, [0.0, 64.0, 1.0], 0.0, 0.0);
+        assert_eq!((flap, lean, lean2), (0.0, 75.0, 0.0));
+        // Falling lifts the flap, at most 32 degrees.
+        assert_eq!(a.cape(1.0, [0.0, 60.0, 0.25], 0.0, 0.0)[0], 32.0);
+        // Gliding takes the lean away.
+        assert_eq!(a.cape(1.0, [0.0, 64.0, 1.0], 0.0, 1.0)[1], 0.0);
+    }
+
     #[test]
     fn depth_far_covers_the_cloud_range() {
         // renderDistance 2 with the default Cloud Distance (128 chunks).

crates/horizon-client-render/src/chat.rs

@@ -653,6 +653,42 @@ pub struct Commands<'a> {
     pub registries: &'a Registries,
 }
 
+/// `CommandSuggestions`' constructor arguments: how a screen's suggestions
+/// parse and where they are drawn.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct SuggestLayout {
+    /// `commandsOnly`: the input is a command without a leading `/`.
+    pub commands_only: bool,
+    /// `onlyShowIfCursorPastError`: completions from the command's start,
+    /// not only past the `/`.
+    pub only_past_error: bool,
+    /// `suggestionLineLimit`.
+    pub line_limit: usize,
+    /// `anchorToBottom`: the list and usage over a box at the bottom, else
+    /// under one at the top (y 72).
+    pub anchor_to_bottom: bool,
+    /// `fillColor`: behind the list and the usage lines.
+    pub fill: i32,
+}
+impl SuggestLayout {
+    /// ChatScreen.init's `CommandSuggestions`.
+    pub const CHAT: Self = Self {
+        commands_only: false,
+        only_past_error: false,
+        line_limit: 10,
+        anchor_to_bottom: true,
+        fill: FILL,
+    };
+    /// AbstractCommandBlockEditScreen.init's `CommandSuggestions`.
+    pub const COMMAND_BLOCK: Self = Self {
+        commands_only: true,
+        only_past_error: true,
+        line_limit: 7,
+        anchor_to_bottom: false,
+        fill: i32::MIN,
+    };
+}
+
 /// The open chat screen: vanilla's `ChatScreen` with its `EditBox` and
 /// `CommandSuggestions` (argument colouring, usage lines, parse errors,
 /// the suggestion list, Tab completion, history).
@@ -680,6 +716,7 @@ pub struct ChatScreen {
     pub auto_suggestions: bool,
     /// `CommandSuggestions.setRestrictions`: what the Chat option allows.
     pub abilities: ChatAbilities,
+    pub layout: SuggestLayout,
 }
 /// Local completions waiting for the server's reply to request `id`.
 struct Awaiting {
@@ -750,6 +787,43 @@ impl ChatScreen {
             keep_suggestions: false,
             auto_suggestions: true,
             abilities,
+            layout: SuggestLayout::CHAT,
+        };
+        s.update_command_info(m, c);
+        s
+    }
+    /// `AbstractCommandBlockEditScreen.init`: the command box at the top,
+    /// focused, holding `command`, with suggestions from the start.
+    pub fn command_block(
+        m: &Measure,
+        c: &Commands,
+        command: &str,
+        width: i32,
+        height: i32,
+    ) -> Self {
+        let mut input = TextField::new(width / 2 - 150, 50, 300, 20);
+        input.max_length = 32500;
+        input.focused = true;
+        input.set_value(m, command);
+        let mut s = Self {
+            input,
+            width,
+            height,
+            history_buffer: String::new(),
+            history_pos: 0,
+            parse: None,
+            pending: None,
+            awaiting: None,
+            request: None,
+            suggestions: None,
+            usage: Vec::new(),
+            usage_position: 0,
+            usage_width: 0,
+            allow_suggestions: true,
+            keep_suggestions: false,
+            auto_suggestions: true,
+            abilities: ChatAbilities::new(ChatVisibility::Full),
+            layout: SuggestLayout::COMMAND_BLOCK,
         };
         s.update_command_info(m, c);
         s
@@ -768,7 +842,11 @@ impl ChatScreen {
             let value = self.input.value.clone();
             let auto = self.auto_suggestions;
             let abilities = self.abilities;
-            *self = Self::new(m, c, &value, self.history_pos, width, height, abilities);
+            *self = if self.layout == SuggestLayout::CHAT {
+                Self::new(m, c, &value, self.history_pos, width, height, abilities)
+            } else {
+                Self::command_block(m, c, &value, width, height)
+            };
             self.auto_suggestions = auto;
         }
     }
@@ -814,11 +892,18 @@ impl ChatScreen {
         self.usage.clear();
         let cursor = self.input.cursor;
         let cursor_b = byte_at(&command, cursor);
-        if command.starts_with('/') {
+        let slash = command.starts_with('/');
+        if self.layout.commands_only || slash {
+            let start = usize::from(slash);
             if self.parse.is_none() {
-                self.parse = Some(c.dispatcher.parse_at(&command, 1, c.registries));
+                self.parse = Some(c.dispatcher.parse_at(&command, start, c.registries));
             }
-            if cursor >= 1 && (self.suggestions.is_none() || !self.keep_suggestions) {
+            let from = if self.layout.only_past_error {
+                start
+            } else {
+                1
+            };
+            if cursor >= from && (self.suggestions.is_none() || !self.keep_suggestions) {
                 let parse = self.parse.as_ref().expect("parsed above");
                 let (range, list, ask) =
                     c.dispatcher
@@ -1002,7 +1087,11 @@ impl ChatScreen {
             0,
             self.input.screen_x(m, 0) + self.input.inner_width() - width,
         );
-        let y = self.height - 12;
+        let y = if self.layout.anchor_to_bottom {
+            self.height - 12
+        } else {
+            72
+        };
         // sortSuggestions: those starting with the word at the cursor first.
         let partial = &value[..byte_at(&value, self.input.cursor)];
         let word = partial[last_word_index(partial)..].to_lowercase();
@@ -1011,9 +1100,16 @@ impl ChatScreen {
                 s.text.starts_with(&word) || s.text.starts_with(&format!("minecraft:{word}"))
             });
         first.extend(rest);
-        let n = first.len().min(10) as i32;
+        // SuggestionsList: beside a bordered box, or over an unbordered one.
+        let n = first.len().min(self.layout.line_limit) as i32;
+        let bordered = i32::from(self.input.bordered);
+        let top = if self.layout.anchor_to_bottom {
+            y - 3 - n * 12
+        } else {
+            y - bordered
+        };
         let mut l = SuggestionList {
-            rect: [x - 1, y - 3 - n * 12, width + 1, n * 12],
+            rect: [x - (1 - bordered), top, width + 1, n * 12],
             original: value,
             list: first,
             offset: 0,
@@ -1042,11 +1138,12 @@ impl ChatScreen {
     }
     fn cycle(&mut self, l: &mut SuggestionList, dir: isize) {
         self.select(l, l.current as isize + dir);
-        let max = l.list.len().saturating_sub(10);
+        let limit = self.layout.line_limit;
+        let max = l.list.len().saturating_sub(limit);
         if l.current < l.offset {
             l.offset = l.current.min(max);
-        } else if l.current > l.offset + 9 {
-            l.offset = (l.current as isize + 1 - 10).clamp(0, max as isize) as usize;
+        } else if l.current >= l.offset + limit {
+            l.offset = (l.current as isize + 1 - limit as isize).clamp(0, max as isize) as usize;
         }
     }
     /// `SuggestionsList.useSuggestion`.
@@ -1074,7 +1171,57 @@ impl ChatScreen {
         ctrl: bool,
     ) -> ChatAction {
         use winit::keyboard::KeyCode as K;
-        // CommandSuggestions.keyPressed.
+        if self.suggestions_key(m, c, key, shift) {
+            return ChatAction::None;
+        }
+        match key {
+            K::Escape => return ChatAction::Close,
+            K::Enter | K::NumpadEnter => {
+                // ChatScreen.keyPressed: without `hasAllowedInput` the input
+                // stays, unsent, and the screen stays open.
+                if !self.abilities.allows(&self.input.value) {
+                    return ChatAction::None;
+                }
+                return ChatAction::Submit(self.normalized());
+            }
+            K::ArrowUp => self.move_in_history(m, c, history, -1),
+            K::ArrowDown => self.move_in_history(m, c, history, 1),
+            _ => {
+                self.field_key(m, c, key, shift, ctrl);
+            }
+        }
+        ChatAction::None
+    }
+    /// The input box's own keys (`EditBox.keyPressed`), the suggestions
+    /// following an edit: whether the box took the key.
+    pub fn field_key(
+        &mut self,
+        m: &Measure,
+        c: &Commands,
+        key: winit::keyboard::KeyCode,
+        shift: bool,
+        ctrl: bool,
+    ) -> bool {
+        match self.input.key(m, key, shift, ctrl) {
+            Some(changed) => {
+                if changed {
+                    self.edited(m, c);
+                }
+                true
+            }
+            None => false,
+        }
+    }
+    /// `CommandSuggestions.keyPressed`: the list's arrows, Tab and Escape,
+    /// and Tab to show it. True when the suggestions took the key.
+    pub fn suggestions_key(
+        &mut self,
+        m: &Measure,
+        c: &Commands,
+        key: winit::keyboard::KeyCode,
+        shift: bool,
+    ) -> bool {
+        use winit::keyboard::KeyCode as K;
         if let Some(mut l) = self.suggestions.take() {
             let handled = match key {
                 K::ArrowUp | K::ArrowDown => {
@@ -1091,37 +1238,18 @@ impl ChatScreen {
                 }
                 K::Escape => {
                     self.input.suggestion = None;
-                    return ChatAction::None;
+                    return true;
                 }
                 _ => false,
             };
             self.suggestions = Some(l);
-            if handled {
-                return ChatAction::None;
-            }
+            handled
         } else if key == K::Tab {
             self.show_suggestions(m);
-            return ChatAction::None;
+            true
+        } else {
+            false
         }
-        match key {
-            K::Escape => return ChatAction::Close,
-            K::Enter | K::NumpadEnter => {
-                // ChatScreen.keyPressed: without `hasAllowedInput` the input
-                // stays, unsent, and the screen stays open.
-                if !self.abilities.allows(&self.input.value) {
-                    return ChatAction::None;
-                }
-                return ChatAction::Submit(self.normalized());
-            }
-            K::ArrowUp => self.move_in_history(m, c, history, -1),
-            K::ArrowDown => self.move_in_history(m, c, history, 1),
-            _ => {
-                if self.input.key(m, key, shift, ctrl) == Some(true) {
-                    self.edited(m, c);
-                }
-            }
-        }
-        ChatAction::None
     }
     /// `ChatScreen.moveInHistory`.
     fn move_in_history(&mut self, m: &Measure, c: &Commands, history: &[String], dir: isize) {
@@ -1175,7 +1303,7 @@ impl ChatScreen {
         if !l.contains(mouse.0, mouse.1) {
             return false;
         }
-        let max = l.list.len().saturating_sub(10) as i32;
+        let max = l.list.len().saturating_sub(self.layout.line_limit) as i32;
         l.offset = ((l.offset as f64 - amount.clamp(-1.0, 1.0)) as i32).clamp(0, max) as usize;
         true
     }
@@ -1246,7 +1374,9 @@ impl ChatScreen {
     ) -> Vec<Draw> {
         let (w, h) = (self.width, self.height);
         let mut out = Vec::new();
-        d::fill(&mut out, 2, h - 14, w - 2, h - 2, background);
+        if self.layout.anchor_to_bottom {
+            d::fill(&mut out, 2, h - 14, w - 2, h - 2, background);
+        }
         let format = |s: &str, o: usize| self.format(s, o);
         self.input.draw(&mut out, m, blink_ms, Some(&format));
         if let Some(mut l) = self.suggestions.take() {
@@ -1254,14 +1384,18 @@ impl ChatScreen {
             self.suggestions = Some(l);
         } else {
             for (i, line) in self.usage.iter().enumerate() {
-                let y = h - 27 - 12 * i as i32;
+                let y = if self.layout.anchor_to_bottom {
+                    h - 27 - 12 * i as i32
+                } else {
+                    72 + 12 * i as i32
+                };
                 d::fill(
                     &mut out,
                     self.usage_position - 1,
                     y,
                     self.usage_position + self.usage_width + 1,
                     y + 12,
-                    FILL,
+                    self.layout.fill,
                 );
                 d::text(&mut out, line.clone(), self.usage_position, y + 2, -1, true);
             }
@@ -1275,7 +1409,7 @@ impl ChatScreen {
         l: &mut SuggestionList,
         mouse: (i32, i32),
     ) {
-        let limit = l.list.len().min(10);
+        let limit = l.list.len().min(self.layout.line_limit);
         let [rx, ry, rw, rh] = l.rect;
         let has_prev = l.offset > 0;
         let has_next = l.list.len() > l.offset + limit;
@@ -1284,8 +1418,8 @@ impl ChatScreen {
             l.last_mouse = mouse;
         }
         if has_prev || has_next {
-            d::fill(out, rx, ry - 1, rx + rw, ry, FILL);
-            d::fill(out, rx, ry + rh, rx + rw, ry + rh + 1, FILL);
+            d::fill(out, rx, ry - 1, rx + rw, ry, self.layout.fill);
+            d::fill(out, rx, ry + rh, rx + rw, ry + rh + 1, self.layout.fill);
             if has_prev {
                 for x in (0..rw).step_by(2) {
                     d::fill(out, rx + x, ry - 1, rx + x + 1, ry, -1);
@@ -1300,7 +1434,7 @@ impl ChatScreen {
         let mut hovered = false;
         for i in 0..limit {
             let y = ry + 12 * i as i32;
-            d::fill(out, rx, y, rx + rw, y + 12, FILL);
+            d::fill(out, rx, y, rx + rw, y + 12, self.layout.fill);
             if mouse.0 > rx && mouse.0 < rx + rw && mouse.1 > y && mouse.1 < y + 12 {
                 if moved {
                     self.select(l, (i + l.offset) as isize);

crates/horizon-client-render/src/chunk/block_entity.rs

@@ -74,9 +74,28 @@ pub enum BlockEntity {
     /// `DaylightDetectorBlockEntity`: no data, only the ticker
     /// (`DaylightDetectorBlock.tickEntity`).
     DaylightDetector,
+    /// Suspicious sand and gravel: saved loot and the transient brushed face.
+    Brushable(Box<Brushable>),
+    /// A shelf holds three displayed item stacks.
+    Shelf(Box<Shelf>),
     /// `ChiseledBookShelfBlockEntity`: a `Container` of six one-book slots.
     ChiseledBookshelf(Box<ChiseledBookshelf>),
 }
+/// `BrushableBlockEntity`: the loot table is resolved on the first brush.
+#[derive(Clone, Debug, Default)]
+pub struct Brushable {
+    pub loot_table: Option<horizon_world::nbt::Tag>,
+    pub loot_seed: Option<horizon_world::nbt::Tag>,
+    pub item: Option<ItemStack>,
+    /// Direction's legacy network id; not saved to disk by vanilla.
+    pub hit_direction: Option<i32>,
+}
+/// `ShelfBlockEntity`'s displayed slots and alignment flag.
+#[derive(Clone, Debug, Default)]
+pub struct Shelf {
+    pub items: [Option<ItemStack>; 3],
+    pub align_to_bottom: bool,
+}
 /// `ChiseledBookShelfBlockEntity`: six slots and `lastInteractedSlot`.
 #[derive(Clone, Debug, PartialEq)]
 pub struct ChiseledBookshelf {
@@ -230,7 +249,7 @@ pub struct Info {
 /// `VibrationSelector`: the closest, then highest-frequency candidate of a tick.
 #[derive(Clone, Debug, Default, PartialEq)]
 pub struct Selector {
-    pub(crate) current: Option<(Info, i64)>,
+    pub current: Option<(Info, i64)>,
 }
 /// `VibrationSystem.Data`.
 #[derive(Clone, Debug, Default, PartialEq)]
@@ -278,7 +297,7 @@ pub struct SpawnData {
 /// Which `SpawnData` is next: one of the potentials (the same object in
 /// vanilla, so changing it changes the potential) or its own.
 #[derive(Clone, Debug, PartialEq)]
-pub(crate) enum Next {
+pub enum Next {
     Potential(usize),
     Own(SpawnData),
 }
@@ -288,7 +307,7 @@ pub struct Spawner {
     pub spawn_delay: i32,
     /// `SpawnPotentials`: data and weight.
     pub potentials: Vec<(SpawnData, i32)>,
-    pub(crate) next: Option<Next>,
+    pub next: Option<Next>,
     pub min_spawn_delay: i32,
     pub max_spawn_delay: i32,
     pub spawn_count: i32,
@@ -301,6 +320,24 @@ pub struct Spawner {
     pub spin: f64,
     pub o_spin: f64,
 }
+impl Default for Spawner {
+    fn default() -> Self {
+        Self {
+            spawn_delay: 20,
+            potentials: Vec::new(),
+            next: None,
+            min_spawn_delay: 200,
+            max_spawn_delay: 800,
+            spawn_count: 4,
+            max_nearby_entities: 6,
+            required_player_range: 16,
+            spawn_range: 4,
+            client_delay: 20,
+            spin: 0.0,
+            o_spin: 0.0,
+        }
+    }
+}
 /// `TrialSpawnerConfig`.
 #[derive(Clone, Debug, PartialEq)]
 pub struct TrialConfig {
@@ -314,6 +351,26 @@ pub struct TrialConfig {
     pub loot_tables_to_eject: Vec<(String, i32)>,
     pub items_to_drop_when_ominous: String,
 }
+impl Default for TrialConfig {
+    /// `TrialSpawnerConfig.Builder`'s defaults.
+    fn default() -> Self {
+        Self {
+            spawn_range: 4,
+            total_mobs: 6.0,
+            simultaneous_mobs: 2.0,
+            total_mobs_added_per_player: 2.0,
+            simultaneous_mobs_added_per_player: 1.0,
+            ticks_between_spawn: 40,
+            spawn_potentials: Vec::new(),
+            loot_tables_to_eject: vec![
+                ("minecraft:spawners/trial_chamber/consumables".into(), 1),
+                ("minecraft:spawners/trial_chamber/key".into(), 1),
+            ],
+            items_to_drop_when_ominous:
+                "minecraft:spawners/trial_chamber/items_to_drop_when_ominous".into(),
+        }
+    }
+}
 /// A `Holder<TrialSpawnerConfig>` as saved: a registry id
 /// (`minecraft:trial_chamber/breeze/normal`) or an inline config.
 #[derive(Clone, Debug, Default, PartialEq)]
@@ -347,6 +404,28 @@ pub struct TrialSpawner {
     /// and their weights (the rolled counts).
     pub dispensing: Option<Vec<ItemStack>>,
 }
+impl Default for TrialSpawner {
+    fn default() -> Self {
+        Self {
+            normal: ConfigSlot::default(),
+            ominous: ConfigSlot::default(),
+            target_cooldown_length: 36000,
+            required_player_range: 14,
+            detected_players: Vec::new(),
+            current_mobs: Vec::new(),
+            cooldown_ends_at: 0,
+            next_mob_spawns_at: 0,
+            total_mobs_spawned: 0,
+            next_spawn_data: None,
+            ejecting_loot_table: None,
+            is_ominous: false,
+            has_display: false,
+            spin: 0.0,
+            o_spin: 0.0,
+            dispensing: None,
+        }
+    }
+}
 /// `VaultConfig`.
 #[derive(Clone, Debug, PartialEq)]
 pub struct VaultConfig {

crates/horizon-client-render/src/containers.rs

@@ -2,14 +2,11 @@
 //! kinds, ticking as `AbstractFurnaceBlockEntity.serverTick` with fuel times
 //! from the data-driven `context_int_provider`/`context_float_provider` files.
 pub use crate::chunk::block_entity::{
-    Banner, Beacon, BlockEntity, Campfire, ChiseledBookshelf, Crafter, CreakingHeart, EndGateway,
-    Furnace, FurnaceKind, Jukebox, Lectern, Skull, SkullSkin,
+    Banner, Beacon, BlockEntity, Brushable, Campfire, ChiseledBookshelf, Crafter, CreakingHeart,
+    EndGateway, Furnace, FurnaceKind, Jukebox, Lectern, Shelf, Skull, SkullSkin,
 };
-use crate::{
-    crafting::Recipes,
-    items::{ItemStack, Items},
-};
-use std::{collections::HashMap, sync::Arc};
+use crate::items::ItemStack;
+use std::collections::HashMap;
 
 impl FurnaceKind {
     pub fn recipe_type(self) -> &'static str {
@@ -45,6 +42,45 @@ pub fn recipe_used_key(id: &str) -> String {
 /// A hopper's slots: the only plain container with five.
 pub const HOPPER_SLOTS: usize = 5;
 
+/// `getDefaultName` of the `BaseContainerBlockEntity` that `block` holds: the
+/// translation key of its menu's title when it has no custom name. Copper
+/// chests hold a `ChestBlockEntity`, shulker boxes of every colour a
+/// `ShulkerBoxBlockEntity`.
+pub fn default_name_key(block: &str) -> Option<&'static str> {
+    Some(match block {
+        "minecraft:chest" | "minecraft:trapped_chest" => "container.chest",
+        n if n.ends_with("copper_chest") => "container.chest",
+        "minecraft:barrel" => "container.barrel",
+        n if n.ends_with("shulker_box") => "container.shulkerBox",
+        "minecraft:dispenser" => "container.dispenser",
+        "minecraft:dropper" => "container.dropper",
+        "minecraft:hopper" => "container.hopper",
+        "minecraft:furnace" => "container.furnace",
+        "minecraft:smoker" => "container.smoker",
+        "minecraft:blast_furnace" => "container.blast_furnace",
+        "minecraft:brewing_stand" => "container.brewing",
+        "minecraft:crafter" => "container.crafter",
+        _ => return None,
+    })
+}
+
+/// `BaseContainerBlockEntity.getDisplayName` (`getName`), the title of the
+/// `ClientboundOpenScreenPacket` that opens it: the block entity's custom
+/// name (`CustomName`, a literal), else its default name.
+pub fn display_name(custom: Option<&str>, default_key: &str) -> horizon_world::nbt::Tag {
+    match custom {
+        Some(name) => horizon_protocol::text::literal(name),
+        None => horizon_protocol::text::translatable(default_key, &[]),
+    }
+}
+
+/// `ChestBlock.MENU_PROVIDER_COMBINER`'s `getDisplayName` for a double chest:
+/// the first half's custom name (the right half, `DoubleBlockCombiner`'s
+/// `FIRST`), else the second's, else `container.chestDouble`.
+pub fn double_chest_name(first: Option<&str>, second: Option<&str>) -> horizon_world::nbt::Tag {
+    display_name(first.or(second), "container.chestDouble")
+}
+
 impl Campfire {
     /// `placeFood`'s slot: the first empty one, given the item's
     /// `campfire_cooking` time; it takes one item of `held`.
@@ -194,6 +230,14 @@ impl BlockEntity {
                 recipes_used: HashMap::new(),
             }));
         }
+        if matches!(
+            name,
+            "minecraft:suspicious_sand"
+                | "minecraft:suspicious_gravel"
+                | "minecraft:brushable_block"
+        ) {
+            return Some(Self::Brushable(Box::default()));
+        }
         if name == "minecraft:creaking_heart" {
             return Some(Self::CreakingHeart(Box::default()));
         }
@@ -256,6 +300,9 @@ impl BlockEntity {
         if name == "minecraft:campfire" || name == "minecraft:soul_campfire" {
             return Some(Self::Campfire(Box::default()));
         }
+        if name == "minecraft:shelf" || name.ends_with("_shelf") {
+            return Some(Self::Shelf(Box::default()));
+        }
         if name == "minecraft:chiseled_bookshelf" {
             return Some(Self::ChiseledBookshelf(Box::default()));
         }
@@ -298,8 +345,10 @@ impl BlockEntity {
             Self::Skull(_) => "minecraft:skull",
             Self::EndGateway(_) => "minecraft:end_gateway",
             Self::DaylightDetector => "minecraft:daylight_detector",
+            Self::Brushable(_) => "minecraft:brushable_block",
             Self::Campfire(_) => "minecraft:campfire",
             Self::ChiseledBookshelf(_) => "minecraft:chiseled_bookshelf",
+            Self::Shelf(_) => "minecraft:shelf",
         }
     }
     pub fn contents(&self) -> Vec<ItemStack> {
@@ -318,13 +367,15 @@ impl BlockEntity {
             | Self::CommandBlock(_)
             | Self::EndGateway(_)
             | Self::Skull(_)
-            | Self::DaylightDetector => Vec::new(),
+            | Self::DaylightDetector
+            | Self::Brushable(_) => Vec::new(),
             Self::Lectern(l) => l.book.iter().cloned().collect(),
             Self::Sculk(_) => Vec::new(),
             Self::Banner(_) => Vec::new(),
             Self::Crafter(c) => c.items.iter().flatten().cloned().collect(),
             Self::Campfire(c) => c.items.iter().flatten().cloned().collect(),
             Self::ChiseledBookshelf(b) => b.items.iter().flatten().cloned().collect(),
+            Self::Shelf(b) => b.items.iter().flatten().cloned().collect(),
         }
     }
     pub fn slots(&self) -> &[Option<ItemStack>] {
@@ -340,9 +391,11 @@ impl BlockEntity {
             | Self::Banner(_)
             | Self::EndGateway(_)
             | Self::Skull(_)
-            | Self::DaylightDetector => &[],
+            | Self::DaylightDetector
+            | Self::Brushable(_) => &[],
             Self::Crafter(c) => &c.items,
             Self::ChiseledBookshelf(b) => &b.items,
+            Self::Shelf(b) => &b.items,
             Self::CreakingHeart(_)
             | Self::Spawner(_)
             | Self::TrialSpawner(_)
@@ -366,9 +419,11 @@ impl BlockEntity {
             | Self::Banner(_)
             | Self::EndGateway(_)
             | Self::Skull(_)
-            | Self::DaylightDetector => &mut [],
+            | Self::DaylightDetector
+            | Self::Brushable(_) => &mut [],
             Self::Crafter(c) => &mut c.items,
             Self::ChiseledBookshelf(b) => &mut b.items,
+            Self::Shelf(b) => &mut b.items,
             Self::CreakingHeart(_)
             | Self::Spawner(_)
             | Self::TrialSpawner(_)
@@ -380,165 +435,56 @@ impl BlockEntity {
     }
 }
 pub use crate::providers::Providers;
-fn remainder(item: &str) -> Option<&'static str> {
-    match item {
-        "minecraft:lava_bucket" | "minecraft:water_bucket" | "minecraft:milk_bucket" => {
-            Some("minecraft:bucket")
-        }
-        _ => None,
-    }
+
+/// A `ChestBlock`, which `ChestBlock.combine` can join into a double chest:
+/// chests, trapped chests and copper chests in every weathering state, waxed
+/// or not (`CopperChestBlock` extends `ChestBlock`). Ender chests are
+/// `EnderChestBlock`s and always single.
+pub fn is_chest_block(name: &str) -> bool {
+    matches!(name, "minecraft:chest" | "minecraft:trapped_chest") || name.ends_with("copper_chest")
 }
-impl Furnace {
-    /// `AbstractFurnaceBlockEntity.setItem` on the input slot: anything but
-    /// the same item with the same components restarts cooking, with the
-    /// total time of the new input's recipe (200 ticks without one).
-    pub fn set_input(&mut self, recipes: &Recipes, stack: Option<ItemStack>) {
-        let same = match (&self.items[0], &stack) {
-            (Some(old), Some(new)) => old.same_item_same_components(new),
-            _ => false,
+
+/// A chest block's name with its `type` and `facing` properties.
+#[derive(Clone, Copy, Debug)]
+pub struct ChestHalf<'a> {
+    pub block: &'a str,
+    pub kind: &'a str,
+    pub facing: &'a str,
+}
+
+impl ChestHalf<'_> {
+    /// `ChestBlock.getConnectedDirection` as an (x, z) step to the other
+    /// half: clockwise from the facing for a left half, counter-clockwise for
+    /// a right one. None for a single chest.
+    pub fn connected_step(&self) -> Option<(i32, i32)> {
+        let step = |facing: &str| match facing {
+            "north" => Some((0, -1)),
+            "south" => Some((0, 1)),
+            "west" => Some((-1, 0)),
+            "east" => Some((1, 0)),
+            _ => None,
         };
-        self.items[0] = stack;
-        if !same {
-            self.cooking_total = self.items[0]
-                .as_ref()
-                .and_then(|input| recipes.cook(self.kind.recipe_type(), input))
-                .map_or(200, |recipe| total_time(recipe.time, self.speed));
-            self.cooking_timer = 0;
+        let (x, z) = step(self.facing)?;
+        // Turning clockwise seen from above takes (x, z) to (-z, x).
+        match self.kind {
+            "left" => Some((-z, x)),
+            "right" => Some((z, -x)),
+            _ => None,
         }
     }
-    /// `recipesUsed`, each recipe with its `experience` (0 for one this data pack does
-    /// not have), in the order `getRecipesToAwardAndPopExperience` pays them.
-    pub fn recipe_experience(&self, recipes: &Recipes) -> Vec<(u32, f32)> {
-        self.recipes_used
-            .iter()
-            .map(|(id, count)| (*count, recipes.cooking_experience(id)))
-            .collect()
-    }
-    /// A menu click wrote its slots into `items`, and `before` was the input
-    /// slot until then: the menu called `setItem` on it only if it changed
-    /// (`Slot.setByPlayer`; partial takes and merges keep the stack).
-    pub fn input_clicked(&mut self, recipes: &Recipes, before: Option<ItemStack>) {
-        if self.items[0] != before {
-            let after = std::mem::replace(&mut self.items[0], before);
-            self.set_input(recipes, after);
-        }
-    }
-    /// One server tick. Returns `Some(lit)` when the LIT block state must change.
-    pub fn tick(
-        &mut self,
-        recipes: &Recipes,
-        items: &Items,
-        providers: &Providers,
-    ) -> Option<bool> {
-        let was_lit = self.lit_remaining > 0;
-        let mut lit = false;
-        if self.lit_remaining > 0 {
-            self.lit_remaining -= 1;
-            lit = self.lit_remaining > 0;
-        }
-        let fast = self.kind.fast();
-        let has_ingredient = self.items[0].is_some();
-        let has_fuel = self.items[1].is_some();
-        if lit || has_fuel && has_ingredient {
-            if let Some(ingredient) = self.items[0].clone() {
-                if let Some(recipe) = recipes.cook(self.kind.recipe_type(), &ingredient) {
-                    if self.cooking_timer == 0 {
-                        self.cooking_total = total_time(recipe.time, self.speed);
-                    }
-                    let max = items.get(&recipe.result.item).map_or(64, |i| i.max_stack);
-                    let can_burn = match &self.items[2] {
-                        None => true,
-                        Some(out) => {
-                            out.item == recipe.result.item && out.count + recipe.result.count <= max
-                        }
-                    };
-                    if can_burn {
-                        if !lit {
-                            let fuel = self.items[1].clone();
-                            let time = fuel
-                                .as_ref()
-                                .map_or(0, |f| providers.burn_time(items, f, fast));
-                            let speed = fuel
-                                .as_ref()
-                                .map_or(1.0, |f| providers.speed(items, f, fast));
-                            self.lit_remaining = time;
-                            self.lit_total = time;
-                            self.speed = speed;
-                            if self.cooking_total > 0 && self.cooking_timer < self.cooking_total {
-                                let ratio = self.cooking_timer as f32 / self.cooking_total as f32;
-                                self.cooking_total = total_time(recipe.time, self.speed);
-                                self.cooking_timer =
-                                    (ratio * self.cooking_total as f32).ceil() as i32;
-                            }
-                            if time > 0 {
-                                if let Some(f) = self.items[1].as_mut() {
-                                    let item = f.item.clone();
-                                    f.count -= 1;
-                                    if f.count == 0 {
-                                        self.items[1] = remainder(&item).map(|r| ItemStack {
-                                            item: Arc::from(r),
-                                            count: 1,
-                                            damage: 0,
-                                            extra: None,
-                                        });
-                                    }
-                                }
-                                lit = true;
-                            }
-                        }
-                        if lit {
-                            self.cooking_timer += 1;
-                            if self.cooking_timer >= self.cooking_total {
-                                self.cooking_timer = 0;
-                                self.cooking_total = total_time(recipe.time, self.speed);
-                                match &mut self.items[2] {
-                                    Some(out) => out.count += recipe.result.count,
-                                    None => self.items[2] = Some(recipe.result.clone()),
-                                }
-                                *self
-                                    .recipes_used
-                                    .entry(recipe_used_key(&recipe.id))
-                                    .or_insert(0) += 1;
-                                // AbstractFurnaceBlockEntity.burn: drying a wet sponge fills
-                                // the bucket in the fuel slot.
-                                if self.items[0]
-                                    .as_ref()
-                                    .is_some_and(|i| &*i.item == "minecraft:wet_sponge")
-                                    && self.items[1]
-                                        .as_ref()
-                                        .is_some_and(|f| &*f.item == "minecraft:bucket")
-                                {
-                                    self.items[1] =
-                                        Some(ItemStack::new("minecraft:water_bucket", 1));
-                                }
-                                if let Some(i) = self.items[0].as_mut() {
-                                    i.count -= 1;
-                                    if i.count == 0 {
-                                        self.items[0] = None;
-                                    }
-                                }
-                            }
-                        } else {
-                            self.cooking_timer = 0;
-                        }
-                    } else {
-                        self.cooking_timer = 0;
-                    }
-                }
-            } else {
-                self.cooking_timer = 0;
-            }
-        } else if self.cooking_timer > 0 {
-            self.cooking_timer = (self.cooking_timer - 2).clamp(0, self.cooking_total);
-        }
-        (was_lit != lit).then_some(lit)
-    }
-}
-fn total_time(time: u32, speed: f32) -> i32 {
-    if speed > 0.0 {
-        (time as f32 / speed).ceil() as i32
-    } else {
-        time as i32
+
+    /// `DoubleBlockCombiner.combineWithNeigbour` as `ChestBlock.combine` calls
+    /// it: `other`, the block in this half's connected direction, is its other
+    /// half when it is the same block, a half of the other side and faces the
+    /// same way. Copper chests in different weathering states never join
+    /// (`CopperChestBlock` keeps both halves in one state instead).
+    pub fn pairs_with(&self, other: &ChestHalf) -> bool {
+        is_chest_block(self.block)
+            && self.kind != "single"
+            && other.block == self.block
+            && other.kind != "single"
+            && other.kind != self.kind
+            && other.facing == self.facing
     }
 }
 
@@ -559,6 +505,24 @@ pub fn create_experience(
     xp
 }
 
+/// The `MenuType` the block entity of a one-block storage container opens
+/// (`createMenu`): `ChestMenu.threeRows` for chests, trapped and copper chests
+/// and barrels, `ShulkerBoxMenu` for shulker boxes of any colour (its
+/// `ShulkerBoxSlot`s refuse shulker boxes), `DispenserMenu` for dispensers
+/// and droppers, `HopperMenu` for hoppers. None for other blocks.
+pub fn block_menu_type(block: &str) -> Option<&'static str> {
+    Some(match block {
+        "minecraft:chest" | "minecraft:trapped_chest" | "minecraft:barrel" => {
+            "minecraft:generic_9x3"
+        }
+        n if n.ends_with("copper_chest") => "minecraft:generic_9x3",
+        n if n.ends_with("shulker_box") => "minecraft:shulker_box",
+        "minecraft:dispenser" | "minecraft:dropper" => "minecraft:generic_3x3",
+        "minecraft:hopper" => "minecraft:hopper",
+        _ => return None,
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/horizon-client-render/src/crash.rs

@@ -3,6 +3,7 @@
 //! Written to `crash-reports/crash-<yyyy-MM-dd_HH.mm.ss>-client.txt` in the game folder when
 //! the main thread panics or `main` gets an error back. It leaves the machine only scrubbed, and
 //! only if the player allows crash reports (`telemetry`).
+use std::cell::{Cell, RefCell};
 use std::fmt::Write as _;
 use std::path::{Path, PathBuf};
 use std::sync::Mutex;
@@ -14,6 +15,51 @@ use chrono::{DateTime, Local};
 static DETAILS: Mutex<Vec<(&'static str, String)>> = Mutex::new(Vec::new());
 static REPORTED: AtomicBool = AtomicBool::new(false);
 
+thread_local! {
+    /// How many `contain` calls this thread is inside.
+    static CONTAINED: Cell<u32> = const { Cell::new(0) };
+    /// The message of the last panic `contain` caught on this thread, from the hook.
+    static CAUGHT: RefCell<Option<String>> = const { RefCell::new(None) };
+}
+
+/// Runs `f`, and returns a panic in it as an error with the panic's message instead of letting
+/// it end the game. For work that is not the game's own and whose failure the caller recovers
+/// from, such as handing a shader pack's programs to the GPU driver's compiler: the panic goes
+/// to the log with its stack, and no crash report is made for it.
+pub fn contain<T>(f: impl FnOnce() -> T) -> Result<T, String> {
+    CONTAINED.with(|c| c.set(c.get() + 1));
+    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(f));
+    CONTAINED.with(|c| c.set(c.get() - 1));
+    result.map_err(|payload| {
+        CAUGHT
+            .with(|c| c.borrow_mut().take())
+            .unwrap_or_else(|| payload_text(&*payload))
+    })
+}
+
+/// For the hook: a panic inside `contain` is logged with its stack and kept for `contain` to
+/// return. False for any other panic.
+fn contained_panic(info: &std::panic::PanicHookInfo) -> bool {
+    if CONTAINED.with(Cell::get) == 0 {
+        return false;
+    }
+    let message = panic_message(info);
+    let stack = stack_lines(
+        &std::backtrace::Backtrace::force_capture().to_string(),
+        true,
+    );
+    log::error!(
+        "Recovered from an error: {message}\n{}",
+        stack
+            .lines()
+            .map(|l| format!("\tat {l}"))
+            .collect::<Vec<_>>()
+            .join("\n")
+    );
+    CAUGHT.with(|c| *c.borrow_mut() = Some(message));
+    true
+}
+
 /// Sets one line of the report's details (replacing the last value under `key`).
 pub fn set_detail(key: &'static str, value: impl Into<String>) {
     let mut details = DETAILS.lock().unwrap_or_else(|e| e.into_inner());
@@ -308,13 +354,35 @@ fn deliver(home: &Path, report: Report) -> Option<PathBuf> {
     }
 }
 
-fn panic_message(info: &std::panic::PanicHookInfo) -> String {
-    let payload = info.payload();
-    let text = payload
+/// The report for a hung server tick, written by the watchdog thread
+/// (`ServerWatchdog`): the stuck thread's stack is not available to Rust, so
+/// the report carries none.
+pub fn report_watchdog(home: &Path, side: &'static str, message: String) -> Option<PathBuf> {
+    deliver(
+        home,
+        Report {
+            time: Local::now(),
+            description: "Watching Server".into(),
+            error: format!("{message} (Watching Server)"),
+            stack: String::new(),
+            thread: thread_name(),
+            side,
+            details: system_details(),
+            log: crate::logging::recent_lines(),
+        },
+    )
+}
+
+fn payload_text(payload: &(dyn std::any::Any + Send)) -> String {
+    payload
         .downcast_ref::<&str>()
         .map(|s| s.to_string())
         .or_else(|| payload.downcast_ref::<String>().cloned())
-        .unwrap_or_else(|| "Box<dyn Any>".into());
+        .unwrap_or_else(|| "Box<dyn Any>".into())
+}
+
+fn panic_message(info: &std::panic::PanicHookInfo) -> String {
+    let text = payload_text(info.payload());
     match info.location() {
         Some(at) => format!("panicked at {at}:\n{text}"),
         None => format!("panicked:\n{text}"),
@@ -326,16 +394,18 @@ fn panic_message(info: &std::panic::PanicHookInfo) -> String {
 /// frames go. Paths inside the workspace lose the build machine's prefix.
 pub fn stack_lines(backtrace: &str, from_panic: bool) -> String {
     // The workspace as it was on the machine that built this binary (it need not exist here).
-    let manifest = env!("CARGO_MANIFEST_DIR");
+    // A report names workspace files the same way on every host, whatever
+    // separator the build machine used.
+    let manifest = env!("CARGO_MANIFEST_DIR").replace('\\', "/");
     let root = manifest
-        .strip_suffix("crates/horizon-client")
-        .unwrap_or(manifest);
+        .strip_suffix("crates/horizon-client-render")
+        .unwrap_or(&manifest);
     let mut frames: Vec<(String, Option<String>)> = Vec::new();
     for line in backtrace.lines() {
         let line = line.trim();
         if let Some(at) = line.strip_prefix("at ") {
             if let Some(frame) = frames.last_mut() {
-                frame.1 = Some(short_path(at, root).to_owned());
+                frame.1 = Some(short_path(&at.replace('\\', "/"), root).to_owned());
             }
         } else if let Some((n, name)) = line.split_once(": ")
             && n.chars().all(|c| c.is_ascii_digit())
@@ -415,10 +485,13 @@ pub fn panic_report(info: &std::panic::PanicHookInfo, side: &'static str) -> Rep
 
 /// Reports panics: on the main thread a crash report (the panic then ends the game, exit code
 /// 101); on other threads the error goes to the log, as vanilla's uncaught exception handler
-/// does. The default hook still prints the panic.
+/// does. The default hook still prints the panic. A panic inside `contain` is only logged.
 pub fn install(home: PathBuf, side: &'static str) {
     let default = std::panic::take_hook();
     std::panic::set_hook(Box::new(move |info| {
+        if contained_panic(info) {
+            return;
+        }
         default(info);
         let main = std::thread::current().name() == Some("main");
         if main {
@@ -603,10 +676,21 @@ mod tests {
         );
         assert_eq!(
             stack_lines(&bt, true),
-            "horizon_client::crash::debug_crash_tick (crates/horizon-client/src/crash.rs:359:9)\nwinit::dispatch (winit-0.30.13/src/event_loop.rs:642:56)\nmain\n"
+            "horizon_client::crash::debug_crash_tick (crates/horizon-client-render/src/crash.rs:359:9)\nwinit::dispatch (winit-0.30.13/src/event_loop.rs:642:56)\nmain\n"
         );
     }
 
+    #[test]
+    fn contained_panics_come_back_as_errors() {
+        assert_eq!(contain(|| 7), Ok(7));
+        let error = contain(|| -> u8 { panic!("a pack's program") }).unwrap_err();
+        assert!(error.contains("a pack's program"), "{error}");
+        // Nested, and the thread is no longer inside one after.
+        let outer = contain(|| contain(|| -> u8 { panic!("inner") }));
+        assert!(outer.unwrap().unwrap_err().contains("inner"));
+        assert_eq!(CONTAINED.with(Cell::get), 0);
+    }
+
     #[test]
     fn the_debug_crash_is_reported_as_vanillas() {
         let error: Box<dyn std::error::Error> = DebugCrash::new().into();

crates/horizon-client-render/src/datapack.rs

@@ -2,7 +2,10 @@
 //! the parts of them commands use: `.mcfunction` functions (with macros and
 //! line continuation), function tags and predicates.
 use crate::zip::Zip;
-use horizon_world::nbt::Tag;
+use horizon_world::{
+    nbt::Tag,
+    worldgen::overrides::{self, PackFile, WorldgenOverrides},
+};
 use std::{
     collections::BTreeMap,
     path::{Path, PathBuf},
@@ -125,6 +128,114 @@ pub fn discover(world: &Path) -> Vec<DataPack> {
     packs
 }
 
+// ---- Create World ------------------------------------------------------------
+
+/// Create World's Data Packs screen (`PackSelectionScreen` on vanilla's
+/// `mcworld-` folder): the folder's packs (`PackSource.WORLD`) and the
+/// built-in one (`resources` holds its `pack.png`), which can be unselected
+/// and stays at the bottom. Horizon has no experiments, so their feature
+/// packs are not offered.
+pub fn screen_packs(dir: &Path, resources: &Path) -> Vec<crate::pack_screen::PackInfo> {
+    use crate::{
+        pack_screen::{Compat, PackInfo, Source, load_icon},
+        packs::Position,
+        text::{Style, Text},
+    };
+    let format = horizon_core::version::DATA_PACK_FORMAT;
+    let mut infos: Vec<PackInfo> = crate::packs::folder(dir, format)
+        .into_iter()
+        .map(|p| PackInfo {
+            icon: p.icon_png().as_deref().and_then(load_icon),
+            id: p.id,
+            title: p.title,
+            description: p.raw_description,
+            description_style: p.description_style,
+            source: Source::World,
+            compat: p.compatibility,
+            required: false,
+            position: Position::Top,
+            fixed: false,
+        })
+        .collect();
+    infos.push(PackInfo {
+        id: "vanilla".into(),
+        title: Text::translate("dataPack.vanilla.name", &[]),
+        description: Text::translate("dataPack.vanilla.description", &[]),
+        description_style: Style::default(),
+        source: Source::BuiltIn,
+        compat: Compat::Compatible,
+        icon: std::fs::read(resources.join("pack.png"))
+            .ok()
+            .as_deref()
+            .and_then(load_icon),
+        required: false,
+        position: Position::Bottom,
+        fixed: false,
+    });
+    infos
+}
+/// A new empty folder for Create World's packs
+/// (`Files.createTempDirectory("mcworld-")`).
+pub fn temp_folder() -> std::io::Result<PathBuf> {
+    let nanos = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_nanos();
+    let dir = std::env::temp_dir().join(format!("mcworld-{}-{nanos}", std::process::id()));
+    std::fs::create_dir_all(&dir)?;
+    Ok(dir)
+}
+/// What's in a folder of packs, to notice packs added or removed while the
+/// screen shows it (`PackSelectionScreen.Watcher`).
+pub fn folder_stamp(dir: &Path) -> Vec<(String, Option<std::time::SystemTime>)> {
+    let mut stamp: Vec<_> = std::fs::read_dir(dir)
+        .into_iter()
+        .flatten()
+        .flatten()
+        .map(|e| {
+            let modified = e.metadata().and_then(|m| m.modified()).ok();
+            (e.file_name().to_string_lossy().into_owned(), modified)
+        })
+        .collect();
+    stamp.sort();
+    stamp
+}
+/// Create World's packs into the new world before it opens
+/// (`copyTempDataPackDirToNewWorld`): every pack of `dir` goes to
+/// `<world>/datapacks`, and `datapacks.json` enables those `selected`
+/// (lowest priority first) and disables the rest.
+pub fn install(dir: &Path, world: &Path, selected: &[String]) -> Result<(), String> {
+    let err = |p: &Path, e: std::io::Error| format!("{}: {e}", p.display());
+    let target = world.join("datapacks");
+    std::fs::create_dir_all(&target).map_err(|e| err(&target, e))?;
+    let mut disabled = Vec::new();
+    for pack in crate::packs::folder(dir, horizon_core::version::DATA_PACK_FORMAT) {
+        let (crate::packs::Source::Dir(from) | crate::packs::Source::Zip(from)) = &pack.source;
+        copy(from, &target.join(pack.id.trim_start_matches("file/")))?;
+        if !selected.contains(&pack.id) {
+            disabled.push(pack.id);
+        }
+    }
+    if !selected.iter().any(|id| id == "vanilla") {
+        disabled.push("vanilla".into());
+    }
+    let json = serde_json::json!({ "enabled": selected, "disabled": disabled });
+    let file = world.join("datapacks.json");
+    std::fs::write(&file, json.to_string()).map_err(|e| err(&file, e))
+}
+/// A file, or a folder and everything in it.
+fn copy(from: &Path, to: &Path) -> Result<(), String> {
+    let err = |e: std::io::Error| format!("{} -> {}: {e}", from.display(), to.display());
+    if !from.is_dir() {
+        return std::fs::copy(from, to).map(drop).map_err(err);
+    }
+    std::fs::create_dir_all(to).map_err(err)?;
+    for e in std::fs::read_dir(from).map_err(err)?.flatten() {
+        copy(&e.path(), &to.join(e.file_name()))?;
+    }
+    Ok(())
+}
+
 // ---- functions ---------------------------------------------------------------
 
 /// A `.mcfunction`: plain command lines and macro lines.
@@ -421,9 +532,138 @@ fn hash_normalize(s: &str) -> String {
     }
 }
 
+/// The ids of `packs` (a world's, from `discover`) that are enabled, lowest
+/// priority first: those `<world>/datapacks.json` lists as enabled, in its
+/// order, then every pack it lists neither way, in name order.
+pub fn enabled_ids(world: &Path, packs: &[DataPack]) -> Vec<String> {
+    let saved: Option<serde_json::Value> = std::fs::read(world.join("datapacks.json"))
+        .ok()
+        .and_then(|b| serde_json::from_slice(&b).ok());
+    let list = |key: &str| -> Vec<String> {
+        saved
+            .as_ref()
+            .and_then(|v| v[key].as_array())
+            .map(|a| {
+                a.iter()
+                    .filter_map(|s| s.as_str().map(str::to_owned))
+                    .collect()
+            })
+            .unwrap_or_default()
+    };
+    let disabled = list("disabled");
+    let mut enabled: Vec<String> = list("enabled")
+        .into_iter()
+        .filter(|id| packs.iter().any(|p| &p.id == id))
+        .collect();
+    for p in packs {
+        if !enabled.contains(&p.id) && !disabled.contains(&p.id) {
+            enabled.push(p.id.clone());
+        }
+    }
+    enabled
+}
+
+// ---- worldgen ----------------------------------------------------------------
+
+/// The worldgen entries of `packs` (lowest priority first, the built-in pack
+/// left out: the prepared bundles are it) for the chunk generator, and what
+/// it leaves out, for the log. `biomes` says which biomes the game has: a
+/// pack's new biome is left out (the game has no colours, sounds or id for it).
+pub fn worldgen_overrides(
+    packs: &[&DataPack],
+    biomes: impl Fn(&str) -> bool,
+) -> (WorldgenOverrides, Vec<String>) {
+    let mut out = WorldgenOverrides::default();
+    let mut not_read: BTreeMap<String, usize> = BTreeMap::new();
+    let mut warnings = Vec::new();
+    for pack in packs {
+        for file in pack.list_kinds(&overrides::PACK_KINDS) {
+            let read = || String::from_utf8(pack.read(&file)?).ok();
+            match out.add_file(&pack.id, &file, read) {
+                PackFile::Read | PackFile::Other => {}
+                PackFile::DimensionType { id, min_y, height } => warnings.push(format!(
+                    "{}: dimension type {id} (min_y {min_y}, height {height}) is not used: \
+                     the dimension keeps its vanilla build height",
+                    pack.id
+                )),
+                PackFile::NotRead(kind) => {
+                    *not_read.entry(format!("{}: {kind}", pack.id)).or_default() += 1
+                }
+                PackFile::Unreadable => warnings.push(format!("{}: {file}: unreadable", pack.id)),
+            }
+        }
+    }
+    warnings.extend(out.finish(biomes));
+    for (kind, files) in not_read {
+        warnings.push(format!("{kind}: {files} files the generator does not read"));
+    }
+    (out, warnings)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    #[test]
+    fn enabled_packs_override_worldgen_in_order() {
+        let dir = std::env::temp_dir().join(format!("hz-datapack-worldgen-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        let write = |pack: &str, p: &str, t: &str| {
+            let path = dir.join("datapacks").join(pack).join(p);
+            std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+            std::fs::write(path, t).unwrap();
+        };
+        for pack in ["a", "b", "off"] {
+            write(pack, "pack.mcmeta", "{}");
+            write(pack, "data/minecraft/worldgen/noise/cave.json", pack);
+            write(
+                pack,
+                "data/minecraft/tags/worldgen/biome/is_hill.json",
+                "{\"values\":[]}",
+            );
+        }
+        write("a", "data/minecraft/worldgen/biome/new_peaks.json", "{}");
+        write("a", "data/minecraft/worldgen/biome/plains.json", "{}");
+        write(
+            "a",
+            "data/minecraft/worldgen/world_preset/normal.json",
+            "{}",
+        );
+        write(
+            "b",
+            "data/minecraft/dimension_type/overworld.json",
+            "{\"min_y\":-64,\"height\":2096}",
+        );
+        // `b` is enabled first, so `a` (enabled after it) wins.
+        std::fs::write(
+            dir.join("datapacks.json"),
+            "{\"enabled\":[\"file/b\",\"file/a\"],\"disabled\":[\"file/off\"]}",
+        )
+        .unwrap();
+        let packs = discover(&dir);
+        let enabled = enabled_ids(&dir, &packs);
+        assert_eq!(enabled, ["file/b", "file/a"]);
+        let enabled: Vec<&DataPack> = enabled
+            .iter()
+            .map(|id| packs.iter().find(|p| &p.id == id).unwrap())
+            .collect();
+        let (o, warnings) = worldgen_overrides(&enabled, |b| b == "minecraft:plains");
+        assert_eq!(
+            o.entries("noises").collect::<Vec<_>>(),
+            [("minecraft:cave", "a")]
+        );
+        assert_eq!(
+            o.entries("biomes").collect::<Vec<_>>(),
+            [("minecraft:plains", "{}")]
+        );
+        let tag_packs: Vec<&str> = o.tags("biome_tags").map(|(_, p, _)| p).collect();
+        assert_eq!(tag_packs, ["file/b", "file/a"]);
+        assert_eq!(warnings.len(), 3, "{warnings:?}");
+        assert!(warnings[0].contains("height 2096"));
+        assert!(warnings[1].contains("minecraft:new_peaks"));
+        assert!(warnings[2].contains("worldgen/world_preset"));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
     use horizon_world::nbt::parse_snbt;
 
     #[test]
@@ -566,4 +806,51 @@ mod tests {
         assert_eq!(p.list_kinds(&kinds), wanted);
         let _ = std::fs::remove_dir_all(&dir);
     }
+
+    #[test]
+    fn create_world_installs_its_packs() {
+        let root = std::env::temp_dir().join(format!("hz-datapack-install-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&root);
+        let (dir, world) = (root.join("mcworld"), root.join("world"));
+        let write = |pack: &str, p: &str, t: &str| {
+            let path = dir.join(pack).join(p);
+            std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+            std::fs::write(path, t).unwrap();
+        };
+        write("fns", "pack.mcmeta", r#"{"pack":{"pack_format":121}}"#);
+        write("fns", "data/x/function/f.mcfunction", "say hi");
+        write("off", "pack.mcmeta", r#"{"pack":{"pack_format":121}}"#);
+        std::fs::create_dir_all(&dir).unwrap();
+        let mut zip = zip::ZipWriter::new(std::fs::File::create(dir.join("old.zip")).unwrap());
+        zip.start_file("pack.mcmeta", zip::write::SimpleFileOptions::default())
+            .unwrap();
+        std::io::Write::write_all(&mut zip, br#"{"pack":{"pack_format":48}}"#).unwrap();
+        zip.finish().unwrap();
+        let infos = screen_packs(&dir, &root);
+        let ids: Vec<&str> = infos.iter().map(|p| p.id.as_str()).collect();
+        assert_eq!(ids, ["file/fns", "file/off", "file/old.zip", "vanilla"]);
+        let compat: Vec<_> = infos.iter().map(|p| p.compat).collect();
+        use crate::pack_screen::Compat;
+        assert_eq!(
+            compat,
+            [
+                Compat::Compatible,
+                Compat::Compatible,
+                Compat::TooOld,
+                Compat::Compatible
+            ]
+        );
+        let selected = ["vanilla", "file/old.zip", "file/fns"].map(String::from);
+        install(&dir, &world, &selected).unwrap();
+        let packs = discover(&world);
+        let ids: Vec<&str> = packs.iter().map(|p| p.id.as_str()).collect();
+        assert_eq!(ids, ["file/fns", "file/off", "file/old.zip"]);
+        let saved: serde_json::Value =
+            serde_json::from_slice(&std::fs::read(world.join("datapacks.json")).unwrap()).unwrap();
+        assert_eq!(
+            saved,
+            serde_json::json!({"enabled": selected, "disabled": ["file/off"]})
+        );
+        let _ = std::fs::remove_dir_all(&root);
+    }
 }

crates/horizon-client-render/src/entity.wgsl

@@ -22,6 +22,7 @@ struct Globals {
     outline_params: vec4<f32>,
     // Horizon Extras' dynamic lights: camera-relative position and level (dynamic_light.rs).
     dynamic_lights: array<vec4<f32>, 16>,
+    sunrise_fan: array<vec4<f32>, 32>,
 }
 @group(0) @binding(0) var<uniform> globals: Globals;
 @group(0) @binding(1) var atlas: texture_2d<f32>;
@@ -263,6 +264,16 @@ fn crumbling_uv(uv: vec2<f32>, packed_origin: vec2<f32>, sprite_size: vec2<f32>,
 
 // rendertype_outline.fsh: the vertex colour (the team colour; outline vertices carry no
 // normal, so no cardinal light) wherever the texture is not fully clear.
+// rendertype_entity_shadow.fsh: the shadow texture times the vertex colour,
+// then fog, with no alpha cutout, so a faint shadow in dim light still draws.
+@fragment fn fs_entity_shadow(in: Out) -> @location(0) vec4<f32> {
+    var color = textureSample(atlas, atlas_sampler, in.uv) * in.color;
+    color *= in.light_color;
+    let f = max(linear_fog(in.spherical, globals.fog.x, globals.fog.y),
+                linear_fog(in.cylindrical, globals.fog.z, globals.fog.w));
+    return vec4(mix(color.rgb, globals.fog_color.rgb, f * globals.fog_color.a), color.a);
+}
+
 @fragment fn fs_outline(in: Out) -> @location(0) vec4<f32> {
     if textureSample(atlas, atlas_sampler, in.uv).a == 0.0 { discard; }
     return vec4(in.color.rgb, 1.0);

crates/horizon-client-render/src/extras.rs

@@ -72,9 +72,8 @@ pub struct Extras {
     pub zoom_smooth: bool,
     /// Divide mouse turning by the zoom.
     pub zoom_sensitivity: bool,
-    /// The FPS counter and keystrokes extras are official mods now
-    /// (`moved_extras`): their old settings stay here until the game has
-    /// installed the mod for a player who had one on.
+    /// The FPS counter and keystrokes extras are official mods now: their
+    /// old settings stay here, kept as they were.
     pub fps: bool,
     pub fps_corner: Corner,
     /// Also show the minimum and 1% low.
@@ -83,8 +82,8 @@ pub struct Extras {
     pub keystrokes_corner: Corner,
     /// Clicks per second under the mouse buttons.
     pub keystrokes_cps: bool,
-    /// The official mods installed for the extras they replace, by mod id
-    /// (`movedToMods`): each is done once.
+    /// The official mods once installed for the extras they replace, by mod
+    /// id (`movedToMods`).
     pub moved: Vec<String>,
     pub minimap: bool,
     pub minimap_corner: Corner,
@@ -97,6 +96,8 @@ pub struct Extras {
     pub minimap_rotate: bool,
     /// Retry lost multiplayer connections (`reconnect`).
     pub auto_reconnect: bool,
+    /// The player's own name tag over its model in third person.
+    pub own_name_tag: bool,
     /// Mouse Tweaks-style drags in the inventory and storage containers.
     pub mouse_tweaks: bool,
     /// With them, the wheel over a slot moves its items one at a time.
@@ -137,6 +138,7 @@ impl Default for Extras {
             minimap_zoom: 1.0,
             minimap_rotate: false,
             auto_reconnect: false,
+            own_name_tag: false,
             mouse_tweaks: false,
             mouse_tweaks_wheel: true,
             sort: false,
@@ -211,6 +213,7 @@ impl Extras {
                 }
                 "minimapRotate" => e.minimap_rotate = flag(e.minimap_rotate),
                 "autoReconnect" => e.auto_reconnect = flag(e.auto_reconnect),
+                "ownNameTag" => e.own_name_tag = flag(e.own_name_tag),
                 "mouseTweaks" => e.mouse_tweaks = flag(e.mouse_tweaks),
                 "mouseTweaksWheel" => e.mouse_tweaks_wheel = flag(e.mouse_tweaks_wheel),
                 "sort" => e.sort = flag(e.sort),
@@ -225,7 +228,7 @@ impl Extras {
     }
     pub fn serialize(&self) -> String {
         format!(
-            "fullbright:{}\ndynamicLights:{}\nzoom:{}\nzoomKey:{}\nzoomLevel:{}\nzoomSmooth:{}\nzoomSensitivity:{}\nfps:{}\nfpsCorner:{}\nfpsLows:{}\nkeystrokes:{}\nkeystrokesCorner:{}\nkeystrokesCps:{}\nmovedToMods:{}\nminimap:{}\nminimapCorner:{}\nminimapSize:{}\nminimapShape:{}\nminimapZoom:{}\nminimapRotate:{}\nautoReconnect:{}\nmouseTweaks:{}\nmouseTweaksWheel:{}\nsort:{}\nsortKey:{}\n{}:{}\nagentControl:{}\ndiscordPresence:{}\n",
+            "fullbright:{}\ndynamicLights:{}\nzoom:{}\nzoomKey:{}\nzoomLevel:{}\nzoomSmooth:{}\nzoomSensitivity:{}\nfps:{}\nfpsCorner:{}\nfpsLows:{}\nkeystrokes:{}\nkeystrokesCorner:{}\nkeystrokesCps:{}\nmovedToMods:{}\nminimap:{}\nminimapCorner:{}\nminimapSize:{}\nminimapShape:{}\nminimapZoom:{}\nminimapRotate:{}\nautoReconnect:{}\nownNameTag:{}\nmouseTweaks:{}\nmouseTweaksWheel:{}\nsort:{}\nsortKey:{}\n{}:{}\nagentControl:{}\ndiscordPresence:{}\n",
             bool_text(self.fullbright),
             bool_text(self.dynamic_lights),
             bool_text(self.zoom),
@@ -251,6 +254,7 @@ impl Extras {
             self.minimap_zoom,
             bool_text(self.minimap_rotate),
             bool_text(self.auto_reconnect),
+            bool_text(self.own_name_tag),
             bool_text(self.mouse_tweaks),
             bool_text(self.mouse_tweaks_wheel),
             bool_text(self.sort),
@@ -282,7 +286,7 @@ impl Extras {
 }
 
 /// The field-of-view modifier target `Camera.tickFov` eases toward: vanilla's
-/// (`getFieldOfViewModifier`) divided by a mod's zoom (`render.set-zoom`). A
+/// (`getFieldOfViewModifier`) divided by a mod's zoom (`native_zoom`). A
 /// zoom of 1 leaves it as is.
 pub fn fov_target(vanilla: f32, zoom: f32) -> f32 {
     if zoom == 1.0 { vanilla } else { vanilla / zoom }
@@ -378,6 +382,7 @@ impl Cps {
 pub enum Item {
     Fullbright,
     DynamicLights,
+    OwnNameTag,
     AutoReconnect,
     MouseTweaks,
     MouseTweaksWheel,
@@ -396,6 +401,8 @@ pub fn rows() -> Vec<Result<Item, &'static str>> {
         Err("Lighting"),
         Ok(Fullbright),
         Ok(DynamicLights),
+        Err("Third person"),
+        Ok(OwnNameTag),
         Err("Inventory"),
         Ok(MouseTweaks),
         Ok(MouseTweaksWheel),
@@ -410,6 +417,7 @@ impl Item {
         match self {
             Item::Fullbright => "Fullbright",
             Item::DynamicLights => "Dynamic lights",
+            Item::OwnNameTag => "Own name tag",
             Item::AutoReconnect => "Auto-reconnect",
             Item::MouseTweaks => "Mouse Tweaks controls",
             Item::MouseTweaksWheel => "Scroll wheel moves items",
@@ -426,7 +434,7 @@ impl Item {
         Some(match self {
             MouseTweaksWheel => MouseTweaks,
             SortKey => Sort,
-            Fullbright | DynamicLights | MouseTweaks | Sort | AutoReconnect | NoAi
+            Fullbright | DynamicLights | OwnNameTag | MouseTweaks | Sort | AutoReconnect | NoAi
             | AgentControl | DiscordPresence => {
                 return None;
             }
@@ -439,6 +447,9 @@ impl Item {
             Item::DynamicLights => {
                 "Torches and other light sources held, dropped or on fire light the blocks around them."
             }
+            Item::OwnNameTag => {
+                "Shows your name above your head in third person, as other players see it. Hidden when the server hides your team's names or you're invisible."
+            }
             Item::AutoReconnect => {
                 "Rejoins a server after a lost connection or a restart, never after a kick or ban."
             }
@@ -471,7 +482,9 @@ impl Item {
         match self {
             Item::Fullbright => Some(Cost::None),
             Item::DynamicLights => Some(Cost::Low),
-            Item::AutoReconnect | Item::MouseTweaks | Item::Sort => Some(Cost::None),
+            Item::OwnNameTag | Item::AutoReconnect | Item::MouseTweaks | Item::Sort => {
+                Some(Cost::None)
+            }
             _ => None,
         }
     }
@@ -480,6 +493,7 @@ impl Item {
         Some(match self {
             Item::Fullbright => e.fullbright,
             Item::DynamicLights => e.dynamic_lights,
+            Item::OwnNameTag => e.own_name_tag,
             Item::AutoReconnect => e.auto_reconnect,
             Item::MouseTweaks => e.mouse_tweaks,
             Item::MouseTweaksWheel => e.mouse_tweaks_wheel,
@@ -506,6 +520,7 @@ impl Item {
         match self {
             Item::Fullbright => e.fullbright = !e.fullbright,
             Item::DynamicLights => e.dynamic_lights = !e.dynamic_lights,
+            Item::OwnNameTag => e.own_name_tag = !e.own_name_tag,
             Item::AutoReconnect => e.auto_reconnect = !e.auto_reconnect,
             Item::MouseTweaks => e.mouse_tweaks = !e.mouse_tweaks,
             Item::MouseTweaksWheel => e.mouse_tweaks_wheel = !e.mouse_tweaks_wheel,
@@ -534,7 +549,7 @@ mod tests {
         let d = Extras::default();
         assert!(!d.fullbright && !d.dynamic_lights);
         assert!(!d.zoom && !d.fps && !d.keystrokes && !d.minimap && !d.auto_reconnect);
-        assert!(!d.mouse_tweaks && !d.sort);
+        assert!(!d.mouse_tweaks && !d.sort && !d.own_name_tag);
         assert!(d.discord_presence);
         assert_eq!(Extras::parse(""), d);
         assert_eq!(Extras::parse(&d.serialize()), d);
@@ -558,6 +573,8 @@ mod tests {
         e.minimap_rotate = true;
         e.minimap_corner = Corner::BottomLeft;
         e.auto_reconnect = true;
+        Item::OwnNameTag.cycle(&mut e, false);
+        assert_eq!(Item::OwnNameTag.switch(&e), Some(true));
         e.mouse_tweaks = true;
         e.mouse_tweaks_wheel = false;
         e.sort = true;

crates/horizon-client-render/src/fog.rs

@@ -203,6 +203,13 @@ pub struct FogInputs<'a> {
     /// `BossHealthOverlay.shouldCreateWorldFog`: a boss bar with
     /// `createWorldFog` is shown (the Ender Dragon's).
     pub boss_world_fog: bool,
+    /// The camera entity is a spectator (`LavaFogEnvironment`).
+    pub spectator: bool,
+    /// The camera entity has Fire Resistance (`LavaFogEnvironment`).
+    pub fire_resistance: bool,
+    /// `GameRenderer.nightVisionScale` while Night Vision is on without
+    /// Darkness, else 0 (`FogRenderer.computeFogColor`'s brightenFactor).
+    pub night_vision: f32,
 }
 
 /// `FogRenderer.setupFog` + `computeFogColor`.
@@ -272,7 +279,11 @@ pub fn setup_fog(tables: &FogTables, state: &FogState, input: &FogInputs) -> Fog
         color[1] += (color[1] * 0.6 - color[1]) * t;
         color[2] += (color[2] * 0.6 - color[2]) * t;
     }
-    let brighten = if eye_in_water { water_vision } else { 0.0 };
+    let brighten = if eye_in_water {
+        water_vision
+    } else {
+        input.night_vision
+    };
     if color.iter().all(|&c| c != 0.0) {
         let scale = 1.0 / color[0].max(color[1]).max(color[2]);
         color = color.map(|c| c + (c * scale - c) * brighten);
@@ -288,10 +299,16 @@ pub fn setup_fog(tables: &FogTables, state: &FogState, input: &FogInputs) -> Fog
     };
     match input.fog_type {
         FogType::Lava => {
-            fog.environmental_start = 0.25;
-            fog.environmental_end = 1.0;
-            fog.sky_end = 1.0;
-            fog.cloud_end = 1.0;
+            // LavaFogEnvironment.setupFog.
+            (fog.environmental_start, fog.environmental_end) = if input.spectator {
+                (-8.0, rd * 0.5)
+            } else if input.fire_resistance {
+                (0.0, 5.0)
+            } else {
+                (0.25, 1.0)
+            };
+            fog.sky_end = fog.environmental_end;
+            fog.cloud_end = fog.environmental_end;
         }
         FogType::PowderSnow => {
             fog.environmental_start = 0.0;
@@ -362,6 +379,22 @@ pub fn setup_fog(tables: &FogTables, state: &FogState, input: &FogInputs) -> Fog
     }
     fog
 }
+/// Horizon's Fog option turned off (`horizon-graphics.txt` `fog:false`):
+/// no distance fog, in any dimension: the dimension's and biome's own fog
+/// (`visual/fog_start_distance`, `fog_end_distance`: the Nether's ends at 96
+/// blocks) and the render-distance fog. The fog of the fluid or powder snow
+/// the camera is in, blindness, darkness and a boss's world fog keep their
+/// limits. Vanilla has no such option.
+pub fn clear_distance_fog(fog: &mut FogData, input: &FogInputs) {
+    if input.fog_type == FogType::Atmospheric
+        && input.darkness.is_none()
+        && !input.boss_world_fog
+        && input.blindness.is_none()
+    {
+        (fog.render_distance_start, fog.render_distance_end) = (1e9, 2e9);
+        (fog.environmental_start, fog.environmental_end) = (1e9, 2e9);
+    }
+}
 /// `AtmosphericFogEnvironment.updateRainFogState`.
 pub fn update_rain_fog(
     state: &mut FogState,
@@ -405,6 +438,9 @@ mod tests {
             darkness: None,
             darken_world: 0.0,
             boss_world_fog: false,
+            spectator: false,
+            fire_resistance: false,
+            night_vision: 0.0,
         }
     }
     #[test]
@@ -432,6 +468,56 @@ mod tests {
         assert_eq!(water.environmental_start, -8.0);
     }
     #[test]
+    fn fog_off_clears_the_nether_fog_too() {
+        // The Nether's visual/fog_start_distance and fog_end_distance (10, 96)
+        // end before the render distance; the Fog option still clears them.
+        let nether = Sky {
+            fog_start: 10.0,
+            fog_end: 96.0,
+            ..Sky::default()
+        };
+        let tables = FogTables {
+            water_fog_end: vec![1.0],
+        };
+        let mut input = inputs(&nether);
+        input.skybox = false;
+        let mut fog = setup_fog(&tables, &FogState::default(), &input);
+        assert_eq!(fog.environmental_end, 96.0);
+        clear_distance_fog(&mut fog, &input);
+        assert!(fog.environmental_start >= 1e9 && fog.render_distance_start >= 1e9);
+    }
+    #[test]
+    fn fog_off_keeps_fluid_and_effect_fog() {
+        let sky = Sky {
+            fog_start: 10.0,
+            fog_end: 96.0,
+            ..Sky::default()
+        };
+        let tables = FogTables {
+            water_fog_end: vec![1.0],
+        };
+        let kept = |input: &FogInputs| {
+            let mut fog = setup_fog(&tables, &FogState::default(), input);
+            let before = fog;
+            clear_distance_fog(&mut fog, input);
+            fog == before
+        };
+        for fog_type in [FogType::Lava, FogType::PowderSnow, FogType::Water] {
+            let mut input = inputs(&sky);
+            input.fog_type = fog_type;
+            assert!(kept(&input), "{fog_type:?}");
+        }
+        let mut input = inputs(&sky);
+        input.blindness = Some((100, false));
+        assert!(kept(&input));
+        let mut input = inputs(&sky);
+        input.darkness = Some(0.5);
+        assert!(kept(&input));
+        let mut input = inputs(&sky);
+        input.boss_world_fog = true;
+        assert!(kept(&input));
+    }
+    #[test]
     fn boss_darkening_dims_fog_color() {
         // FogRenderer.computeFogColor: lerp toward 70/60/60% of each channel.
         let sky = Sky {

crates/horizon-client-render/src/font.rs

@@ -8,7 +8,7 @@
 //! offsets), styled drawing and StringSplitter-style line wrapping.
 use crate::{
     hud::Rect,
-    text::{Style, Text},
+    text::{Span, Style, Text, legacy_format},
     zip::Zip,
 };
 use ab_glyph::{Font as _, ScaleFont as _};
@@ -130,6 +130,8 @@ pub struct Font {
     atlas: (u32, u32),
     region: (u32, u32),
     cache: RefCell<Cache>,
+    /// Set anew for each font and each `reset_cache` (see `epoch`).
+    generation: std::cell::Cell<u64>,
     /// "Force Unicode Font": the `uniform` filter option.
     pub uniform: bool,
     /// "Japanese Glyph Variants": the `jp` filter option.
@@ -559,6 +561,11 @@ impl Region {
         Some((ax, ay))
     }
 }
+/// A value no font has had yet (`Font::epoch`).
+fn next_generation() -> u64 {
+    static NEXT: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(0);
+    NEXT.fetch_add(1, std::sync::atomic::Ordering::Relaxed)
+}
 impl Font {
     /// Build from the atlas holding the bitmap font sheets (`sprites`, of
     /// `atlas` size) with `region` the reserved rows.
@@ -603,6 +610,7 @@ impl Font {
                         .map_or(0, |d| d.as_nanos() as i64),
                 ),
             }),
+            generation: std::cell::Cell::new(next_generation()),
             uniform: false,
             japanese: false,
         };
@@ -661,6 +669,13 @@ impl Font {
         }
         cache.region.cursor = (0, 0);
         cache.region.row = 0;
+        self.generation.set(next_generation());
+    }
+    /// Changes whenever a glyph may come out different: another font, a
+    /// cache reset (glyphs move in the atlas) or other font options. Text laid
+    /// out under one epoch can be kept until it changes.
+    pub fn epoch(&self) -> u64 {
+        self.generation.get() << 2 | u64::from(self.uniform) << 1 | u64::from(self.japanese)
     }
     /// The glyph for a character in the default font (FontSet.getGlyph).
     pub fn glyph(&self, c: char) -> Glyph {
@@ -881,6 +896,9 @@ impl Font {
         std::mem::take(&mut self.cache.borrow_mut().region.pending)
     }
     pub fn advance(&self, c: char, style: &Style) -> f32 {
+        if c == '\u{fffc}' && style.inline_object.is_some() {
+            return 8.0;
+        }
         let g = self.glyph_styled(c, style);
         g.advance + if style.is_bold() { g.offset } else { 0.0 }
     }
@@ -951,6 +969,83 @@ impl Font {
         }
         out
     }
+    /// `Font.split`: `StringSplitter.splitLines(text, width, Style.EMPTY)` over
+    /// the text's parts with their `§` codes in. A code styles what follows
+    /// (`§r` back to no style while measuring), and the part a line breaks in
+    /// goes on in the style at the break. Lines keep their codes for drawing.
+    pub fn split_formatted(&self, t: &Text, max_width: f32) -> Vec<Text> {
+        let max_width = max_width.max(1.0);
+        let mut parts: Vec<(Vec<char>, Style)> = t
+            .spans
+            .iter()
+            .filter(|s| !s.text.is_empty())
+            .map(|s| (s.text.chars().collect(), s.style.clone()))
+            .collect();
+        let mut flat: Vec<char> = parts.iter().flat_map(|p| p.0.iter().copied()).collect();
+        let mut out = Vec::new();
+        let mut force_new_line = false;
+        // One LineBreakFinder per line, over the parts left.
+        while let Some((at, split_style)) = self.line_break(&parts, max_width) {
+            let tail = flat[at];
+            let new_line = tail == '\n';
+            let skip = usize::from(new_line || tail == ' ');
+            force_new_line = new_line;
+            out.push(split_at(&mut parts, at, skip, &split_style));
+            flat.drain(..at + skip);
+        }
+        if !parts.is_empty() {
+            let mut rest = Text::default();
+            rest.spans = parts
+                .into_iter()
+                .map(|(text, style)| Span {
+                    text: text.into_iter().collect(),
+                    style,
+                })
+                .collect();
+            out.push(rest);
+        } else if force_new_line {
+            out.push(Text::empty());
+        }
+        out
+    }
+    /// `StringSplitter.LineBreakFinder` fed by `StringDecomposer.iterateFormatted`:
+    /// where the parts break (a character index) and the style there.
+    fn line_break(&self, parts: &[(Vec<char>, Style)], max_width: f32) -> Option<(usize, Style)> {
+        let (mut width, mut had_visible, mut last_space) = (0.0f32, false, None);
+        let mut offset = 0;
+        for (contents, part_style) in parts {
+            let mut style = part_style.clone();
+            let mut i = 0;
+            while i < contents.len() {
+                let c = contents[i];
+                if c == '§' {
+                    // A `§` that ends its part ends only that part.
+                    let Some(&code) = contents.get(i + 1) else {
+                        break;
+                    };
+                    style = legacy_format(&style, code, &Style::default());
+                    i += 2;
+                    continue;
+                }
+                let at = offset + i;
+                if c == '\n' {
+                    return Some((at, style));
+                }
+                if c == ' ' {
+                    last_space = Some((at, style.clone()));
+                }
+                let advance = self.advance(c, &style);
+                width += advance;
+                if had_visible && width > max_width {
+                    return Some(last_space.unwrap_or((at, style)));
+                }
+                had_visible |= advance != 0.0;
+                i += 1;
+            }
+            offset += contents.len();
+        }
+        None
+    }
     /// `ComponentRenderUtils.wrapComponents`: the split lines, wrapped ones
     /// indented by an unstyled space; one empty line for empty text.
     pub fn wrap_components(&self, t: &Text, max_width: i32) -> Vec<Text> {
@@ -1044,6 +1139,47 @@ impl Font {
     }
 }
 
+/// `StringSplitter.FlatComponents.splitAt`: the parts before `at` as a line,
+/// `skip` characters dropped, and the part it ends in restyled as `style`.
+fn split_at(parts: &mut Vec<(Vec<char>, Style)>, at: usize, skip: usize, style: &Style) -> Text {
+    let mut line = Text::default();
+    let mut push = |text: &[char], style: &Style| {
+        line.spans.push(Span {
+            text: text.iter().collect(),
+            style: style.clone(),
+        })
+    };
+    // Each part done is removed, so the one at hand is always the first.
+    let (mut position, mut in_skip) = (at, false);
+    while let Some((text, part_style)) = parts.first() {
+        let size = text.len();
+        if !in_skip {
+            if position > size {
+                push(text, part_style);
+                parts.remove(0);
+                position -= size;
+                continue;
+            }
+            if position > 0 {
+                push(&text[..position], part_style);
+            }
+            position += skip;
+            in_skip = true;
+        }
+        if position <= size {
+            if position == size {
+                parts.remove(0);
+            } else {
+                parts[0] = (text[position..].to_vec(), style.clone());
+            }
+            break;
+        }
+        parts.remove(0);
+        position -= size;
+    }
+    line
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1206,6 +1342,37 @@ mod tests {
         assert!(!font.take_patches().is_empty());
     }
 
+    /// StringDecomposer.iterateFormatted: a `§` that ends a part stops that
+    /// part only; the next part is still measured and can break.
+    #[test]
+    fn a_section_sign_ending_a_part_still_breaks_the_next() {
+        let sheet = png(16, 8, |x, _| x < 2);
+        let default = br#"{"providers":[{"type":"space","advances":{" ":4}},{"type":"bitmap","file":"minecraft:font/a.png","ascent":7,"chars":["ab"]}]}"#;
+        let root = root(
+            "section-sign",
+            &[
+                ("assets/minecraft/font/default.json", default),
+                ("assets/minecraft/textures/font/a.png", &sheet),
+            ],
+        );
+        let font = load(&root);
+        let _ = std::fs::remove_dir_all(&root);
+        let mut text = Text::default();
+        text.spans = ["a§", "a a"]
+            .map(|part| Span {
+                text: part.into(),
+                style: Style::default(),
+            })
+            .into();
+        // 3 + 3 + 4 + 3 is past 12: the line breaks at the space.
+        let lines: Vec<String> = font
+            .split_formatted(&text, 12.0)
+            .iter()
+            .map(Text::plain)
+            .collect();
+        assert_eq!(lines, ["a§a", "a"]);
+    }
+
     /// A renderer rebuilt over the same font (the loading screen's handoff)
     /// makes its atlas texture from the textures alone, so the glyphs it had
     /// rasterized into the previous texture must be placed into the new one.

crates/horizon-client-render/src/gfx/animate.rs

@@ -103,10 +103,11 @@ impl SpriteAnimator {
         let mut counts: Vec<usize> = Vec::new();
         let mut sprites = Vec::with_capacity(animations.len());
         for animation in animations {
-            let chains: Vec<_> = (0..animation.frame_count())
-                .map(|frame| source_chain(animation.pixels(frame), size, settings, animation.layer))
+            let pixels: Vec<_> = (0..animation.frame_count())
+                .map(|frame| animation.pixels(frame))
                 .collect();
-            let bytes: u64 = chains.iter().map(|(chain, _)| chain.len() as u64).sum();
+            let (chains, edge) = source_chains(&pixels, size, settings, animation.layer);
+            let bytes: u64 = chains.iter().map(|chain| chain.len() as u64).sum();
             if bytes > limit {
                 log::warn!(
                     "Horizon: layer {}'s animation ({bytes} bytes) does not fit in a storage buffer; it stays still",
@@ -124,7 +125,7 @@ impl SpriteAnimator {
             let data = &mut frames[buffer];
             let offsets = chains
                 .iter()
-                .map(|(chain, _)| {
+                .map(|chain| {
                     let offset = (data.len() / 4) as u32;
                     data.extend_from_slice(chain);
                     offset
@@ -142,7 +143,7 @@ impl SpriteAnimator {
                 shown: None,
                 layer: animation.layer % split,
                 frames: offsets,
-                edge: chains[0].1,
+                edge,
                 group,
             });
         }
@@ -424,15 +425,63 @@ fn mix_level(frames: &[u8], [_, current, next, millis, edge]: [u32; 5], width: u
 /// array's size from its own size's chain, its first level repeated into the
 /// larger levels: that chain, which the shader repeats. Any other sprite: its
 /// chain at the array's size.
+#[cfg(test)]
 fn source_chain(pixels: &[u8], size: u32, settings: &[Settings], layer: u32) -> (Vec<u8>, u32) {
-    let native = settings.get(layer as usize).map_or(0, |s| s.native_size);
-    let edge = if native.is_power_of_two() && native < size {
-        native
+    let (mut chains, edge) = source_chains(&[pixels], size, settings, layer);
+    (chains.swap_remove(0), edge)
+}
+
+/// Every frame's chain, laid out as one frame's `source_chain`, but mipmapped as
+/// vanilla's `SpriteContents.increaseMipLevel` does: over the whole animation
+/// sheet (the frames stacked), so `solidify` and the alpha-to-coverage scale
+/// of each level are the sheet's, not each frame's. A frame alone has a
+/// single texel square at its 2x2 level, and its coverage scale could round
+/// a whole far frame transparent (kelp blinking out at distance).
+fn source_chains(
+    frames: &[&[u8]],
+    size: u32,
+    settings: &[Settings],
+    layer: u32,
+) -> (Vec<Vec<u8>>, u32) {
+    let s = settings.get(layer as usize).copied().unwrap_or_default();
+    let edge = if s.native_size.is_power_of_two() && s.native_size < size {
+        s.native_size
     } else {
         size
     };
-    let frame = crate::sprites::resample(pixels, size, edge);
-    (super::mip_chain(&frame, edge, settings, layer, 1).0, edge)
+    let mut sheet = crate::mipmap::Image {
+        width: edge,
+        height: edge * frames.len() as u32,
+        pixels: Vec::with_capacity((edge * edge) as usize * frames.len()),
+    };
+    for frame in frames {
+        let frame = crate::sprites::resample(frame, size, edge);
+        sheet.pixels.extend_from_slice(frame.as_chunks::<4>().0);
+    }
+    let has_transparent = s.has_transparent || sheet.pixels.iter().any(|p| p[3] == 0);
+    let levels = crate::mipmap::generate(
+        sheet,
+        edge.trailing_zeros(),
+        Settings {
+            has_transparent,
+            ..s
+        },
+    );
+    let chains = (0..frames.len())
+        .map(|frame| {
+            let mut chain = Vec::new();
+            for level in &levels {
+                let texels = (level.width * level.width) as usize;
+                chain.extend(
+                    level.pixels[frame * texels..(frame + 1) * texels]
+                        .iter()
+                        .flatten(),
+                );
+            }
+            chain
+        })
+        .collect();
+    (chains, edge)
 }
 
 #[cfg(test)]
@@ -572,6 +621,63 @@ mod tests {
         }
     }
 
+    #[test]
+    fn kelp_frames_share_the_sheet_mips() {
+        let root = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("../../.local/horizon-client")
+            .join(horizon_core::VANILLA_VERSION);
+        if !root
+            .join("assets/minecraft/textures/block/kelp.png")
+            .exists()
+        {
+            return;
+        }
+        let mut sprites = crate::sprites::Sprites::default();
+        for name in ["kelp", "kelp_plant", "seagrass", "tall_seagrass_top"] {
+            sprites
+                .insert(&root, &format!("minecraft:block/{name}"))
+                .unwrap();
+        }
+        sprites.finish();
+        // A level drawn nowhere: no texel passes the cutout's alpha test.
+        let blank = |chain: &[u8], edge: u32| {
+            let mut start = 0;
+            let mut level = edge;
+            let mut blank = Vec::new();
+            while level > 0 {
+                let bytes = (level * level * 4) as usize;
+                let texels = &chain[start..start + bytes];
+                blank.push(texels.as_chunks::<4>().0.iter().all(|p| p[3] < 128));
+                start += bytes;
+                level >>= 1;
+            }
+            blank
+        };
+        let mut blinked = 0;
+        for animation in &sprites.animations {
+            let size = sprites.size;
+            let pixels: Vec<_> = (0..animation.frame_count())
+                .map(|f| animation.pixels(f))
+                .collect();
+            let (chains, edge) = source_chains(&pixels, size, &sprites.mips, animation.layer);
+            for (frame, chain) in chains.iter().enumerate() {
+                // The 1x1 level has no texel square to measure coverage on
+                // (vanilla leaves it unscaled); every larger level shows.
+                let levels = blank(chain, edge);
+                assert!(
+                    !levels[..levels.len() - 1].contains(&true),
+                    "layer {} frame {frame}: {levels:?}",
+                    animation.layer
+                );
+                let (alone, _) = source_chain(pixels[frame], size, &sprites.mips, animation.layer);
+                let alone = blank(&alone, edge);
+                blinked += usize::from(alone[..alone.len() - 1].contains(&true));
+            }
+        }
+        // Mipmapped frame by frame, some kelp frames vanished at the 2x2 level.
+        assert!(blinked > 0);
+    }
+
     #[test]
     fn rounding_matches_f32_mix_but_for_exact_halves() {
         // The CPU blend this replaced: f32 mix, then rounded. They differ
@@ -730,8 +836,11 @@ mod tests {
             queue.submit([encoder.finish()]);
             for animation in &animations {
                 let blend = animation.blend(tick);
-                let chain = |f| source_chain(animation.pixels(f), size, &mips, animation.layer);
-                let ((current, edge), (next, _)) = (chain(blend.frame), chain(blend.next));
+                let pixels: Vec<_> = (0..animation.frame_count())
+                    .map(|f| animation.pixels(f))
+                    .collect();
+                let (chains, edge) = source_chains(&pixels, size, &mips, animation.layer);
+                let (current, next) = (&chains[blend.frame], &chains[blend.next]);
                 let layers = read_back(
                     &device,
                     &queue,
@@ -739,7 +848,7 @@ mod tests {
                 );
                 assert_eq!(
                     layers[(animation.layer % split) as usize],
-                    reference(&current, &next, blend.millis, edge, size),
+                    reference(current, next, blend.millis, edge, size),
                     "layer {} at tick {tick}",
                     animation.layer
                 );

crates/horizon-client-render/src/gfx/compositor.rs

@@ -0,0 +1,214 @@
+//! Splitscreen: several players' renderers draw offscreen on one device, and the
+//! compositor copies each frame into its place on a window's surface. A window holds views but
+//! never owns them, so a view can later move to another window (another monitor, detached).
+use super::Renderer;
+use crate::Result;
+use std::sync::Arc;
+use winit::window::Window;
+
+pub struct Compositor {
+    surface: wgpu::Surface<'static>,
+    device: wgpu::Device,
+    queue: wgpu::Queue,
+    config: wgpu::SurfaceConfiguration,
+    present_modes: Vec<wgpu::PresentMode>,
+    suspended: bool,
+}
+
+impl Renderer {
+    /// A compositor for `window` on this renderer's device, presenting on the surface it gave up.
+    pub fn compositor(&self, window: Arc<Window>) -> Result<Compositor> {
+        // The surface this renderer set aside for its successor (`release_surface`), else a new
+        // one: a window can't keep two.
+        let spare = self
+            .spare_surface
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner)
+            .take();
+        let surface = match spare {
+            Some(surface) => surface,
+            None => self.instance.create_surface(window.clone())?,
+        };
+        Compositor::new(
+            surface,
+            &self.adapter,
+            &self.device,
+            &self.queue,
+            window.inner_size().into(),
+        )
+    }
+
+    /// The last offscreen frame (`--offscreen`), for the compositor.
+    pub fn offscreen_frame(&self) -> Option<&wgpu::Texture> {
+        self.offscreen.as_ref()
+    }
+
+    /// Splitscreen turned off: a compositor's surface, set aside for the renderer that draws on
+    /// the window again (it takes it, as after `release_surface`).
+    pub fn take_back(&self, compositor: Compositor) {
+        *self
+            .spare_surface
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner) = Some(compositor.surface);
+    }
+}
+
+impl Compositor {
+    /// Present offscreen BGRA frames on a compatible surface using their existing device.
+    /// The surface must support COPY_DST and Bgra8Unorm; unsupported surfaces return an error.
+    pub fn new(
+        surface: wgpu::Surface<'static>,
+        adapter: &wgpu::Adapter,
+        device: &wgpu::Device,
+        queue: &wgpu::Queue,
+        size: [u32; 2],
+    ) -> Result<Self> {
+        let caps = surface.get_capabilities(adapter);
+        // ponytail: a plain texture copy needs the offscreen frames' format; a blit pass would
+        // take any surface format (Rgba8Unorm on some Linux drivers).
+        if !caps.usages.contains(wgpu::TextureUsages::COPY_DST) {
+            return Err("surface does not support copying offscreen frames".into());
+        }
+        let format = wgpu::TextureFormat::Bgra8Unorm;
+        if !caps.formats.contains(&format) {
+            return Err(format!(
+                "splitscreen needs a {format:?} surface; this one offers {:?}",
+                caps.formats
+            )
+            .into());
+        }
+        let max = device.limits().max_texture_dimension_2d;
+        let config = wgpu::SurfaceConfiguration {
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_DST,
+            format,
+            width: size[0].clamp(1, max),
+            height: size[1].clamp(1, max),
+            present_mode: wgpu::PresentMode::Fifo,
+            desired_maximum_frame_latency: 2,
+            alpha_mode: wgpu::CompositeAlphaMode::Opaque,
+            view_formats: vec![],
+            color_space: wgpu::SurfaceColorSpace::default(),
+        };
+        surface.configure(device, &config);
+        Ok(Compositor {
+            surface,
+            device: device.clone(),
+            queue: queue.clone(),
+            config,
+            present_modes: caps.present_modes,
+            suspended: !super::drawable_size(size[0], size[1], max),
+        })
+    }
+
+    /// Vsync on: presents wait for the display. Off: they don't (Mailbox, else Immediate).
+    pub fn set_vsync(&mut self, vsync: bool) {
+        let mode = [wgpu::PresentMode::Mailbox, wgpu::PresentMode::Immediate]
+            .into_iter()
+            .find(|m| !vsync && self.present_modes.contains(m))
+            .unwrap_or(wgpu::PresentMode::Fifo);
+        if mode != self.config.present_mode {
+            self.config.present_mode = mode;
+            self.surface.configure(&self.device, &self.config);
+        }
+    }
+
+    pub fn resize(&mut self, width: u32, height: u32) {
+        self.suspended =
+            !super::drawable_size(width, height, self.device.limits().max_texture_dimension_2d);
+        if !self.suspended {
+            self.config.width = width;
+            self.config.height = height;
+            self.surface.configure(&self.device, &self.config);
+        }
+    }
+
+    /// Copy each view's frame to its top-left corner on the window and present. Frames that
+    /// don't fit are clipped; parts of the window no view covers (a view before its first frame,
+    /// one still at its old size after a resize) are black. Nothing when the window has no frame
+    /// to give (occluded, resized, timed out). Returns true when a frame was submitted.
+    pub fn present(&mut self, views: &[(&wgpu::Texture, [u32; 2])]) -> bool {
+        if self.suspended {
+            return false;
+        }
+        let frame = match self.surface.get_current_texture() {
+            wgpu::CurrentSurfaceTexture::Success(f)
+            | wgpu::CurrentSurfaceTexture::Suboptimal(f) => f,
+            wgpu::CurrentSurfaceTexture::Outdated | wgpu::CurrentSurfaceTexture::Lost => {
+                self.surface.configure(&self.device, &self.config);
+                return false;
+            }
+            _ => return false,
+        };
+        let mut encoder = self
+            .device
+            .create_command_encoder(&wgpu::CommandEncoderDescriptor {
+                label: Some("Splitscreen compositor"),
+            });
+        let target = frame.texture.create_view(&Default::default());
+        drop(encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("Splitscreen compositor clear"),
+            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                view: &target,
+                depth_slice: None,
+                resolve_target: None,
+                ops: wgpu::Operations {
+                    load: wgpu::LoadOp::Clear(wgpu::Color::BLACK),
+                    store: wgpu::StoreOp::Store,
+                },
+            })],
+            ..Default::default()
+        }));
+        for &(texture, [x, y]) in views {
+            let [width, height] = clipped_size(
+                [texture.width(), texture.height()],
+                [x, y],
+                [self.config.width, self.config.height],
+            );
+            if width == 0 || height == 0 {
+                continue;
+            }
+            encoder.copy_texture_to_texture(
+                texture.as_image_copy(),
+                wgpu::TexelCopyTextureInfo {
+                    origin: wgpu::Origin3d { x, y, z: 0 },
+                    ..frame.texture.as_image_copy()
+                },
+                wgpu::Extent3d {
+                    width,
+                    height,
+                    depth_or_array_layers: 1,
+                },
+            );
+        }
+        self.queue.submit([encoder.finish()]);
+        self.queue.present(frame);
+        true
+    }
+}
+
+/// Copies never reach past the surface, including while a resized view still has its old frame.
+fn clipped_size(view: [u32; 2], at: [u32; 2], surface: [u32; 2]) -> [u32; 2] {
+    [
+        view[0].min(surface[0].saturating_sub(at[0])),
+        view[1].min(surface[1].saturating_sub(at[1])),
+    ]
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn frames_are_clipped_to_the_window_during_resize() {
+        assert_eq!(clipped_size([640, 480], [0, 0], [1280, 720]), [640, 480]);
+        assert_eq!(
+            clipped_size([640, 480], [1000, 600], [1280, 720]),
+            [280, 120]
+        );
+        assert_eq!(clipped_size([640, 480], [1280, 720], [1280, 720]), [0, 0]);
+        assert_eq!(
+            clipped_size([640, 480], [u32::MAX, 0], [1280, 720]),
+            [0, 480]
+        );
+    }
+}

crates/horizon-client-render/src/gfx/entity_batch.rs

@@ -2,13 +2,14 @@
 use super::Vertex;
 
 /// Entity materials by a quad's overlay (`Vertex::layer`), in draw order:
-/// ordinary entities, breaking cracks (11), translucent breaking cracks (12),
-/// the boat water mask (13, `RenderPipelines.WATER_MASK`), energy swirls
-/// (34, `RenderPipelines.ENERGY_SWIRL`), entity shadows (14,
+/// ordinary entities, world text drawn with a depth bias (35,
+/// `RenderPipelines.TEXT_POLYGON_OFFSET`), breaking cracks (11), translucent
+/// breaking cracks (12), the boat water mask (13, `RenderPipelines.WATER_MASK`),
+/// energy swirls (34, `RenderPipelines.ENERGY_SWIRL`), entity shadows (14,
 /// `RenderPipelines.ENTITY_SHADOW`), translucent-layer particles (15, drawn
 /// after translucent terrain: `SubmitNodeCollection.submitQuadParticleGroup`)
 /// and translucent item quads (32, drawn without depth writes).
-const MATERIALS: usize = 8;
+const MATERIALS: usize = 9;
 /// The overlay of depth-only quads that hide water (`RenderTypes.waterMask`).
 pub const WATER_MASK_OVERLAY: u32 = 13;
 /// The overlay of energy swirl quads (`RenderTypes.energySwirl`: the charged creeper's and the
@@ -24,13 +25,31 @@ pub const TRANSLUCENT_PARTICLE_OVERLAY: u32 = 15;
 pub const TRANSLUCENT_ITEM_OVERLAY: u32 = 32;
 /// A translucent item with an enchantment glint.
 pub const TRANSLUCENT_GLINT_ITEM_OVERLAY: u32 = 33;
+/// The overlay of text in `Font.DisplayMode.POLYGON_OFFSET` (text displays):
+/// drawn like an ordinary entity, pulled toward the camera.
+pub const TEXT_POLYGON_OFFSET_OVERLAY: u32 = 35;
+
+/// The material of a quad by its overlay (`MATERIALS` order).
+fn material(layer: u32) -> usize {
+    match layer {
+        TEXT_POLYGON_OFFSET_OVERLAY => 1,
+        11 => 2,
+        12 => 3,
+        WATER_MASK_OVERLAY => 4,
+        ENERGY_SWIRL_OVERLAY => 5,
+        SHADOW_OVERLAY => 6,
+        TRANSLUCENT_PARTICLE_OVERLAY => 7,
+        TRANSLUCENT_ITEM_OVERLAY | TRANSLUCENT_GLINT_ITEM_OVERLAY => 8,
+        _ => 0,
+    }
+}
 
 #[derive(Default)]
 pub(super) struct EntityBatch {
-    // Quad indices avoid copying vertices twice while grouping materials.
-    // Keep initialized high-water storage; local counts delimit active entries.
-    // Each bucket can hold all quads, removing per-quad Vec growth checks.
-    buckets: [Vec<usize>; MATERIALS],
+    // Runs of consecutive quads of one material (first quad, quad count): a
+    // model's quads share one, so whole runs are copied at once. Cleared each
+    // frame, keeping their storage.
+    runs: [Vec<(usize, usize)>; MATERIALS],
     pub(super) combined: Vec<Vertex>,
 }
 
@@ -43,50 +62,29 @@ impl EntityBatch {
         see_through: &[Vertex],
     ) -> [u32; MATERIALS] {
         let quads = entities.as_chunks::<4>().0;
-        for bucket in &mut self.buckets {
-            if bucket.len() < quads.len() {
-                bucket.resize(quads.len(), 0);
-            }
+        for runs in &mut self.runs {
+            runs.clear();
         }
         let mut counts = [0usize; MATERIALS];
-        for (index, quad) in quads.iter().enumerate() {
-            let material = match quad[0].layer {
-                11 => 1,
-                12 => 2,
-                WATER_MASK_OVERLAY => 3,
-                ENERGY_SWIRL_OVERLAY => 4,
-                SHADOW_OVERLAY => 5,
-                TRANSLUCENT_PARTICLE_OVERLAY => 6,
-                TRANSLUCENT_ITEM_OVERLAY | TRANSLUCENT_GLINT_ITEM_OVERLAY => 7,
-                _ => 0,
-            };
-            self.buckets[material][counts[material]] = index;
-            counts[material] += 1;
+        let mut start = 0;
+        while start < quads.len() {
+            let kind = material(quads[start][0].layer);
+            let end = quads[start + 1..]
+                .iter()
+                .position(|quad| material(quad[0].layer) != kind)
+                .map_or(quads.len(), |n| start + 1 + n);
+            self.runs[kind].push((start, end - start));
+            counts[kind] += end - start;
+            start = end;
         }
         let entity_vertices = quads.len() * 4;
-        self.combined.reserve(
-            (entity_vertices + additive.len() + hand.len() + see_through.len())
-                .saturating_sub(self.combined.len()),
-        );
+        self.combined.clear();
         self.combined
-            .resize(entity_vertices, bytemuck::Zeroable::zeroed());
-        if counts.contains(&quads.len()) {
-            // Uniform materials are already ordered; copy the whole batch.
-            self.combined.copy_from_slice(&entities[..entity_vertices]);
-        } else {
-            let mut offset = 0;
-            for (bucket, &count) in self.buckets.iter().zip(&counts) {
-                let bucket = &bucket[..count];
-                let end = offset + count * 4;
-                for (output, &index) in self.combined[offset..end]
-                    .as_chunks_mut::<4>()
-                    .0
-                    .iter_mut()
-                    .zip(bucket)
-                {
-                    *output = quads[index];
-                }
-                offset = end;
+            .reserve(entity_vertices + additive.len() + hand.len() + see_through.len());
+        for runs in &self.runs {
+            for &(first, count) in runs {
+                self.combined
+                    .extend_from_slice(&entities[first * 4..(first + count) * 4]);
             }
         }
         self.combined.extend_from_slice(additive);
@@ -109,9 +107,10 @@ mod tests {
     ) -> (Vec<Vertex>, [u32; MATERIALS]) {
         let mut combined = Vec::with_capacity(entities.len() + additive.len() + hand.len());
         let mut counts = [0; MATERIALS];
-        for (i, layer) in [0, 11, 12, 13, 34, 14, 15].into_iter().enumerate() {
+        for (i, layer) in [0, 35, 11, 12, 13, 34, 14, 15].into_iter().enumerate() {
             for quad in entities.as_chunks::<4>().0 {
                 let material = match quad[0].layer {
+                    35 => 35,
                     11 => 11,
                     12 => 12,
                     13 => 13,
@@ -137,7 +136,7 @@ mod tests {
                 pos: [index as f32, 2.0, 3.0],
                 uv: [index as f32, 5.0],
                 layer: if mixed {
-                    [7, 11, 14, 12, 4, 13, 15, 0][index / 4 % 8]
+                    [7, 11, 14, 35, 12, 4, 13, 15, 0][index / 4 % 9]
                 } else {
                     0
                 },
@@ -174,12 +173,12 @@ mod tests {
         let hand = geometry(2, false);
         // Warm every bucket and the combined buffer to their maximum sizes.
         equivalent(&mut batch, &entities, &additive, &hand);
-        let capacities = batch.buckets.each_ref().map(|b| b.capacity());
+        let capacities = batch.runs.each_ref().map(|b| b.capacity());
         let capacity = batch.combined.capacity();
         let pointer = batch.combined.as_ptr();
         for length in [0, 1, 3, 4, 511, entities.len(), 17, 0, entities.len()] {
             equivalent(&mut batch, &entities[..length], &additive[..5], &hand[..3]);
-            assert_eq!(batch.buckets.each_ref().map(|b| b.capacity()), capacities);
+            assert_eq!(batch.runs.each_ref().map(|b| b.capacity()), capacities);
             assert_eq!(batch.combined.capacity(), capacity);
             assert_eq!(batch.combined.as_ptr(), pointer);
         }
@@ -188,11 +187,11 @@ mod tests {
         // Grow again, then confirm empty/small frames retain the new storage.
         let larger = geometry(8192, true);
         equivalent(&mut batch, &larger, &additive, &hand);
-        let capacities = batch.buckets.each_ref().map(|b| b.capacity());
+        let capacities = batch.runs.each_ref().map(|b| b.capacity());
         let capacity = batch.combined.capacity();
         for entities in [&larger[..7], &larger[..], &[]] {
             equivalent(&mut batch, entities, &[], &[]);
-            assert_eq!(batch.buckets.each_ref().map(|b| b.capacity()), capacities);
+            assert_eq!(batch.runs.each_ref().map(|b| b.capacity()), capacities);
             assert_eq!(batch.combined.capacity(), capacity);
         }
     }
@@ -255,9 +254,9 @@ mod tests {
                 before[7] as f64 / after[7] as f64,
                 batch.combined.capacity() * std::mem::size_of::<Vertex>()
                     + batch
-                        .buckets
+                        .runs
                         .iter()
-                        .map(|b| b.capacity() * std::mem::size_of::<usize>())
+                        .map(|b| b.capacity() * std::mem::size_of::<(usize, usize)>())
                         .sum::<usize>()
             );
         }

crates/horizon-client-render/src/gfx/hdr.rs

@@ -14,6 +14,12 @@ pub enum Output {
 }
 
 impl Output {
+    pub fn name(self) -> &'static str {
+        match self {
+            Self::Pq => "HDR10 (PQ)",
+            Self::ScRgb => "scRGB",
+        }
+    }
     pub fn format(self) -> wgpu::TextureFormat {
         match self {
             Self::Pq => wgpu::TextureFormat::Rgb10a2Unorm,
@@ -57,6 +63,12 @@ struct Targets {
 pub struct Hdr {
     layout: wgpu::BindGroupLayout,
     pipeline: wgpu::RenderPipeline,
+    /// Zeroes the frame's alpha once the world is kept (`keep_world`): what draws after,
+    /// the hand, HUD and menus, raises it, so HDR output knows where they cover the world.
+    clear_alpha: wgpu::RenderPipeline,
+    /// Scales the frame's alpha down to 1/255 where the hand drew (`mark_hand`), so HDR
+    /// output keeps the hand at the world's brightness.
+    hand_mark: wgpu::RenderPipeline,
     params: wgpu::Buffer,
     pub output: Output,
     /// The frame's format: what every other pipeline draws in.
@@ -67,6 +79,10 @@ pub struct Hdr {
     /// Paper white and peak brightness, in nits.
     pub paper_white: f32,
     pub peak: f32,
+    /// The display's black level, in nits: shadows are lifted onto it (`hdr.wgsl`).
+    pub black: f32,
+    /// The HUD and menus' brightness, as a share of paper white (0.25..=1).
+    pub ui: f32,
 }
 
 impl Hdr {
@@ -132,6 +148,48 @@ impl Hdr {
             multiview_mask: None,
             cache: None,
         });
+        let alpha_pass = |label, blend| {
+            device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+                label: Some(label),
+                layout: Some(&device.create_pipeline_layout(&Default::default())),
+                vertex: wgpu::VertexState {
+                    module: &shader,
+                    entry_point: Some("vs_hdr"),
+                    compilation_options: Default::default(),
+                    buffers: &[],
+                },
+                primitive: Default::default(),
+                depth_stencil: None,
+                multisample: Default::default(),
+                fragment: Some(wgpu::FragmentState {
+                    module: &shader,
+                    entry_point: Some("fs_clear_alpha"),
+                    compilation_options: Default::default(),
+                    targets: &[Some(wgpu::ColorTargetState {
+                        format,
+                        blend,
+                        write_mask: wgpu::ColorWrites::ALPHA,
+                    })],
+                }),
+                multiview_mask: None,
+                cache: None,
+            })
+        };
+        let clear_alpha = alpha_pass("Horizon HDR UI mask", None);
+        // Alpha times the blend constant (1/255): the hand's 1 becomes 1/255, the world's 0
+        // stays 0.
+        let scale_alpha = wgpu::BlendComponent {
+            src_factor: wgpu::BlendFactor::Zero,
+            dst_factor: wgpu::BlendFactor::Constant,
+            operation: wgpu::BlendOperation::Add,
+        };
+        let hand_mark = alpha_pass(
+            "Horizon HDR hand mark",
+            Some(wgpu::BlendState {
+                color: scale_alpha,
+                alpha: scale_alpha,
+            }),
+        );
         let params = device.create_buffer(&wgpu::BufferDescriptor {
             label: Some("Horizon HDR parameters"),
             size: 32,
@@ -141,6 +199,8 @@ impl Hdr {
         Self {
             layout,
             pipeline,
+            clear_alpha,
+            hand_mark,
             params,
             output,
             format,
@@ -148,6 +208,8 @@ impl Hdr {
             debug: std::env::var_os("HORIZON_HDR_DEBUG").is_some_and(|v| v == "1"),
             paper_white: 200.0,
             peak: 1000.0,
+            black: 0.0,
+            ui: 1.0,
         }
     }
 
@@ -204,7 +266,9 @@ impl Hdr {
         self.targets.as_ref().unwrap().frame.clone()
     }
 
-    /// Keeps the world as drawn so far, before the hand and HUD cover it.
+    /// Keeps the world as drawn so far, before the hand and HUD cover it, then zeroes the
+    /// frame's alpha: the world's marks live on in the copy, and whatever draws from here
+    /// on raises the alpha where it covers the world.
     pub fn keep_world(&self, encoder: &mut wgpu::CommandEncoder) {
         let Some(t) = &self.targets else {
             return;
@@ -214,6 +278,56 @@ impl Hdr {
             t.world.as_image_copy(),
             t.frame.size(),
         );
+        let view = t.frame.create_view(&Default::default());
+        let attachments = [Some(wgpu::RenderPassColorAttachment {
+            view: &view,
+            resolve_target: None,
+            depth_slice: None,
+            ops: wgpu::Operations {
+                load: wgpu::LoadOp::Load,
+                store: wgpu::StoreOp::Store,
+            },
+        })];
+        let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("Horizon HDR UI mask"),
+            color_attachments: &attachments,
+            ..Default::default()
+        });
+        pass.set_pipeline(&self.clear_alpha);
+        pass.draw(0..3, 0..1);
+    }
+
+    /// After the hand: its pixels' alpha goes down to 1/255, below anything the HUD and
+    /// menus leave, so HDR output tells the hand (the world's brightness, never lifted)
+    /// from the UI (UI Brightness).
+    pub fn mark_hand(&self, encoder: &mut wgpu::CommandEncoder) {
+        let Some(t) = &self.targets else {
+            return;
+        };
+        let view = t.frame.create_view(&Default::default());
+        let attachments = [Some(wgpu::RenderPassColorAttachment {
+            view: &view,
+            resolve_target: None,
+            depth_slice: None,
+            ops: wgpu::Operations {
+                load: wgpu::LoadOp::Load,
+                store: wgpu::StoreOp::Store,
+            },
+        })];
+        let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("Horizon HDR hand mark"),
+            color_attachments: &attachments,
+            ..Default::default()
+        });
+        pass.set_pipeline(&self.hand_mark);
+        let a = 1.0 / 255.0;
+        pass.set_blend_constant(wgpu::Color {
+            r: a,
+            g: a,
+            b: a,
+            a,
+        });
+        pass.draw(0..3, 0..1);
     }
 
     /// Writes the finished frame to the swapchain image `target`.
@@ -234,8 +348,8 @@ impl Hdr {
             f32::from(u8::from(world)),
             f32::from(u8::from(self.debug)),
             f32::from(u8::from(self.output == Output::Pq)),
-            0.0,
-            0.0,
+            self.black.clamp(0.0, paper),
+            self.ui.clamp(0.25, 1.0),
             0.0,
         ];
         queue.write_buffer(&self.params, 0, bytemuck::cast_slice(&params));

crates/horizon-client-render/src/gfx/lightning.rs

@@ -15,10 +15,19 @@ pub struct Bolt {
 #[derive(Default)]
 pub struct Input<'a> {
     pub bolts: &'a [Bolt],
-    /// Current atlas white texel; a changed rect invalidates retained vertices.
+    /// Current atlas white texel ([`white_uv`]); a changed rect invalidates
+    /// retained vertices.
     pub uv: [f32; 2],
 }
 
+/// The atlas point an untextured quad (`RenderTypes.lightning` has no
+/// texture) samples: the middle of the white sprite. Its corner (`u0`, `v0`)
+/// is on the sprite's border, where the atlas's nearest sampling picks the
+/// neighbouring, transparent texels for most fragments.
+pub fn white_uv(white: &crate::hud::Rect) -> [f32; 2] {
+    [(white.u0 + white.u1) / 2.0, (white.v0 + white.v1) / 2.0]
+}
+
 // Four layers, fourteen segments (eight trunk, two branches of three), four quads.
 pub(super) const QUADS: u32 = 4 * 14 * 4;
 

crates/horizon-client-render/src/gfx/lightning/tests/mod.rs

@@ -496,3 +496,253 @@ fn retained_gpu_draw_matches_transient_additive_draw() {
         assert_eq!(pixels[0], pixels[1], "frame {frame}: GPU output differs");
     }
 }
+
+/// `horizon/white` (4x4 texels) at (40, 12) of a 64x32 atlas.
+const ATLAS: (u32, u32) = (64, 32);
+fn white_sprite() -> crate::hud::Rect {
+    let (w, h) = (ATLAS.0 as f32, ATLAS.1 as f32);
+    crate::hud::Rect {
+        u0: 40.0 / w,
+        v0: 12.0 / h,
+        u1: 44.0 / w,
+        v1: 16.0 / h,
+        w: 4,
+        h: 4,
+    }
+}
+
+/// The white sprite's corner is on its border with the next atlas texels,
+/// which nearest sampling picks for most of a bolt's fragments (#3171): the
+/// point sampled is at least a texel inside the sprite.
+#[test]
+fn white_uv_is_inside_the_white_sprite() {
+    let [u, v] = white_uv(&white_sprite());
+    let (x, y) = (u * ATLAS.0 as f32, v * ATLAS.1 as f32);
+    assert!((41.0..=43.0).contains(&x), "u at texel {x}");
+    assert!((13.0..=15.0).contains(&y), "v at texel {y}");
+}
+
+/// A bolt seen from 14 blocks through the atlas as the game binds it (nearest
+/// sampling, only the white sprite opaque) draws the same pixels as through a
+/// texture that is white everywhere (#3171: the sprite's corner left a few
+/// scattered pixels). Run explicitly, like the test above.
+#[test]
+#[ignore = "requires GPU; run separately with --ignored --exact"]
+fn bolt_through_the_atlas_white_sprite_is_fully_drawn() {
+    let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_without_display_handle());
+    let Ok(adapter) = pollster::block_on(instance.request_adapter(&Default::default())) else {
+        eprintln!("no GPU adapter: skipped");
+        return;
+    };
+    let (device, queue) = pollster::block_on(adapter.request_device(&Default::default())).unwrap();
+    let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+        label: None,
+        source: wgpu::ShaderSource::Wgsl(crate::gfx::entity_shader().into()),
+    });
+    let attributes = wgpu::vertex_attr_array![0=>Float32x3,1=>Float32x2,2=>Uint32,3=>Unorm8x4,4=>Uint8x4,5=>Snorm8x4,6=>Float32x2];
+    let offsets = wgpu::vertex_attr_array![7=>Float32x3];
+    let buffers = [
+        Some(wgpu::VertexBufferLayout {
+            array_stride: std::mem::size_of::<Vertex>() as u64,
+            step_mode: wgpu::VertexStepMode::Vertex,
+            attributes: &attributes,
+        }),
+        Some(wgpu::VertexBufferLayout {
+            array_stride: 12,
+            step_mode: wgpu::VertexStepMode::Instance,
+            attributes: &offsets,
+        }),
+    ];
+    // The lightning pipeline (gfx.rs): additive, into RGBA8.
+    let additive = wgpu::BlendComponent {
+        src_factor: wgpu::BlendFactor::SrcAlpha,
+        dst_factor: wgpu::BlendFactor::One,
+        operation: wgpu::BlendOperation::Add,
+    };
+    let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+        label: None,
+        layout: None,
+        vertex: wgpu::VertexState {
+            module: &shader,
+            entry_point: Some("vs_lightning"),
+            compilation_options: Default::default(),
+            buffers: &buffers,
+        },
+        primitive: wgpu::PrimitiveState {
+            cull_mode: None,
+            ..Default::default()
+        },
+        depth_stencil: None,
+        multisample: Default::default(),
+        fragment: Some(wgpu::FragmentState {
+            module: &shader,
+            entry_point: Some("fs_celestial"),
+            compilation_options: Default::default(),
+            targets: &[Some(wgpu::ColorTargetState {
+                format: wgpu::TextureFormat::Rgba8Unorm,
+                blend: Some(wgpu::BlendState {
+                    color: additive,
+                    alpha: additive,
+                }),
+                write_mask: wgpu::ColorWrites::ALL,
+            })],
+        }),
+        multiview_mask: None,
+        cache: None,
+    });
+    // The game's camera: 70 degrees, reversed depth, the bolt 14 blocks ahead.
+    let globals = crate::gfx::Globals {
+        view_proj: (glam::Mat4::perspective_rh(70f32.to_radians(), 1.0, 400.0, 0.05)
+            * glam::Mat4::look_at_rh(glam::Vec3::ZERO, glam::Vec3::Z, glam::Vec3::Y))
+        .to_cols_array_2d(),
+        ..bytemuck::Zeroable::zeroed()
+    };
+    let globals = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+        label: None,
+        contents: bytemuck::bytes_of(&globals),
+        usage: wgpu::BufferUsages::UNIFORM,
+    });
+    let texture = |(width, height): (u32, u32), data: &[u8]| {
+        device
+            .create_texture_with_data(
+                &queue,
+                &wgpu::TextureDescriptor {
+                    label: None,
+                    size: wgpu::Extent3d {
+                        width,
+                        height,
+                        depth_or_array_layers: 1,
+                    },
+                    mip_level_count: 1,
+                    sample_count: 1,
+                    dimension: wgpu::TextureDimension::D2,
+                    format: wgpu::TextureFormat::Rgba8Unorm,
+                    usage: wgpu::TextureUsages::TEXTURE_BINDING,
+                    view_formats: &[],
+                },
+                wgpu::util::TextureDataOrder::LayerMajor,
+                data,
+            )
+            .create_view(&Default::default())
+    };
+    let white = texture((1, 1), &[255; 4]);
+    // Transparent but for the white sprite.
+    let mut texels = vec![0u8; (ATLAS.0 * ATLAS.1 * 4) as usize];
+    for y in 12..16 {
+        for x in 40..44 {
+            let i = ((y * ATLAS.0 + x) * 4) as usize;
+            texels[i..i + 4].copy_from_slice(&[255; 4]);
+        }
+    }
+    let atlas = texture(ATLAS, &texels);
+    // The atlas sampler (gfx.rs): wgpu's default, nearest.
+    let sampler = device.create_sampler(&Default::default());
+    let indices = crate::gfx::Renderer::quad_indices(&device, QUADS);
+    let size = 256;
+    let extent = wgpu::Extent3d {
+        width: size,
+        height: size,
+        depth_or_array_layers: 1,
+    };
+    let draw = |view: &wgpu::TextureView, uv: [f32; 2]| -> Vec<u8> {
+        let group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label: None,
+            layout: &pipeline.get_bind_group_layout(0),
+            entries: &[
+                wgpu::BindGroupEntry {
+                    binding: 0,
+                    resource: globals.as_entire_binding(),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 1,
+                    resource: wgpu::BindingResource::TextureView(view),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 2,
+                    resource: wgpu::BindingResource::Sampler(&sampler),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 3,
+                    resource: wgpu::BindingResource::TextureView(&white),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 4,
+                    resource: wgpu::BindingResource::Sampler(&sampler),
+                },
+            ],
+        });
+        let bolts = [Bolt {
+            seed: 123,
+            at: [0.0, -1.62, 14.0],
+        }];
+        let input = Input { bolts: &bolts, uv };
+        let mut renderer = Renderer::new();
+        let mut uploads = Uploads::new(&device);
+        let mut encoder = device.create_command_encoder(&Default::default());
+        renderer.prepare(&device, &mut uploads, &mut encoder, &input, DVec3::ZERO);
+        let color = device.create_texture(&wgpu::TextureDescriptor {
+            label: None,
+            size: extent,
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: wgpu::TextureFormat::Rgba8Unorm,
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
+            view_formats: &[],
+        });
+        {
+            let target = color.create_view(&Default::default());
+            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+                label: None,
+                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                    view: &target,
+                    resolve_target: None,
+                    depth_slice: None,
+                    ops: wgpu::Operations {
+                        load: wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
+                        store: wgpu::StoreOp::Store,
+                    },
+                })],
+                ..Default::default()
+            });
+            pass.set_pipeline(&pipeline);
+            pass.set_bind_group(0, &group, &[]);
+            pass.set_index_buffer(indices.slice(..), wgpu::IndexFormat::Uint32);
+            renderer.draw(&mut pass, &input);
+        }
+        let read = device.create_buffer(&wgpu::BufferDescriptor {
+            label: None,
+            size: u64::from(size * size * 4),
+            usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
+            mapped_at_creation: false,
+        });
+        encoder.copy_texture_to_buffer(
+            color.as_image_copy(),
+            wgpu::TexelCopyBufferInfo {
+                buffer: &read,
+                layout: wgpu::TexelCopyBufferLayout {
+                    offset: 0,
+                    bytes_per_row: Some(size * 4),
+                    rows_per_image: None,
+                },
+            },
+            extent,
+        );
+        uploads.finish(&encoder);
+        queue.submit([encoder.finish()]);
+        read.slice(..)
+            .map_async(wgpu::MapMode::Read, |r| r.unwrap());
+        device.poll(wgpu::PollType::wait_indefinitely()).unwrap();
+        read.slice(..).get_mapped_range().unwrap().to_vec()
+    };
+    let lit = |pixels: &[u8]| pixels.chunks(4).filter(|p| p[3] != 0).count();
+    let expected = draw(&white, [0.5; 2]);
+    let drawn = draw(&atlas, white_uv(&white_sprite()));
+    assert!(lit(&expected) > 1000, "{} pixels", lit(&expected));
+    assert_eq!(
+        lit(&drawn),
+        lit(&expected),
+        "pixels drawn through the atlas"
+    );
+    assert!(drawn == expected, "the bolt's colours through the atlas");
+}

crates/horizon-client-render/src/gfx/pack_post.rs

@@ -476,10 +476,12 @@ fn sampler(
     })
 }
 
-/// Runs `create` and returns its validation error, if any.
+/// Runs `create` and returns its validation error, if any. A panic while it runs is an error
+/// too: naga's backends turn a module they cannot write into a panic as the driver gets the
+/// pipeline (#3525), which a pack's program must not turn into a crash.
 fn checked<T>(device: &wgpu::Device, create: impl FnOnce() -> T) -> Result<T, String> {
     let scope = device.push_error_scope(wgpu::ErrorFilter::Validation);
-    let value = create();
+    let value = crate::crash::contain(create);
     match pollster::block_on(scope.pop()) {
         Some(e) => {
             // The details are in the error's description or its sources.
@@ -494,7 +496,7 @@ fn checked<T>(device: &wgpu::Device, create: impl FnOnce() -> T) -> Result<T, St
             }
             Err(message)
         }
-        None => Ok(value),
+        None => value.map_err(|panic| format!("the shader compiler failed: {panic}")),
     }
 }
 
@@ -2629,6 +2631,38 @@ mod tests {
         assert_eq!(used, [1, 2, 3]);
     }
 
+    /// #3525: naga's SPIR-V writer panicked on Photon's gbuffers programs as the pipeline was
+    /// made. Such a panic skips the pass, as a validation error does, and the device goes on.
+    #[test]
+    fn a_shader_compiler_panic_skips_the_pass() {
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_without_display_handle());
+        let Ok(adapter) = pollster::block_on(instance.request_adapter(&Default::default())) else {
+            return;
+        };
+        let Ok((device, _queue)) = pollster::block_on(adapter.request_device(&Default::default()))
+        else {
+            return;
+        };
+        let failed = checked(&device, || -> wgpu::Buffer {
+            panic!("internal error: entered unreachable code: Expression [89] is not cached!")
+        });
+        let error = failed.expect_err("the panic comes back as an error");
+        assert!(error.contains("Expression [89] is not cached!"), "{error}");
+        let buffer = |usage| {
+            checked(&device, || {
+                device.create_buffer(&wgpu::BufferDescriptor {
+                    label: None,
+                    size: 16,
+                    usage,
+                    mapped_at_creation: false,
+                })
+            })
+        };
+        // The device still makes things, and its errors still come back.
+        assert!(buffer(wgpu::BufferUsages::UNIFORM).is_ok());
+        assert!(buffer(wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::MAP_WRITE).is_err());
+    }
+
     #[test]
     fn pack_formats_map_to_renderable_ones() {
         let f = |name| texture_format(Format::parse(name).unwrap(), wgpu::Features::empty());

crates/horizon-client-render/src/gfx/readback.rs

@@ -0,0 +1,213 @@
+//! Screenshots of a swapchain that cannot be copied from. OpenGL's surfaces
+//! offer `RENDER_ATTACHMENT` only, so a frame whose pixels are read back
+//! (the screenshot key, a world's icon) is drawn into a texture that can be,
+//! then drawn onto the swapchain image as a fullscreen triangle.
+
+/// The texture a frame to read back is drawn into, and the pass that puts it
+/// on the swapchain afterwards.
+#[derive(Default)]
+pub struct Readback {
+    texture: Option<wgpu::Texture>,
+    blitter: Option<(wgpu::TextureFormat, wgpu::util::TextureBlitter)>,
+    /// A frame drew into `texture` and still has to reach the swapchain.
+    drawn: bool,
+}
+
+impl Readback {
+    /// The texture this frame draws into instead of the swapchain image
+    /// `surface`: `None` unless the frame is read back (`screenshot`) and the
+    /// image cannot be copied from.
+    pub fn target(
+        &mut self,
+        device: &wgpu::Device,
+        surface: &wgpu::Texture,
+        screenshot: bool,
+    ) -> Option<wgpu::Texture> {
+        if !screenshot || surface.usage().contains(wgpu::TextureUsages::COPY_SRC) {
+            return None;
+        }
+        let format = surface.format().remove_srgb_suffix();
+        if self
+            .texture
+            .as_ref()
+            .is_none_or(|t| t.size() != surface.size() || t.format() != format)
+        {
+            self.texture = Some(device.create_texture(&wgpu::TextureDescriptor {
+                label: Some("Horizon screenshot frame"),
+                size: surface.size(),
+                mip_level_count: 1,
+                sample_count: 1,
+                dimension: wgpu::TextureDimension::D2,
+                format,
+                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
+                    | wgpu::TextureUsages::COPY_SRC
+                    | wgpu::TextureUsages::TEXTURE_BINDING,
+                view_formats: &[],
+            }));
+        }
+        self.drawn = true;
+        self.texture.clone()
+    }
+
+    /// Draws the frame `target` gave onto the swapchain image `surface`; nothing
+    /// when this frame drew straight into it.
+    pub fn present(
+        &mut self,
+        device: &wgpu::Device,
+        encoder: &mut wgpu::CommandEncoder,
+        surface: &wgpu::Texture,
+    ) {
+        if !std::mem::take(&mut self.drawn) {
+            return;
+        }
+        let Some(texture) = &self.texture else {
+            return;
+        };
+        // The frame's passes write the swapchain through its non-sRGB view
+        // (`view_formats`), so the copy goes there unconverted too.
+        let format = surface.format().remove_srgb_suffix();
+        if self.blitter.as_ref().is_none_or(|b| b.0 != format) {
+            self.blitter = Some((format, wgpu::util::TextureBlitter::new(device, format)));
+        }
+        let target = surface.create_view(&wgpu::TextureViewDescriptor {
+            format: Some(format),
+            ..Default::default()
+        });
+        let source = texture.create_view(&Default::default());
+        if let Some((_, blitter)) = &self.blitter {
+            blitter.copy(device, encoder, &source, &target);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn device() -> Option<(wgpu::Device, wgpu::Queue)> {
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_without_display_handle());
+        let adapter = pollster::block_on(instance.request_adapter(&Default::default())).ok()?;
+        pollster::block_on(adapter.request_device(&Default::default())).ok()
+    }
+
+    fn texture(device: &wgpu::Device, usage: wgpu::TextureUsages) -> wgpu::Texture {
+        device.create_texture(&wgpu::TextureDescriptor {
+            label: None,
+            size: wgpu::Extent3d {
+                width: 70,
+                height: 3,
+                depth_or_array_layers: 1,
+            },
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: wgpu::TextureFormat::Bgra8Unorm,
+            usage,
+            view_formats: &[],
+        })
+    }
+
+    fn clear(encoder: &mut wgpu::CommandEncoder, texture: &wgpu::Texture, color: wgpu::Color) {
+        let view = texture.create_view(&Default::default());
+        encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: None,
+            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                view: &view,
+                resolve_target: None,
+                depth_slice: None,
+                ops: wgpu::Operations {
+                    load: wgpu::LoadOp::Clear(color),
+                    store: wgpu::StoreOp::Store,
+                },
+            })],
+            ..Default::default()
+        });
+    }
+
+    fn read(device: &wgpu::Device, buffer: &wgpu::Buffer) -> Vec<u8> {
+        buffer.map_async(wgpu::MapMode::Read, .., |r| r.unwrap());
+        device.poll(wgpu::PollType::wait_indefinitely()).unwrap();
+        buffer.get_mapped_range(..).unwrap().to_vec()
+    }
+
+    /// The last pixel of the last row of a 70x3 frame read back by `copy_frame`.
+    fn last_pixel(device: &wgpu::Device, buffer: &wgpu::Buffer) -> Vec<u8> {
+        let pixels = read(device, buffer);
+        let row = 70usize * 4;
+        let last = row.next_multiple_of(256) * 2 + row - 4;
+        pixels[last..last + 4].to_vec()
+    }
+
+    /// The renderer's screenshot path on a surface like OpenGL's (#3510): the
+    /// frame is drawn into `target`, read back with `copy_frame` and drawn on
+    /// the swapchain, with no validation error (the copy used to need the
+    /// swapchain's missing `COPY_SRC`), and the swapchain shows the frame.
+    #[test]
+    fn screenshot_of_a_surface_without_copy_src() {
+        let Some((device, queue)) = device() else {
+            return;
+        };
+        // Sampled only so the test can look at what reached it.
+        let surface = texture(
+            &device,
+            wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
+        );
+        let check = texture(
+            &device,
+            wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
+        );
+        let blitter = wgpu::util::TextureBlitter::new(&device, wgpu::TextureFormat::Bgra8Unorm);
+        let mut readback = Readback::default();
+        let colors = [
+            (1.0, [0, 0, 255, 255]),
+            // A second screenshot reuses the texture.
+            (0.0, [255, 0, 0, 255]),
+        ];
+        for (r, bgra) in colors {
+            let color = wgpu::Color {
+                r,
+                g: 0.0,
+                b: 1.0 - r,
+                a: 1.0,
+            };
+            let scope = device.push_error_scope(wgpu::ErrorFilter::Validation);
+            let mut encoder = device.create_command_encoder(&Default::default());
+            let frame = readback
+                .target(&device, &surface, true)
+                .unwrap_or_else(|| surface.clone());
+            clear(&mut encoder, &frame, color);
+            let buffer = crate::gfx::copy_frame(&device, &mut encoder, &frame, [70, 3]);
+            readback.present(&device, &mut encoder, &surface);
+            queue.submit([encoder.finish()]);
+            if let Some(error) = pollster::block_on(scope.pop()) {
+                panic!("{error}");
+            }
+            assert_eq!(last_pixel(&device, &buffer), bgra);
+            let mut encoder = device.create_command_encoder(&Default::default());
+            let view = |t: &wgpu::Texture| t.create_view(&Default::default());
+            blitter.copy(&device, &mut encoder, &view(&surface), &view(&check));
+            let buffer = crate::gfx::copy_frame(&device, &mut encoder, &check, [70, 3]);
+            queue.submit([encoder.finish()]);
+            assert_eq!(last_pixel(&device, &buffer), bgra);
+        }
+        assert!(!readback.drawn);
+    }
+
+    /// A surface that can be copied from, or a frame nobody reads back,
+    /// draws straight into the swapchain image.
+    #[test]
+    fn frames_draw_straight_to_a_readable_surface() {
+        let Some((device, _)) = device() else {
+            return;
+        };
+        let mut readback = Readback::default();
+        let readable = texture(
+            &device,
+            wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
+        );
+        assert!(readback.target(&device, &readable, true).is_none());
+        let surface = texture(&device, wgpu::TextureUsages::RENDER_ATTACHMENT);
+        assert!(readback.target(&device, &surface, false).is_none());
+        assert!(readback.texture.is_none() && !readback.drawn);
+    }
+}