feat(tui): fast-mode marker/hint and transient /fast toast

Surface which models have a fast variant: a dim "f" badge on the
active-model chip, the /model picker, and the /provider wizard, plus a
focused-row "fast: <name>" hint (the pickers are keyboard-driven, so the
selected row is the reveal). All read Registry.FastVariant, so coverage
tracks the catalog automatically.

Give /fast a distinctive voice and stop it cluttering the transcript:
reword its messages and show the result as a transient toast pill in the
row above the composer, auto-dismissed after 3s (seq-gated, same pattern
as the copy-status flash).

.github/workflows/zero-action-smoke.yml

@@ -4,12 +4,14 @@ on:
   pull_request:
     paths:
       - action.yml
+      - docs/GITHUB_ACTION.md
       - .github/workflows/zero-action-smoke.yml
   push:
     branches:
       - main
     paths:
       - action.yml
+      - docs/GITHUB_ACTION.md
       - .github/workflows/zero-action-smoke.yml
 
 jobs:
@@ -29,7 +31,8 @@ jobs:
           import sys, yaml
 
           with open("action.yml", "r", encoding="utf-8") as handle:
-              doc = yaml.safe_load(handle)
+              action_raw = handle.read()
+          doc = yaml.safe_load(action_raw)
 
           assert isinstance(doc, dict), "action.yml must be a mapping"
           assert doc.get("name"), "action must declare a name"
@@ -65,6 +68,19 @@ jobs:
           assert "--skip-permissions-unsafe" not in serialized, \
               "action must never pass --skip-permissions-unsafe"
 
+          run_zero = next((step for step in steps if step.get("name") == "Run ZERO"), None)
+          assert run_zero is not None, "action.yml must contain a Run ZERO step"
+          run_zero_script = run_zero.get("run") or ""
+          assert 'export "${ZERO_INPUT_API_KEY_ENV}=${ZERO_INPUT_API_KEY}"' in run_zero_script, \
+              "Run ZERO must export the provider key for the current step"
+          assert "later steps inherit" not in action_raw.lower(), \
+              "provider keys must not be documented as inherited by later steps"
+          for line in run_zero_script.splitlines():
+              if "GITHUB_ENV" in line and (
+                  "ZERO_INPUT_API_KEY" in line or "ZERO_INPUT_API_KEY_ENV" in line
+              ):
+                  raise AssertionError("provider key must not be persisted to GITHUB_ENV")
+
           print(f"action.yml OK: {len(inputs)} inputs, {len(outputs)} outputs, {len(steps)} steps")
           PY
 

AGENTS.md

@@ -26,7 +26,7 @@ Accepted file names, in priority order at each level:
 | `./ZERO.md` | Brand-specific alias. Same format, lower priority. |
 | `./.zero/AGENTS.md` | Project-local, hidden, gitignored. Personal notes that stay out of git. |
 
-Matching is **case-insensitive** on the basename, so `AGENTS.md`, `Agents.md`, and `agents.md` resolve to the same file on Windows and macOS. The git-tracked filename in this repo is `AGENTS.MD` (uppercase `MD`) — keep that on case-sensitive filesystems (Linux, the WSL filesystem, or a CI runner) to match what the loader looks for.
+Matching is **case-insensitive** on the basename, so `AGENTS.md`, `Agents.md`, and `agents.md` resolve to the same file on Windows and macOS. The git-tracked filename in this repo is `AGENTS.md` — keep that on case-sensitive filesystems (Linux, the WSL filesystem, or a CI runner) to match what the loader looks for.
 
 Both files use the same format. YAML frontmatter is optional; the markdown body is loaded as instructions for the agent. Zero reads the file once at session start, so changes take effect on the next `zero` launch — not mid-session.
 

Makefile

@@ -1,4 +1,4 @@
-# Zero build/test/lint targets. AGENTS.MD says "Build with `make`" and "Run `make
+# Zero build/test/lint targets. AGENTS.md says "Build with `make`" and "Run `make
 # lint` before opening a PR" — these targets back those instructions.
 .DEFAULT_GOAL := build
 .PHONY: build build-all test test-race vet fmt fmt-check lint tidy clean help

README.md

@@ -59,20 +59,24 @@ Bun does not run dependency lifecycle scripts by default, so the `postinstall`
 that fetches the Zero binary is skipped and the first run fails with
 `No native binary found next to the npm wrapper`.
 
-Install with Bun, then fetch the binary in one of two ways:
+The simplest fix is to trust the package after installing, which runs the
+blocked postinstall. This works for project and global installs:
 
 ```bash
-# Option A: run the installer manually
+# project install
 bun add @gitlawb/zero
-node node_modules/@gitlawb/zero/scripts/postinstall.mjs
+bun pm trust @gitlawb/zero
 
-# Option B: allow the postinstall to run on install
-# add to your package.json:  "trustedDependencies": ["@gitlawb/zero"]
-bun add @gitlawb/zero
+# global install
+bun add -g @gitlawb/zero
+bun pm -g trust @gitlawb/zero
 ```
 
-For global installs (`bun add -g @gitlawb/zero`), use Option A against the
-global install path, or prefer the install scripts below.
+Alternatives: allow the postinstall up front by adding
+`"trustedDependencies": ["@gitlawb/zero"]` to your project's package.json
+before `bun add`, or run the installer manually
+(`node node_modules/@gitlawb/zero/scripts/postinstall.mjs`) on Bun versions
+that do not have `bun pm trust`.
 
 ### Install scripts
 

README_ZH.md

@@ -44,19 +44,19 @@ npm 包安装一个小型包装器以及与你平台匹配的 Zero 二进制文
 
 Bun 默认不运行依赖的生命周期脚本，因此获取 Zero 二进制文件的 `postinstall` 会被跳过，首次运行会失败并显示 `No native binary found next to the npm wrapper`。
 
-使用 Bun 安装后，通过以下两种方式之一获取二进制文件：
+最简单的解决方法是安装后信任该包，这会运行被阻止的 postinstall。项目安装和全局安装均适用：
 
 ```bash
-# 选项 A：手动运行安装程序
+# 项目安装
 bun add @gitlawb/zero
-node node_modules/@gitlawb/zero/scripts/postinstall.mjs
+bun pm trust @gitlawb/zero
 
-# 选项 B：允许 postinstall 在安装时运行
-# 添加到你的 package.json:  "trustedDependencies": ["@gitlawb/zero"]
-bun add @gitlawb/zero
+# 全局安装
+bun add -g @gitlawb/zero
+bun pm -g trust @gitlawb/zero
 ```
 
-对于全局安装（`bun add -g @gitlawb/zero`），请对全局安装路径使用选项 A，或使用下面的安装脚本。
+其他方式：在 `bun add` 之前将 `"trustedDependencies": ["@gitlawb/zero"]` 添加到项目的 package.json 以提前允许 postinstall；或在不支持 `bun pm trust` 的旧版 Bun 上手动运行安装程序（`node node_modules/@gitlawb/zero/scripts/postinstall.mjs`）。
 
 ### 安装脚本
 

action.yml

@@ -27,14 +27,14 @@ inputs:
   api-key:
     description: >-
       The provider API key. Pass it from a repository or organization secret;
-      it is exported into the step environment and never written to the log.
+      it is exported only for the ZERO step and never written to the log.
     required: false
     default: ""
   api-key-env:
     description: >-
       Name of the environment variable the chosen provider reads its key from
       (for example OPENAI_API_KEY or ANTHROPIC_API_KEY). When set together with
-      api-key, that variable is exported for the run. Leave the action
+      api-key, that variable is exported only for the ZERO step. Leave the action
       provider-agnostic by passing the env name your provider expects rather
       than hardcoding one here.
     required: false
@@ -192,10 +192,9 @@ runs:
             echo "::error::api-key-env must be a valid environment variable name." >&2
             exit 2
           fi
-          # Export in-process so the zero invocation in this same run block sees
-          # it, and append to GITHUB_ENV so any later steps inherit it too.
+          # Export in-process for this Run ZERO step so zero can read it; do
+          # not persist provider credentials to later job steps.
           export "${ZERO_INPUT_API_KEY_ENV}=${ZERO_INPUT_API_KEY}"
-          printf '%s=%s\n' "${ZERO_INPUT_API_KEY_ENV}" "${ZERO_INPUT_API_KEY}" >> "${GITHUB_ENV}"
         fi
         if [ -n "${ZERO_INPUT_PROVIDER}" ]; then
           export ZERO_PROVIDER="${ZERO_INPUT_PROVIDER}"

bin/zero.js

@@ -66,10 +66,12 @@ if (!existsSync(nativePath)) {
       '\n' +
       (ranByBun
         ? 'You installed with Bun, which does not run dependency lifecycle scripts\n' +
-          'by default. To let it run on future installs, add zero to your\n' +
-          'project\'s trustedDependencies:\n' +
+          'by default. Trust the package to run the blocked postinstall:\n' +
+          '  bun pm trust @gitlawb/zero       (project install)\n' +
+          '  bun pm -g trust @gitlawb/zero    (global install)\n' +
+          'On Bun versions without `bun pm trust`, add\n' +
           '  "trustedDependencies": ["@gitlawb/zero"]\n' +
-          'then reinstall.\n' +
+          'to your project package.json and reinstall.\n' +
           '\n'
         : '') +
       'If that fails, build from source: https://github.com/Gitlawb/zero\n' +

docs/GITHUB_ACTION.md

@@ -41,8 +41,9 @@ jobs:
 > provider-neutral: `api-key-env` is the environment variable name the chosen
 > provider reads its key from (for example `ANTHROPIC_API_KEY`, `GEMINI_API_KEY`,
 > `OPENROUTER_API_KEY`), and `api-key` is the secret value. The action exports
-> that variable for the run and never prints it. If your repository already
-> commits a `.zero/config.json` with an active provider, you can omit `provider`.
+> that variable only for the ZERO step and never prints it. If your repository
+> already commits a `.zero/config.json` with an active provider, you can omit
+> `provider`.
 
 ## Inputs
 
@@ -51,8 +52,8 @@ jobs:
 | `prompt` | one of `prompt`/`prompt-file` | `""` | The instruction for ZERO to execute. |
 | `prompt-file` | one of `prompt`/`prompt-file` | `""` | Path (relative to `working-directory`) to a file whose contents are the prompt. |
 | `provider` | no | `""` | Provider id to activate (e.g. `openai`, `anthropic`, `gemini`, `ollama`, or any compatible endpoint). |
-| `api-key` | no | `""` | The provider API key. Pass from a secret; never logged. |
-| `api-key-env` | no | `""` | Env var name the provider reads its key from (e.g. `OPENAI_API_KEY`). Exported with `api-key`. |
+| `api-key` | no | `""` | The provider API key. Pass from a secret; exported only for the ZERO step and never logged. |
+| `api-key-env` | no | `""` | Env var name the provider reads its key from (e.g. `OPENAI_API_KEY`). Exported only for the ZERO step when used with `api-key`. |
 | `model` | no | `""` | Model id. Defaults to the resolved provider's default. |
 | `mode` | no | `""` | Run mode (`zero exec --mode`), e.g. `smart`, `deep`, `fast`. |
 | `auto` | no | `low` | Autonomy ceiling (`zero exec --auto`): `low`, `medium`, or `high`. Conservative by default. |
@@ -162,9 +163,10 @@ jobs:
 ## Security notes
 
 - **Secrets are passed as Action secrets and never logged.** The action exports
-  `api-key` (under `api-key-env`) and `slack-webhook-url` into the step
-  environment only. They are never echoed, and ZERO redacts secret-shaped
-  strings from its own output.
+  `api-key` (under `api-key-env`) only for the ZERO step. `slack-webhook-url`
+  is passed only to the Slack post step. They are never echoed or persisted to
+  later workflow steps, and ZERO redacts secret-shaped strings from its own
+  output.
 - **The sandbox is always active.** This action never passes
   `--skip-permissions-unsafe`, so writes stay inside the checked-out repository
   (plus any roots you grant with `add-dir`). Unsafe mode is never enabled

docs/INSTALL.md

@@ -31,15 +31,24 @@ dependencies (only the installing project's own scripts), so the `postinstall`
 that fetches the Zero binary is silently skipped. The first run then fails with
 `No native binary found next to the npm wrapper`.
 
-To install with Bun, either run the installer manually after installing:
+The simplest fix is to trust the package after installing, which runs the
+blocked postinstall. This works for project and global installs:
 
 ```bash
+# project install
 bun add @gitlawb/zero
-node node_modules/@gitlawb/zero/scripts/postinstall.mjs
+bun pm trust @gitlawb/zero
+
+# global install
+bun add -g @gitlawb/zero
+bun pm -g trust @gitlawb/zero
 ```
 
-Or allow the postinstall to run by adding the package to your project's
-`trustedDependencies` before installing:
+`bun pm untrusted` (or `bun pm -g untrusted`) lists the blocked postinstalls if
+you want to inspect before trusting.
+
+Alternatively, allow the postinstall to run at install time by adding the
+package to your project's `trustedDependencies` before installing:
 
 ```json
 {
@@ -51,8 +60,12 @@ Or allow the postinstall to run by adding the package to your project's
 bun add @gitlawb/zero
 ```
 
-For global installs (`bun add -g @gitlawb/zero`), run the installer manually
-against the global install path, or use the install scripts below.
+On Bun versions that do not have `bun pm trust`, run the installer manually
+after installing:
+
+```bash
+node node_modules/@gitlawb/zero/scripts/postinstall.mjs
+```
 
 Reference: <https://bun.sh/docs/pm/lifecycle>
 

internal/agent/additional_permissions_validation_test.go

@@ -0,0 +1,146 @@
+package agent
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/Gitlawb/zero/internal/tools"
+)
+
+// A shell call that sets sandbox_permissions: with_additional_permissions but
+// omits (or malforms) additional_permissions can never succeed: the same
+// validation runs again at grant time regardless of the user's decision. It
+// must be rejected as a plain tool error BEFORE any permission prompt, not
+// surfaced as a confusing "approved but denied" prompt outcome.
+func TestExecuteToolCallRejectsMissingAdditionalPermissionsBeforePrompt(t *testing.T) {
+	root := t.TempDir()
+	registry := tools.NewRegistry()
+	registry.Register(tools.NewBashTool(root))
+
+	promptCalls := 0
+	result, err := executeToolCall(
+		context.Background(),
+		registry,
+		ToolCall{
+			ID:        "c1",
+			Name:      "bash",
+			Arguments: `{"command":"echo hi","sandbox_permissions":"with_additional_permissions"}`,
+		},
+		PermissionModeAuto,
+		Options{
+			OnPermissionRequest: func(ctx context.Context, request PermissionRequest) (PermissionDecision, error) {
+				promptCalls++
+				return PermissionDecision{Action: PermissionDecisionAllow}, nil
+			},
+		},
+	)
+	if err != nil {
+		t.Fatalf("executeToolCall: %v", err)
+	}
+	if result.Status != tools.StatusError {
+		t.Fatalf("status = %q, want error", result.Status)
+	}
+	if promptCalls != 0 {
+		t.Fatalf("OnPermissionRequest called %d times, want 0 (must reject before prompting)", promptCalls)
+	}
+}
+
+// The mismatched-flag case (additional_permissions present without the
+// sandbox_permissions flag) must be rejected the same way.
+func TestExecuteToolCallRejectsAdditionalPermissionsWithoutFlagBeforePrompt(t *testing.T) {
+	root := t.TempDir()
+	registry := tools.NewRegistry()
+	registry.Register(tools.NewBashTool(root))
+
+	promptCalls := 0
+	result, err := executeToolCall(
+		context.Background(),
+		registry,
+		ToolCall{
+			ID:        "c1",
+			Name:      "bash",
+			Arguments: `{"command":"echo hi","additional_permissions":{"network":{"enabled":true}}}`,
+		},
+		PermissionModeAuto,
+		Options{
+			OnPermissionRequest: func(ctx context.Context, request PermissionRequest) (PermissionDecision, error) {
+				promptCalls++
+				return PermissionDecision{Action: PermissionDecisionAllow}, nil
+			},
+		},
+	)
+	if err != nil {
+		t.Fatalf("executeToolCall: %v", err)
+	}
+	if result.Status != tools.StatusError {
+		t.Fatalf("status = %q, want error", result.Status)
+	}
+	if promptCalls != 0 {
+		t.Fatalf("OnPermissionRequest called %d times, want 0 (must reject before prompting)", promptCalls)
+	}
+}
+
+// The rejection message must show a concrete, correctly-shaped example: a
+// model that gets this wrong once (attaching sandbox_permissions out of habit
+// from an earlier call, without a valid payload) needs enough in the error to
+// self-correct on retry instead of repeating the identical mistake.
+func TestExecuteToolCallMissingAdditionalPermissionsErrorIsActionable(t *testing.T) {
+	root := t.TempDir()
+	registry := tools.NewRegistry()
+	registry.Register(tools.NewBashTool(root))
+
+	result, err := executeToolCall(
+		context.Background(),
+		registry,
+		ToolCall{
+			ID:        "c1",
+			Name:      "bash",
+			Arguments: `{"command":"ping example.com","sandbox_permissions":"with_additional_permissions"}`,
+		},
+		PermissionModeAuto,
+		Options{},
+	)
+	if err != nil {
+		t.Fatalf("executeToolCall: %v", err)
+	}
+	if !strings.Contains(result.Output, `{"network": {"enabled": true}}`) {
+		t.Fatalf("output = %q, want a concrete additional_permissions example", result.Output)
+	}
+	if !strings.Contains(result.Output, "omit sandbox_permissions") {
+		t.Fatalf("output = %q, want guidance that the flag can simply be omitted", result.Output)
+	}
+}
+
+// A well-formed additional_permissions payload must still reach the normal
+// permission prompt: this fix only rejects malformed payloads.
+func TestExecuteToolCallStillPromptsForValidAdditionalPermissions(t *testing.T) {
+	root := t.TempDir()
+	registry := tools.NewRegistry()
+	registry.Register(tools.NewBashTool(root))
+
+	promptCalls := 0
+	_, err := executeToolCall(
+		context.Background(),
+		registry,
+		ToolCall{
+			ID:   "c1",
+			Name: "bash",
+			Arguments: `{"command":"echo hi","sandbox_permissions":"with_additional_permissions",` +
+				`"additional_permissions":{"network":{"enabled":true}}}`,
+		},
+		PermissionModeAuto,
+		Options{
+			OnPermissionRequest: func(ctx context.Context, request PermissionRequest) (PermissionDecision, error) {
+				promptCalls++
+				return PermissionDecision{Action: PermissionDecisionDeny}, nil
+			},
+		},
+	)
+	if err != nil {
+		t.Fatalf("executeToolCall: %v", err)
+	}
+	if promptCalls != 1 {
+		t.Fatalf("OnPermissionRequest called %d times, want exactly 1 for a valid elevation request", promptCalls)
+	}
+}

internal/agent/compaction.go

@@ -21,12 +21,17 @@ import (
 // the agent loop owns the provider wiring.
 
 // defaultCompactionPreserveLast is how many trailing messages are kept verbatim
-// when the caller does not specify a preserve count.
-const defaultCompactionPreserveLast = 8
+// when the caller does not specify a preserve count. Kept in sync with the replay
+// reconstruction default in internal/sessions/replay.go.
+const defaultCompactionPreserveLast = 6
 
 // compactionTriggerRatio is the fraction of the context window at which
-// proactive compaction kicks in (top of each turn).
-const compactionTriggerRatio = 0.8
+// proactive compaction kicks in (top of each turn). NOTE: this is speculative
+// tuning — validate against the per-turn latency/compaction metrics (roadmap 5.2)
+// before trusting it. Measured fixed overhead is ~7.4k tokens (not the ~16k the
+// roadmap assumed), so context fills slower; if data shows 0.7 triggers redundant
+// summarization, raise it back toward 0.8.
+const compactionTriggerRatio = 0.7
 
 // summaryLabel prefixes the injected summary so it is unmistakable in the
 // transcript (and so tests can assert on it).

internal/agent/loop.go

@@ -816,6 +816,25 @@ func executeToolCall(ctx context.Context, registry *tools.Registry, call ToolCal
 		}
 	}
 
+	// A shell command that sets sandbox_permissions: with_additional_permissions
+	// must carry a valid additional_permissions payload; inlineAdditionalPermissionsProfile
+	// is the single source of truth for that shape, and buildPermissionEvent (below)
+	// calls it again to render the prompt's scope text. Check it here, before any
+	// permission prompt is shown: a malformed payload can never be satisfied no
+	// matter what the user decides, so surfacing it as a plain tool error (which the
+	// model can see and retry) is both clearer and avoids presenting a normal-looking
+	// prompt whose "allow" path is guaranteed to fail with a confusing denial.
+	if toolFound && isShellCommandTool(call.Name) {
+		if _, _, err := inlineAdditionalPermissionsProfile(args, options.Cwd); err != nil {
+			return ToolResult{
+				ToolCallID: call.ID,
+				Name:       call.Name,
+				Status:     tools.StatusError,
+				Output:     "Error: " + err.Error(),
+			}, nil
+		}
+	}
+
 	// ask_user is intercepted in the loop (like permissions) so the question can
 	// be routed to an interactive front-end instead of blocking inside the tool.
 	// When no front-end is wired up it degrades to the tool's own graceful Run().
@@ -2322,7 +2341,12 @@ func inlineAdditionalPermissionsProfile(args map[string]any, basePath string) (s
 	}
 	raw, ok := args["additional_permissions"]
 	if !ok || raw == nil {
-		return sandbox.RequestPermissionProfile{}, true, fmt.Errorf("missing additional_permissions; provide at least one of network or file_system")
+		return sandbox.RequestPermissionProfile{}, true, fmt.Errorf(
+			"sandbox_permissions was set to %q but no additional_permissions object was provided. "+
+				`Include one, for example additional_permissions: {"network": {"enabled": true}} or `+
+				`{"file_system": {"write": ["/path"]}}. If this command does not need elevated permissions, `+
+				"omit sandbox_permissions entirely and retry",
+			tools.SandboxPermissionsWithAdditionalPermissions)
 	}
 	data, err := json.Marshal(raw)
 	if err != nil {
@@ -2337,7 +2361,9 @@ func inlineAdditionalPermissionsProfile(args map[string]any, basePath string) (s
 		return sandbox.RequestPermissionProfile{}, true, err
 	}
 	if normalized.Empty() {
-		return sandbox.RequestPermissionProfile{}, true, fmt.Errorf("additional_permissions must include at least one requested permission in network or file_system")
+		return sandbox.RequestPermissionProfile{}, true, fmt.Errorf(
+			"additional_permissions must include at least one of network or file_system, for example " +
+				`{"network": {"enabled": true}} or {"file_system": {"write": ["/path"]}}`)
 	}
 	grantProfile, err := sandbox.RequestPermissionGrantProfile(normalized)
 	if err != nil {
@@ -2470,76 +2496,97 @@ func partitionTools(registry *tools.Registry, permissionMode PermissionMode, opt
 
 	active := options.DeferThreshold > 0 && eligible >= options.DeferThreshold && loaderUsable
 
-	definitions := make([]zeroruntime.ToolDefinition, 0, len(visible))
-	exposedNames := make(map[string]bool, len(visible))
+	// INACTIVE: every visible tool eager (except tool_search), alpha-sorted. With no
+	// deferral there is no mid-session loading, so this is byte-stable across turns
+	// and byte-identical to the pre-deferral output.
+	if !active {
+		definitions := make([]zeroruntime.ToolDefinition, 0, len(visible))
+		for _, tool := range visible {
+			if tool.Name() == tools.ToolSearchToolName {
+				continue
+			}
+			definitions = append(definitions, runtimeToolDefinition(tool))
+		}
+		sort.Slice(definitions, func(left int, right int) bool {
+			return definitions[left].Name < definitions[right].Name
+		})
+		return definitions, ""
+	}
+
+	// ACTIVE: lay the tools array out so its cacheable prefix does NOT shift when a
+	// deferred tool loads mid-session. The tools block is part of the provider's
+	// cached prefix; if a load reorders it, the cache invalidates from that point
+	// through the system prompt and messages — on EVERY load. Previously the whole
+	// array was alpha-sorted each turn, so a newly loaded tool was INSERTED into the
+	// middle and shifted every later definition. Instead we build three append-only
+	// regions:
+	//   1. non-deferred tools, alpha-sorted — always present, identical every turn;
+	//   2. tool_search — always present, right after the stable block;
+	//   3. loaded deferred tools, alpha-sorted — APPENDED, so an unloaded->loaded
+	//      transition grows the tail instead of inserting into the eager block.
+	// (tool_search's discovery text still shrinks as tools load, so keeping it and
+	// the loaded tail AFTER the eager block preserves the eager tools' cache across a
+	// load; fully stabilizing the loader's own description is a scoped follow-up.)
+	eager := make([]zeroruntime.ToolDefinition, 0, len(visible))
+	loadedTail := make([]zeroruntime.ToolDefinition, 0)
 	var hiddenTools []tools.Tool
 	for _, tool := range visible {
 		name := tool.Name()
-		deferred := tools.IsDeferred(tool)
-
-		if !active {
-			// Inactive: byte-identical to legacy, but tool_search is never advertised.
-			if name == tools.ToolSearchToolName {
-				continue
+		if name == tools.ToolSearchToolName {
+			continue // added explicitly between the eager block and the loaded tail
+		}
+		if tools.IsDeferred(tool) {
+			if loaded[name] {
+				loadedTail = append(loadedTail, runtimeToolDefinition(tool))
+			} else {
+				hiddenTools = append(hiddenTools, tool)
 			}
-			definitions = append(definitions, zeroruntime.ToolDefinition{
-				Name:        name,
-				Description: tool.Description(),
-				Parameters:  schemaToRuntimeMap(tool.Parameters()),
-			})
-			exposedNames[name] = true
 			continue
 		}
-
-		// Active path.
-		if deferred && !loaded[name] {
-			hiddenTools = append(hiddenTools, tool)
-			continue
-		}
-		definitions = append(definitions, zeroruntime.ToolDefinition{
-			Name:        name,
-			Description: tool.Description(),
-			Parameters:  schemaToRuntimeMap(tool.Parameters()),
-		})
-		exposedNames[name] = true
+		eager = append(eager, runtimeToolDefinition(tool))
 	}
-
-	// On the ACTIVE path tool_search is guaranteed runnable (active implies
-	// loaderUsable), so it must ALWAYS be reachable — even when a non-empty
-	// EnabledTools allowlist omits it (the operator allowlisted the deferred
-	// tools, not the loader). Expose its full definition whenever it is not
-	// already in the exposed set. This never runs on the inactive path, so the
-	// byte-identical below-threshold output is preserved.
-	discovery := ""
-	if active && len(hiddenTools) > 0 {
-		discovery = tools.BuildToolSearchDescription(hiddenTools)
-	}
-	if active && !exposedNames[tools.ToolSearchToolName] {
-		description := loader.Description()
-		if discovery != "" {
-			description = discovery
-		}
-		definitions = append(definitions, zeroruntime.ToolDefinition{
-			Name:        loader.Name(),
-			Description: description,
-			Parameters:  schemaToRuntimeMap(loader.Parameters()),
-		})
-	} else if active && discovery != "" {
-		for i := range definitions {
-			if definitions[i].Name == tools.ToolSearchToolName {
-				definitions[i].Description = discovery
-				break
-			}
-		}
-	}
-
-	sort.Slice(definitions, func(left int, right int) bool {
-		return definitions[left].Name < definitions[right].Name
+	sort.Slice(eager, func(left int, right int) bool {
+		return eager[left].Name < eager[right].Name
+	})
+	sort.Slice(loadedTail, func(left int, right int) bool {
+		return loadedTail[left].Name < loadedTail[right].Name
 	})
 
+	discovery := ""
+	if len(hiddenTools) > 0 {
+		discovery = tools.BuildToolSearchDescription(hiddenTools)
+	}
+
+	// tool_search is guaranteed runnable on the active path, so it is ALWAYS exposed
+	// — even when a non-empty EnabledTools allowlist omits it (the operator
+	// allowlisted the deferred tools, not the loader). It sits right after the stable
+	// eager block and carries the discovery list for still-hidden tools.
+	description := loader.Description()
+	if discovery != "" {
+		description = discovery
+	}
+	definitions := make([]zeroruntime.ToolDefinition, 0, len(eager)+1+len(loadedTail))
+	definitions = append(definitions, eager...)
+	definitions = append(definitions, zeroruntime.ToolDefinition{
+		Name:        loader.Name(),
+		Description: description,
+		Parameters:  schemaToRuntimeMap(loader.Parameters()),
+	})
+	definitions = append(definitions, loadedTail...)
+
 	return definitions, discovery
 }
 
+// runtimeToolDefinition renders a tool's advertised definition (name, description,
+// JSON-schema parameters) as sent to the provider.
+func runtimeToolDefinition(tool tools.Tool) zeroruntime.ToolDefinition {
+	return zeroruntime.ToolDefinition{
+		Name:        tool.Name(),
+		Description: tool.Description(),
+		Parameters:  schemaToRuntimeMap(tool.Parameters()),
+	}
+}
+
 func ToolVisible(tool tools.Tool, permissionMode PermissionMode, enabledTools []string, disabledTools []string) bool {
 	return ToolAllowedByFilters(tool.Name(), enabledTools, disabledTools) && ToolAdvertised(tool, permissionMode)
 }

internal/agent/partition_cache_stable_test.go

@@ -0,0 +1,44 @@
+package agent
+
+import (
+	"testing"
+
+	"github.com/Gitlawb/zero/internal/tools"
+)
+
+func TestPartitionToolsActiveAppendsLoadedToolAfterEagerBlock(t *testing.T) {
+	// Cache-stability property: loading a deferred tool must APPEND it after the
+	// always-eager tools, not sort it into the middle of them — otherwise the tool
+	// definitions (the provider's cacheable prefix) shift on every load. The old
+	// behaviour alpha-sorted the whole array, so "mcp__srv__alpha" jumped ahead of
+	// "read_file".
+	root := t.TempDir()
+	registry := tools.NewRegistry()
+	registry.Register(tools.NewReadFileTool(root)) // non-deferred, "read_file"
+	registry.Register(fakeToolSearchTool{})
+	registry.Register(fakeDeferredTool{name: "mcp__srv__alpha", desc: "alpha"})
+	registry.Register(fakeDeferredTool{name: "mcp__srv__beta", desc: "beta"})
+
+	exposed, _ := partitionTools(registry, PermissionModeAuto, Options{DeferThreshold: 2}, map[string]bool{"mcp__srv__alpha": true})
+
+	pos := func(name string) int {
+		for i := range exposed {
+			if exposed[i].Name == name {
+				return i
+			}
+		}
+		return -1
+	}
+	readPos, searchPos, alphaPos := pos("read_file"), pos("tool_search"), pos("mcp__srv__alpha")
+	if readPos < 0 || searchPos < 0 || alphaPos < 0 {
+		t.Fatalf("expected read_file, tool_search and loaded alpha all exposed, got %#v", exposed)
+	}
+	// The eager tools must precede the loaded deferred tool (appended, not inserted).
+	if !(readPos < alphaPos && searchPos < alphaPos) {
+		t.Fatalf("loaded deferred tool must be appended after the eager block; got read=%d search=%d alpha=%d", readPos, searchPos, alphaPos)
+	}
+	// beta was never loaded — it stays hidden.
+	if pos("mcp__srv__beta") != -1 {
+		t.Fatalf("unloaded deferred tool must stay hidden, got %#v", exposed)
+	}
+}

internal/agent/prompt_budget_test.go

@@ -0,0 +1,51 @@
+package agent
+
+import (
+	"testing"
+
+	"github.com/Gitlawb/zero/internal/tools"
+)
+
+// These ceilings are a deliberate ratchet on Zero's fixed per-turn overhead — the
+// system prompt and the eager tool schemas that ride on EVERY request. They are
+// set ~10% above the current measured cost, using ApproxTextTokens (the same
+// estimate the compaction loop and /context use, ~non-whitespace-bytes/4). A change
+// that pushes either past its ceiling must be justified (and the ceiling raised
+// deliberately) or trimmed — the per-turn floor should not creep up silently.
+//
+// Measured baselines (2026-07): base system prompt ~3160 tokens; the tools a normal
+// (auto permission-mode) interactive turn sends ~2430 tokens. The tool figure is
+// the auto-mode advertised set, not the full core registry — higher-risk tools that
+// only advertise in other modes are excluded, matching what a real turn actually
+// pays.
+const (
+	maxBaseSystemPromptTokens = 3500
+	maxEagerToolSchemaTokens  = 2700
+)
+
+func TestSystemPromptTokenBudget(t *testing.T) {
+	// Minimal render: a model is set (so the session block renders) but no Cwd, so
+	// the workspace map, project guidelines, and repo map are excluded — this is the
+	// fixed base every session pays regardless of the workspace it runs in.
+	prompt := buildSystemPrompt(Options{Model: "claude-opus-4-8"})
+	got := ApproxTextTokens(prompt)
+	t.Logf("base system prompt: %d tokens (%d bytes)", got, len(prompt))
+	if got > maxBaseSystemPromptTokens {
+		t.Fatalf("base system prompt is %d tokens, over the %d ceiling — trim it or raise the ceiling deliberately", got, maxBaseSystemPromptTokens)
+	}
+}
+
+func TestEagerToolSchemaTokenBudget(t *testing.T) {
+	registry := tools.NewRegistry()
+	for _, tool := range tools.CoreToolsScoped(t.TempDir(), nil) {
+		registry.Register(tool)
+	}
+	// Options{} keeps DeferThreshold at 0, so deferral is inactive and every core
+	// tool is exposed eagerly — exactly what a plugin-free session sends each turn.
+	exposed, _ := partitionTools(registry, PermissionModeAuto, Options{}, map[string]bool{})
+	got := estimateToolDefTokens(exposed)
+	t.Logf("eager core tool schemas: %d tokens across %d tools", got, len(exposed))
+	if got > maxEagerToolSchemaTokens {
+		t.Fatalf("eager tool schemas are %d tokens, over the %d ceiling — defer a tool or raise the ceiling deliberately", got, maxEagerToolSchemaTokens)
+	}
+}

internal/agent/skills_context_test.go

@@ -0,0 +1,63 @@
+package agent
+
+import (
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func TestSkillsContextCapsLongList(t *testing.T) {
+	skills := make([]SkillInfo, 0, 40)
+	for i := 0; i < 40; i++ {
+		n := strconv.Itoa(i)
+		skills = append(skills, SkillInfo{Name: "skill-" + n, Description: "does something useful, number " + n})
+	}
+	got := skillsContext(Options{Skills: skills})
+	if len(got) > 1200 {
+		t.Fatalf("skills block should stay bounded, got %d bytes:\n%s", len(got), got)
+	}
+	if !strings.Contains(got, "more (call skill") {
+		t.Fatalf("expected an overflow summary line, got:\n%s", got)
+	}
+	// The first skill is always listed regardless of budget.
+	if !strings.Contains(got, "- skill-0:") {
+		t.Fatalf("expected the first skill to always be listed, got:\n%s", got)
+	}
+}
+
+func TestSkillsContext(t *testing.T) {
+	if got := skillsContext(Options{}); got != "" {
+		t.Fatalf("no skills should yield an empty section, got %q", got)
+	}
+	got := skillsContext(Options{Skills: []SkillInfo{
+		{Name: "commit-writer", Description: "Write a conventional-commit message."},
+		{Name: "  ", Description: "nameless, should be skipped"},
+		{Name: "reviewer"},
+	}})
+	if !strings.Contains(got, "<available_skills>") || !strings.Contains(got, "</available_skills>") {
+		t.Fatalf("missing available_skills block: %q", got)
+	}
+	if !strings.Contains(got, "- commit-writer: Write a conventional-commit message.") {
+		t.Fatalf("missing commit-writer line: %q", got)
+	}
+	if !strings.Contains(got, "- reviewer\n") {
+		t.Fatalf("reviewer (no description) line missing: %q", got)
+	}
+	if strings.Contains(got, "nameless") {
+		t.Fatalf("nameless entry should be skipped: %q", got)
+	}
+}
+
+func TestSystemPromptIncludesSkillsOnlyWhenInstalled(t *testing.T) {
+	with := buildSystemPrompt(Options{Skills: []SkillInfo{
+		{Name: "commit-writer", Description: "Write a commit message."},
+	}})
+	if !strings.Contains(with, "<available_skills>") || !strings.Contains(with, "skill tool") {
+		t.Fatalf("expected available_skills guidance in system prompt: %q", with)
+	}
+	// Default (no skills) must reproduce the prior prompt: no skills block.
+	without := buildSystemPrompt(Options{})
+	if strings.Contains(without, "<available_skills>") {
+		t.Fatalf("available_skills block must not appear without skills")
+	}
+}

internal/agent/system_prompt.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
 	"unicode/utf8"
 
@@ -86,6 +87,9 @@ func buildSystemPrompt(options Options) string {
 	if delegation := specialistDelegationContext(options); delegation != "" {
 		sections = append(sections, delegation)
 	}
+	if skillsBlock := skillsContext(options); skillsBlock != "" {
+		sections = append(sections, skillsBlock)
+	}
 	if style := responseStyleContext(options); style != "" {
 		sections = append(sections, style)
 	}
@@ -164,6 +168,64 @@ func specialistDelegationContext(options Options) string {
 	return b.String()
 }
 
+// skillsContext lists the reusable skills the model can pull in on demand via the
+// skill tool, so it invokes the right one on the first try instead of guessing a
+// name, failing, and reading the error. It mirrors specialistDelegationContext:
+// names + one-line descriptions only (never skill bodies), and it renders nothing
+// when no skills are installed, so a skill-less run reproduces the previous prompt
+// byte-for-byte.
+// skillsContextListBudget bounds the bytes spent listing individual skills so a
+// workspace with dozens of them can't bloat every turn's prompt. Skills past the
+// budget are summarized as a count rather than dropped — the model can still load
+// any of them by name (an unknown name returns the full list from the skill tool).
+const skillsContextListBudget = 640
+
+func skillsContext(options Options) string {
+	if len(options.Skills) == 0 {
+		return ""
+	}
+	var b strings.Builder
+	b.WriteString("<available_skills>\n")
+	b.WriteString("Reusable, on-demand instruction sets you can load with the skill tool. When a request matches one, call skill with its exact name to pull in its guidance before acting — do not guess names or skip a relevant skill.\n")
+	listed, spent, omitted := 0, 0, 0
+	for _, info := range options.Skills {
+		name := strings.TrimSpace(info.Name)
+		if name == "" {
+			continue
+		}
+		line := "- " + name
+		if desc := strings.TrimSpace(info.Description); desc != "" {
+			line += ": " + truncateForSkillLine(desc)
+		}
+		line += "\n"
+		// Always list at least one skill; past the budget, summarize the remainder
+		// as a count instead of silently dropping it.
+		if listed > 0 && spent+len(line) > skillsContextListBudget {
+			omitted++
+			continue
+		}
+		b.WriteString(line)
+		spent += len(line)
+		listed++
+	}
+	if omitted > 0 {
+		b.WriteString("- …and " + strconv.Itoa(omitted) + " more (call skill with a name; an unknown name lists them all)\n")
+	}
+	b.WriteString("</available_skills>")
+	return b.String()
+}
+
+// truncateForSkillLine keeps a skill's one-line description short so a single
+// verbose description can't dominate the skills-list budget.
+func truncateForSkillLine(desc string) string {
+	const maxDescRunes = 100
+	runes := []rune(desc)
+	if len(runes) <= maxDescRunes {
+		return desc
+	}
+	return strings.TrimSpace(string(runes[:maxDescRunes])) + "…"
+}
+
 func sessionRuntimeContext(options Options) string {
 	provider := strings.TrimSpace(options.ProviderName)
 	model := strings.TrimSpace(options.Model)
@@ -310,9 +372,9 @@ func projectGuidelineLabel(match, gitRoot string) string {
 
 // findProjectContextFile returns the first matching project guideline file
 // in dir. Lookup is case-insensitive on the basename and on the actual
-// filename returned, so a git-tracked file like AGENTS.MD (uppercase MD)
-// still resolves to its true filename on case-sensitive filesystems — the
-// returned path is what should appear in the project guidelines label.
+// filename returned, so a git-tracked file like AGENTS.md still resolves to
+// its true filename on case-sensitive filesystems — the returned path is what
+// should appear in the project guidelines label.
 // Returns "" when nothing matches.
 func findProjectContextFile(dir string) string {
 	for _, name := range projectContextFiles {

internal/agent/system_prompt.md

@@ -46,14 +46,10 @@ work.
    formatting-only edits unless the user asked for them.
 4. **Verify.** Verify after edits; see the testing gate below. This is
    mandatory.
-5. **Summarize.** For a substantial task, close with an ELABORATE, well-structured
-   summary — never a single throwaway line. Use short headings and bullets: a
-   one-line "what I built/changed"; **Where it lives** — the key files and how they
-   fit together; **How each requirement is met** — walk through each requirement
-   from the request and name the specifics that satisfy it; what validation ran and
-   what was NOT verified; and a brief "Next steps" or "Want me to…?" offer. Scale
-   the depth to the work — a big build earns several sections, a trivial fix earns
-   a line or two.
+5. **Summarize.** Close with a summary scaled to the work: a trivial fix earns one
+   line; a substantial change earns a few short bullets covering what changed, where
+   it lives, and what you did and did not verify. Lead with the outcome, and never
+   pad — do not restate the task or narrate steps the user already watched you take.
 
 ## Editing discipline
 
@@ -64,7 +60,9 @@ work.
 - Make one tool call per file. Do not batch multi-file writes into a single
   shell or script invocation.
 - For edits to existing files, prefer edit_file or apply_patch with minimal,
-  targeted diffs. Match the existing indentation, imports, and idioms.
+  targeted diffs. Match the existing indentation, imports, and idioms. Match the
+  file's comment density: do not add explanatory comments unless the user asks or
+  the code is already comment-dense.
 - Preserve behavior you were not asked to change. Do not delete or rewrite code
   you did not author unless the task requires it; if you must, say so.
 

internal/agent/system_prompt_models.go

@@ -6,11 +6,13 @@ import "strings"
 //
 // Different model families respond to different framing: the GPT family benefits
 // from an explicit markdown/output spec and a strong "prefer native tools" nudge;
-// Gemini benefits from explicit tool-preference and conciseness guidance; the
-// Claude family is already well-aligned with the core prompt and only needs a
-// light comment-discipline nudge. modelPromptAddendum returns the family-specific
-// block appended after the core prompt. Classification is by model id (the agent
-// only has the model string — no registry dependency).
+// Gemini benefits from explicit tool-preference and conciseness guidance. The
+// Claude family is already aligned with the core prompt and needs no addendum —
+// comment discipline is universal in the core prompt now, so every family gets it.
+// modelPromptAddendum returns the family-specific block appended after the core
+// prompt, or "" when the family is unknown or needs no specialization.
+// Classification is by model id (the agent only has the model string — no registry
+// dependency).
 
 const (
 	familyOpenAI    = "openai"
@@ -45,9 +47,10 @@ func modelPromptAddendum(model string) string {
 		return openAIPromptAddendum
 	case familyGemini:
 		return geminiPromptAddendum
-	case familyAnthropic:
-		return anthropicPromptAddendum
 	default:
+		// Anthropic (aligned with the core prompt) and unknown families get no
+		// family-specific block; comment discipline now lives in the core prompt
+		// for every model.
 		return ""
 	}
 }
@@ -70,8 +73,3 @@ const geminiPromptAddendum = `<model_guidance>
   in one short clause why it is needed.
 - Use update_plan for any multi-step task and keep it current.
 </model_guidance>`
-
-const anthropicPromptAddendum = `<model_guidance>
-- Do not add code comments unless the user asks or the surrounding code is
-  comment-dense; match the file's existing comment density.
-</model_guidance>`

internal/agent/system_prompt_models_test.go

@@ -29,9 +29,11 @@ func TestBuildSystemPromptAppendsModelAddendum(t *testing.T) {
 	if got := buildSystemPrompt(Options{Model: "gpt-5"}); !strings.Contains(got, openAIPromptAddendum) {
 		t.Fatalf("expected the OpenAI addendum in the gpt-5 prompt")
 	}
+	// Claude is aligned with the core prompt and gets no family addendum now that
+	// comment discipline is universal; it must not pick up another family's block.
 	claude := buildSystemPrompt(Options{Model: "claude-opus-4-6"})
-	if !strings.Contains(claude, anthropicPromptAddendum) {
-		t.Fatalf("expected the Anthropic addendum in the claude prompt")
+	if strings.Contains(claude, "<model_guidance>") {
+		t.Fatalf("expected no model_guidance block for Claude (aligned with core prompt)")
 	}
 	if strings.Contains(claude, openAIPromptAddendum) {
 		t.Fatalf("the claude prompt must not contain the OpenAI addendum")

internal/agent/system_prompt_test.go

@@ -23,7 +23,8 @@ func TestCoreSystemPromptIncludesCodingQualityRules(t *testing.T) {
 		"avoid broad refactors",
 		"search the web before answering",
 		"do not recognize",
-		"how each requirement is met",
+		"scaled to the work",
+		"comment density",
 	} {
 		if !strings.Contains(prompt, want) {
 			t.Fatalf("expected core system prompt to include %q, got:\n%s", want, buildSystemPrompt(Options{}))
@@ -128,7 +129,7 @@ func systemPromptTestBlock(t *testing.T, prompt, start, end string) string {
 }
 
 func TestBuildSystemPromptInjectsProjectGuidelinesCaseInsensitive(t *testing.T) {
-	// Git tracks AGENTS.MD (uppercase MD) on a case-sensitive filesystem; the
+	// Git tracks AGENTS.md on a case-sensitive filesystem; the
 	// loader must still resolve it when the cwd lookup uses lowercase.
 	cwd := t.TempDir()
 	if err := os.WriteFile(filepath.Join(cwd, "AGENTS.MD"), []byte("Always run `make lint`."), 0o644); err != nil {

internal/agent/types.go

@@ -174,6 +174,16 @@ type SpecialistInfo struct {
 	WhenToUse string
 }
 
+// SkillInfo is a one-line summary of a reusable, on-demand skill (its name and
+// frontmatter description) surfaced to the system prompt so the model can invoke
+// the right skill with the skill tool on the first try instead of guessing a name
+// and reading the failure. Like SpecialistInfo it is plain data, so the agent
+// package needs no dependency on internal/skills.
+type SkillInfo struct {
+	Name        string
+	Description string
+}
+
 type Options struct {
 	MaxTurns int
 	// DeferThreshold activates deferred MCP-tool loading: when the number of
@@ -189,6 +199,12 @@ type Options struct {
 	// populated only where the Task tool is actually registered, so an empty slice
 	// (the default) reproduces the previous prompt byte-for-byte.
 	Specialists []SpecialistInfo
+	// Skills lists the reusable skills installed for this run (the default skills
+	// dir merged with any plugin skill roots). When non-empty the system prompt
+	// gains an <available_skills> block naming them so the model loads the right one
+	// via the skill tool on the first try. Empty (the default) reproduces the
+	// previous prompt byte-for-byte.
+	Skills []SkillInfo
 	// Specialist/sub-agent metadata is carried through exec now and consumed by
 	// the specialist runtime in later slices.
 	SessionID        string

internal/cli/app.go

@@ -80,6 +80,7 @@ type appDeps struct {
 	runTUI                 func(context.Context, tui.Options) int
 	runEditor              func(string) error
 	checkUpdate            func(context.Context, update.Options) (update.Result, error)
+	applyUpdate            func(context.Context, update.Options) (update.ApplyResult, error)
 	now                    func() time.Time
 }
 
@@ -180,6 +181,7 @@ func defaultAppDeps() appDeps {
 		runTUI:           tui.Run,
 		runEditor:        openEditor,
 		checkUpdate:      update.Check,
+		applyUpdate:      update.Apply,
 		now:              time.Now,
 	}
 }
@@ -383,6 +385,8 @@ func runWithDeps(args []string, stdout io.Writer, stderr io.Writer, deps appDeps
 		return runSandbox(args[1:], stdout, stderr, deps)
 	case "update":
 		return runUpdate(args[1:], stdout, stderr, deps)
+	case "upgrade":
+		return runUpgrade(args[1:], stdout, stderr, deps)
 	case "worktrees", "worktree":
 		return runWorktrees(args[1:], stdout, stderr, deps)
 	case "verify":
@@ -515,6 +519,9 @@ func fillAppDeps(deps appDeps) appDeps {
 	if deps.checkUpdate == nil {
 		deps.checkUpdate = defaults.checkUpdate
 	}
+	if deps.applyUpdate == nil {
+		deps.applyUpdate = defaults.applyUpdate
+	}
 	if deps.now == nil {
 		deps.now = defaults.now
 	}
@@ -557,8 +564,19 @@ func runInteractiveTUIWithSetup(stderr io.Writer, deps appDeps, permissionMode a
 		if !errors.Is(err, config.ErrNoActiveProvider) && !errors.Is(err, config.ErrProviderRequiresModel) {
 			return writeAppError(stderr, err.Error(), 1)
 		}
-		resolved = config.ResolvedConfig{}
-		forceSetup = true
+		// ErrNoActiveProvider can mean "nothing configured yet" (needs onboarding)
+		// or "providers ARE configured, just none marked active" (e.g. config.json's
+		// activeProvider is blank/stale). In the second case resolved.Providers still
+		// carries the already-normalized list — prefer falling back to one of those
+		// over wiping everything and forcing the user to re-enter credentials they
+		// already saved.
+		if usable, ok := firstUsableProvider(resolved.Providers); errors.Is(err, config.ErrNoActiveProvider) && ok {
+			resolved.Provider = usable
+			resolved.ActiveProvider = usable.Name
+		} else {
+			resolved = config.ResolvedConfig{}
+			forceSetup = true
+		}
 	}
 	userConfigPath, err := deps.userConfigPath()
 	if err != nil {
@@ -740,9 +758,11 @@ func runInteractiveTUIWithSetup(stderr io.Writer, deps appDeps, permissionMode a
 			Hooks:          newHookDispatcherWithExtra(workspaceRoot, pluginActivation.hooks),
 			DeferThreshold: resolved.Tools.DeferThreshold,
 			Specialists:    specialistRuntime.specialists,
+			Skills:         pluginActivation.skillInfos(deps.skillsDir()),
 		},
 		PermissionMode: permissionMode,
 		Notify:         resolved.Notify,
+		KeyBindings:    resolved.KeyBindings,
 		Setup: tui.SetupOptions{
 			Visible:    setupVisible,
 			Required:   needsSetup,
@@ -1158,7 +1178,8 @@ func profileHasCredential(profile config.ProviderProfile) bool {
 }
 
 // baseURLIsLoopback reports whether a provider base_url points at a loopback host
-// (a keyless local provider like Ollama/LM Studio), which needs no API key.
+// or a private-network host (192.168.x.y / 10.x.y.z / 172.16.x.y) — a local
+// provider like Ollama/LM Studio that needs no API key.
 func baseURLIsLoopback(baseURL string) bool {
 	u := strings.TrimSpace(baseURL)
 	if u == "" {
@@ -1173,7 +1194,7 @@ func baseURLIsLoopback(baseURL string) bool {
 		return true
 	}
 	if addr, err := netip.ParseAddr(host); err == nil {
-		return addr.IsLoopback()
+		return addr.IsLoopback() || addr.IsPrivate()
 	}
 	return false
 }

internal/cli/app_test.go

@@ -205,6 +205,67 @@ func TestRunNoArgsEntersSetupWhenResolveReportsNoActiveProvider(t *testing.T) {
 	}
 }
 
+func TestRunNoArgsFallsBackToUsableProviderWhenNoneMarkedActive(t *testing.T) {
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	cwd := t.TempDir()
+	setCLIUserConfigRoot(t)
+	userConfigPath := filepath.Join(t.TempDir(), "zero", "config.json")
+	var launchedOptions tui.Options
+	launched := false
+	var providerProfile config.ProviderProfile
+	fake := &cliFakeProvider{}
+
+	usable := config.ProviderProfile{
+		Name:         "work",
+		ProviderKind: config.ProviderKindOpenAI,
+		BaseURL:      config.OpenAIBaseURL,
+		APIKey:       "sk-test",
+		Model:        "gpt-test",
+	}
+
+	exitCode := runWithDeps([]string{}, &stdout, &stderr, appDeps{
+		getwd: func() (string, error) {
+			return cwd, nil
+		},
+		resolveConfig: func(workspaceRoot string, overrides config.Overrides) (config.ResolvedConfig, error) {
+			// config.json has providers configured but none marked active (e.g. a
+			// blank/stale activeProvider field) — Resolve returns the successfully
+			// normalized providers list alongside ErrNoActiveProvider.
+			return config.ResolvedConfig{Providers: []config.ProviderProfile{usable}},
+				fmt.Errorf("%w: active provider %q not found", config.ErrNoActiveProvider, "")
+		},
+		newProvider: func(profile config.ProviderProfile) (zeroruntime.Provider, error) {
+			providerProfile = profile
+			return fake, nil
+		},
+		userConfigPath: func() (string, error) {
+			return userConfigPath, nil
+		},
+		registerMCPTools: func(context.Context, *tools.Registry, config.MCPConfig, mcp.RegisterOptions) (mcpToolRuntime, error) {
+			return noopMCPRuntime{}, nil
+		},
+		runTUI: func(ctx context.Context, options tui.Options) int {
+			launched = true
+			launchedOptions = options
+			return 0
+		},
+	})
+
+	if exitCode != 0 {
+		t.Fatalf("exit code = %d, want 0, stderr=%q", exitCode, stderr.String())
+	}
+	if !launched {
+		t.Fatal("TUI was not launched")
+	}
+	if launchedOptions.Setup.Visible || launchedOptions.Setup.Required {
+		t.Fatalf("Setup = %#v, want no setup wizard — a usable saved provider exists", launchedOptions.Setup)
+	}
+	if providerProfile.Name != "work" {
+		t.Fatalf("provider used = %q, want fallback to the usable saved provider %q", providerProfile.Name, "work")
+	}
+}
+
 func TestRunNoArgsFailsWhenResolveErrorIsNotProviderRelated(t *testing.T) {
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer
@@ -1267,6 +1328,153 @@ func TestRunUpdateReportsUpToDate(t *testing.T) {
 	}
 }
 
+func TestRunUpdateApplyTextAndJSON(t *testing.T) {
+	applyResult := update.ApplyResult{
+		Result: update.Result{
+			CurrentVersion:  "dev",
+			LatestVersion:   "0.2.0",
+			UpdateAvailable: true,
+		},
+		Applied:       true,
+		InstallMethod: update.InstallMethodStandalone,
+		BinaryPath:    "/usr/local/bin/zero",
+		Message:       "updated to 0.2.0",
+	}
+	var gotOptions update.Options
+	deps := appDeps{
+		applyUpdate: func(_ context.Context, options update.Options) (update.ApplyResult, error) {
+			gotOptions = options
+			return applyResult, nil
+		},
+		checkUpdate: func(context.Context, update.Options) (update.Result, error) {
+			t.Fatal("checkUpdate should not run for --apply")
+			return update.Result{}, nil
+		},
+	}
+
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	exitCode := runWithDeps([]string{"update", "--apply"}, &stdout, &stderr, deps)
+	if exitCode != exitSuccess {
+		t.Fatalf("expected exit code %d, got %d: %s", exitSuccess, exitCode, stderr.String())
+	}
+	if !strings.Contains(stdout.String(), "updated to 0.2.0") {
+		t.Fatalf("unexpected apply text: %q", stdout.String())
+	}
+	if gotOptions.CurrentVersion != "dev" {
+		t.Fatalf("unexpected options passed to applyUpdate: %#v", gotOptions)
+	}
+
+	stdout.Reset()
+	stderr.Reset()
+	exitCode = runWithDeps([]string{"update", "--apply", "--json"}, &stdout, &stderr, deps)
+	if exitCode != exitSuccess {
+		t.Fatalf("expected exit code %d, got %d: %s", exitSuccess, exitCode, stderr.String())
+	}
+	var payload struct {
+		Applied       bool   `json:"applied"`
+		InstallMethod string `json:"installMethod"`
+		BinaryPath    string `json:"binaryPath"`
+	}
+	if err := json.Unmarshal(stdout.Bytes(), &payload); err != nil {
+		t.Fatalf("apply JSON did not decode: %v\n%s", err, stdout.String())
+	}
+	if !payload.Applied || payload.InstallMethod != string(update.InstallMethodStandalone) || payload.BinaryPath != applyResult.BinaryPath {
+		t.Fatalf("unexpected apply JSON: %#v", payload)
+	}
+}
+
+func TestRunUpgradeDefaultsToApply(t *testing.T) {
+	var applyCalled bool
+	deps := appDeps{
+		applyUpdate: func(context.Context, update.Options) (update.ApplyResult, error) {
+			applyCalled = true
+			return update.ApplyResult{Message: "already up to date"}, nil
+		},
+		checkUpdate: func(context.Context, update.Options) (update.Result, error) {
+			t.Fatal("checkUpdate should not run for `zero upgrade`")
+			return update.Result{}, nil
+		},
+	}
+
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	exitCode := runWithDeps([]string{"upgrade"}, &stdout, &stderr, deps)
+	if exitCode != exitSuccess {
+		t.Fatalf("expected exit code %d, got %d: %s", exitSuccess, exitCode, stderr.String())
+	}
+	if !applyCalled {
+		t.Fatal("expected `zero upgrade` to call applyUpdate")
+	}
+}
+
+func TestRunUpdateRejectsCheckAndApplyTogether(t *testing.T) {
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	exitCode := runWithDeps([]string{"update", "--check", "--apply"}, &stdout, &stderr, appDeps{
+		checkUpdate: func(context.Context, update.Options) (update.Result, error) {
+			t.Fatal("checkUpdate should not run")
+			return update.Result{}, nil
+		},
+		applyUpdate: func(context.Context, update.Options) (update.ApplyResult, error) {
+			t.Fatal("applyUpdate should not run")
+			return update.ApplyResult{}, nil
+		},
+	})
+
+	if exitCode != exitUsage {
+		t.Fatalf("expected usage exit code, got %d", exitCode)
+	}
+	if got := stderr.String(); !strings.Contains(got, "only one of --check or --apply") {
+		t.Fatalf("expected --check/--apply usage error, got %q", got)
+	}
+}
+
+func TestRunUpdateRejectsTargetWithApply(t *testing.T) {
+	for _, args := range [][]string{
+		{"update", "--apply", "--target", "linux-arm64"},
+		{"upgrade", "--target", "linux-arm64"},
+	} {
+		t.Run(strings.Join(args, " "), func(t *testing.T) {
+			var stdout bytes.Buffer
+			var stderr bytes.Buffer
+
+			exitCode := runWithDeps(args, &stdout, &stderr, appDeps{
+				applyUpdate: func(context.Context, update.Options) (update.ApplyResult, error) {
+					t.Fatal("applyUpdate should not run when --target is combined with --apply")
+					return update.ApplyResult{}, nil
+				},
+			})
+
+			if exitCode != exitUsage {
+				t.Fatalf("expected usage exit code, got %d", exitCode)
+			}
+			if got := stderr.String(); !strings.Contains(got, "--target cannot be combined with --apply") {
+				t.Fatalf("expected --target/--apply usage error, got %q", got)
+			}
+		})
+	}
+}
+
+func TestRunUpdateReportsApplyError(t *testing.T) {
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	exitCode := runWithDeps([]string{"update", "--apply"}, &stdout, &stderr, appDeps{
+		applyUpdate: func(context.Context, update.Options) (update.ApplyResult, error) {
+			return update.ApplyResult{}, errors.New("download failed")
+		},
+	})
+
+	if exitCode == exitSuccess {
+		t.Fatalf("expected non-success exit code, got %d", exitCode)
+	}
+	if got := stderr.String(); !strings.Contains(got, "download failed") {
+		t.Fatalf("expected apply error, got %q", got)
+	}
+}
+
 func assertHelpOutput(t *testing.T, args []string) {
 	t.Helper()
 

internal/cli/auth.go

@@ -301,12 +301,27 @@ func runAuthLogin(args []string, stdout io.Writer, stderr io.Writer, deps appDep
 	if len(parsed.positional) != 1 {
 		return writeExecUsageError(stderr, "usage: zero auth login <provider> [--device] [--scope <scope>]")
 	}
+	provider := parsed.positional[0]
+	// ChatGPT (Codex) requires a fixed redirect_uri (http://localhost:1455/
+	// auth/callback) and mandatory authorize params (id_token_add_organizations,
+	// codex_cli_simplified_flow, originator) that the generic loopback flow
+	// cannot supply. Route it to the dedicated ChatGPT login so
+	// `zero auth login chatgpt` behaves identically to `zero auth chatgpt`.
+	if strings.EqualFold(provider, "chatgpt") {
+		if parsed.device {
+			return writeExecUsageError(stderr, "ChatGPT login does not support --device (it is loopback-only)")
+		}
+		if len(parsed.scopes) > 0 {
+			return writeExecUsageError(stderr, "ChatGPT login does not support --scope (the required scopes are fixed by the Codex client registration)")
+		}
+		return runAuthChatGPT(nil, stdout, stderr, deps)
+	}
 	manager, err := newAuthManager(deps, stdout)
 	if err != nil {
 		return writeAppError(stderr, redaction.ErrorMessage(err, redaction.Options{}), exitCrash)
 	}
 	status, err := manager.Login(context.Background(), oauth.LoginOptions{
-		Provider:    parsed.positional[0],
+		Provider:    provider,
 		Device:      parsed.device,
 		ExtraScopes: parsed.scopes,
 	})
@@ -489,8 +504,9 @@ Commands:
 A provider is any OAuth 2.0 / OIDC server. "openrouter" ('zero auth openrouter')
 works out of the box. "xai" ('zero auth login xai') uses a built-in preset that is
 off by default — enable it with ZERO_OAUTH_ALLOW_PRESETS=1, or set the
-ZERO_OAUTH_XAI_* vars yourself. Any preset field is overridable via the env vars
-below. For a custom provider named <name>, set:
+ZERO_OAUTH_XAI_* vars yourself. "chatgpt" ('zero auth login chatgpt' or
+'zero auth chatgpt') uses a fixed-port loopback flow against the Codex backend.
+Any preset field is overridable via the env vars below. For a custom provider named <name>, set:
   ZERO_OAUTH_<NAME>_CLIENT_ID       (required)
   ZERO_OAUTH_<NAME>_CLIENT_SECRET   (optional)
   ZERO_OAUTH_<NAME>_AUTHORIZE_URL   ZERO_OAUTH_<NAME>_TOKEN_URL

internal/cli/auth_test.go

@@ -156,3 +156,44 @@ func TestRunAuthHelp(t *testing.T) {
 		}
 	}
 }
+
+// TestRunAuthLoginChatGPTRoutesToDedicatedFlow verifies `zero auth login
+// chatgpt` reaches the dedicated ChatGPT login (fixed-port loopback + mandatory
+// authorize params), not the generic manager path. The generic login accepts
+// --device, so a ChatGPT-specific rejection proves the routing took effect.
+// See issue #430: the generic path built a random-port 127.0.0.1 redirect_uri
+// without the required extra params, so OpenAI's authorize endpoint rejected it.
+func TestRunAuthLoginChatGPTRoutesToDedicatedFlow(t *testing.T) {
+	withAuthStore(t)
+	var stdout, stderr bytes.Buffer
+	if code := runWithDeps([]string{"auth", "login", "chatgpt", "--device"}, &stdout, &stderr, appDeps{}); code == exitSuccess {
+		t.Fatal("auth login chatgpt --device should be rejected (ChatGPT is loopback-only)")
+	}
+	if !strings.Contains(stderr.String(), "ChatGPT login does not support --device") {
+		t.Fatalf("stderr = %q, want the ChatGPT-specific --device rejection", stderr.String())
+	}
+	// Case-insensitive provider name should still route.
+	stdout.Reset()
+	stderr.Reset()
+	if code := runWithDeps([]string{"auth", "login", "ChatGPT", "--device"}, &stdout, &stderr, appDeps{}); code == exitSuccess {
+		t.Fatal("auth login ChatGPT --device should be rejected")
+	}
+	if !strings.Contains(stderr.String(), "ChatGPT login does not support --device") {
+		t.Fatalf("stderr = %q, want the ChatGPT-specific rejection (case-insensitive)", stderr.String())
+	}
+}
+
+// TestRunAuthLoginChatGPTRejectsScope mirrors the --device rejection: --scope
+// must not be silently dropped on the ChatGPT path. The Codex client
+// registration pins a fixed scope set (incl. api.connectors.*), so custom
+// scopes are rejected up front rather than plumbed through.
+func TestRunAuthLoginChatGPTRejectsScope(t *testing.T) {
+	withAuthStore(t)
+	var stdout, stderr bytes.Buffer
+	if code := runWithDeps([]string{"auth", "login", "chatgpt", "--scope", "custom-scope"}, &stdout, &stderr, appDeps{}); code == exitSuccess {
+		t.Fatal("auth login chatgpt --scope should be rejected")
+	}
+	if !strings.Contains(stderr.String(), "ChatGPT login does not support --scope") {
+		t.Fatalf("stderr = %q, want the ChatGPT-specific --scope rejection", stderr.String())
+	}
+}

internal/cli/exec.go

@@ -508,6 +508,7 @@ func runExec(args []string, stdout io.Writer, stderr io.Writer, deps appDeps) in
 		ContextWindow:    resolveAgentContextWindow(runCtx, modelRegistry, resolved.Provider),
 		DeferThreshold:   effectiveDeferThreshold,
 		Specialists:      specialistRuntime.specialistInfos(),
+		Skills:           pluginActivation.skillInfos(deps.skillsDir()),
 		SessionID:        preparedSession.Session.SessionID,
 		CallingSessionID: options.callingSessionID,
 		CallingToolUseID: options.callingToolUseID,

internal/cli/plugin_activate.go

@@ -3,7 +3,9 @@ package cli
 import (
 	"fmt"
 	"io"
+	"strings"
 
+	"github.com/Gitlawb/zero/internal/agent"
 	"github.com/Gitlawb/zero/internal/hooks"
 	"github.com/Gitlawb/zero/internal/plugins"
 	"github.com/Gitlawb/zero/internal/tools"
@@ -57,6 +59,27 @@ func activatePlugins(workspaceRoot string, registry *tools.Registry, deps appDep
 	return pluginActivation{hooks: result.Hooks, skillRoots: result.SkillRoots}
 }
 
+// skillInfos resolves the reusable skills the model can load via the skill tool —
+// the default skills dir merged with any plugin skill roots, the same set the
+// plugin-aware skill tool resolves against — as plain data for the agent's system
+// prompt. It returns nil when no skills are installed, so a skill-less run leaves
+// the prompt byte-identical.
+func (a pluginActivation) skillInfos(defaultDir string) []agent.SkillInfo {
+	merged, _ := plugins.MergedSkills(defaultDir, a.skillRoots)
+	if len(merged) == 0 {
+		return nil
+	}
+	infos := make([]agent.SkillInfo, 0, len(merged))
+	for _, skill := range merged {
+		name := strings.TrimSpace(skill.Name)
+		if name == "" {
+			continue
+		}
+		infos = append(infos, agent.SkillInfo{Name: name, Description: strings.TrimSpace(skill.Description)})
+	}
+	return infos
+}
+
 // formatLoadDiagnostic renders a plugin load diagnostic into a single warning
 // line, prefixing the diagnostic kind and appending the most specific locator
 // available (manifest path, then plugin path, then plugin ID) so an operator can

internal/cli/setup.go

@@ -3,6 +3,7 @@ package cli
 import (
 	"fmt"
 	"io"
+	"net"
 	"net/url"
 	"strconv"
 	"strings"
@@ -453,6 +454,11 @@ func providerProfileIsLocal(profile config.ProviderProfile) bool {
 	case "localhost", "127.0.0.1", "::1":
 		return true
 	}
+	// Also treat explicit private-network IPs (192.168.x.y, 10.x.y.z,
+	// 172.16-31.x.y) as local — the user is pointing at their own LAN box.
+	if ip := net.ParseIP(parsed.Hostname()); ip != nil && ip.IsPrivate() {
+		return true
+	}
 	return false
 }
 

internal/cli/update.go

@@ -12,6 +12,7 @@ import (
 
 type updateOptions struct {
 	check      bool
+	apply      bool
 	json       bool
 	repository string
 	endpoint   string
@@ -20,6 +21,18 @@ type updateOptions struct {
 }
 
 func runUpdate(args []string, stdout io.Writer, stderr io.Writer, deps appDeps) int {
+	return runUpdateCommand(args, stdout, stderr, deps, false)
+}
+
+func runUpgrade(args []string, stdout io.Writer, stderr io.Writer, deps appDeps) int {
+	return runUpdateCommand(args, stdout, stderr, deps, true)
+}
+
+// runUpdateCommand backs both `zero update` and `zero upgrade`. defaultApply
+// makes `--apply` the implicit behavior for `zero upgrade` when neither
+// `--check` nor `--apply` is passed explicitly; `zero update` keeps requiring
+// one of the two so existing scripts around `zero update --check` don't change.
+func runUpdateCommand(args []string, stdout io.Writer, stderr io.Writer, deps appDeps, defaultApply bool) int {
 	options, help, err := parseUpdateArgs(args)
 	if err != nil {
 		return writeUsageError(stderr, err.Error())
@@ -30,10 +43,19 @@ func runUpdate(args []string, stdout io.Writer, stderr io.Writer, deps appDeps)
 		}
 		return exitSuccess
 	}
-	if !options.check {
-		return writeUsageError(stderr, "Only `zero update --check` is available right now.")
+	if options.check && options.apply {
+		return writeUsageError(stderr, "Pass only one of --check or --apply.")
 	}
-	checkOptions := update.Options{
+	if !options.check && !options.apply {
+		if !defaultApply {
+			return writeUsageError(stderr, "Pass --check to check for updates or --apply to install one (or use `zero upgrade`).")
+		}
+		options.apply = true
+	}
+	if options.apply && options.target != "" {
+		return writeUsageError(stderr, "--target cannot be combined with --apply; it only verifies release assets for --check.")
+	}
+	updateOptions := update.Options{
 		CurrentVersion: version,
 		Repository:     options.repository,
 		Endpoint:       options.endpoint,
@@ -44,10 +66,26 @@ func runUpdate(args []string, stdout io.Writer, stderr io.Writer, deps appDeps)
 		if err != nil {
 			return writeUsageError(stderr, err.Error())
 		}
-		checkOptions.GOOS = target.GOOS
-		checkOptions.GOARCH = target.GOARCH
+		updateOptions.GOOS = target.GOOS
+		updateOptions.GOARCH = target.GOARCH
 	}
-	result, err := deps.checkUpdate(context.Background(), checkOptions)
+	if options.apply {
+		result, err := deps.applyUpdate(context.Background(), updateOptions)
+		if err != nil {
+			return writeAppError(stderr, "Could not install update: "+err.Error(), exitCrash)
+		}
+		if options.json {
+			if err := writePrettyJSON(stdout, result); err != nil {
+				return exitCrash
+			}
+			return exitSuccess
+		}
+		if _, err := fmt.Fprintln(stdout, update.FormatApply(result)); err != nil {
+			return exitCrash
+		}
+		return exitSuccess
+	}
+	result, err := deps.checkUpdate(context.Background(), updateOptions)
 	if err != nil {
 		return writeAppError(stderr, "Could not check for updates: "+err.Error(), exitCrash)
 	}
@@ -72,6 +110,8 @@ func parseUpdateArgs(args []string) (updateOptions, bool, error) {
 			return options, true, nil
 		case arg == "--check":
 			options.check = true
+		case arg == "--apply":
+			options.apply = true
 		case arg == "--json":
 			options.json = true
 		case arg == "--repo":
@@ -155,14 +195,17 @@ func parseUpdateTarget(value string) (string, error) {
 func writeUpdateHelp(w io.Writer) error {
 	_, err := fmt.Fprint(w, `Usage:
   zero update --check [flags]
+  zero update --apply [flags]
+  zero upgrade [flags]
 
 Flags:
       --check                 Check the latest GitHub release without installing
-      --json                  Print the update check result as JSON
+      --apply                 Download, verify, and install the latest release
+      --json                  Print the update result as JSON
       --repo <owner/repo>     Repository to check when no endpoint is provided
       --endpoint <url|repo>   Release API URL or owner/repo slug to check
       --timeout <duration>    Release check timeout (default 5s)
-      --target <platform>     Release target to verify (for example windows-x64)
+      --target <platform>     Release target to verify with --check (for example windows-x64); not valid with --apply
   -h, --help                  Show this help
 `)
 	return err

internal/cli/workflow_test.go

@@ -662,3 +662,144 @@ func TestRunExecRejectsWorktreeDirWithoutWorktree(t *testing.T) {
 		t.Fatalf("expected empty stdout, got %q", stdout.String())
 	}
 }
+
+func TestParseChangesArgsAuto(t *testing.T) {
+	// 1. Correct parsing of auto
+	for _, args := range [][]string{
+		{"--auto"},
+		{"-a"},
+	} {
+		options, help, err := parseChangesArgs(args, "commit")
+		if err != nil {
+			t.Fatalf("parseChangesArgs(%v) error: %v", args, err)
+		}
+		if help {
+			t.Fatalf("parseChangesArgs(%v) returned help", args)
+		}
+		if !options.auto {
+			t.Fatalf("auto = false, want true (args %v)", args)
+		}
+	}
+
+	// 2. Reject --auto on inspect
+	_, _, err := parseChangesArgs([]string{"--auto"}, "inspect")
+	if err == nil || !strings.Contains(err.Error(), "--auto") {
+		t.Fatalf("expected --auto rejection on inspect, got %v", err)
+	}
+
+	// 3. Reject both --message and --auto on commit
+	_, _, err = parseChangesArgs([]string{"--message", "foo", "--auto"}, "commit")
+	if err == nil || !strings.Contains(err.Error(), "cannot specify both --message and --auto") {
+		t.Fatalf("expected --message and --auto conflict error, got %v", err)
+	}
+
+	// 4. Reject both empty message and --auto on commit
+	_, _, err = parseChangesArgs([]string{"--message=", "--auto"}, "commit")
+	if err == nil || !strings.Contains(err.Error(), "cannot specify both --message and --auto") {
+		t.Fatalf("expected empty --message and --auto conflict error, got %v", err)
+	}
+}
+
+type mockCommitMsgProvider struct {
+	response string
+	req      zeroruntime.CompletionRequest
+}
+
+func (p *mockCommitMsgProvider) StreamCompletion(ctx context.Context, request zeroruntime.CompletionRequest) (<-chan zeroruntime.StreamEvent, error) {
+	p.req = request
+	events := make(chan zeroruntime.StreamEvent, 2)
+	events <- zeroruntime.StreamEvent{Type: zeroruntime.StreamEventText, Content: p.response}
+	events <- zeroruntime.StreamEvent{Type: zeroruntime.StreamEventDone}
+	close(events)
+	return events, nil
+}
+
+func TestRunChangesCommitAuto(t *testing.T) {
+	cwd := t.TempDir()
+	summary := zerogit.ChangeSummary{
+		Root:   cwd,
+		Branch: "main",
+		Files:  []zerogit.FileChange{{Path: "README.md", Status: "modified"}},
+		Diff:   "some diff content with ghp_SECRETKEYHERE",
+	}
+
+	mockProv := &mockCommitMsgProvider{
+		response: "```\nfeat: auto commit message\n```",
+	}
+
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	commitCalled := false
+
+	exitCode := runWithDeps([]string{"changes", "commit", "--auto"}, &stdout, &stderr, appDeps{
+		getwd: func() (string, error) { return cwd, nil },
+		inspectChanges: func(ctx context.Context, options zerogit.InspectOptions) (zerogit.ChangeSummary, error) {
+			return summary, nil
+		},
+		resolveConfig: func(workspaceRoot string, overrides config.Overrides) (config.ResolvedConfig, error) {
+			cfg := execResolvedConfig()
+			cfg.Provider.Name = "openai"
+			cfg.Provider.Model = "gpt-4o"
+			return cfg, nil
+		},
+		newProvider: func(profile config.ProviderProfile) (zeroruntime.Provider, error) {
+			return mockProv, nil
+		},
+		commitChanges: func(ctx context.Context, options zerogit.CommitOptions) (zerogit.CommitResult, error) {
+			commitCalled = true
+			if options.Message != "feat: auto commit message" {
+				t.Fatalf("expected commit message 'feat: auto commit message', got %q", options.Message)
+			}
+			return zerogit.CommitResult{
+				Root:       cwd,
+				Message:    options.Message,
+				Committed:  true,
+				CommitHash: "abc1234",
+				Before:     summary,
+			}, nil
+		},
+	})
+
+	if exitCode != exitSuccess {
+		t.Fatalf("expected exit code %d, got %d: %s", exitSuccess, exitCode, stderr.String())
+	}
+	if !commitCalled {
+		t.Fatal("expected commitChanges to be called")
+	}
+	// Verify that secret in the diff was redacted
+	promptContent := mockProv.req.Messages[0].Content
+	if strings.Contains(promptContent, "ghp_SECRETKEYHERE") {
+		t.Fatal("expected secret in diff to be redacted, but it was found in the prompt")
+	}
+	if !strings.Contains(promptContent, "[REDACTED]") && !strings.Contains(promptContent, "REDACTED") {
+		t.Fatalf("expected redacted diff content in prompt, got: %q", promptContent)
+	}
+	if !strings.Contains(stdout.String(), "Generating commit message using LLM...") {
+		t.Fatalf("expected status message in stdout, got %q", stdout.String())
+	}
+
+	t.Run("EmptyLLMResponse", func(t *testing.T) {
+		mockProvEmpty := &mockCommitMsgProvider{
+			response: "   \n\n   ",
+		}
+		var stdout, stderr bytes.Buffer
+		code := runWithDeps([]string{"changes", "commit", "--auto"}, &stdout, &stderr, appDeps{
+			getwd: func() (string, error) { return cwd, nil },
+			inspectChanges: func(ctx context.Context, options zerogit.InspectOptions) (zerogit.ChangeSummary, error) {
+				return summary, nil
+			},
+			resolveConfig: func(workspaceRoot string, overrides config.Overrides) (config.ResolvedConfig, error) {
+				return execResolvedConfig(), nil
+			},
+			newProvider: func(profile config.ProviderProfile) (zeroruntime.Provider, error) {
+				return mockProvEmpty, nil
+			},
+		})
+		if code == exitSuccess {
+			t.Fatal("expected command to fail when LLM returns empty response, got success")
+		}
+		if !strings.Contains(stderr.String(), "empty commit message") {
+			t.Fatalf("expected empty commit message error in stderr, got %q", stderr.String())
+		}
+	})
+}

internal/cli/workflows.go

@@ -6,13 +6,16 @@ import (
 	"io"
 	"strconv"
 	"strings"
+	"time"
 
+	"github.com/Gitlawb/zero/internal/config"
 	"github.com/Gitlawb/zero/internal/redaction"
 	"github.com/Gitlawb/zero/internal/selfverify"
 	"github.com/Gitlawb/zero/internal/testrunner"
 	"github.com/Gitlawb/zero/internal/verify"
 	"github.com/Gitlawb/zero/internal/worktrees"
 	"github.com/Gitlawb/zero/internal/zerogit"
+	"github.com/Gitlawb/zero/internal/zeroruntime"
 )
 
 type worktreeCommandOptions struct {
@@ -35,8 +38,10 @@ type changesCommandOptions struct {
 	cwd          string
 	baseRef      string
 	message      string
+	hasMessage   bool
 	dryRun       bool
 	maxDiffBytes int
+	auto         bool
 }
 
 func runWorktrees(args []string, stdout io.Writer, stderr io.Writer, deps appDeps) int {
@@ -198,9 +203,52 @@ func runChanges(args []string, stdout io.Writer, stderr io.Writer, deps appDeps)
 		}
 		return exitSuccess
 	case "commit":
+		var message string
+		if options.auto {
+			summary, err := deps.inspectChanges(context.Background(), zerogit.InspectOptions{
+				Cwd:          workspaceRoot,
+				MaxDiffBytes: options.maxDiffBytes,
+			})
+			if err != nil {
+				return writeExecUsageError(stderr, fmt.Sprintf("failed to inspect changes: %v", err))
+			}
+			if summary.Clean {
+				return writeExecUsageError(stderr, "no changes to commit")
+			}
+
+			resolved, err := deps.resolveConfig(workspaceRoot, config.Overrides{})
+			if err != nil {
+				return writeExecUsageError(stderr, fmt.Sprintf("failed to resolve config: %v", err))
+			}
+			if !config.HasProviderProfile(resolved.Provider) {
+				return writeExecUsageError(stderr, "no provider configured for auto-commit message")
+			}
+			provider, err := deps.newProvider(resolved.Provider)
+			if err != nil {
+				return writeExecUsageError(stderr, fmt.Sprintf("failed to create provider: %v", err))
+			}
+
+			if !options.json {
+				if _, err := fmt.Fprintln(stdout, "Generating commit message using LLM..."); err != nil {
+					return exitCrash
+				}
+			}
+
+			safeSummary := redactChangeSummary(summary)
+			genCtx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
+			defer cancel()
+			msg, err := generateAutoCommitMessage(genCtx, provider, resolved.Provider.Model, safeSummary)
+			if err != nil {
+				return writeExecUsageError(stderr, fmt.Sprintf("failed to generate commit message: %v", err))
+			}
+			message = msg
+		} else {
+			message = options.message
+		}
+
 		result, err := deps.commitChanges(context.Background(), zerogit.CommitOptions{
 			Cwd:          workspaceRoot,
-			Message:      options.message,
+			Message:      message,
 			DryRun:       options.dryRun,
 			MaxDiffBytes: options.maxDiffBytes,
 		})
@@ -395,9 +443,11 @@ func parseChangesArgs(args []string, command string) (changesCommandOptions, boo
 				return options, false, err
 			}
 			options.message = value
+			options.hasMessage = true
 			index = next
 		case strings.HasPrefix(arg, "--message="):
 			options.message = strings.TrimSpace(strings.TrimPrefix(arg, "--message="))
+			options.hasMessage = true
 		case arg == "--diff-bytes":
 			value, next, err := nextFlagValue(args, index, arg)
 			if err != nil {
@@ -415,14 +465,19 @@ func parseChangesArgs(args []string, command string) (changesCommandOptions, boo
 				return options, false, err
 			}
 			options.maxDiffBytes = maxDiffBytes
+		case arg == "-a" || arg == "--auto":
+			options.auto = true
 		case strings.HasPrefix(arg, "-"):
 			return options, false, execUsageError{fmt.Sprintf("unknown changes flag %q", arg)}
 		default:
 			return options, false, execUsageError{fmt.Sprintf("unexpected changes argument %q", arg)}
 		}
 	}
-	if command != "commit" && (options.message != "" || options.dryRun) {
-		return options, false, execUsageError{"--message and --dry-run are only valid with `zero changes commit`"}
+	if command != "commit" && (options.hasMessage || options.dryRun || options.auto) {
+		return options, false, execUsageError{"--message, --dry-run, and --auto are only valid with `zero changes commit`"}
+	}
+	if command == "commit" && options.hasMessage && options.auto {
+		return options, false, execUsageError{"cannot specify both --message and --auto"}
 	}
 	if command == "commit" && options.baseRef != "" {
 		return options, false, execUsageError{"--base is only valid with `zero changes inspect`"}
@@ -712,9 +767,47 @@ Flags:
       --base <ref>        Diff against <ref>...HEAD instead of the working tree
       --diff-bytes <n>    Maximum diff bytes to include
   -m, --message <text>    Commit message for `+"`zero changes commit`"+`
+  -a, --auto              Auto-generate commit message using LLM (use --dry-run to preview)
       --dry-run           Preview commit metadata without mutating git state
       --json              Print JSON output
   -h, --help              Show this help
 `)
 	return err
 }
+
+func generateAutoCommitMessage(ctx context.Context, provider zeroruntime.Provider, model string, summary zerogit.ChangeSummary) (string, error) {
+	var promptBuilder strings.Builder
+	promptBuilder.WriteString("Analyze the following git diff and generate a concise, conventional commit message.\n")
+	promptBuilder.WriteString("The commit message subject line must be 72 characters or fewer, starting with a conventional commit type (e.g., feat, fix, docs, style, refactor, test, chore) followed by a colon and space, and a lowercase description.\n")
+	promptBuilder.WriteString("You may optionally include a blank line and a bulleted list of changes for the body if there are multiple files or complex changes.\n")
+	promptBuilder.WriteString("Output ONLY the raw commit message text. Do not wrap the message in markdown code block fence, do not include quotes or any introduction/explanation.\n\n")
+	promptBuilder.WriteString("Git Diff:\n")
+	promptBuilder.WriteString(summary.Diff)
+
+	request := zeroruntime.CompletionRequest{
+		Messages: []zeroruntime.Message{
+			{Role: zeroruntime.MessageRoleUser, Content: promptBuilder.String()},
+		},
+	}
+	stream, err := provider.StreamCompletion(ctx, request)
+	if err != nil {
+		return "", err
+	}
+	collected := zeroruntime.CollectStream(ctx, stream)
+	if collected.Error != "" {
+		return "", fmt.Errorf("%s", collected.Error)
+	}
+
+	msg := strings.TrimSpace(collected.Text)
+	if strings.HasPrefix(msg, "```") {
+		if idx := strings.Index(msg, "\n"); idx != -1 {
+			msg = msg[idx+1:]
+		}
+	}
+	msg = strings.TrimSuffix(msg, "```")
+	msg = strings.TrimSpace(msg)
+	if msg == "" {
+		return "", fmt.Errorf("provider returned empty commit message")
+	}
+	return msg, nil
+}

internal/config/resolver.go

@@ -130,7 +130,11 @@ func Resolve(options ResolveOptions) (ResolvedConfig, error) {
 
 	providers, active, err := normalizeProviders(cfg.Providers, cfg.ActiveProvider, options.Env)
 	if err != nil {
-		return ResolvedConfig{}, err
+		// On ErrNoActiveProvider, providers may still hold the successfully
+		// normalized (but active-less) profile list — keep it so a caller can fall
+		// back to an already-configured usable provider instead of treating this
+		// like a config with nothing set up at all.
+		return ResolvedConfig{Providers: providers}, err
 	}
 
 	return ResolvedConfig{
@@ -144,6 +148,7 @@ func Resolve(options ResolveOptions) (ResolvedConfig, error) {
 		Tools:          cfg.Tools,
 		Swarm:          cfg.Swarm,
 		Preferences:    cfg.Preferences,
+		KeyBindings:    cfg.KeyBindings,
 		LocalControl:   cfg.LocalControl,
 	}, nil
 }
@@ -225,6 +230,7 @@ func mergeConfig(dst *FileConfig, src FileConfig) {
 		dst.Preferences.Theme = strings.TrimSpace(src.Preferences.Theme)
 	}
 	mergeLocalControlConfig(&dst.LocalControl, src.LocalControl)
+	mergeKeyBindings(&dst.KeyBindings, src.KeyBindings)
 }
 
 func mergeProjectConfig(dst *FileConfig, src FileConfig) error {
@@ -277,6 +283,7 @@ func mergeProjectConfig(dst *FileConfig, src FileConfig) error {
 	if src.Swarm.MaxTeamSize != 0 {
 		dst.Swarm.MaxTeamSize = src.Swarm.MaxTeamSize
 	}
+	mergeKeyBindings(&dst.KeyBindings, src.KeyBindings)
 	// Local control is intentionally user-config/override only. A cloned project
 	// must not be able to make browser, desktop, or terminal automation tools
 	// appear in the model's tool surface.
@@ -665,6 +672,7 @@ func applyOverrides(cfg *FileConfig, overrides Overrides) {
 		cfg.Tools.deferThresholdSet = true
 	}
 	mergeLocalControlConfig(&cfg.LocalControl, overrides.LocalControl)
+	mergeKeyBindings(&cfg.KeyBindings, overrides.KeyBindings)
 	for _, provider := range overrides.Providers {
 		mergeProvider(cfg, provider)
 	}
@@ -700,6 +708,24 @@ func mergeLocalControlDriverConfig(dst *LocalControlDriverConfig, src LocalContr
 	}
 }
 
+func mergeKeyBindings(dst *KeyBindingsConfig, src KeyBindingsConfig) {
+	if src.ToggleDetailed != "" {
+		dst.ToggleDetailed = src.ToggleDetailed
+	}
+	if src.ToggleMouse != "" {
+		dst.ToggleMouse = src.ToggleMouse
+	}
+	if src.CycleReasoning != "" {
+		dst.CycleReasoning = src.CycleReasoning
+	}
+	if src.TogglePlan != "" {
+		dst.TogglePlan = src.TogglePlan
+	}
+	if src.ToggleSidebar != "" {
+		dst.ToggleSidebar = src.ToggleSidebar
+	}
+}
+
 func mergeMCPConfig(dst *MCPConfig, src MCPConfig) {
 	if len(src.Servers) == 0 {
 		return
@@ -834,7 +860,11 @@ func normalizeProvidersWithOptions(providers []ProviderProfile, activeName strin
 	}
 
 	if !activeFound {
-		return nil, ProviderProfile{}, fmt.Errorf("%w: active provider %q not found", ErrNoActiveProvider, activeName)
+		// Return the successfully normalized list alongside the error (rather than
+		// nil) so a caller like the interactive TUI can still fall back to an
+		// already-configured, usable provider instead of forcing a full
+		// re-onboarding wizard just because none was marked active.
+		return normalized, ProviderProfile{}, fmt.Errorf("%w: active provider %q not found", ErrNoActiveProvider, activeName)
 	}
 	if active.Model == "" {
 		return nil, ProviderProfile{}, &setupFixableError{

internal/config/resolver_test.go

@@ -916,6 +916,25 @@ func TestResolveRejectsActiveProviderWithoutConfiguredProfiles(t *testing.T) {
 	}
 }
 
+func TestResolveKeepsNormalizedProvidersWhenNoneMarkedActive(t *testing.T) {
+	// Multiple providers configured (e.g. via `zero provider add`) but
+	// activeProvider is blank/stale — a caller like the interactive TUI still
+	// needs the normalized list to fall back to an already-usable provider
+	// instead of forcing a full re-onboarding wizard.
+	path := writeConfig(t, `{"providers":[
+		{"name":"work","provider_kind":"openai","apiKey":"sk-test","model":"gpt-test"},
+		{"name":"other","provider_kind":"openai","apiKey":"sk-other","model":"gpt-test"}
+	]}`)
+
+	resolved, err := Resolve(ResolveOptions{ProjectConfigPath: path, Env: map[string]string{}})
+	if !errors.Is(err, ErrNoActiveProvider) {
+		t.Fatalf("error = %v, want errors.Is(err, ErrNoActiveProvider)", err)
+	}
+	if len(resolved.Providers) != 2 {
+		t.Fatalf("Providers = %#v, want the 2 normalized profiles preserved despite the error", resolved.Providers)
+	}
+}
+
 func TestResolveTrimsProviderProfileAliasesBeforeFallback(t *testing.T) {
 	path := writeConfig(t, `{
 		"activeProvider": "custom",

internal/config/types.go

@@ -112,6 +112,25 @@ func (p PreferencesConfig) RecapsEnabled() bool {
 	return p.Recaps == nil || *p.Recaps
 }
 
+// KeyBindingDef defines one key binding string (e.g. "ctrl+o") that the TUI
+// can remap. An empty string means "use the built-in default" for that action.
+type KeyBindingDef string
+
+// KeyBindingsConfig holds the subset of TUI keybindings that users may remap
+// via config.json. Each field defaults to a sensible built-in when empty.
+type KeyBindingsConfig struct {
+	// ToggleDetailed toggles the detailed transcript view (default: ctrl+o).
+	ToggleDetailed KeyBindingDef `json:"toggleDetailed,omitempty"`
+	// ToggleMouse toggles mouse capture release (default: ctrl+e).
+	ToggleMouse KeyBindingDef `json:"toggleMouse,omitempty"`
+	// CycleReasoning cycles through reasoning effort levels (default: ctrl+t).
+	CycleReasoning KeyBindingDef `json:"cycleReasoning,omitempty"`
+	// TogglePlan toggles the plan panel expansion (default: ctrl+p).
+	TogglePlan KeyBindingDef `json:"togglePlan,omitempty"`
+	// ToggleSidebar toggles the right context sidebar (default: ctrl+b).
+	ToggleSidebar KeyBindingDef `json:"toggleSidebar,omitempty"`
+}
+
 // LocalControlConfig controls local browser/desktop/terminal automation helpers.
 // Helpers are discovered lazily by the tool that needs them; no setup command or
 // background probe is required during startup.
@@ -206,6 +225,7 @@ type FileConfig struct {
 	Tools          ToolsConfig        `json:"tools,omitempty"`
 	Swarm          SwarmConfig        `json:"swarm,omitempty"`
 	Preferences    PreferencesConfig  `json:"preferences,omitempty"`
+	KeyBindings    KeyBindingsConfig  `json:"keybindings,omitempty"`
 	LocalControl   LocalControlConfig `json:"localControl,omitempty"`
 }
 
@@ -220,6 +240,7 @@ func (cfg FileConfig) MarshalJSON() ([]byte, error) {
 		Tools          ToolsConfig         `json:"tools,omitempty"`
 		Swarm          SwarmConfig         `json:"swarm,omitempty"`
 		Preferences    PreferencesConfig   `json:"preferences,omitempty"`
+		KeyBindings    KeyBindingsConfig   `json:"keybindings,omitempty"`
 		LocalControl   *LocalControlConfig `json:"localControl,omitempty"`
 	}
 	raw := rawConfig{
@@ -232,6 +253,7 @@ func (cfg FileConfig) MarshalJSON() ([]byte, error) {
 		Tools:          cfg.Tools,
 		Swarm:          cfg.Swarm,
 		Preferences:    cfg.Preferences,
+		KeyBindings:    cfg.KeyBindings,
 	}
 	if !cfg.LocalControl.Empty() {
 		raw.LocalControl = &cfg.LocalControl
@@ -256,6 +278,7 @@ type Overrides struct {
 	Sandbox        SandboxConfig
 	Notify         NotifyConfig
 	Tools          ToolsConfig
+	KeyBindings    KeyBindingsConfig
 	LocalControl   LocalControlConfig
 }
 
@@ -270,6 +293,7 @@ type ResolvedConfig struct {
 	Tools          ToolsConfig
 	Swarm          SwarmConfig
 	Preferences    PreferencesConfig
+	KeyBindings    KeyBindingsConfig
 	LocalControl   LocalControlConfig
 }
 
@@ -316,6 +340,7 @@ func (cfg *FileConfig) UnmarshalJSON(data []byte) error {
 		Tools           ToolsConfig                `json:"tools"`
 		Swarm           SwarmConfig                `json:"swarm"`
 		Preferences     PreferencesConfig          `json:"preferences"`
+		KeyBindings     KeyBindingsConfig          `json:"keybindings"`
 		LocalControl    LocalControlConfig         `json:"localControl"`
 		MCPServers      map[string]MCPServerConfig `json:"mcpServers"`
 		MCPServersSnake map[string]MCPServerConfig `json:"mcp_servers"`
@@ -342,6 +367,7 @@ func (cfg *FileConfig) UnmarshalJSON(data []byte) error {
 	cfg.Tools = raw.Tools
 	cfg.Swarm = raw.Swarm
 	cfg.Preferences = raw.Preferences
+	cfg.KeyBindings = raw.KeyBindings
 	cfg.LocalControl = raw.LocalControl
 	if cfg.MCP.Servers == nil && (len(raw.MCPServers) > 0 || len(raw.MCPServersSnake) > 0) {
 		cfg.MCP.Servers = map[string]MCPServerConfig{}

internal/modelregistry/catalog.go

@@ -3,6 +3,7 @@ package modelregistry
 import (
 	"fmt"
 	"strings"
+	"sync"
 )
 
 const DefaultModelID = "gpt-4.1"
@@ -42,8 +43,20 @@ type ListOptions struct {
 	Capability        ModelCapability
 }
 
-func DefaultRegistry() (Registry, error) {
+// defaultRegistry builds the default registry exactly once and caches the result.
+// The default catalog is static, every accessor returns clones, and a built
+// Registry is never mutated (concurrent reads of its maps are safe), so a single
+// shared instance is correct — and it avoids re-cloning all entries and
+// recompiling every fuzzy-match regex on the per-frame TUI paths (title chip,
+// context gauge, pickers) that call DefaultRegistry each render.
+var defaultRegistry = sync.OnceValues(func() (Registry, error) {
 	return NewRegistry(DefaultModelEntries())
+})
+
+// DefaultRegistry returns the shared, immutable default model registry, building
+// it on first use.
+func DefaultRegistry() (Registry, error) {
+	return defaultRegistry()
 }
 
 func DefaultModelEntries() []ModelEntry {
@@ -76,11 +89,13 @@ func decorateModelDepth(entries []ModelEntry) {
 		patterns      []string
 		deprecation   *DeprecationRule
 		upgradeTarget string
+		fastVariant   string
 	}{
 		"claude-sonnet-4.5": {
 			defaultEffort: ReasoningEffortMedium,
 			patterns:      []string{`(?i)^sonnet[^a-z0-9]*4[.\s]?5$`},
 			upgradeTarget: "claude-opus-4.1",
+			fastVariant:   "claude-haiku-4.5",
 		},
 		"claude-opus-4.1": {
 			defaultEffort: ReasoningEffortHigh,
@@ -94,6 +109,7 @@ func decorateModelDepth(entries []ModelEntry) {
 		"gemini-2.5-pro": {
 			defaultEffort: ReasoningEffortMedium,
 			patterns:      []string{`(?i)^gemini[^a-z0-9]*pro$`},
+			fastVariant:   "gemini-2.5-flash",
 		},
 		"gemini-2.5-flash": {
 			defaultEffort: ReasoningEffortLow,
@@ -102,6 +118,12 @@ func decorateModelDepth(entries []ModelEntry) {
 		"gemini-2.5-flash-lite": {
 			upgradeTarget: "gemini-2.5-flash",
 		},
+		"gpt-4.1": {
+			fastVariant: "gpt-4.1-mini",
+		},
+		"gpt-4o": {
+			fastVariant: "gpt-4o-mini",
+		},
 		"gpt-4.1-mini": {
 			upgradeTarget: "gpt-4.1",
 		},
@@ -143,6 +165,9 @@ func decorateModelDepth(entries []ModelEntry) {
 		if extra.upgradeTarget != "" {
 			entries[index].UpgradeTargetID = extra.upgradeTarget
 		}
+		if extra.fastVariant != "" {
+			entries[index].FastVariantID = extra.fastVariant
+		}
 	}
 }
 

internal/modelregistry/models.go

@@ -110,7 +110,14 @@ type ModelEntry struct {
 	// during mid-run escalation. Empty means no escalation target (e.g. top-tier
 	// models). Resolved and availability-checked by Registry.UpgradeTarget.
 	UpgradeTargetID string
-	Description     string
+	// FastVariantID, when set, names a genuinely faster same-family model this one
+	// can drop down to (e.g. claude-sonnet-4.5 -> claude-haiku-4.5). Empty means no
+	// fast variant. It is the single source of truth for the /fast command and the
+	// "f" fast-mode marker: Registry.FastVariant walks it forward and BaseVariant
+	// walks it in reverse, so a model is "in fast mode" iff another model names it
+	// here. Resolved and availability-checked like UpgradeTargetID.
+	FastVariantID string
+	Description   string
 }
 
 // DeprecationRule describes how a deprecated model is phased out and what to use
@@ -368,6 +375,18 @@ func NewRegistry(entries []ModelEntry) (Registry, error) {
 			return Registry{}, fmt.Errorf("model %q upgrade target %q does not resolve to a known model", entry.ID, targetID)
 		}
 	}
+	// A non-empty FastVariantID must resolve to a known model, mirroring the
+	// UpgradeTargetID check — otherwise /fast and the "f" fast-mode marker would
+	// silently vanish at runtime on a catalog typo instead of failing loudly here.
+	for _, entry := range registry.models {
+		fastID := strings.TrimSpace(entry.FastVariantID)
+		if fastID == "" {
+			continue
+		}
+		if _, ok := registry.Get(fastID); !ok {
+			return Registry{}, fmt.Errorf("model %q fast variant %q does not resolve to a known model", entry.ID, fastID)
+		}
+	}
 	return registry, nil
 }
 

internal/modelregistry/variants.go

@@ -0,0 +1,75 @@
+package modelregistry
+
+import "strings"
+
+// The base<->fast model mapping is data, not logic: it lives entirely in each
+// ModelEntry's FastVariantID field (populated in the catalog, validated in
+// NewRegistry). Adding a pair is a one-line catalog change — never a code change
+// here. Both directions derive from that one field: FastVariant walks a model to
+// the fast id it names, BaseVariant scans for the model that names id as its fast
+// variant. This is why "fast mode" is encoded by model identity and needs no flag.
+//
+// Only models with an unambiguous 1:1 fast counterpart carry a FastVariantID. A
+// model with no clean counterpart (e.g. a top-tier Opus, where both Sonnet and
+// Haiku would be candidates) is intentionally left unset, so /fast reports "no
+// fast mode available" for it rather than guessing.
+
+// FastVariant resolves id to its configured faster same-family counterpart. It
+// resolves id to a concrete entry, reads that entry's FastVariantID, and returns
+// the target only when it resolves and is not deprecated. Returns (_, false) when
+// id is unknown, has no fast variant, or the variant is unavailable/deprecated.
+// Mirrors Registry.UpgradeTarget.
+func (registry Registry) FastVariant(id string) (ModelEntry, bool) {
+	source, ok := registry.Resolve(id)
+	if !ok {
+		return ModelEntry{}, false
+	}
+	fastID := strings.TrimSpace(source.FastVariantID)
+	if fastID == "" {
+		return ModelEntry{}, false
+	}
+	target, ok := registry.Resolve(fastID)
+	if !ok || target.Status == ModelStatusDeprecated {
+		return ModelEntry{}, false
+	}
+	return target, true
+}
+
+// BaseVariant resolves id to the base model that declares id as its fast variant
+// — the reverse of FastVariant. A non-empty result therefore means id IS a fast
+// model: this is exactly how the /fast command derives "currently in fast mode"
+// without storing any flag. Same resolution and availability rules as FastVariant.
+func (registry Registry) BaseVariant(id string) (ModelEntry, bool) {
+	source, ok := registry.Resolve(id)
+	if !ok {
+		return ModelEntry{}, false
+	}
+	for _, entry := range registry.models {
+		fastID := strings.TrimSpace(entry.FastVariantID)
+		if fastID == "" {
+			continue
+		}
+		target, ok := registry.Resolve(fastID)
+		if !ok || target.ID != source.ID {
+			continue
+		}
+		if entry.Status == ModelStatusDeprecated {
+			return ModelEntry{}, false
+		}
+		base, ok := registry.Resolve(entry.ID)
+		if !ok {
+			return ModelEntry{}, false
+		}
+		return base, true
+	}
+	return ModelEntry{}, false
+}
+
+// HasFastVariant reports whether id has an available fast variant — i.e. whether
+// `/fast on` would switch to a faster model from here. It is the predicate the
+// TUI uses to show the "f" fast-mode marker on a model (in the model/provider
+// pickers and the active-model indicator).
+func (registry Registry) HasFastVariant(id string) bool {
+	_, ok := registry.FastVariant(id)
+	return ok
+}

internal/modelregistry/variants_test.go

@@ -0,0 +1,145 @@
+package modelregistry
+
+import "testing"
+
+func testRegistry(t *testing.T) Registry {
+	t.Helper()
+	registry, err := DefaultRegistry()
+	if err != nil {
+		t.Fatalf("DefaultRegistry() error = %v", err)
+	}
+	return registry
+}
+
+// expectedFastPairs is the known-good base->fast mapping. It is a literal
+// regression guard: if the catalog silently drops or mis-wires a FastVariantID,
+// the forward/reverse assertions below fail loudly rather than making /fast a
+// quiet no-op. Keep in sync with the FastVariantID fields in catalog.go.
+var expectedFastPairs = map[string]string{
+	"claude-sonnet-4.5": "claude-haiku-4.5",
+	"gpt-4.1":           "gpt-4.1-mini",
+	"gpt-4o":            "gpt-4o-mini",
+	"gemini-2.5-pro":    "gemini-2.5-flash",
+}
+
+// Every FastVariantID declared in the catalog must resolve to a real, non-self,
+// non-deprecated model. NewRegistry already rejects an unresolvable id at build
+// time; this additionally guards the runtime availability contract that /fast and
+// the "f" marker depend on.
+func TestCatalogFastVariantsResolve(t *testing.T) {
+	registry := testRegistry(t)
+	for _, entry := range registry.List(ListOptions{IncludeDeprecated: true}) {
+		if entry.FastVariantID == "" {
+			continue
+		}
+		target, ok := registry.Resolve(entry.FastVariantID)
+		if !ok {
+			t.Errorf("model %q fast variant %q does not resolve", entry.ID, entry.FastVariantID)
+			continue
+		}
+		if target.ID == entry.ID {
+			t.Errorf("model %q names itself as its fast variant", entry.ID)
+		}
+		if target.Status == ModelStatusDeprecated {
+			t.Errorf("model %q fast variant %q is deprecated", entry.ID, entry.FastVariantID)
+		}
+	}
+}
+
+// No model may be both a base and a fast, or the two directions become ambiguous
+// (a model would be "currently fast" AND advertise a fast variant). Derived from
+// the registry so a bad catalog edit — e.g. chaining mini->nano — is caught.
+func TestFastVariantPairsUnambiguous(t *testing.T) {
+	registry := testRegistry(t)
+	role := map[string]string{} // canonical id -> "base" | "fast"
+	assign := func(id, r string) {
+		entry, ok := registry.Resolve(id)
+		if !ok {
+			return
+		}
+		if prev, seen := role[entry.ID]; seen && prev != r {
+			t.Fatalf("model %q is declared as both a base and a fast variant", entry.ID)
+		}
+		role[entry.ID] = r
+	}
+	for _, entry := range registry.List(ListOptions{IncludeDeprecated: true}) {
+		if entry.FastVariantID == "" {
+			continue
+		}
+		assign(entry.ID, "base")
+		assign(entry.FastVariantID, "fast")
+	}
+}
+
+// The known pairs must be present and wired in both directions, and neither end
+// may leak into the other role (a base is not itself fast; a fast has no fast).
+func TestFastVariantAndBaseVariant(t *testing.T) {
+	registry := testRegistry(t)
+
+	for base, fast := range expectedFastPairs {
+		// base -> fast (forward), and the fast id has NO fast variant of its own.
+		if got, ok := registry.FastVariant(base); !ok {
+			t.Errorf("FastVariant(%q) = not found, want the fast variant", base)
+		} else if canon, _ := registry.Resolve(fast); got.ID != canon.ID {
+			t.Errorf("FastVariant(%q).ID = %q, want %q", base, got.ID, canon.ID)
+		}
+		if _, ok := registry.FastVariant(fast); ok {
+			t.Errorf("FastVariant(%q) resolved, but a fast model should have no fast variant", fast)
+		}
+
+		// fast -> base (reverse), and the base id is NOT itself a fast variant.
+		if got, ok := registry.BaseVariant(fast); !ok {
+			t.Errorf("BaseVariant(%q) = not found, want the base variant", fast)
+		} else if canon, _ := registry.Resolve(base); got.ID != canon.ID {
+			t.Errorf("BaseVariant(%q).ID = %q, want %q", fast, got.ID, canon.ID)
+		}
+		if _, ok := registry.BaseVariant(base); ok {
+			t.Errorf("BaseVariant(%q) resolved, but a base model is not a fast variant", base)
+		}
+	}
+}
+
+// HasFastVariant is the TUI marker predicate: true only for base models with an
+// available fast variant, false for the fast models themselves, unpaired models,
+// and unknown ids.
+func TestHasFastVariant(t *testing.T) {
+	registry := testRegistry(t)
+	for base, fast := range expectedFastPairs {
+		if !registry.HasFastVariant(base) {
+			t.Errorf("HasFastVariant(%q) = false, want true", base)
+		}
+		if registry.HasFastVariant(fast) {
+			t.Errorf("HasFastVariant(%q) = true, want false (a fast model has no fast variant)", fast)
+		}
+	}
+	for _, id := range []string{"claude-opus-4.1", "definitely-not-a-real-model", ""} {
+		if registry.HasFastVariant(id) {
+			t.Errorf("HasFastVariant(%q) = true, want false", id)
+		}
+	}
+}
+
+func TestFastVariantAbsentAndUnknown(t *testing.T) {
+	registry := testRegistry(t)
+
+	// A real model with no configured fast/base variant reports none in both
+	// directions (a valid, handled case — /fast will say "no fast mode available").
+	const noVariant = "claude-opus-4.1"
+	if _, ok := registry.Resolve(noVariant); !ok {
+		t.Skipf("%q not in registry; skipping no-variant case", noVariant)
+	}
+	if _, ok := registry.FastVariant(noVariant); ok {
+		t.Errorf("FastVariant(%q) resolved, want none", noVariant)
+	}
+	if _, ok := registry.BaseVariant(noVariant); ok {
+		t.Errorf("BaseVariant(%q) resolved, want none", noVariant)
+	}
+
+	// An unknown id resolves to nothing in either direction.
+	if _, ok := registry.FastVariant("definitely-not-a-real-model"); ok {
+		t.Error("FastVariant(unknown) resolved, want none")
+	}
+	if _, ok := registry.BaseVariant("definitely-not-a-real-model"); ok {
+		t.Error("BaseVariant(unknown) resolved, want none")
+	}
+}

internal/oauth/encrypt.go

@@ -114,7 +114,12 @@ func createSecretFile(path string) ([]byte, error) {
 			}
 			return writeNewSecretFile(path)
 		}
-		if !errors.Is(err, os.ErrExist) {
+		// On Windows a concurrent holder's os.Remove leaves the lock file in a
+		// "delete pending" state, so an O_EXCL create races it with
+		// ERROR_ACCESS_DENIED (os.ErrPermission) rather than ErrExist. Treat that
+		// as contention and retry too — mirroring acquireFileLock in lock.go —
+		// otherwise concurrent secret creation spuriously fails on Windows.
+		if !errors.Is(err, os.ErrExist) && !errors.Is(err, os.ErrPermission) {
 			return nil, fmt.Errorf("oauth: create token secret lock: %w", err)
 		}
 		if data, rerr := readSecretFileRetry(path); rerr == nil {

internal/providerhealth/connectivity_client_test.go

@@ -169,8 +169,8 @@ func TestValidateEndpointAllowsLoopbackOnlyForLocalProvider(t *testing.T) {
 		if err := validateEndpoint(ctx, ep, r, true); err != nil {
 			t.Errorf("local provider endpoint %q should be allowed with allowLoopback=true, got %v", ep, err)
 		}
-		if !endpointIsLoopback(ep) {
-			t.Errorf("endpointIsLoopback(%q) = false, want true", ep)
+		if !endpointIsLoopbackOrPrivate(ep) {
+			t.Errorf("endpointIsLoopbackOrPrivate(%q) = false, want true", ep)
 		}
 	}
 
@@ -179,14 +179,27 @@ func TestValidateEndpointAllowsLoopbackOnlyForLocalProvider(t *testing.T) {
 		t.Error("loopback must remain blocked when allowLoopback=false (redirects / non-local)")
 	}
 
-	// allowLoopback relaxes loopback ONLY — other special ranges (cloud metadata,
-	// link-local, private) stay blocked even for a local provider config.
-	for _, ep := range []string{"http://169.254.169.254/latest/meta-data", "http://10.0.0.5:8080/v1"} {
+	// allowLoopbackOrPrivate relaxes loopback AND private-network ranges — but
+	// link-local and other special ranges (cloud metadata, documentation) stay
+	// blocked even for a local provider config.
+	for _, ep := range []string{"http://169.254.169.254/latest/meta-data", "http://192.0.2.1:8080/v1"} {
 		if err := validateEndpoint(ctx, ep, staticResolver{addr: netip.MustParseAddr("169.254.169.254")}, true); err == nil {
-			t.Errorf("non-loopback special address %q must stay blocked even with allowLoopback=true", ep)
+			t.Errorf("special-use address %q must stay blocked even with flag=true", ep)
 		}
-		if endpointIsLoopback(ep) {
-			t.Errorf("endpointIsLoopback(%q) = true, want false", ep)
+		if endpointIsLoopbackOrPrivate(ep) {
+			t.Errorf("endpointIsLoopbackOrPrivate(%q) = true, want false", ep)
+		}
+	}
+
+	// Private-network addresses (192.168.x.y / 10.x.y.z / 172.16.x.y) are
+	// now allowed when the flag is true — the user is pointing at their own
+	// LAN box (e.g. llama.cpp on another local machine).
+	for _, ep := range []string{"http://192.168.1.100:8080/v1", "http://10.0.0.5:8080/v1", "http://172.16.0.10:8080/v1"} {
+		if err := validateEndpoint(ctx, ep, staticResolver{addr: netip.MustParseAddr("192.168.1.100")}, true); err != nil {
+			t.Errorf("private-network address %q should be allowed with flag=true, got %v", ep, err)
+		}
+		if !endpointIsLoopbackOrPrivate(ep) {
+			t.Errorf("endpointIsLoopbackOrPrivate(%q) = false, want true", ep)
 		}
 	}
 }

internal/providerhealth/providerhealth.go

@@ -269,7 +269,7 @@ func connectivityCheck(ctx context.Context, profile config.ProviderProfile, kind
 	requestCtx, cancel := context.WithTimeout(ctx, timeout)
 	defer cancel()
 
-	request, allowLoopback, err := healthRequest(requestCtx, profile, kind, options)
+	request, allowLoopbackOrPrivate, err := healthRequest(requestCtx, profile, kind, options)
 	if err != nil {
 		category := CategoryConfig
 		var safety endpointSafetyError
@@ -280,7 +280,7 @@ func connectivityCheck(ctx context.Context, profile config.ProviderProfile, kind
 	}
 	client := options.HTTPClient
 	if client == nil {
-		client = newConnectivityClient(timeout, options.Resolver, sensitiveAuthHeaderNames(profile, kind), allowLoopback)
+		client = newConnectivityClient(timeout, options.Resolver, sensitiveAuthHeaderNames(profile, kind), allowLoopbackOrPrivate)
 	}
 	response, err := client.Do(request)
 	if err != nil {
@@ -332,8 +332,8 @@ func healthRequest(ctx context.Context, profile config.ProviderProfile, kind con
 	// Loopback is permitted only when the user's OWN configured base_url is loopback
 	// (a local provider like Ollama/LM Studio) — never for a redirect target. This is
 	// the flag returned to the caller so the dial path applies the same policy. (AUDIT-H1)
-	allowLoopback := endpointIsLoopback(endpoint)
-	if err := validateEndpoint(ctx, endpoint, options.Resolver, allowLoopback); err != nil {
+	allowLoopbackOrPrivate := endpointIsLoopbackOrPrivate(endpoint)
+	if err := validateEndpoint(ctx, endpoint, options.Resolver, allowLoopbackOrPrivate); err != nil {
 		return nil, false, err
 	}
 	request, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
@@ -344,7 +344,7 @@ func healthRequest(ctx context.Context, profile config.ProviderProfile, kind con
 		request.Header.Set("User-Agent", options.UserAgent)
 	}
 	applyAuth(request, profile, kind)
-	return request, allowLoopback, nil
+	return request, allowLoopbackOrPrivate, nil
 }
 
 func resolvedBaseURL(profile config.ProviderProfile, kind config.ProviderKind) (string, error) {
@@ -367,11 +367,11 @@ func resolvedBaseURL(profile config.ProviderProfile, kind config.ProviderKind) (
 }
 
 // validateEndpoint enforces the SSRF policy for the provider connectivity probe.
-// allowLoopback permits loopback hosts (localhost / 127.0.0.0/8 / ::1) ONLY — it is
-// set true exclusively for the user's own explicitly-configured local provider
-// base_url (e.g. Ollama/LM Studio), never for redirect targets, and it relaxes
-// loopback alone (other private/special ranges, incl. cloud metadata, stay blocked).
-func validateEndpoint(ctx context.Context, endpoint string, resolver Resolver, allowLoopback bool) error {
+// allowLoopbackOrPrivate permits loopback hosts (localhost / 127.0.0.0/8 / ::1)
+// and private-network hosts (192.168.0.0/16 / 10.0.0.0/8 / 172.16.0.0/12) — it
+// is set true exclusively for the user's own explicitly-configured base_url
+// (e.g. Ollama/LM Studio on the LAN), never for redirect targets.
+func validateEndpoint(ctx context.Context, endpoint string, resolver Resolver, allowLoopbackOrPrivate bool) error {
 	parsed, err := url.Parse(endpoint)
 	if err != nil {
 		return err
@@ -385,13 +385,13 @@ func validateEndpoint(ctx context.Context, endpoint string, resolver Resolver, a
 	}
 	normalized := strings.TrimSuffix(strings.ToLower(host), ".")
 	if normalized == "localhost" || strings.HasSuffix(normalized, ".localhost") {
-		if allowLoopback {
+		if allowLoopbackOrPrivate {
 			return nil // user-configured local provider; loopback is intentional
 		}
 		return endpointSafetyError{message: "provider connectivity URL is unsafe: localhost hosts are blocked"}
 	}
 	if addr, err := netip.ParseAddr(normalized); err == nil {
-		if reason := blockedAddrReason(addr); reason != "" && !(allowLoopback && addr.IsLoopback()) {
+		if reason := blockedAddrReason(addr); reason != "" && !(allowLoopbackOrPrivate && (addr.IsLoopback() || addr.IsPrivate())) {
 			return endpointSafetyError{message: "provider connectivity URL is unsafe: " + reason}
 		}
 		return nil
@@ -407,17 +407,19 @@ func validateEndpoint(ctx context.Context, endpoint string, resolver Resolver, a
 		return endpointSafetyError{message: "provider connectivity host resolved to no addresses"}
 	}
 	for _, addr := range addrs {
-		if reason := blockedAddrReason(addr); reason != "" && !(allowLoopback && addr.IsLoopback()) {
+		if reason := blockedAddrReason(addr); reason != "" && !(allowLoopbackOrPrivate && (addr.IsLoopback() || addr.IsPrivate())) {
 			return endpointSafetyError{message: "provider connectivity URL is unsafe: " + reason}
 		}
 	}
 	return nil
 }
 
-// endpointIsLoopback reports whether the configured endpoint's host is a loopback
-// host the user typed themselves (localhost or a 127.0.0.0/8 / ::1 literal). Used to
-// decide whether the connectivity probe may reach the user's own local provider.
-func endpointIsLoopback(endpoint string) bool {
+// endpointIsLoopbackOrPrivate reports whether the configured endpoint's host is a loopback
+// or private-network host the user typed themselves — a local provider on the LAN
+// (e.g. 192.168.x.y / 10.x.y.z) or localhost. Used to decide whether the
+// connectivity probe may relax address-blocking and reach the user's own
+// explicitly-configured provider.
+func endpointIsLoopbackOrPrivate(endpoint string) bool {
 	parsed, err := url.Parse(endpoint)
 	if err != nil {
 		return false
@@ -427,7 +429,7 @@ func endpointIsLoopback(endpoint string) bool {
 		return true
 	}
 	if addr, err := netip.ParseAddr(host); err == nil {
-		return addr.IsLoopback()
+		return addr.IsLoopback() || addr.IsPrivate()
 	}
 	return false
 }
@@ -446,7 +448,7 @@ const maxConnectivityRedirects = 5
 //     time and then dials the validated IP literal, closing the TOCTOU window
 //     between the pre-flight validateEndpoint check and the actual connection
 //     (DNS rebinding).
-func newConnectivityClient(timeout time.Duration, resolver Resolver, sensitiveHeaders []string, allowLoopback bool) *http.Client {
+func newConnectivityClient(timeout time.Duration, resolver Resolver, sensitiveHeaders []string, allowLoopbackOrPrivate bool) *http.Client {
 	if resolver == nil {
 		resolver = defaultResolver{}
 	}
@@ -456,7 +458,7 @@ func newConnectivityClient(timeout time.Duration, resolver Resolver, sensitiveHe
 	} else {
 		transport = &http.Transport{}
 	}
-	transport.DialContext = safeDialContext(resolver, allowLoopback)
+	transport.DialContext = safeDialContext(resolver, allowLoopbackOrPrivate)
 	return &http.Client{
 		Timeout:   timeout,
 		Transport: transport,
@@ -476,8 +478,8 @@ func newConnectivityClient(timeout time.Duration, resolver Resolver, sensitiveHe
 				}
 			}
 			// Redirects are NEVER allowed to reach loopback, even for a local provider:
-			// allowLoopback covers only the user's own configured base_url, not a 3xx
-			// target (which could be attacker-controlled SSRF). (AUDIT-H1)
+			// allowLoopbackOrPrivate covers only the user's own configured base_url,
+			// not a 3xx target (which could be attacker-controlled SSRF). (AUDIT-H1)
 			return validateEndpoint(req.Context(), req.URL.String(), resolver, false)
 		},
 	}
@@ -519,7 +521,7 @@ func sensitiveAuthHeaderNames(profile config.ProviderProfile, kind config.Provid
 // safeDialContext returns a dial function that resolves the target host, refuses
 // the connection if any resolved address is blocked, then dials the validated IP
 // literal so the kernel cannot re-resolve to a different address after the check.
-func safeDialContext(resolver Resolver, allowLoopback bool) func(context.Context, string, string) (net.Conn, error) {
+func safeDialContext(resolver Resolver, allowLoopbackOrPrivate bool) func(context.Context, string, string) (net.Conn, error) {
 	dialer := &net.Dialer{Timeout: 10 * time.Second, KeepAlive: 30 * time.Second}
 	return func(ctx context.Context, network, address string) (net.Conn, error) {
 		host, port, err := net.SplitHostPort(address)
@@ -527,7 +529,7 @@ func safeDialContext(resolver Resolver, allowLoopback bool) func(context.Context
 			return nil, err
 		}
 		if addr, parseErr := netip.ParseAddr(host); parseErr == nil {
-			if reason := blockedAddrReason(addr); reason != "" && !(allowLoopback && addr.IsLoopback()) {
+			if reason := blockedAddrReason(addr); reason != "" && !(allowLoopbackOrPrivate && (addr.IsLoopback() || addr.IsPrivate())) {
 				return nil, endpointSafetyError{message: "provider connectivity URL is unsafe: " + reason}
 			}
 			return dialer.DialContext(ctx, network, address)
@@ -540,7 +542,7 @@ func safeDialContext(resolver Resolver, allowLoopback bool) func(context.Context
 			return nil, endpointSafetyError{message: "provider connectivity host resolved to no addresses"}
 		}
 		for _, addr := range addrs {
-			if reason := blockedAddrReason(addr); reason != "" && !(allowLoopback && addr.IsLoopback()) {
+			if reason := blockedAddrReason(addr); reason != "" && !(allowLoopbackOrPrivate && (addr.IsLoopback() || addr.IsPrivate())) {
 				return nil, endpointSafetyError{message: "provider connectivity URL is unsafe: " + reason}
 			}
 		}

internal/sandbox/manager_test.go

@@ -72,6 +72,9 @@ func TestPermissionProfileFromPolicyIncludesDefaultTempWriteRoots(t *testing.T)
 	if !writeRootsContain(profile.FileSystem.WriteRoots, tmpdir) {
 		t.Fatalf("write roots = %#v, want temp root %q", profile.FileSystem.WriteRoots, tmpdir)
 	}
+	// /tmp is a default temp write root on POSIX only (see
+	// defaultTempWriteRootCandidatesForGOOS); on Windows the bare path resolves
+	// against the current drive, so a stray C:\tmp must not turn this on.
 	if runtime.GOOS != "windows" && pathExists("/tmp") && !writeRootsContain(profile.FileSystem.WriteRoots, "/tmp") {
 		t.Fatalf("write roots = %#v, want /tmp", profile.FileSystem.WriteRoots)
 	}

internal/sandbox/scope_test.go

@@ -129,6 +129,9 @@ func TestNewScopeNormalizesAndValidatesExtraRoots(t *testing.T) {
 	if !stringSliceContains(roots, normalizeWorkspaceRootBestEffort(extra)) {
 		t.Fatalf("Roots()=%v want extra root %q", roots, normalizeWorkspaceRootBestEffort(extra))
 	}
+	// /tmp is a default temp write root on POSIX only (see
+	// defaultTempWriteRootCandidatesForGOOS); on Windows the bare path resolves
+	// against the current drive, so a stray C:\tmp must not turn this on.
 	if runtime.GOOS != "windows" && pathExists("/tmp") && !stringSliceContains(roots, normalizeWorkspaceRootBestEffort("/tmp")) {
 		t.Fatalf("Roots()=%v want default /tmp write root", roots)
 	}

internal/sandbox/windows_unelevated.go

@@ -61,8 +61,10 @@ func buildWindowsUnelevatedAppliedPlan(config WindowsSandboxCommandConfig) (Wind
 
 // loadWindowsUnelevatedSetupMarker reads the marker; a missing file is the
 // common first-run state and returns an empty marker, not an error. A marker
-// with an unexpected schema version is treated as empty so the runner re-applies
-// (and rewrites) rather than failing.
+// with an unexpected schema version or a corrupt/truncated body is likewise
+// treated as empty so the runner re-applies (and rewrites) rather than failing:
+// the marker only memoizes idempotent ACL applies, so resetting it can only
+// cost redundant work, never skip enforcement.
 func loadWindowsUnelevatedSetupMarker(sandboxHome string) (WindowsUnelevatedSetupMarker, error) {
 	sandboxHome = strings.TrimSpace(sandboxHome)
 	if sandboxHome == "" {
@@ -78,7 +80,7 @@ func loadWindowsUnelevatedSetupMarker(sandboxHome string) (WindowsUnelevatedSetu
 	}
 	var marker WindowsUnelevatedSetupMarker
 	if err := json.Unmarshal(bytes, &marker); err != nil {
-		return WindowsUnelevatedSetupMarker{}, fmt.Errorf("parse windows unelevated setup marker %s: %w", path, err)
+		return WindowsUnelevatedSetupMarker{SchemaVersion: windowsUnelevatedSetupMarkerSchemaVersion}, nil
 	}
 	if marker.SchemaVersion != windowsUnelevatedSetupMarkerSchemaVersion {
 		return WindowsUnelevatedSetupMarker{SchemaVersion: windowsUnelevatedSetupMarkerSchemaVersion}, nil

internal/sandbox/windows_unelevated_test.go

@@ -138,6 +138,38 @@ func TestWindowsUnelevatedSetupMarkerEvictsOldestPastCap(t *testing.T) {
 	}
 }
 
+func TestLoadWindowsUnelevatedSetupMarkerSelfHealsCorruptFile(t *testing.T) {
+	home := filepath.Join(t.TempDir(), ".zero-sandbox")
+	if err := os.MkdirAll(home, 0o700); err != nil {
+		t.Fatalf("mkdir sandbox home: %v", err)
+	}
+	path := WindowsUnelevatedSetupMarkerPath(home)
+	// A truncated body must reset like an unknown schema, not brick every
+	// unelevated command until the file is hand-deleted.
+	if err := os.WriteFile(path, []byte(`{"schemaVersion":1,"appliedPlans":[{"aclPlanHash":"h`), 0o600); err != nil {
+		t.Fatalf("write corrupt marker: %v", err)
+	}
+	marker, err := loadWindowsUnelevatedSetupMarker(home)
+	if err != nil {
+		t.Fatalf("corrupt marker must self-heal, got error: %v", err)
+	}
+	if len(marker.AppliedPlans) != 0 || marker.SchemaVersion != windowsUnelevatedSetupMarkerSchemaVersion {
+		t.Fatalf("corrupt marker must reset to empty current-schema marker, got %+v", marker)
+	}
+	// The healed marker must accept new recordings over the corrupt file.
+	applied := WindowsUnelevatedAppliedPlan{ACLPlanHash: "hash-heal", ACLPlanEntries: 2}
+	if err := recordWindowsUnelevatedAppliedPlan(home, applied); err != nil {
+		t.Fatalf("record over corrupt marker: %v", err)
+	}
+	marker, err = loadWindowsUnelevatedSetupMarker(home)
+	if err != nil {
+		t.Fatalf("reload healed marker: %v", err)
+	}
+	if !marker.contains(applied) {
+		t.Fatalf("healed marker = %+v, want the recorded plan", marker)
+	}
+}
+
 func TestLoadWindowsUnelevatedSetupMarkerResetsUnknownSchema(t *testing.T) {
 	home := filepath.Join(t.TempDir(), ".zero-sandbox")
 	if err := os.MkdirAll(home, 0o700); err != nil {

internal/sessions/exec_session.go

@@ -160,10 +160,7 @@ func FormatExecPrompt(prompt string, prepared PreparedExec) string {
 	if prepared.Mode == ModeNew || len(prepared.ContextEvents) == 0 {
 		return prompt
 	}
-	events := prepared.ContextEvents
-	if len(events) > 20 {
-		events = events[len(events)-20:]
-	}
+	events := promptContextEvents(prepared.ContextEvents)
 
 	lines := []string{}
 	for _, event := range events {
@@ -187,6 +184,25 @@ func FormatExecPrompt(prompt string, prepared PreparedExec) string {
 	}, "\n")
 }
 
+func promptContextEvents(events []Event) []Event {
+	const maxPromptContextEvents = 80
+
+	filtered := make([]Event, 0, len(events))
+	for _, event := range events {
+		switch event.Type {
+		case EventMessage, EventCompaction, EventSessionFork, EventSessionChild, EventSpecialistStart, EventSpecialistStop, EventError:
+			filtered = append(filtered, event)
+		}
+	}
+	if len(filtered) == 0 {
+		filtered = append(filtered, events...)
+	}
+	if len(filtered) > maxPromptContextEvents {
+		filtered = filtered[len(filtered)-maxPromptContextEvents:]
+	}
+	return filtered
+}
+
 func forkTitle(title string) string {
 	if title == "" {
 		return ""

internal/sessions/replay.go

@@ -71,7 +71,7 @@ type CompactionPayload struct {
 	Truncated                bool       `json:"truncated,omitempty"`
 }
 
-const defaultCompactionPreserveLast = 8
+const defaultCompactionPreserveLast = 6
 const defaultCompactionMaxPromptChars = 8000
 
 func (store *Store) PlanRewind(sessionID string, options RewindOptions) (RewindPlan, error) {

internal/sessions/store_test.go

@@ -555,6 +555,91 @@ func TestPrepareExecSessionResolvesResumeAndFork(t *testing.T) {
 	}
 }
 
+func TestFormatExecPromptKeepsConversationMessagesWhenNoisyEventsFollow(t *testing.T) {
+	events := []Event{
+		{Sequence: 1, Type: EventMessage, Payload: json.RawMessage(`{"role":"user","content":"first user request"}`)},
+		{Sequence: 2, Type: EventMessage, Payload: json.RawMessage(`{"role":"assistant","content":"first assistant answer"}`)},
+	}
+	for sequence := 3; sequence <= 45; sequence++ {
+		events = append(events, Event{Sequence: sequence, Type: EventToolResult, Payload: json.RawMessage(`{"name":"read_file","output":"noisy tool result"}`)})
+	}
+	events = append(events, Event{Sequence: 46, Type: EventMessage, Payload: json.RawMessage(`{"role":"user","content":"latest user request"}`)})
+
+	prompt := FormatExecPrompt("continue", PreparedExec{
+		Mode:          ModeResume,
+		Session:       Metadata{SessionID: "session-with-noise"},
+		ContextEvents: events,
+	})
+
+	for _, want := range []string{"first user request", "first assistant answer", "latest user request", "Current user request:", "continue"} {
+		if !strings.Contains(prompt, want) {
+			t.Fatalf("expected prompt to contain %q, got %q", want, prompt)
+		}
+	}
+	if strings.Contains(prompt, "noisy tool result") {
+		t.Fatalf("expected prompt to omit noisy non-conversation events, got %q", prompt)
+	}
+}
+
+func TestFormatExecPromptTruncatesConversationMessagesAfterFilteringNoise(t *testing.T) {
+	events := make([]Event, 0, 100)
+	for sequence := 1; sequence <= 85; sequence++ {
+		events = append(events, Event{
+			Sequence: sequence,
+			Type:     EventMessage,
+			Payload:  json.RawMessage(fmt.Sprintf(`{"role":"user","content":"conversation message %03d"}`, sequence)),
+		})
+		if sequence%10 == 0 {
+			events = append(events, Event{
+				Sequence: 1000 + sequence,
+				Type:     EventToolResult,
+				Payload:  json.RawMessage(fmt.Sprintf(`{"name":"read_file","output":"noisy tool result %03d"}`, sequence)),
+			})
+		}
+	}
+	events = append(events, Event{
+		Sequence: 2000,
+		Type:     EventToolResult,
+		Payload:  json.RawMessage(`{"name":"bash","output":"trailing noisy tool result"}`),
+	})
+
+	contextEvents := promptContextEvents(events)
+	if len(contextEvents) != 80 {
+		t.Fatalf("expected prompt context to keep 80 events, got %d", len(contextEvents))
+	}
+	if contextEvents[0].Sequence != 6 || contextEvents[len(contextEvents)-1].Sequence != 85 {
+		t.Fatalf("expected prompt context to keep message sequences 6-85, got first=%d last=%d", contextEvents[0].Sequence, contextEvents[len(contextEvents)-1].Sequence)
+	}
+
+	prompt := FormatExecPrompt("continue", PreparedExec{
+		Mode:          ModeResume,
+		Session:       Metadata{SessionID: "long-session-with-noise"},
+		ContextEvents: events,
+	})
+
+	if got, want := strings.Count(prompt, "- #"), len(contextEvents); got != want {
+		t.Fatalf("expected prompt to contain %d context event lines, got %d in %q", want, got, prompt)
+	}
+	for _, want := range []string{"conversation message 006", "conversation message 085", "Current user request:", "continue"} {
+		if !strings.Contains(prompt, want) {
+			t.Fatalf("expected prompt to contain %q, got %q", want, prompt)
+		}
+	}
+	for _, unwanted := range []string{
+		"conversation message 001",
+		"conversation message 002",
+		"conversation message 003",
+		"conversation message 004",
+		"conversation message 005",
+		"noisy tool result",
+		"trailing noisy tool result",
+	} {
+		if strings.Contains(prompt, unwanted) {
+			t.Fatalf("expected prompt to omit %q, got %q", unwanted, prompt)
+		}
+	}
+}
+
 func TestPrepareExecPersistsSpecialistMetadataForNewSession(t *testing.T) {
 	store := NewStore(StoreOptions{RootDir: t.TempDir(), Now: fixedClock("2026-06-04T14:30:00Z")})
 

internal/tools/bash_tool_test.go

@@ -161,6 +161,35 @@ func TestDetectShellCommandIssueRequiresActualLSCommand(t *testing.T) {
 	}
 }
 
+func TestDetectShellCommandIssueFlagsPipedPosixUtilities(t *testing.T) {
+	for _, command := range []string{
+		`git log --oneline -- pinokio_compat.py | head`,
+		`git blame -L 40,46 pinokio_compat.py --format=%author | grep summary`,
+		`cat file.txt | wc -l`,
+		`some_command | tail -n 20`,
+	} {
+		if issue := detectShellCommandIssue(command, "windows"); issue == nil {
+			t.Fatalf("expected POSIX utility pipeline to be flagged for %q", command)
+		}
+	}
+}
+
+func TestDetectShellCommandIssueAllowsUnrelatedCommands(t *testing.T) {
+	for _, command := range []string{
+		`git log --oneline`,
+		`dir /b`,
+		`findstr /r "summary" file.txt`,
+		`echo header text`,
+		`tail-log.sh`,
+		`grep-cli --version`,
+		`sed.exe --help`,
+	} {
+		if issue := detectShellCommandIssue(command, "windows"); issue != nil {
+			t.Fatalf("expected unrelated command to pass for %q, got %#v", command, issue)
+		}
+	}
+}
+
 func TestDetectShellOutputIssueAddsWindowsSyntaxHint(t *testing.T) {
 	issue := detectShellOutputIssue(`cd /d/tmp/zero-pr-158 && ls -la`, "The syntax of the command is incorrect.", "windows")
 	if issue == nil {

internal/tools/shell_runtime.go

@@ -20,6 +20,11 @@ type shellIssue struct {
 var (
 	windowsBashStyleCDPattern = regexp.MustCompile(`(?i)(^|[&|;]\s*)cd\s+/(?:[a-ce-z0-9_./~-]|d[a-z0-9_./~-])[a-z0-9_./~-]*`)
 	windowsLSCommandPattern   = regexp.MustCompile(`(?i)(^|[&|;]\s*)ls\b(?:\s+|$)`)
+	// windowsPosixUtilityPattern catches the other common POSIX coreutils/grep
+	// family commands cmd.exe has no equivalent for (unlike `dir`/`findstr`,
+	// which sound similar enough that a model might reach for the POSIX name
+	// instead) — most often seen piped in, e.g. `git log ... | head`.
+	windowsPosixUtilityPattern = regexp.MustCompile(`(?i)(^|[&|;]\s*)(head|tail|grep|wc|awk|sed|cut|xargs|tr)(?:\s+|$)`)
 )
 
 func detectShellRuntime(goos string) shellRuntime {
@@ -57,6 +62,13 @@ func detectShellCommandIssue(command string, goos string) *shellIssue {
 			Suggestion: "Use the cwd argument instead of cd, use Windows cmd.exe syntax, or use native tools such as list_directory, read_file, grep, and glob.",
 		}
 	}
+	if windowsPosixUtilityPattern.MatchString(trimmed) {
+		return &shellIssue{
+			Kind:       "windows_shell_syntax",
+			Message:    "Command uses a POSIX utility (head/tail/grep/wc/awk/sed/cut/xargs/tr) that Windows cmd.exe does not have.",
+			Suggestion: "Use cmd.exe equivalents (e.g. `findstr` for grep, `more` to page output) or Zero's native tools (grep, read_file with offset/limit) instead of piping to a POSIX utility.",
+		}
+	}
 	return nil
 }
 

internal/tui/binding_test.go

@@ -0,0 +1,291 @@
+package tui
+
+import (
+	"testing"
+
+	tea "charm.land/bubbletea/v2"
+	"github.com/Gitlawb/zero/internal/config"
+)
+
+func TestParseBindingLabel(t *testing.T) {
+	tests := []struct {
+		input string
+		want  string // expected Label()
+	}{
+		{"option+o", "Alt+O"},
+		{"ctrl+o", "Ctrl+O"},
+		{"ctrl+e", "Ctrl+E"},
+		{"option+b", "Alt+B"},
+		{"option+O", "Alt+O"},
+		{"alt+o", "Alt+O"},
+		{"cmd+o", "Cmd+O"},
+		{"super+o", "Cmd+O"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			p := parseBinding(tt.input)
+			got := p.Label()
+			if got != tt.want {
+				t.Errorf("parseBinding(%q).Label() = %q, want %q", tt.input, got, tt.want)
+			}
+			if p.isZero() {
+				t.Errorf("parseBinding(%q).isZero() = true, want false", tt.input)
+			}
+		})
+	}
+}
+
+func TestOptionOMatchesOptionO(t *testing.T) {
+	p := parseBinding("option+o")
+	matcher := p.Matcher()
+
+	// Simulate iTerm2 with "Option as Meta" pressing Option+O
+	// Terminal sends ESC o → KeyPressEvent{Code: 'o', Mod: ModAlt}
+	msg := tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModAlt})
+
+	if !matcher(msg) {
+		t.Errorf("option+o matcher should match {Code:'o', Mod:ModAlt}")
+	}
+
+	// Should NOT match plain 'o'
+	msg2 := tea.KeyPressMsg(tea.Key{Code: 'o'})
+	if matcher(msg2) {
+		t.Errorf("option+o matcher should NOT match {Code:'o'} without ModAlt")
+	}
+
+	// Should NOT match ctrl+o
+	msg3 := tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModCtrl})
+	if matcher(msg3) {
+		t.Errorf("option+o matcher should NOT match {Code:'o', Mod:ModCtrl}")
+	}
+}
+
+func TestOptionOMatchesComposedCharacters(t *testing.T) {
+	p := parseBinding("option+o")
+	matcher := p.Matcher()
+
+	// On macOS without "Option as Meta", Option+O produces ø (U+00F8)
+	msg := tea.KeyPressMsg(tea.Key{Code: 0xF8, Text: "ø"})
+	if matcher(msg) {
+		t.Logf("NOTE: option+o matcher also matches option+ø (macOS compose behavior)")
+	}
+}
+
+func TestCtrlEMatchesDefault(t *testing.T) {
+	p := parseBinding("ctrl+e")
+	matcher := p.Matcher()
+
+	// Terminal sends Ctrl+E → byte 0x05 → KeyPressEvent{Code: 'e', Mod: ModCtrl}
+	msg := tea.KeyPressMsg(tea.Key{Code: 'e', Mod: tea.ModCtrl})
+
+	if !matcher(msg) {
+		t.Errorf("ctrl+e matcher should match {Code:'e', Mod:ModCtrl}")
+	}
+}
+
+func TestCtrlBindingRejectsSupersetModifiers(t *testing.T) {
+	// Configured ctrl+e must NOT match ctrl+alt+e or ctrl+shift+e
+	// (Mod.Contains superset correctness for the ctrl-letter fast path).
+	p := parseBinding("ctrl+e")
+	matcher := p.Matcher()
+
+	bad := []struct {
+		name string
+		msg  tea.KeyMsg
+	}{
+		{"ctrl+alt+e", tea.KeyPressMsg(tea.Key{Code: 'e', Mod: tea.ModCtrl | tea.ModAlt})},
+		{"ctrl+shift+e", tea.KeyPressMsg(tea.Key{Code: 'e', Mod: tea.ModCtrl | tea.ModShift})},
+		{"ctrl+alt+shift+e", tea.KeyPressMsg(tea.Key{Code: 'e', Mod: tea.ModCtrl | tea.ModAlt | tea.ModShift})},
+		{"ctrl+cmd+e", tea.KeyPressMsg(tea.Key{Code: 'e', Mod: tea.ModCtrl | tea.ModSuper})},
+	}
+
+	for _, tt := range bad {
+		t.Run(tt.name, func(t *testing.T) {
+			if matcher(tt.msg) {
+				t.Errorf("ctrl+e matcher should NOT match %s", tt.name)
+			}
+		})
+	}
+}
+
+func TestAltBindingRejectsSupersetModifiers(t *testing.T) {
+	// Configured alt+o must NOT match alt+shift+o (code path, exact mod).
+	p := parseBinding("alt+o")
+	matcher := p.Matcher()
+
+	bad := []struct {
+		name string
+		msg  tea.KeyMsg
+	}{
+		{"alt+shift+o", tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModAlt | tea.ModShift})},
+		{"alt+ctrl+o", tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModAlt | tea.ModCtrl})},
+		{"alt+cmd+o", tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModAlt | tea.ModSuper})},
+	}
+
+	for _, tt := range bad {
+		t.Run(tt.name, func(t *testing.T) {
+			if matcher(tt.msg) {
+				t.Errorf("alt+o matcher should NOT match %s", tt.name)
+			}
+		})
+	}
+}
+
+func TestPlainKeyBindingRejectsModifiers(t *testing.T) {
+	// A configured plain-key binding (no modifiers, e.g. "o") should only
+	// match when Mod is exactly 0, not when a modifier is held.
+	p := parseBinding("o")
+	matcher := p.Matcher()
+
+	plain := tea.KeyPressMsg(tea.Key{Code: 'o'})
+	if !matcher(plain) {
+		t.Errorf("'o' matcher should match {Code:'o'} with no modifiers")
+	}
+
+	bad := []struct {
+		name string
+		msg  tea.KeyMsg
+	}{
+		{"ctrl+o", tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModCtrl})},
+		{"alt+o", tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModAlt})},
+		{"shift+o", tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModShift})},
+	}
+
+	for _, tt := range bad {
+		t.Run(tt.name, func(t *testing.T) {
+			if matcher(tt.msg) {
+				t.Errorf("'o' matcher should NOT match %s", tt.name)
+			}
+		})
+	}
+}
+
+func TestParseBindingUTF8Character(t *testing.T) {
+	// A 2-byte UTF-8 key like é (U+00E9) should parse as a single character,
+	// not be rejected by a byte-length check.
+	p := parseBinding("é")
+	if p.isZero() {
+		t.Errorf("parseBinding('é') should not be zero — it's a valid single character")
+	}
+	if p.code != 'é' {
+		t.Errorf("parseBinding('é').code = %d (U+%04X), want %d (U+00E9)", p.code, p.code, 'é')
+	}
+	if p.text != "" {
+		t.Errorf("parseBinding('é').text = %q, want empty string", p.text)
+	}
+
+	// Also verify the matcher works
+	matcher := p.Matcher()
+	msg := tea.KeyPressMsg(tea.Key{Code: 'é', Text: "é"})
+	if !matcher(msg) {
+		t.Errorf("'é' matcher should match {Code:'é', Text:'é'}")
+	}
+
+	// Should not match with a modifier
+	msgAlt := tea.KeyPressMsg(tea.Key{Code: 'é', Text: "é", Mod: tea.ModAlt})
+	if matcher(msgAlt) {
+		t.Errorf("'é' matcher should NOT match with modifier")
+	}
+}
+
+func TestDispatchRejectsSupersetModifiers(t *testing.T) {
+	// Integration: model.keyMatch with a configured binding must reject
+	// modifier supersets.
+	cfg := config.KeyBindingsConfig{
+		ToggleDetailed: "ctrl+o",
+	}
+	bindings := resolveKeyBindings(cfg)
+	defaultFn := func(tea.KeyMsg) bool { return false }
+	m := model{keyBindings: bindings}
+
+	// Ctrl+O should match
+	msgCtrlO := tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModCtrl})
+	if !m.keyMatch(bindings.toggleDetailed, msgCtrlO, defaultFn) {
+		t.Errorf("keyMatch should match ctrl+o when configured")
+	}
+
+	// Ctrl+Alt+O should NOT match
+	msgCtrlAltO := tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModCtrl | tea.ModAlt})
+	if m.keyMatch(bindings.toggleDetailed, msgCtrlAltO, defaultFn) {
+		t.Errorf("keyMatch should NOT match ctrl+alt+o when ctrl+o is configured")
+	}
+}
+
+func TestConfigToBindingPipeline(t *testing.T) {
+	cfg := config.KeyBindingsConfig{
+		ToggleDetailed: "option+o",
+		ToggleMouse:    "ctrl+e",
+		CycleReasoning: "ctrl+t",
+		TogglePlan:     "ctrl+p",
+		ToggleSidebar:  "option+b",
+	}
+
+	bindings := resolveKeyBindings(cfg)
+
+	tests := []struct {
+		name    string
+		binding parsedBinding
+		wantKey string
+	}{
+		{"toggleDetailed", bindings.toggleDetailed, "Alt+O"},
+		{"toggleMouse", bindings.toggleMouse, "Ctrl+E"},
+		{"cycleReasoning", bindings.cycleReasoning, "Ctrl+T"},
+		{"togglePlan", bindings.togglePlan, "Ctrl+P"},
+		{"toggleSidebar", bindings.toggleSidebar, "Alt+B"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.binding.isZero() {
+				t.Errorf("%s binding is zero (unset) — config not loaded", tt.name)
+			}
+			if got := tt.binding.Label(); got != tt.wantKey {
+				t.Errorf("%s.Label() = %q, want %q", tt.name, got, tt.wantKey)
+			}
+		})
+	}
+}
+
+func TestHelpBindingSubstitution(t *testing.T) {
+	// Verify that the help overlay correctly shows user-configured bindings
+	// by checking that Label() returns non-empty for config-sourced bindings.
+	cfg := config.KeyBindingsConfig{
+		ToggleDetailed: "option+o",
+		ToggleSidebar:  "option+b",
+	}
+
+	bindings := resolveKeyBindings(cfg)
+
+	if l := bindings.toggleDetailed.Label(); l != "Alt+O" {
+		t.Errorf("toggleDetailed.Label() = %q, want %q", l, "Alt+O")
+	}
+	if l := bindings.toggleSidebar.Label(); l != "Alt+B" {
+		t.Errorf("toggleSidebar.Label() = %q, want %q", l, "Alt+B")
+	}
+}
+
+// TestDispatchOptionO is an integration-style test: it verifies that pressing
+// Option+O dispatches as toggleDetailed when configured.
+func TestDispatchOptionO(t *testing.T) {
+	cfg := config.KeyBindingsConfig{
+		ToggleDetailed: "option+o",
+	}
+	bindings := resolveKeyBindings(cfg)
+
+	// Simulate Option+O in iTerm2 with "Option as Meta" → ESC o → {Code:'o', Mod:ModAlt}
+	msg := tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModAlt})
+	defaultFn := func(tea.KeyMsg) bool { return false }
+
+	// This is the dispatch check the model uses
+	m := model{keyBindings: bindings}
+	if !m.keyMatch(bindings.toggleDetailed, msg, defaultFn) {
+		t.Errorf("model.keyMatch should match option+o")
+	}
+
+	// Also verify default doesn't match
+	msgCtrlO := tea.KeyPressMsg(tea.Key{Code: 'o', Mod: tea.ModCtrl})
+	if m.keyMatch(bindings.toggleDetailed, msgCtrlO, defaultFn) {
+		t.Errorf("model.keyMatch should NOT match ctrl+o when option+o is configured")
+	}
+}

internal/tui/command_polish_test.go

@@ -377,7 +377,7 @@ func TestContextCommandCardHandlesNilRegistryAndStableStyle(t *testing.T) {
 	for _, want := range []string{
 		"Context",
 		"0 tools",
-		"style      balanced",
+		"style      concise",
 		"root        unknown",
 	} {
 		assertContains(t, text, want)

internal/tui/command_views.go

@@ -559,6 +559,21 @@ func (m model) modelText(args string) string {
 	})
 }
 
+// avgTurnLatencyText reports the session's rolling average turn wall-time for
+// /context — the "is it slow?" signal a user otherwise can only feel. "n/a" until
+// a turn has completed.
+func (m model) avgTurnLatencyText() string {
+	if m.turnLatencyCount == 0 {
+		return "n/a"
+	}
+	avgSeconds := m.turnLatencySum.Seconds() / float64(m.turnLatencyCount)
+	if m.turnTTFTCount > 0 {
+		ttftSeconds := m.turnTTFTSum.Seconds() / float64(m.turnTTFTCount)
+		return fmt.Sprintf("%.1fs avg (%.1fs to first token, %d turns)", avgSeconds, ttftSeconds, m.turnLatencyCount)
+	}
+	return fmt.Sprintf("%.1fs avg (%d turns)", avgSeconds, m.turnLatencyCount)
+}
+
 func (m model) contextText() string {
 	toolCount := len(m.registeredTools())
 	return renderCommandCardTranscript(commandCard{
@@ -578,6 +593,8 @@ func (m model) contextText() string {
 					{Key: "effort", Value: m.effortDisplay()},
 					{Key: "style", Value: displayValue(m.responseStyle, defaultResponseStyle)},
 					{Key: "usage", Value: m.usageSummaryText()},
+					{Key: "cache", Value: m.cacheEfficiencyText()},
+					{Key: "latency", Value: m.avgTurnLatencyText()},
 					{Key: "max turns", Value: fmt.Sprint(m.agentOptions.MaxTurns)},
 				},
 			},

internal/tui/commands.go

@@ -41,6 +41,8 @@ const (
 	commandAddDir
 	commandSelfCorrect
 	commandTurns
+	commandNew
+	commandFast
 	commandUnknown
 )
 
@@ -154,6 +156,13 @@ var commandDefinitions = []commandDefinition{
 		description: "Clear the visible transcript.",
 		kind:        commandClear,
 	},
+	{
+		name:        "/new",
+		usage:       "/new",
+		group:       commandGroupSession,
+		description: "Start a fresh session; the current one stays resumable via /resume.",
+		kind:        commandNew,
+	},
 	{
 		name:        "/search",
 		aliases:     []string{"/find"},
@@ -227,6 +236,13 @@ var commandDefinitions = []commandDefinition{
 		description: "Show or set reasoning effort for supported models.",
 		kind:        commandEffort,
 	},
+	{
+		name:        "/fast",
+		usage:       "/fast [on|off]",
+		group:       commandGroupModel,
+		description: "Enable fast mode for the current model (/fast off to disable).",
+		kind:        commandFast,
+	},
 	{
 		name:        "/style",
 		usage:       "/style [list|balanced|concise|explanatory|review]",

internal/tui/fast_command.go

@@ -0,0 +1,111 @@
+package tui
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/Gitlawb/zero/internal/modelregistry"
+)
+
+// fastPlan is the pure decision `/fast` makes before touching any state: either
+// a terminal message to show the user, or a target model to switch to.
+type fastPlan struct {
+	message  string // terminal notice; shown as-is when targetID is empty
+	targetID string // model to switch to ("" means no switch — show message)
+	toFast   bool   // the target is a fast model (drives the ⚡ prefix)
+}
+
+// planFastCommand resolves what `/fast [on|off]` should do for the current model
+// using only the registry — no side effects. State is DERIVED from the model
+// identity: the session is "in fast mode" iff the current model has a base
+// variant. Returns a terminal message, or a target model to switch to.
+func planFastCommand(registry modelregistry.Registry, currentModel, arg string) fastPlan {
+	// 1. Parse the argument (case-insensitive): no arg / "on" => enable fast,
+	//    "off" => return to base, anything else => usage error.
+	enable := true
+	switch strings.ToLower(strings.TrimSpace(arg)) {
+	case "", "on":
+		enable = true
+	case "off":
+		enable = false
+	default:
+		return fastPlan{message: fmt.Sprintf("⚡ /fast takes on or off, not %q", strings.TrimSpace(arg))}
+	}
+
+	// 2. Read the current model.
+	current := strings.TrimSpace(currentModel)
+	if current == "" {
+		return fastPlan{message: "⚡ Pick a model first · /model"}
+	}
+	short := modelShortName(registry, current)
+
+	// 3. Derived state: in fast mode iff the current model has a base variant.
+	_, isFast := registry.BaseVariant(current)
+
+	// 4. No-op cases — already in the requested state.
+	if enable && isFast {
+		return fastPlan{message: "⚡ Already in the fast lane · " + short}
+	}
+	if !enable && !isFast {
+		return fastPlan{message: "Already on base · " + short}
+	}
+
+	// 5. Resolve the target variant.
+	var target modelregistry.ModelEntry
+	var ok bool
+	if enable {
+		target, ok = registry.FastVariant(current)
+	} else {
+		target, ok = registry.BaseVariant(current)
+	}
+	if !ok {
+		return fastPlan{message: "⚡ No fast lane for " + short}
+	}
+
+	// Switching TO a fast model iff the target itself has a base variant.
+	_, toFast := registry.BaseVariant(target.ID)
+	return fastPlan{targetID: target.ID, toFast: toFast}
+}
+
+// handleFastCommand implements `/fast [on|off]`: toggle the session model between
+// its base and fast variant within the same family. The actual switch is
+// delegated to handleModelCommand — the same path /model uses — so provider
+// rebuild, the compaction-before-switch guard, and persistence all apply; this
+// never mutates model state directly.
+func (m model) handleFastCommand(arg string) (model, string) {
+	registry, err := modelregistry.DefaultRegistry()
+	if err != nil {
+		return m, "Failed to load the model registry: " + err.Error()
+	}
+
+	plan := planFastCommand(registry, m.modelName, arg)
+	if plan.targetID == "" {
+		return m, plan.message
+	}
+
+	var switchText string
+	m, switchText = m.handleModelCommand(plan.targetID)
+	if m.modelName != plan.targetID {
+		// The switch did not complete — either an error, or a "compact first"
+		// guard prompt from handleModelCommand. Surface its own message so the
+		// user sees the real reason instead of a misleading "Switched to ...".
+		return m, switchText
+	}
+
+	short := modelShortName(registry, plan.targetID)
+	if plan.toFast {
+		return m, "⚡ Fast lane on · " + short
+	}
+	return m, "Fast lane off · " + short
+}
+
+// modelShortName returns a model's short display name, falling back to the id
+// when the model is unknown or has no display name.
+func modelShortName(registry modelregistry.Registry, id string) string {
+	if entry, ok := registry.Get(id); ok {
+		if name := strings.TrimSpace(entry.DisplayName); name != "" {
+			return name
+		}
+	}
+	return strings.TrimSpace(id)
+}

internal/tui/fast_command_test.go

@@ -0,0 +1,200 @@
+package tui
+
+import (
+	"context"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/Gitlawb/zero/internal/config"
+	"github.com/Gitlawb/zero/internal/modelregistry"
+	"github.com/Gitlawb/zero/internal/zeroruntime"
+)
+
+func fastTestRegistry(t *testing.T) modelregistry.Registry {
+	t.Helper()
+	registry, err := modelregistry.DefaultRegistry()
+	if err != nil {
+		t.Fatalf("DefaultRegistry() error = %v", err)
+	}
+	return registry
+}
+
+// planFastCommand is the pure decision layer — every argument/state case is
+// exercised here without touching the switch machinery.
+func TestPlanFastCommand(t *testing.T) {
+	registry := fastTestRegistry(t)
+
+	cases := []struct {
+		name        string
+		model       string
+		arg         string
+		wantMessage string // substring expected when the plan is terminal
+		wantTarget  string // model id expected when the plan switches
+		wantToFast  bool
+	}{
+		{name: "invalid arg", model: "gpt-4.1", arg: "turbo", wantMessage: `/fast takes on or off, not "turbo"`},
+		{name: "no model set", model: "", arg: "on", wantMessage: "Pick a model first"},
+		{name: "enable while already fast", model: "gpt-4.1-mini", arg: "on", wantMessage: "Already in the fast lane"},
+		{name: "disable while already base", model: "gpt-4.1", arg: "off", wantMessage: "Already on base"},
+		{name: "enable with no fast variant", model: "claude-opus-4.1", arg: "on", wantMessage: "No fast lane"},
+		{name: "enable (no arg) resolves fast", model: "gpt-4.1", arg: "", wantTarget: "gpt-4.1-mini", wantToFast: true},
+		{name: "enable (on) resolves fast", model: "gpt-4.1", arg: "ON", wantTarget: "gpt-4.1-mini", wantToFast: true},
+		{name: "disable resolves base", model: "gpt-4.1-mini", arg: "off", wantTarget: "gpt-4.1", wantToFast: false},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			plan := planFastCommand(registry, tc.model, tc.arg)
+			if tc.wantTarget != "" {
+				canon, ok := registry.Resolve(tc.wantTarget)
+				if !ok {
+					t.Fatalf("test fixture %q does not resolve", tc.wantTarget)
+				}
+				if plan.targetID != canon.ID {
+					t.Fatalf("targetID = %q, want %q", plan.targetID, canon.ID)
+				}
+				if plan.toFast != tc.wantToFast {
+					t.Fatalf("toFast = %v, want %v", plan.toFast, tc.wantToFast)
+				}
+				if plan.message != "" {
+					t.Fatalf("switching plan should carry no message, got %q", plan.message)
+				}
+				return
+			}
+			if plan.targetID != "" {
+				t.Fatalf("expected a terminal message, got target %q", plan.targetID)
+			}
+			if !strings.Contains(plan.message, tc.wantMessage) {
+				t.Fatalf("message = %q, want it to contain %q", plan.message, tc.wantMessage)
+			}
+		})
+	}
+}
+
+// handleFastCommand's terminal cases return the plan message without switching,
+// so a bare model exercises them.
+func TestHandleFastCommandTerminalCases(t *testing.T) {
+	cases := []struct {
+		name         string
+		model        string
+		arg          string
+		wantContains string
+	}{
+		{"invalid arg", "gpt-4.1", "sideways", `/fast takes on or off, not "sideways"`},
+		{"no model", "", "on", "Pick a model first"},
+		{"already fast", "gpt-4.1-mini", "on", "Already in the fast lane"},
+		{"already base", "gpt-4.1", "off", "Already on base"},
+		{"no fast variant", "claude-opus-4.1", "on", "No fast lane"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			m := model{modelName: tc.model}
+			got, notice := m.handleFastCommand(tc.arg)
+			if got.modelName != tc.model {
+				t.Fatalf("model must not change on a terminal case: %q -> %q", tc.model, got.modelName)
+			}
+			if !strings.Contains(notice, tc.wantContains) {
+				t.Fatalf("notice = %q, want it to contain %q", notice, tc.wantContains)
+			}
+		})
+	}
+}
+
+func newFastTestModel(t *testing.T, modelID string) model {
+	t.Helper()
+	configPath := filepath.Join(t.TempDir(), "zero.json")
+	profile := config.ProviderProfile{
+		Name:         "openai",
+		ProviderKind: config.ProviderKindOpenAI,
+		BaseURL:      config.OpenAIBaseURL,
+		APIKey:       "sk-test",
+		Model:        modelID,
+	}
+	if _, err := config.UpsertProvider(configPath, profile, true); err != nil {
+		t.Fatalf("write user config: %v", err)
+	}
+	return newModel(context.Background(), Options{
+		UserConfigPath:  configPath,
+		ProviderName:    "openai",
+		ModelName:       modelID,
+		ProviderProfile: profile,
+		Provider:        &fakeProvider{},
+		NewProvider: func(config.ProviderProfile) (zeroruntime.Provider, error) {
+			return &fakeProvider{}, nil
+		},
+	})
+}
+
+// Enabling switches base -> fast with a ⚡ notice; disabling switches back to the
+// base with a plain notice. Uses the same switch path /model uses.
+func TestHandleFastCommandSwitchesToFastAndBack(t *testing.T) {
+	registry := fastTestRegistry(t)
+	m := newFastTestModel(t, "gpt-4.1")
+
+	m, notice := m.handleFastCommand("on")
+	if m.modelName != "gpt-4.1-mini" {
+		t.Fatalf("enable: modelName = %q, want gpt-4.1-mini", m.modelName)
+	}
+	if want := "⚡ Fast lane on · " + modelShortName(registry, "gpt-4.1-mini"); notice != want {
+		t.Fatalf("enable notice = %q, want exactly %q (bolt + fast-lane-on + target short name)", notice, want)
+	}
+
+	m, notice = m.handleFastCommand("off")
+	if m.modelName != "gpt-4.1" {
+		t.Fatalf("disable: modelName = %q, want gpt-4.1", m.modelName)
+	}
+	if want := "Fast lane off · " + modelShortName(registry, "gpt-4.1"); notice != want {
+		t.Fatalf("disable notice = %q, want exactly %q (plain fast-lane-off, no bolt)", notice, want)
+	}
+}
+
+// The no-op and no-variant notices must carry their full spec decoration — the ⚡
+// prefix and the (<short>) name — so a regression dropping either fails loudly
+// rather than passing a bare substring assertion.
+func TestFastCommandNoOpAndNoVariantMessagesAreDecorated(t *testing.T) {
+	registry := fastTestRegistry(t)
+
+	plan := planFastCommand(registry, "gpt-4.1-mini", "on")
+	if want := "⚡ Already in the fast lane · " + modelShortName(registry, "gpt-4.1-mini"); plan.message != want {
+		t.Fatalf("already-fast message = %q, want %q", plan.message, want)
+	}
+
+	plan = planFastCommand(registry, "gpt-4.1", "off")
+	if want := "Already on base · " + modelShortName(registry, "gpt-4.1"); plan.message != want {
+		t.Fatalf("already-base message = %q, want %q", plan.message, want)
+	}
+
+	// An unknown / off-catalog model id also reaches the no-variant branch, where
+	// <short> falls back to the raw id.
+	plan = planFastCommand(registry, "some-custom-live-provider-model", "on")
+	if want := "⚡ No fast lane for some-custom-live-provider-model"; plan.message != want {
+		t.Fatalf("no-variant (unknown id) message = %q, want %q", plan.message, want)
+	}
+}
+
+// When the underlying switch fails, /fast surfaces the error and leaves the
+// model unchanged (here: a valid base model but no provider profile to rebuild).
+func TestHandleFastCommandSurfacesSwitchError(t *testing.T) {
+	m := model{modelName: "gpt-4.1"} // no providerProfile / newProvider wired
+	got, notice := m.handleFastCommand("on")
+	if got.modelName != "gpt-4.1" {
+		t.Fatalf("model must be unchanged on switch failure, got %q", got.modelName)
+	}
+	if strings.HasPrefix(notice, "⚡ Fast lane on ") || strings.HasPrefix(notice, "Fast lane off ") {
+		t.Fatalf("a failed switch must not claim success, got %q", notice)
+	}
+	if strings.TrimSpace(notice) == "" {
+		t.Fatal("a failed switch must surface a reason")
+	}
+}
+
+func TestModelShortName(t *testing.T) {
+	registry := fastTestRegistry(t)
+	if got := modelShortName(registry, "gpt-4.1"); strings.TrimSpace(got) == "" {
+		t.Fatal("a known model should resolve to a non-empty short name")
+	}
+	if got := modelShortName(registry, "totally-unknown-model-xyz"); got != "totally-unknown-model-xyz" {
+		t.Fatalf("an unknown model short name = %q, want the raw id", got)
+	}
+}

internal/tui/fast_marker.go

@@ -0,0 +1,87 @@
+package tui
+
+import (
+	"strings"
+	"time"
+
+	tea "charm.land/bubbletea/v2"
+	"charm.land/lipgloss/v2"
+
+	"github.com/Gitlawb/zero/internal/modelregistry"
+)
+
+// fastMarkerGlyph is the compact "f" badge shown next to a model that has an
+// available fast variant — i.e. one where `/fast on` would switch down to a
+// faster same-family model. It marks the BASE model, never the fast one.
+const fastMarkerGlyph = "f"
+
+// fastVariantEntryFor resolves the fast variant of an arbitrary model id, if any.
+// Like modelContextWindow, it reads the default registry on demand rather than
+// caching derived state, so a marker can never go stale after a model switch.
+// DefaultRegistry is memoized, so even the per-frame callers (the active-model
+// chip renders every frame; the pickers render per keystroke) pay only a map
+// lookup here, not a registry rebuild.
+func fastVariantEntryFor(id string) (modelregistry.ModelEntry, bool) {
+	id = strings.TrimSpace(id)
+	if id == "" {
+		return modelregistry.ModelEntry{}, false
+	}
+	registry, err := modelregistry.DefaultRegistry()
+	if err != nil {
+		return modelregistry.ModelEntry{}, false
+	}
+	return registry.FastVariant(id)
+}
+
+// currentModelFastVariant resolves the fast variant of the session's active model.
+func (m model) currentModelFastVariant() (modelregistry.ModelEntry, bool) {
+	return fastVariantEntryFor(m.modelName)
+}
+
+// renderFastBadge renders the "f" fast-mode marker in the given (surface-aware)
+// style, prefixed with a space so it reads as a distinct badge rather than a
+// trailing letter of the adjacent model name.
+func renderFastBadge(style lipgloss.Style) string {
+	return " " + style.Render(fastMarkerGlyph)
+}
+
+// fastVariantHint is the one-line reveal shown against a focused/selected
+// fast-capable model. The TUI has no floating-tooltip primitive, so the "hover"
+// affordance is this inline detail on the active row: it names the target model
+// and the command that gets there.
+func fastVariantHint(variantName string) string {
+	variantName = strings.TrimSpace(variantName)
+	if variantName == "" {
+		return ""
+	}
+	return "⚡ fast: " + variantName + " · /fast on"
+}
+
+// fastToastDuration is how long a /fast toast stays up before auto-dismissing.
+const fastToastDuration = 3 * time.Second
+
+// fastToastExpiredMsg clears a fast-lane toast after fastToastDuration. It is
+// seq-gated so a newer toast is never dismissed by an older timer.
+type fastToastExpiredMsg struct{ seq int }
+
+// showFastToast raises a transient fast-lane notice in the row above the composer
+// and schedules its dismissal. It replaces the persistent transcript line the
+// /fast command used to append, so repeated toggles never pile up in history.
+func (m model) showFastToast(text string) (model, tea.Cmd) {
+	text = strings.TrimSpace(strings.ReplaceAll(text, "\n", " "))
+	if text == "" {
+		return m, nil
+	}
+	m.fastToastSeq++
+	m.fastToast = text
+	seq := m.fastToastSeq
+	return m, tea.Tick(fastToastDuration, func(time.Time) tea.Msg {
+		return fastToastExpiredMsg{seq: seq}
+	})
+}
+
+// renderFastToast styles the toast as a filled brand pill so it reads as a
+// transient popup rather than a permanent status line.
+func renderFastToast(text string) string {
+	return zeroTheme.badge.Render(" " + strings.TrimSpace(text) + " ")
+}

internal/tui/fast_marker_test.go

@@ -0,0 +1,151 @@
+package tui
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/charmbracelet/x/ansi"
+
+	"github.com/Gitlawb/zero/internal/modelregistry"
+)
+
+// hasFastBadge reports whether a rendered (styled) line ends with the " f"
+// fast-mode badge, ignoring trailing layout padding. Labels used in these tests
+// deliberately contain no trailing " f" so the badge is unambiguous.
+func hasFastBadge(rendered string) bool {
+	return strings.HasSuffix(strings.TrimRight(ansi.Strip(rendered), " "), " "+fastMarkerGlyph)
+}
+
+func TestFastVariantHint(t *testing.T) {
+	if got := fastVariantHint("Claude Haiku 4.5"); got != "⚡ fast: Claude Haiku 4.5 · /fast on" {
+		t.Errorf("fastVariantHint = %q", got)
+	}
+	if got := fastVariantHint("   "); got != "" {
+		t.Errorf("fastVariantHint(blank) = %q, want empty", got)
+	}
+}
+
+func TestRenderFastBadge(t *testing.T) {
+	if got := ansi.Strip(renderFastBadge(zeroTheme.accent)); got != " "+fastMarkerGlyph {
+		t.Errorf("renderFastBadge visible text = %q, want %q", got, " "+fastMarkerGlyph)
+	}
+}
+
+// The active-model chip carries the "f" badge only when the current model has a
+// fast variant — base models yes, fast models and unpaired top-tier models no.
+func TestTitleModelSegmentFastBadge(t *testing.T) {
+	cases := []struct {
+		model string
+		want  bool
+	}{
+		{"gpt-4.1", true},          // base with a fast variant
+		{"gpt-4.1-mini", false},    // the fast variant itself has none
+		{"claude-opus-4.1", false}, // top-tier, intentionally unpaired
+		{"definitely-not-real", false},
+		{"", false},
+	}
+	for _, tc := range cases {
+		seg := model{modelName: tc.model}.titleModelSegment()
+		if got := hasFastBadge(seg); got != tc.want {
+			t.Errorf("titleModelSegment(%q) badge = %v, want %v (visible %q)", tc.model, got, tc.want, ansi.Strip(seg))
+		}
+	}
+}
+
+// A /model picker row shows the badge iff its FastVariant field is populated,
+// and the field is populated only for base models by decorateFastVariantItems.
+func TestRenderModelPickerRowFastBadge(t *testing.T) {
+	withFast := renderModelPickerRow(60, false, pickerItem{Label: "gpt-4.1", Value: "gpt-4.1", FastVariant: "GPT-4.1 mini"})
+	if !hasFastBadge(withFast) {
+		t.Errorf("fast-capable row missing badge: %q", ansi.Strip(withFast))
+	}
+	withoutFast := renderModelPickerRow(60, false, pickerItem{Label: "gpt-4.1", Value: "gpt-4.1"})
+	if hasFastBadge(withoutFast) {
+		t.Errorf("row without FastVariant should have no badge: %q", ansi.Strip(withoutFast))
+	}
+}
+
+func TestModelPickerItemDetailIncludesFastHint(t *testing.T) {
+	detail := modelPickerItemDetail(pickerItem{Label: "GPT-4.1", Value: "gpt-4.1", FastVariant: "GPT-4.1 mini"})
+	if !strings.Contains(detail, "⚡ fast: GPT-4.1 mini · /fast on") {
+		t.Errorf("detail missing fast hint: %q", detail)
+	}
+	plain := modelPickerItemDetail(pickerItem{Label: "Claude Opus 4.1", Value: "claude-opus-4.1"})
+	if strings.Contains(plain, "fast:") {
+		t.Errorf("non-fast detail should have no hint: %q", plain)
+	}
+}
+
+// decorateFastVariantItems stamps the fast variant's display name onto base-model
+// rows only, using the real registry — the single source of truth for the badge.
+func TestDecorateFastVariantItems(t *testing.T) {
+	registry, err := modelregistry.DefaultRegistry()
+	if err != nil {
+		t.Fatalf("DefaultRegistry: %v", err)
+	}
+	items := []pickerItem{
+		{Value: "gpt-4.1"},           // base -> GPT-4.1 mini
+		{Value: "gpt-4.1-mini"},      // fast, no variant
+		{Value: "claude-opus-4.1"},   // unpaired
+		{Value: "some-custom-model"}, // not in registry
+		{Value: ""},
+	}
+	decorateFastVariantItems(registry, items)
+	if items[0].FastVariant != "GPT-4.1 mini" {
+		t.Errorf("gpt-4.1 FastVariant = %q, want %q", items[0].FastVariant, "GPT-4.1 mini")
+	}
+	for _, i := range []int{1, 2, 3, 4} {
+		if items[i].FastVariant != "" {
+			t.Errorf("items[%d].FastVariant = %q, want empty", i, items[i].FastVariant)
+		}
+	}
+}
+
+func TestShowFastToast(t *testing.T) {
+	// A non-empty message raises the toast, bumps the seq, and schedules dismissal.
+	m, cmd := model{}.showFastToast("⚡ Fast lane on · GPT-4.1 mini")
+	if m.fastToast != "⚡ Fast lane on · GPT-4.1 mini" {
+		t.Fatalf("fastToast = %q", m.fastToast)
+	}
+	if m.fastToastSeq != 1 {
+		t.Fatalf("fastToastSeq = %d, want 1", m.fastToastSeq)
+	}
+	if cmd == nil {
+		t.Fatal("showFastToast must return a dismissal tick cmd")
+	}
+
+	// A multi-line switch-guard message is flattened so the toast stays one line
+	// (the footer slot is fixed-height).
+	m2, _ := model{}.showFastToast("Model\nCannot switch while a run is active.")
+	if strings.Contains(m2.fastToast, "\n") {
+		t.Fatalf("toast must be flattened to one line, got %q", m2.fastToast)
+	}
+
+	// Blank text is a no-op: no toast, no timer.
+	m3, cmd3 := model{}.showFastToast("   ")
+	if m3.fastToast != "" || cmd3 != nil {
+		t.Fatalf("blank text should not raise a toast, got %q / cmd!=nil=%v", m3.fastToast, cmd3 != nil)
+	}
+}
+
+func TestRenderFastToastShowsMessage(t *testing.T) {
+	got := ansi.Strip(renderFastToast("⚡ No fast lane for gpt-5.5"))
+	if !strings.Contains(got, "⚡ No fast lane for gpt-5.5") {
+		t.Fatalf("rendered toast = %q, want it to contain the message", got)
+	}
+}
+
+func TestProviderWizardModelFastBadgeAndHint(t *testing.T) {
+	wizard := &providerWizardState{selectedModel: 0}
+	withFast := wizard.renderSelectableModel(60, 0, providerWizardModel{ID: "gpt-4.1"})
+	if !hasFastBadge(withFast) {
+		t.Errorf("provider wizard base-model row missing badge: %q", ansi.Strip(withFast))
+	}
+	plain := wizard.renderSelectableModel(60, 1, providerWizardModel{ID: "claude-opus-4.1"})
+	if hasFastBadge(plain) {
+		t.Errorf("provider wizard unpaired-model row should have no badge: %q", ansi.Strip(plain))
+	}
+	if detail := providerWizardModelDetail(providerWizardModel{ID: "gpt-4.1"}); !strings.Contains(detail, "⚡ fast:") {
+		t.Errorf("provider wizard detail missing fast hint: %q", detail)
+	}
+}

internal/tui/flush_test.go

@@ -105,11 +105,14 @@ func TestClearResetsFlushFrontier(t *testing.T) {
 	m.input.SetValue("/clear")
 	updated, _ := m.Update(testKey(tea.KeyEnter))
 	next := updated.(model)
-	if len(next.transcript) != 1 || next.transcript[0].kind != rowWelcome {
-		t.Fatalf("expected /clear to reset transcript, got %#v", next.transcript)
+	if len(next.transcript) != 2 || next.transcript[0].kind != rowWelcome {
+		t.Fatalf("expected /clear to reset transcript to welcome + note, got %#v", next.transcript)
 	}
-	if next.flushed > 1 {
-		t.Fatalf("expected frontier reset after /clear, got %d", next.flushed)
+	if !transcriptContains(next.transcript, "/new") {
+		t.Fatalf("expected /clear to point users to /new, got %#v", next.transcript)
+	}
+	if next.flushed != len(next.transcript) {
+		t.Fatalf("expected frontier reset to match cleared transcript (%d rows), got %d", len(next.transcript), next.flushed)
 	}
 }
 

internal/tui/human_count_test.go

@@ -0,0 +1,28 @@
+package tui
+
+import "testing"
+
+func TestHumanCount(t *testing.T) {
+	cases := []struct {
+		n    int
+		want string
+	}{
+		{0, "0"},
+		{999, "999"},
+		{1000, "1K"},
+		{12400, "12.4K"},
+		{200000, "200K"},
+		{999999, "1000K"},
+		// The bug: a million-scale count must switch to an M suffix instead
+		// of continuing to render as "1000K", "1200K", etc.
+		{1_000_000, "1M"},
+		{1_048_576, "1M"},
+		{1_200_000, "1.2M"},
+		{-5, "0"},
+	}
+	for _, c := range cases {
+		if got := humanCount(c.n); got != c.want {
+			t.Errorf("humanCount(%d) = %q, want %q", c.n, got, c.want)
+		}
+	}
+}

internal/tui/keybinding_help.go

@@ -5,6 +5,10 @@
 // lists them grouped, so the keymap is discoverable the way the reference TUIs
 // do it. The list is declarative and hand-curated to match the real handlers in
 // model.go's Update switch; keep them in sync when a binding changes.
+//
+// Configurable bindings (toggleDetailed, toggleMouse, cycleReasoning,
+// togglePlan, toggleSidebar) pull their key label from m.keyBindings so a user
+// who remaps them in config.json sees the actual chords, not the defaults.
 package tui
 
 import "strings"
@@ -21,63 +25,67 @@ type keybindingGroup struct {
 	bindings []keybinding
 }
 
-// keybindingGroups is the full, grouped shortcut list shown by the `?` overlay.
+// buildKeybindingGroups returns the full, grouped shortcut list shown by the
+// `?` overlay. Configurable bindings use the user's remapped labels (via
+// m.keyBindings) when present; unconfigured bindings get their built-in labels.
 // Sourced from the real key cases in model.go (Update) — not invented. When a
-// binding is added/changed there, update it here too (a test guards that the
-// data is non-empty and well-formed, but it can't verify the bindings exist).
-var keybindingGroups = []keybindingGroup{
-	{
-		title: "Chat",
-		bindings: []keybinding{
-			{"Enter", "send the message"},
-			{"Alt+Enter", "insert a newline (multi-line compose)"},
-			{"Esc (×2)", "cancel the run / dismiss a popup / clear the input"},
-			{"Ctrl+C", "cancel the run, then quit"},
-			{"?", "show this help (on an empty input)"},
+// binding is added/changed there, update this method too.
+func (m model) buildKeybindingGroups() []keybindingGroup {
+	return []keybindingGroup{
+		{
+			title: "Chat",
+			bindings: []keybinding{
+				{"Enter", "send the message"},
+				{"Alt+Enter", "insert a newline (multi-line compose)"},
+				{"Esc (\u00d72)", "cancel the run / dismiss a popup / clear the input"},
+				{"Ctrl+C", "cancel the run, then quit"},
+				{"?", "show this help (on an empty input)"},
+			},
 		},
-	},
-	{
-		title: "Model & run controls",
-		bindings: []keybinding{
-			{"Ctrl+T", "cycle reasoning effort (auto → low → medium → high)"},
-			{"Shift+Tab", "cycle permission mode (auto ↔ ask)"},
-			{"Ctrl+P", "expand / collapse the plan panel"},
+		{
+			title: "Model & run controls",
+			bindings: []keybinding{
+				{labelOr(m.keyBindings.cycleReasoning, "Ctrl+T"), "cycle reasoning effort (auto \u2192 low \u2192 medium \u2192 high)"},
+				{"Shift+Tab", "cycle permission mode (auto \u2194 ask)"},
+				{labelOr(m.keyBindings.togglePlan, "Ctrl+P"), "expand / collapse the plan panel"},
+			},
 		},
-	},
-	{
-		title: "Navigation & scrollback",
-		bindings: []keybinding{
-			{"PgUp / PgDn", "scroll the transcript by a page"},
-			{"↑ / ↓", "scroll, or move within a popup / multi-line input"},
-			{"Ctrl+O", "toggle the detailed (full-screen) transcript"},
-			{"Ctrl+B", "hide / show the right context sidebar"},
-			{"Ctrl+E", "release the mouse to drag-select & copy text"},
-			{"Tab", "accept the autocomplete / picker selection"},
+		{
+			title: "Navigation & scrollback",
+			bindings: []keybinding{
+				{"PgUp / PgDn", "scroll the transcript by a page"},
+				{"\u2191 / \u2193", "scroll, or move within a popup / multi-line input"},
+				{labelOr(m.keyBindings.toggleDetailed, "Ctrl+O"), "toggle the detailed (full-screen) transcript"},
+				{labelOr(m.keyBindings.toggleSidebar, "Ctrl+B"), "hide / show the right context sidebar"},
+				{labelOr(m.keyBindings.toggleMouse, "Ctrl+E"), "release the mouse to drag-select & copy text"},
+				{"Tab", "accept the autocomplete / picker selection"},
+			},
 		},
-	},
-	{
-		title: "Specialists & pickers",
-		bindings: []keybinding{
-			{"Click a specialist card", "drill into its sub-session"},
-			{"↑ / Esc (in a sub-session)", "return to the main chat"},
-			{"Ctrl+F (in /model)", "toggle the highlighted model as a favorite"},
-			{"Click a tool card", "expand / collapse its output"},
-			{"Right-click", "paste the clipboard"},
+		{
+			title: "Specialists & pickers",
+			bindings: []keybinding{
+				{"Click a specialist card", "drill into its sub-session"},
+				{"\u2191 / Esc (in a sub-session)", "return to the main chat"},
+				{"Ctrl+F (in /model)", "toggle the highlighted model as a favorite"},
+				{"Click a tool card", "expand / collapse its output"},
+				{"Right-click", "paste the clipboard"},
+			},
 		},
-	},
+	}
 }
 
 // keybindingHelpFooter is the dismiss hint shown at the bottom of the overlay.
-const keybindingHelpFooter = "? or Esc to close · /help for slash commands"
+const keybindingHelpFooter = "? or Esc to close \u00b7 /help for slash commands"
 
 // renderKeybindingHelpLines builds the overlay body lines (group titles +
 // aligned key/description rows + footer), wrapped to the inner width. Exposed
 // separately from the framed renderer so tests can assert on content without
 // the border chrome.
 func (m model) renderKeybindingHelpLines(innerWidth int) []string {
-	keyColumn := keybindingKeyColumnWidth()
+	groups := m.buildKeybindingGroups()
+	keyColumn := keybindingKeyColumnWidth(groups)
 	lines := make([]string, 0, 64)
-	for index, group := range keybindingGroups {
+	for index, group := range groups {
 		if index > 0 {
 			lines = append(lines, "")
 		}
@@ -93,9 +101,9 @@ func (m model) renderKeybindingHelpLines(innerWidth int) []string {
 
 // keybindingKeyColumnWidth returns the width of the key column: the widest key
 // chord across all groups, so the descriptions align in a clean second column.
-func keybindingKeyColumnWidth() int {
+func keybindingKeyColumnWidth(groups []keybindingGroup) int {
 	widest := 0
-	for _, group := range keybindingGroups {
+	for _, group := range groups {
 		for _, binding := range group.bindings {
 			if n := len([]rune(binding.keys)); n > widest {
 				widest = n

internal/tui/keybinding_help_test.go

@@ -87,11 +87,13 @@ func TestHelpOverlayViewRendersGroupsAndKeys(t *testing.T) {
 	}
 }
 
-func TestKeybindingGroupsAreWellFormed(t *testing.T) {
-	if len(keybindingGroups) == 0 {
-		t.Fatal("keybindingGroups must not be empty")
+func TestBuildKeybindingGroupsAreWellFormed(t *testing.T) {
+	m := newModel(context.Background(), Options{ModelName: "gpt-4o"})
+	groups := m.buildKeybindingGroups()
+	if len(groups) == 0 {
+		t.Fatal("buildKeybindingGroups must not return empty")
 	}
-	for _, group := range keybindingGroups {
+	for _, group := range groups {
 		if strings.TrimSpace(group.title) == "" {
 			t.Fatal("every keybinding group needs a title")
 		}

internal/tui/keybindings.go

@@ -0,0 +1,265 @@
+package tui
+
+import (
+	"strings"
+	"unicode/utf8"
+
+	tea "charm.land/bubbletea/v2"
+
+	"github.com/Gitlawb/zero/internal/config"
+)
+
+// parsedBinding is the parsed representation of a keybinding string such as
+// "ctrl+o" or "alt+enter". The zero value is a sentinel meaning "use default".
+type parsedBinding struct {
+	ctrl  bool
+	alt   bool
+	shift bool
+	cmd   bool   // ⌘ Command (macOS) / ⊞ Win → ModSuper
+	code  rune   // tea.KeyCode or 0 for text-based matching
+	text  string // for text-based matching (e.g. "?")
+}
+
+// isZero returns true when p is the nil sentinel (no binding configured).
+func (p parsedBinding) isZero() bool {
+	return p.code == 0 && p.text == ""
+}
+
+// Label returns a human-readable representation of the binding, e.g. "Ctrl+O"
+// or "Cmd+Shift+Enter". Used in the help overlay. Returns empty string for
+// zero (unset) bindings.
+func (p parsedBinding) Label() string {
+	if p.isZero() {
+		return ""
+	}
+	var b strings.Builder
+	if p.ctrl {
+		b.WriteString("Ctrl+")
+	}
+	if p.alt {
+		b.WriteString("Alt+")
+	}
+	if p.shift {
+		b.WriteString("Shift+")
+	}
+	if p.cmd {
+		b.WriteString("Cmd+")
+	}
+	if p.text != "" {
+		b.WriteString(p.text)
+	} else if p.code != 0 {
+		switch p.code {
+		case tea.KeyEnter:
+			b.WriteString("Enter")
+		case tea.KeyTab:
+			b.WriteString("Tab")
+		case tea.KeyEsc:
+			b.WriteString("Esc")
+		case tea.KeySpace:
+			b.WriteString("Space")
+		case tea.KeyBackspace:
+			b.WriteString("Backspace")
+		case tea.KeyDelete:
+			b.WriteString("Delete")
+		case tea.KeyUp:
+			b.WriteString("↑")
+		case tea.KeyDown:
+			b.WriteString("↓")
+		case tea.KeyLeft:
+			b.WriteString("←")
+		case tea.KeyRight:
+			b.WriteString("→")
+		case tea.KeyHome:
+			b.WriteString("Home")
+		case tea.KeyEnd:
+			b.WriteString("End")
+		case tea.KeyPgUp:
+			b.WriteString("PgUp")
+		case tea.KeyPgDown:
+			b.WriteString("PgDn")
+		default:
+			// Printable character — uppercase for display
+			if p.code >= 'a' && p.code <= 'z' {
+				b.WriteRune(p.code - 32)
+			} else {
+				b.WriteRune(p.code)
+			}
+		}
+	}
+	return b.String()
+}
+
+// Matcher returns a function that matches a tea.KeyMsg against this binding.
+// It is the hot path for the key dispatch — kept cheap intentionally.
+func (p parsedBinding) Matcher() func(tea.KeyMsg) bool {
+	if p.isZero() {
+		// A zero binding should never be matched — the caller is expected to
+		// check useDefault() first and fall through to the built-in check.
+		return func(tea.KeyMsg) bool { return false }
+	}
+
+	// Build the required modifier mask from the parsed flags.
+	var mod tea.KeyMod
+	if p.ctrl {
+		mod |= tea.ModCtrl
+	}
+	if p.alt {
+		mod |= tea.ModAlt
+	}
+	if p.shift {
+		mod |= tea.ModShift
+	}
+	if p.cmd {
+		mod |= tea.ModSuper // ⌘ Command on macOS, ⊞ Win on Windows
+	}
+
+	// ctrl+letter fast path — use exact modifier equality so that a
+	// configured ctrl+o does NOT fire on ctrl+alt+o or ctrl+shift+o.
+	// Note: in raw terminal mode Bubble Tea may report ctrl+letter as
+	// {Code:letter, Mod:ModCtrl} (handled below), or as a control char
+	// code (e.g. 0x0F) without a modifier flag.  The latter is handled by
+	// the text-based fallback in model.go for default bindings; for
+	// configured bindings the code+mod path below is what the user
+	// expressed.
+	if mod == tea.ModCtrl && p.code >= 'a' && p.code <= 'z' {
+		return func(msg tea.KeyMsg) bool {
+			return msg.Key().Code == p.code && msg.Key().Mod == mod
+		}
+	}
+
+	if p.text != "" {
+		return func(msg tea.KeyMsg) bool {
+			return msg.Key().Text == p.text && msg.Key().Mod == mod
+		}
+	}
+
+	return func(msg tea.KeyMsg) bool {
+		return msg.Key().Code == p.code && msg.Key().Mod == mod
+	}
+}
+
+// parseBinding converts a user-written keybinding string (e.g. "ctrl+o") into
+// a parsedBinding. The empty string returns zero parsedBinding (the "use
+// default" sentinel).
+func parseBinding(s string) parsedBinding {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return parsedBinding{}
+	}
+
+	parts := strings.Split(strings.ToLower(s), "+")
+	var p parsedBinding
+	var keyPart string
+	for _, part := range parts {
+		part = strings.TrimSpace(part)
+		switch part {
+		case "ctrl", "control":
+			p.ctrl = true
+		case "alt", "option":
+			p.alt = true
+		case "shift":
+			p.shift = true
+		case "cmd", "command":
+			p.cmd = true
+		case "super":
+			// "super" matches the Bubble Tea naming; on macOS this is ⌘
+			p.cmd = true
+		default:
+			keyPart = part
+		}
+	}
+
+	if p.ctrl && len(keyPart) == 1 && keyPart[0] >= 'a' && keyPart[0] <= 'z' {
+		// ctrl+<letter> — store the code so the match is exact
+		p.code = []rune(keyPart)[0]
+		p.text = ""
+		return p
+	}
+
+	// Map named keys to their tea.KeyCode
+	switch keyPart {
+	case "enter", "return":
+		p.code = tea.KeyEnter
+	case "tab":
+		p.code = tea.KeyTab
+	case "esc", "escape":
+		p.code = tea.KeyEsc
+	case "space":
+		p.code = tea.KeySpace
+	case "backspace":
+		p.code = tea.KeyBackspace
+	case "delete":
+		p.code = tea.KeyDelete
+	case "up":
+		p.code = tea.KeyUp
+	case "down":
+		p.code = tea.KeyDown
+	case "left":
+		p.code = tea.KeyLeft
+	case "right":
+		p.code = tea.KeyRight
+	case "home":
+		p.code = tea.KeyHome
+	case "end":
+		p.code = tea.KeyEnd
+	case "pgup", "pageup":
+		p.code = tea.KeyPgUp
+	case "pgdown", "pagedown":
+		p.code = tea.KeyPgDown
+	case "?":
+		p.text = "?"
+		p.code = 0
+	default:
+		// Single character, any modifier context
+		if utf8.RuneCountInString(keyPart) == 1 {
+			p.code = []rune(keyPart)[0]
+		}
+		// else unrecognised — leave zero so it falls through to default
+	}
+
+	return p
+}
+
+// labelOr returns b.Label() when b is configured (non-zero), otherwise it
+// returns the caller-supplied default label string.  This is the display-layer
+// counterpart to keyMatch — dispatch falls through to the hardcoded default
+// function, so the label displayed in help / hints must match that fallback.
+func labelOr(b parsedBinding, defaultLabel string) string {
+	if !b.isZero() {
+		return b.Label()
+	}
+	return defaultLabel
+}
+
+// keyBindings holds the parsed, resolved key bindings the model uses at
+// dispatch time. When a binding's parsedBinding is zero, the built-in default
+// check in model.go's updateModel should be used.
+type keyBindings struct {
+	toggleDetailed parsedBinding
+	toggleMouse    parsedBinding
+	cycleReasoning parsedBinding
+	togglePlan     parsedBinding
+	toggleSidebar  parsedBinding
+}
+
+// resolveKeyBindings converts a user-facing KeyBindingsConfig into the
+// dispatch-ready parsed form, using empty-is-default semantics.
+func resolveKeyBindings(cfg config.KeyBindingsConfig) keyBindings {
+	return keyBindings{
+		toggleDetailed: parseBinding(string(cfg.ToggleDetailed)),
+		toggleMouse:    parseBinding(string(cfg.ToggleMouse)),
+		cycleReasoning: parseBinding(string(cfg.CycleReasoning)),
+		togglePlan:     parseBinding(string(cfg.TogglePlan)),
+		toggleSidebar:  parseBinding(string(cfg.ToggleSidebar)),
+	}
+}
+
+// keyMatch returns true when msg matches either the user-configured binding b
+// or (when b is zero/unset) the built-in default matcher defaultFn. This is
+// the bridge between the config surface and the hot dispatch path in model.go.
+func (m model) keyMatch(b parsedBinding, msg tea.KeyMsg, defaultFn func(tea.KeyMsg) bool) bool {
+	if !b.isZero() {
+		return b.Matcher()(msg)
+	}
+	return defaultFn(msg)
+}

internal/tui/latency_test.go

@@ -0,0 +1,33 @@
+package tui
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/Gitlawb/zero/internal/sessions"
+)
+
+func TestAvgTurnLatencyText(t *testing.T) {
+	m := newModel(context.Background(), Options{})
+	if got := m.avgTurnLatencyText(); got != "n/a" {
+		t.Fatalf("empty latency = %q, want n/a", got)
+	}
+	m.turnLatencySum = 9 * time.Second
+	m.turnLatencyCount = 2
+	if got := m.avgTurnLatencyText(); got != "4.5s avg (2 turns)" {
+		t.Fatalf("avgTurnLatencyText = %q, want \"4.5s avg (2 turns)\"", got)
+	}
+	// With TTFT recorded, the line also reports time-to-first-token.
+	m.turnTTFTSum = 3 * time.Second
+	m.turnTTFTCount = 2
+	if got := m.avgTurnLatencyText(); got != "4.5s avg (1.5s to first token, 2 turns)" {
+		t.Fatalf("avgTurnLatencyText with ttft = %q, want \"4.5s avg (1.5s to first token, 2 turns)\"", got)
+	}
+	// /new must reset the rolling latency + ttft so a fresh session starts from zero.
+	m.activeSession = sessions.Metadata{SessionID: "x"}
+	next := m.startNewSession()
+	if next.turnLatencyCount != 0 || next.turnLatencySum != 0 || next.turnTTFTCount != 0 || next.turnTTFTSum != 0 {
+		t.Fatalf("startNewSession must reset latency+ttft, got latency=%d/%v ttft=%d/%v", next.turnLatencyCount, next.turnLatencySum, next.turnTTFTCount, next.turnTTFTSum)
+	}
+}

internal/tui/model.go

@@ -36,7 +36,7 @@ import (
 )
 
 const tuiToolOutputLimit = 240
-const defaultResponseStyle = "balanced"
+const defaultResponseStyle = "concise"
 const chatWheelScrollLines = 5
 const ctrlCExitConfirmDuration = 3 * time.Second
 const ctrlCExitConfirmText = "Press Ctrl+C again to exit"
@@ -100,35 +100,43 @@ type model struct {
 	titledSessions map[string]bool
 	// retitle* drive the sequential /retitle backfill: queued session ids still
 	// awaiting a title, whether a backfill is running, and its progress counters.
-	retitleQueue          []string
-	retitleActive         bool
-	retitleTotal          int
-	retitleDone           int
-	retitleOK             int
-	usageTracker          *usage.Tracker
-	sessionCompactor      SessionCompactor
-	prService             *PrService
-	prState               PrState
-	prWatcherStop         func()
-	runtimeMessageSink    func(tea.Msg)
-	agentOptions          agent.Options
-	notifier              *notify.Notifier
-	permissionMode        agent.PermissionMode
-	selfCorrectTests      bool
-	reasoningEffort       modelregistry.ReasoningEffort
-	responseStyle         string
-	themeMode             themeMode // palette preference: auto (default), dark, light
-	hasDarkBg             bool      // last terminal background-detection result (auto mode)
-	userAgent             string
-	compactRequests       int
-	compactInFlight       bool
-	compactFrame          int
-	lastCompactResult     *CompactResult
-	lastCompactError      string
-	unpricedRequests      int
-	unpricedTokens        int
-	lastUsage             usage.Normalized
-	lastUsageSeen         bool
+	retitleQueue       []string
+	retitleActive      bool
+	retitleTotal       int
+	retitleDone        int
+	retitleOK          int
+	usageTracker       *usage.Tracker
+	sessionCompactor   SessionCompactor
+	prService          *PrService
+	prState            PrState
+	prWatcherStop      func()
+	runtimeMessageSink func(tea.Msg)
+	agentOptions       agent.Options
+	notifier           *notify.Notifier
+	permissionMode     agent.PermissionMode
+	selfCorrectTests   bool
+	reasoningEffort    modelregistry.ReasoningEffort
+	responseStyle      string
+	keyBindings        keyBindings
+	themeMode          themeMode // palette preference: auto (default), dark, light
+	hasDarkBg          bool      // last terminal background-detection result (auto mode)
+	userAgent          string
+	compactRequests    int
+	compactInFlight    bool
+	compactFrame       int
+	lastCompactResult  *CompactResult
+	lastCompactError   string
+	unpricedRequests   int
+	unpricedTokens     int
+	lastUsage          usage.Normalized
+	lastUsageSeen      bool
+	// turnLatencySum / turnLatencyCount accumulate completed-run wall time so
+	// /context can show a rolling average turn latency (the "is it slow?" signal).
+	// Reset by /new.
+	turnLatencySum        time.Duration
+	turnLatencyCount      int
+	turnTTFTSum           time.Duration
+	turnTTFTCount         int
 	transcript            []transcriptRow
 	transcriptDetailed    bool
 	helpOverlay           bool // the `?` keyboard-shortcut overlay is open
@@ -318,9 +326,14 @@ type model struct {
 	// mouse cursor with no button pressed, so it renders in a distinct style —
 	// the visual cue that it's clickable. Requires AllMotion mouse reporting
 	// (see wantsMouseCapture) since idle cursor movement carries no button.
-	hover             hoverTarget
-	copyStatus        string
-	copyStatusSeq     int
+	hover         hoverTarget
+	copyStatus    string
+	copyStatusSeq int
+	// fastToast is a transient /fast notice shown in the row above the composer for
+	// fastToastDuration, then auto-cleared (seq-gated). It keeps ephemeral fast-lane
+	// feedback out of the persistent transcript.
+	fastToast         string
+	fastToastSeq      int
 	exitConfirmActive bool
 	exitConfirmSeq    int
 	// cancelConfirmActive/cancelConfirmSeq mirror exitConfirmActive/exitConfirmSeq
@@ -451,6 +464,9 @@ type agentResponseMsg struct {
 	// Turn metadata for settled rows that do not otherwise carry it.
 	turnTools   int
 	turnElapsed time.Duration
+	// ttft is time-to-first-token for the turn (0 when nothing streamed — a
+	// tool-only or errored turn). Set only on the success path.
+	ttft time.Duration
 }
 
 type agentRowMsg struct {
@@ -726,6 +742,7 @@ func newModel(ctx context.Context, options Options) model {
 		permissionMode:              permissionMode,
 		reasoningEffort:             options.ReasoningEffort,
 		responseStyle:               defaultedResponseStyle(options.ResponseStyle),
+		keyBindings:                 resolveKeyBindings(options.KeyBindings),
 		themeMode:                   resolveThemeMode(options.Theme, os.Getenv("ZERO_THEME"), options.SavedTheme),
 		hasDarkBg:                   true,
 		userAgent:                   options.UserAgent,
@@ -1003,6 +1020,11 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 			m.copyStatus = ""
 		}
 		return m, nil
+	case fastToastExpiredMsg:
+		if msg.seq == m.fastToastSeq {
+			m.fastToast = ""
+		}
+		return m, nil
 	case exitConfirmExpiredMsg:
 		if msg.seq == m.exitConfirmSeq {
 			m.exitConfirmActive = false
@@ -1078,7 +1100,7 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 		switch {
 		case keyCtrl(msg, 'c'):
 			return m.handleCtrlC()
-		case keyCtrl(msg, 'o'):
+		case m.keyMatch(m.keyBindings.toggleDetailed, msg, func(tea.KeyMsg) bool { return keyCtrl(msg, 'o') }):
 			return m.toggleDetailedTranscript(), nil
 		case m.fileView.active && m.noBlockingModal() && m.composerValue() == "" && (keyText(msg) == "d" || keyText(msg) == "f"):
 			// Mode toggle for the file drill-in, only while the composer is empty
@@ -1088,12 +1110,13 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 				return m.setFileViewMode(fileViewFull), nil
 			}
 			return m.setFileViewMode(fileViewDiff), nil
-		case keyCtrl(msg, 'e'):
+		case m.keyMatch(m.keyBindings.toggleMouse, msg, func(tea.KeyMsg) bool { return keyCtrl(msg, 'e') }):
 			// Release/recapture the mouse so the user can drag-select and copy text
 			// natively (mouse capture otherwise intercepts terminal selection).
 			m.mouseReleased = !m.mouseReleased
 			if m.mouseReleased {
-				return m.appendSystemNotice("Mouse released — drag to select and copy text. Press Ctrl+E again to re-enable mouse interaction (clicks, right-click paste)."), nil
+				mouseKey := labelOr(m.keyBindings.toggleMouse, "Ctrl+E")
+				return m.appendSystemNotice(fmt.Sprintf("Mouse released — drag to select and copy text. Press %s again to re-enable mouse interaction (clicks, right-click paste).", mouseKey)), nil
 			}
 			return m.appendSystemNotice("Mouse interaction re-enabled."), nil
 		case keyIs(msg, tea.KeyEsc):
@@ -1268,7 +1291,7 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 				m.permissionMode = nextPermissionMode(m.permissionMode)
 				return m, nil
 			}
-		case keyCtrl(msg, 't'):
+		case m.keyMatch(m.keyBindings.cycleReasoning, msg, func(tea.KeyMsg) bool { return keyCtrl(msg, 't') }):
 			if m.transcriptDetailed {
 				return m, nil
 			}
@@ -1281,20 +1304,20 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 			if m.noBlockingModal() {
 				return m.cycleReasoningEffort()
 			}
-		case keyCtrl(msg, 'p'):
+		case m.keyMatch(m.keyBindings.togglePlan, msg, func(tea.KeyMsg) bool { return keyCtrl(msg, 'p') }):
 			// Ctrl+P toggles the plan panel expansion (collapse/expand step list).
 			if m.noBlockingModal() && !m.plan.isEmpty() {
 				m.plan.expanded = !m.plan.expanded
 				return m, nil
 			}
-		case keyCtrl(msg, 'b'):
+		case m.keyMatch(m.keyBindings.toggleSidebar, msg, func(tea.KeyMsg) bool { return keyCtrl(msg, 'b') }):
 			// Ctrl+B collapses / restores the right context sidebar. Only acts when
 			// the sidebar would otherwise be on screen (managed mode, wide enough,
 			// real conversation) so it's a no-op — not a confusing notice — on the
 			// home screen or a narrow terminal. Hiding reflows the chat to full
 			// width, so mirror the width-change bookkeeping (re-wrap the streaming
 			// fade, resize the composer) the WindowSizeMsg path does.
-			if m.noBlockingModal() && m.sidebarAvailable() {
+			if m.noBlockingModal() && m.sidebarToggleAllowed() {
 				// Just show/hide — no transcript notice. The reflow IS the feedback,
 				// and emitting a line every toggle piled up noise in the chat.
 				m.sidebarHidden = !m.sidebarHidden
@@ -1856,6 +1879,16 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.streamingText = ""
 		m.streamingReasoning = ""
 		m.streamingReasoningExpanded = false
+		// Roll the completed run's wall-time into the session's rolling average so
+		// /context can surface typical turn latency, not just token counts.
+		if msg.turnElapsed > 0 {
+			m.turnLatencySum += msg.turnElapsed
+			m.turnLatencyCount++
+		}
+		if msg.ttft > 0 {
+			m.turnTTFTSum += msg.ttft
+			m.turnTTFTCount++
+		}
 		if msg.specReview != nil {
 			m = m.activateSpecReview(*msg.specReview)
 		}
@@ -2324,7 +2357,9 @@ func (m model) footerView(width int) string {
 	// a faint idle affordance — discoverable key hints on the left, a jump-to-bottom
 	// cue on the right when scrolled up. Always one line (blank when nothing shows),
 	// so the footer height is unchanged.
-	if copyStatus := strings.TrimSpace(m.copyStatus); copyStatus != "" {
+	if toast := strings.TrimSpace(m.fastToast); toast != "" {
+		footer.WriteString(rightAlignedLine(renderFastToast(toast), width))
+	} else if copyStatus := strings.TrimSpace(m.copyStatus); copyStatus != "" {
 		footer.WriteString(rightAlignedLine(zeroTheme.ink.Render(copyStatus), width))
 	} else if left, right := m.composerIdleHint(), m.jumpToBottomHint(); left != "" || right != "" {
 		footer.WriteString(fitStyledLine(joinHeaderLine("  "+left, right, width), width))
@@ -2360,6 +2395,10 @@ func (m model) composerIdleHint() string {
 		m.subchat.active || m.suggestionsActive() || m.transcriptDetailed {
 		return ""
 	}
+	sidebarKey := labelOr(m.keyBindings.toggleSidebar, "Ctrl+B")
+	detailKey := labelOr(m.keyBindings.toggleDetailed, "Ctrl+O")
+	mouseKey := labelOr(m.keyBindings.toggleMouse, "Ctrl+E")
+
 	var hint string
 	switch widthTier(m.width) {
 	case tierTiny:
@@ -2367,9 +2406,9 @@ func (m model) composerIdleHint() string {
 	case tierNarrow:
 		hint = "? shortcuts"
 	case tierMedium:
-		hint = "? shortcuts · Ctrl+B sidebar · Ctrl+E copy"
+		hint = fmt.Sprintf("? shortcuts · %s sidebar · %s copy", sidebarKey, mouseKey)
 	default:
-		hint = "? shortcuts · Ctrl+B sidebar · Ctrl+O detail · Ctrl+E copy · Shift+Tab mode"
+		hint = fmt.Sprintf("? shortcuts · %s sidebar · %s detail · %s copy · Shift+Tab mode", sidebarKey, detailKey, mouseKey)
 	}
 	return zeroTheme.faint.Render(hint)
 }
@@ -3615,10 +3654,23 @@ func (m model) handleSubmit() (tea.Model, tea.Cmd) {
 		return m, nil
 	case commandClear:
 		m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionClear})
+		// Clearing wipes the visible transcript only — the session's context is
+		// intact, so the next prompt still replays the full history. Say so, and
+		// point to /new, so "cleared screen" isn't mistaken for "fresh context."
+		m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionAppendSystem, text: "Transcript cleared. The agent still has the full session context — use /new to start a fresh session."})
 		// Scrollback above can't be un-printed; a faint divider marks where the
 		// cleared surface ended and the frontier restarts for the fresh transcript.
 		m.resetFlushFrontier("· cleared ·")
 		return m, nil
+	case commandNew:
+		// A fresh session mid-run would strand the in-flight turn's events; make the
+		// user cancel first. Idle, /new saves the current session (already on disk)
+		// and clears the conversation in place.
+		if m.pending || m.compactInFlight {
+			m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionAppendSystem, text: "A run is in progress. Press Esc to cancel it first, then /new."})
+			return m, nil
+		}
+		return m.startNewSession(), nil
 	case commandExit:
 		// /exit gets the same protection as Ctrl+C: cancel any in-flight run and
 		// defer the quit until its checkpoint session events flush — quitting
@@ -3774,6 +3826,12 @@ func (m model) handleSubmit() (tea.Model, tea.Cmd) {
 		m, text = m.handleEffortCommand(command.text)
 		m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionAppendSystem, text: text})
 		return m, nil
+	case commandFast:
+		var text string
+		m, text = m.handleFastCommand(command.text)
+		// Fast-lane feedback is ephemeral: show it as a transient toast above the
+		// composer (auto-dismissed) instead of a permanent transcript line.
+		return m.showFastToast(text)
 	case commandStyle:
 		text := ""
 		m, text = m.handleStyleCommand(command.text)
@@ -4103,6 +4161,9 @@ func selfCorrectAutonomyForMode(mode agent.PermissionMode) string {
 func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt string, images []zeroruntime.ImageBlock, runOptions tuiAgentRunOptions) tea.Cmd {
 	return func() tea.Msg {
 		started := m.now()
+		// firstTokenAt is stamped when the first token (reasoning or text) streams,
+		// so the turn can report time-to-first-token alongside total wall time.
+		var firstTokenAt time.Time
 		toolCalls := 0
 		rows := []transcriptRow{}
 		usageEvents := []zeroruntime.Usage{}
@@ -4195,6 +4256,9 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 
 		onText := options.OnText
 		options.OnText = func(delta string) {
+			if firstTokenAt.IsZero() {
+				firstTokenAt = m.now()
+			}
 			if strings.TrimSpace(reasoningText) != "" {
 				flushReasoning(m.now())
 			}
@@ -4290,6 +4354,9 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 		onReasoning := options.OnReasoning
 		options.OnReasoning = func(delta string) {
 			now := m.now()
+			if firstTokenAt.IsZero() && strings.TrimSpace(delta) != "" {
+				firstTokenAt = now
+			}
 			if strings.TrimSpace(reasoningText) == "" && strings.TrimSpace(delta) != "" {
 				reasoningStarted = now
 			}
@@ -4526,6 +4593,10 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 		}
 		flushReasoning(m.now())
 		elapsed := m.now().Sub(started)
+		ttft := time.Duration(0)
+		if !firstTokenAt.IsZero() {
+			ttft = firstTokenAt.Sub(started)
+		}
 		rows = append(rows, transcriptRow{
 			kind:        rowAssistant,
 			text:        result.FinalAnswer,
@@ -4543,7 +4614,7 @@ func (m model) runAgentWithOptions(runID int, runCtx context.Context, prompt str
 				"content": result.FinalAnswer,
 			},
 		})
-		return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, sessionEvents: sessionEvents, turnTools: toolCalls, turnElapsed: elapsed}
+		return agentResponseMsg{runID: runID, rows: rows, usageEvents: usageEvents, usageModelID: usageModelID, sessionEvents: sessionEvents, turnTools: toolCalls, turnElapsed: elapsed, ttft: ttft}
 	}
 }
 

internal/tui/model_test.go

@@ -340,8 +340,11 @@ func TestClearCommandResetsTranscript(t *testing.T) {
 	updated, _ := m.Update(testKey(tea.KeyEnter))
 	next := updated.(model)
 
-	if len(next.transcript) != 1 || next.transcript[0].kind != rowWelcome {
-		t.Fatalf("expected clear to reset transcript, got %#v", next.transcript)
+	if len(next.transcript) != 2 || next.transcript[0].kind != rowWelcome {
+		t.Fatalf("expected clear to reset transcript to welcome + note, got %#v", next.transcript)
+	}
+	if !transcriptContains(next.transcript, "/new") {
+		t.Fatalf("expected clear to point users to /new, got %#v", next.transcript)
 	}
 }
 

internal/tui/new_session_test.go

@@ -0,0 +1,72 @@
+package tui
+
+import (
+	"context"
+	"testing"
+
+	tea "charm.land/bubbletea/v2"
+
+	"github.com/Gitlawb/zero/internal/sessions"
+	"github.com/Gitlawb/zero/internal/zeroruntime"
+)
+
+func TestStartNewSessionResetsState(t *testing.T) {
+	m := newModel(context.Background(), Options{})
+	m.activeSession = sessions.Metadata{SessionID: "sess-old"}
+	m.sessionEvents = []sessions.Event{{Type: sessions.EventMessage}}
+	m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionAppendUser, text: "hello"})
+	// Stage attachments + a queued message that /new must not leak into the new session.
+	m.pendingImages = make([]zeroruntime.ImageBlock, 1)
+	m.pendingImageLabels = []string{"pic.png"}
+	m.pendingDocuments = []pendingDocument{{label: "doc.pdf"}}
+	m.queuedMessage = "queued"
+
+	next := m.startNewSession()
+
+	if next.activeSession.SessionID != "" {
+		t.Fatalf("expected active session id cleared, got %q", next.activeSession.SessionID)
+	}
+	if len(next.sessionEvents) != 0 {
+		t.Fatalf("expected session events cleared, got %d", len(next.sessionEvents))
+	}
+	if len(next.transcript) != 2 || next.transcript[0].kind != rowWelcome {
+		t.Fatalf("expected transcript reset to welcome + note, got %#v", next.transcript)
+	}
+	// The note must name the prior session id so the user can /resume it.
+	if !transcriptContains(next.transcript, "sess-old") {
+		t.Fatalf("expected note to reference previous session id, got %#v", next.transcript)
+	}
+	// Staged attachments and the queued message must not leak into the new session.
+	if len(next.pendingImages) != 0 || len(next.pendingImageLabels) != 0 || len(next.pendingDocuments) != 0 || next.queuedMessage != "" {
+		t.Fatalf("startNewSession must clear staged input, got images=%d labels=%d docs=%d queued=%q",
+			len(next.pendingImages), len(next.pendingImageLabels), len(next.pendingDocuments), next.queuedMessage)
+	}
+}
+
+func TestNewCommandStartsFreshSession(t *testing.T) {
+	m := newModel(context.Background(), Options{})
+	m.activeSession = sessions.Metadata{SessionID: "sess-old"}
+	m.input.SetValue("/new")
+
+	updated, _ := m.Update(testKey(tea.KeyEnter))
+	next := updated.(model)
+
+	if next.activeSession.SessionID != "" {
+		t.Fatalf("expected /new to clear the active session, got %q", next.activeSession.SessionID)
+	}
+}
+
+func TestNewCommandDoesNotResetDuringRun(t *testing.T) {
+	m := newModel(context.Background(), Options{})
+	m.activeSession = sessions.Metadata{SessionID: "sess-old"}
+	m.pending = true
+	m.input.SetValue("/new")
+
+	updated, _ := m.Update(testKey(tea.KeyEnter))
+	next := updated.(model)
+
+	// The safety invariant: /new must never strand an in-flight session.
+	if next.activeSession.SessionID != "sess-old" {
+		t.Fatalf("/new must not reset an in-flight session, got %q", next.activeSession.SessionID)
+	}
+}

internal/tui/options.go

@@ -64,6 +64,10 @@ type Options struct {
 	// Notify configures completion / awaiting-input notifications.
 	Notify config.NotifyConfig
 
+	// KeyBindings configures remappable TUI keybindings. An empty/zero
+	// KeyBindingsConfig means "use built-in defaults" for each action.
+	KeyBindings config.KeyBindingsConfig
+
 	// AltScreen tells the model it is running inside Bubble Tea's alternate
 	// screen. Run sets this for the interactive app; tests can leave it false
 	// to exercise the native scrollback renderer.

internal/tui/picker.go

@@ -43,6 +43,10 @@ type pickerItem struct {
 	Remote        bool
 	Local         bool
 	Favorite      bool
+	// FastVariant is the display name of this model's faster same-family variant
+	// (empty when it has none). Set only for /model rows; drives the "f" fast-mode
+	// badge and the focused-row "⚡ fast: … · /fast on" hint.
+	FastVariant string
 }
 
 // commandPicker is a generic single-select overlay reused by /model and /effort
@@ -155,9 +159,35 @@ func (m model) newModelPicker() *commandPicker {
 	if len(items) == 0 {
 		return nil
 	}
+	decorateFastVariantItems(registry, items)
 	return &commandPicker{kind: pickerModel, title: "Choose a model", items: items, allItems: append([]pickerItem{}, items...), selected: 0}
 }
 
+// decorateFastVariantItems stamps each /model row with the display name of its
+// fast variant (if any), in one pass over the assembled list rather than in every
+// item builder. Rows whose model id is not in the curated registry (custom or
+// live-discovered) simply keep an empty FastVariant and show no badge.
+func decorateFastVariantItems(registry modelregistry.Registry, items []pickerItem) {
+	for index := range items {
+		id := strings.TrimSpace(items[index].Value)
+		if id == "" {
+			continue
+		}
+		if fast, ok := registry.FastVariant(id); ok {
+			items[index].FastVariant = fastVariantDisplayName(fast)
+		}
+	}
+}
+
+// fastVariantDisplayName is the user-facing name of a fast variant, preferring
+// its display name and falling back to the id.
+func fastVariantDisplayName(entry modelregistry.ModelEntry) string {
+	if name := strings.TrimSpace(entry.DisplayName); name != "" {
+		return name
+	}
+	return strings.TrimSpace(entry.ID)
+}
+
 // modelPickerProviders returns the providers to list in /model: all saved
 // providers, falling back to the active profile when none were threaded in.
 func (m model) modelPickerProviders() []config.ProviderProfile {
@@ -619,7 +649,15 @@ func (m model) normalizeProfileForProvider(provider providercatalog.Descriptor)
 		strings.TrimSpace(profile.Name) == "" ||
 		strings.TrimSpace(profile.CatalogID) == ""
 	if normalizeIdentity {
-		profile.Name = provider.ID
+		// Only canonicalize an empty or generic placeholder name — never clobber a
+		// real user-provided profile name. The credential store is keyed by
+		// profile.Name (SecureProviderProfile stores under Name), so rewriting it
+		// here made the later profileWithCredential lookup miss the saved key and
+		// rebuild a keyless provider — a 401 on every /model switch for any profile
+		// named differently from its catalog id (e.g. "my-openai").
+		if strings.TrimSpace(profile.Name) == "" || genericProviderCatalogID(profile.Name) {
+			profile.Name = provider.ID
+		}
 		profile.CatalogID = provider.ID
 	}
 	if strings.TrimSpace(profile.BaseURL) == "" {

internal/tui/picker_test.go

@@ -976,3 +976,49 @@ func TestSwitchProviderModelWarmsDiscoveryForTheNewProvider(t *testing.T) {
 		t.Fatal("switching to ollama should warm both the generic and ollama-specific discovery commands")
 	}
 }
+
+func TestNormalizeProfileForProviderPreservesCustomName(t *testing.T) {
+	openai, ok := providercatalog.Get("openai")
+	if !ok {
+		t.Fatal("openai descriptor missing from catalog")
+	}
+
+	// A first-party provider set up with a custom profile name and the baseURL at
+	// the catalog default. normalizeIdentity is true here (baseURL matches), but
+	// the real name must survive: it is the credential-store key, so clobbering it
+	// dropped the saved key and 401'd every /model switch (issue #440).
+	m := model{providerProfile: config.ProviderProfile{
+		Name:         "my-openai",
+		CatalogID:    "openai",
+		BaseURL:      openai.DefaultBaseURL,
+		APIKeyStored: true,
+	}}
+	got := m.normalizeProfileForProvider(openai)
+	if got.Name != "my-openai" {
+		t.Fatalf("Name = %q, want it preserved as %q (credential store is keyed by Name)", got.Name, "my-openai")
+	}
+	if got.CatalogID != "openai" {
+		t.Fatalf("CatalogID = %q, want it canonicalized to %q", got.CatalogID, "openai")
+	}
+}
+
+func TestNormalizeProfileForProviderCanonicalizesPlaceholderName(t *testing.T) {
+	openai, ok := providercatalog.Get("openai")
+	if !ok {
+		t.Fatal("openai descriptor missing from catalog")
+	}
+
+	// Empty and generic placeholder names still get canonicalized to the catalog
+	// id — those carry no meaningful credential-store key to preserve.
+	for _, name := range []string{"", "custom-openai-compatible"} {
+		m := model{providerProfile: config.ProviderProfile{
+			Name:      name,
+			BaseURL:   openai.DefaultBaseURL,
+			CatalogID: name,
+		}}
+		got := m.normalizeProfileForProvider(openai)
+		if got.Name != "openai" {
+			t.Fatalf("Name = %q for placeholder %q, want canonicalized to %q", got.Name, name, "openai")
+		}
+	}
+}

internal/tui/provider_wizard.go

@@ -297,6 +297,7 @@ type providerWizardState struct {
 	selectedProvider int
 	models           []providerWizardModel
 	selectedModel    int
+	providerSearch   string
 	modelSearch      string
 	baseURL          string
 	profileName      string
@@ -343,7 +344,18 @@ func providerWizardProviders() []providercatalog.Descriptor {
 }
 
 func (wizard *providerWizardState) currentProvider() providercatalog.Descriptor {
-	if wizard == nil || len(wizard.providers) == 0 {
+	if wizard == nil {
+		return providercatalog.Descriptor{}
+	}
+	if wizard.step == providerWizardStepProvider {
+		providers := wizard.filteredProviders()
+		if len(providers) == 0 {
+			return providercatalog.Descriptor{}
+		}
+		wizard.selectedProvider = clampInt(wizard.selectedProvider, 0, len(providers)-1)
+		return providers[wizard.selectedProvider]
+	}
+	if len(wizard.providers) == 0 {
 		return providercatalog.Descriptor{}
 	}
 	wizard.selectedProvider = clampInt(wizard.selectedProvider, 0, len(wizard.providers)-1)
@@ -399,10 +411,11 @@ func (wizard *providerWizardState) move(delta int) {
 		}
 		wizard.selectedMethod = ((wizard.selectedMethod+delta)%len(options) + len(options)) % len(options)
 	case providerWizardStepProvider:
-		if len(wizard.providers) == 0 {
+		providers := wizard.filteredProviders()
+		if len(providers) == 0 {
 			return
 		}
-		wizard.selectedProvider = ((wizard.selectedProvider+delta)%len(wizard.providers) + len(wizard.providers)) % len(wizard.providers)
+		wizard.selectedProvider = ((wizard.selectedProvider+delta)%len(providers) + len(providers)) % len(providers)
 		wizard.selectedModel = 0
 		wizard.modelSearch = ""
 		wizard.baseURL = ""
@@ -450,6 +463,21 @@ func (wizard *providerWizardState) advance() {
 		if wizard.oauthMode {
 			return
 		}
+		if len(wizard.filteredProviders()) == 0 {
+			return
+		}
+		// Resolve the selected provider's index in the full list before clearing
+		// the search — selectedProvider is an index into the filtered slice, and
+		// clearing the search swaps to the full list.
+		if selected := wizard.currentProvider(); selected.ID != "" {
+			for i, p := range wizard.providers {
+				if p.ID == selected.ID {
+					wizard.selectedProvider = i
+					break
+				}
+			}
+		}
+		wizard.providerSearch = ""
 		wizard.refreshModels()
 		wizard.err = ""
 		if providerWizardNeedsEndpoint(wizard.currentProvider()) {
@@ -513,6 +541,7 @@ func (wizard *providerWizardState) retreat() {
 		wizard.step = providerWizardStepMethod
 	case providerWizardStepEndpoint:
 		wizard.step = providerWizardStepProvider
+		wizard.providerSearch = ""
 	case providerWizardStepName:
 		wizard.step = providerWizardStepEndpoint
 	case providerWizardStepCredential:
@@ -628,6 +657,20 @@ func (m model) handleProviderWizardKey(msg tea.KeyMsg) (model, tea.Cmd) {
 		m.providerWizard.currentProvider().OAuthDeviceFlow {
 		return m.startProviderDeviceLogin()
 	}
+	if m.providerWizard.step == providerWizardStepProvider {
+		switch {
+		case keyText(msg) != "":
+			m.providerWizard.appendProviderSearch(keyRunes(msg))
+			return m, nil
+		case keyBackspace(msg):
+			m.providerWizard.deleteProviderSearchRune()
+			return m, nil
+		case keyCtrl(msg, 'u'):
+			m.providerWizard.providerSearch = ""
+			m.providerWizard.selectedProvider = 0
+			return m, nil
+		}
+	}
 	if m.providerWizard.step == providerWizardStepEndpoint {
 		switch {
 		case keyText(msg) != "":
@@ -746,6 +789,8 @@ func (m model) handleProviderWizardPaste(content string) (model, tea.Cmd) {
 		return m, nil
 	}
 	switch m.providerWizard.step {
+	case providerWizardStepProvider:
+		m.providerWizard.appendProviderSearch([]rune(content))
 	case providerWizardStepEndpoint:
 		m.providerWizard.appendBaseURL([]rune(content))
 	case providerWizardStepName:
@@ -879,6 +924,50 @@ func (wizard *providerWizardState) deleteModelSearchRune() {
 	wizard.selectedModel = 0
 }
 
+func (wizard *providerWizardState) appendProviderSearch(runes []rune) {
+	for _, r := range runes {
+		if unicode.IsControl(r) {
+			continue
+		}
+		wizard.providerSearch += string(r)
+	}
+	wizard.selectedProvider = 0
+}
+
+func (wizard *providerWizardState) deleteProviderSearchRune() {
+	if wizard.providerSearch == "" {
+		return
+	}
+	runes := []rune(wizard.providerSearch)
+	wizard.providerSearch = string(runes[:len(runes)-1])
+	wizard.selectedProvider = 0
+}
+
+func (wizard *providerWizardState) filteredProviders() []providercatalog.Descriptor {
+	if wizard == nil {
+		return nil
+	}
+	query := strings.ToLower(strings.TrimSpace(wizard.providerSearch))
+	if query == "" {
+		return append([]providercatalog.Descriptor{}, wizard.providers...)
+	}
+	providers := make([]providercatalog.Descriptor, 0, len(wizard.providers))
+	for _, provider := range wizard.providers {
+		if providerMatchesQuery(provider, query) {
+			providers = append(providers, provider)
+		}
+	}
+	return providers
+}
+
+func providerMatchesQuery(provider providercatalog.Descriptor, query string) bool {
+	if query == "" {
+		return true
+	}
+	haystack := strings.ToLower(strings.Join([]string{provider.ID, provider.Name, strings.Join(provider.Aliases, " ")}, " "))
+	return strings.Contains(haystack, query)
+}
+
 func (m model) applyProviderWizard() (model, tea.Cmd) {
 	wizard := m.providerWizard
 	if wizard == nil {
@@ -1248,9 +1337,15 @@ func (wizard *providerWizardState) renderProviderStep(width int) []string {
 		header = "Choose an OAuth provider"
 	}
 	lines := []string{zeroTheme.accent.Render(header)}
-	maxVisible := minInt(maxProviderWizardProvidersVisible, len(wizard.providers))
-	start := selectableListStart(len(wizard.providers), maxVisible, wizard.selectedProvider)
-	for offset, provider := range wizard.providers[start : start+maxVisible] {
+	lines = append(lines, wizard.renderProviderSearch(width))
+	providers := wizard.filteredProviders()
+	if len(providers) == 0 {
+		lines = append(lines, zeroTheme.faint.Render("  no matching providers"))
+		return lines
+	}
+	maxVisible := minInt(maxProviderWizardProvidersVisible, len(providers))
+	start := selectableListStart(len(providers), maxVisible, wizard.selectedProvider)
+	for offset, provider := range providers[start : start+maxVisible] {
 		lines = append(lines, wizard.renderSelectableProvider(width, start+offset, provider))
 	}
 	// A failed OAuth attempt leaves the wizard on this list (it does not advance),
@@ -1265,6 +1360,11 @@ func (wizard *providerWizardState) renderProviderStep(width int) []string {
 	return lines
 }
 
+func (wizard *providerWizardState) renderProviderSearch(width int) string {
+	query := strings.TrimSpace(wizard.providerSearch)
+	return providerWizardInputLine("search > ", query, "provider name, id, or alias...", width)
+}
+
 // providerWizardOAuthErrHint returns a provider-specific next step for a failed
 // OAuth login. Hugging Face ships no public client_id (unlike xAI), so a login
 // can only work once the operator registers an app and supplies its client_id.
@@ -1467,6 +1567,9 @@ func (wizard *providerWizardState) renderSelectableModel(width int, index int, m
 		marker = surface(zeroTheme.accent).Render("❯ ")
 	}
 	left := marker + surface(zeroTheme.ink).Render(model.displayLabel())
+	if _, ok := fastVariantEntryFor(model.ID); ok {
+		left += renderFastBadge(surface(zeroTheme.accent))
+	}
 	return fitStyledLine(left, width)
 }
 
@@ -1478,6 +1581,9 @@ func providerWizardModelDetail(model providerWizardModel) string {
 	if meta := strings.TrimSpace(model.Meta); meta != "" {
 		parts = append(parts, meta)
 	}
+	if fast, ok := fastVariantEntryFor(model.ID); ok {
+		parts = append(parts, fastVariantHint(fastVariantDisplayName(fast)))
+	}
 	return strings.Join(parts, " · ")
 }
 
@@ -1602,7 +1708,7 @@ func providerWizardEndpointError(value string) string {
 		return "endpoint URL must start with http:// or https://"
 	}
 	if parsed.Scheme == "http" && !providerWizardIsLoopbackHost(parsed.Hostname()) {
-		return "endpoint URL must use https:// unless it is local loopback"
+		return "endpoint URL must use https:// unless it is local loopback or a private network address"
 	}
 	return ""
 }
@@ -1613,7 +1719,7 @@ func providerWizardIsLoopbackHost(host string) bool {
 		return true
 	}
 	ip := net.ParseIP(host)
-	return ip != nil && ip.IsLoopback()
+	return ip != nil && (ip.IsLoopback() || ip.IsPrivate())
 }
 
 func providerWizardDisplayName(provider providercatalog.Descriptor, baseURL string, profileName string) string {

internal/tui/provider_wizard_test.go

@@ -1355,3 +1355,139 @@ func TestApplyProviderWizardPersistFailureLeavesLiveStateUnchanged(t *testing.T)
 		t.Fatalf("%s = %q, want it unchanged on persist failure (children would diverge from parent)", config.ActiveProviderEnv, got)
 	}
 }
+
+func TestProviderSearchFiltersByNameIDAndAlias(t *testing.T) {
+	wizard := &providerWizardState{
+		step: providerWizardStepProvider,
+		providers: []providercatalog.Descriptor{
+			{ID: "openai", Name: "OpenAI", Aliases: []string{"chatgpt"}},
+			{ID: "anthropic", Name: "Anthropic", Aliases: []string{"claude"}},
+			{ID: "google", Name: "Google", Aliases: []string{"gemini"}},
+			{ID: "groq", Name: "Groq", Aliases: []string{}},
+		},
+	}
+
+	tests := []struct {
+		query string
+		want  []string
+	}{
+		{"openai", []string{"openai"}},
+		{"anthropic", []string{"anthropic"}},
+		{"claude", []string{"anthropic"}},
+		{"gemini", []string{"google"}},
+		{"chatgpt", []string{"openai"}},
+		{"groq", []string{"groq"}},
+		{"GROQ", []string{"groq"}},
+		{"nomatch", nil},
+		{"", []string{"openai", "anthropic", "google", "groq"}},
+	}
+
+	for _, tt := range tests {
+		t.Run("query="+tt.query, func(t *testing.T) {
+			wizard.providerSearch = tt.query
+			got := wizard.filteredProviders()
+			if len(got) != len(tt.want) {
+				t.Fatalf("filteredProviders(%q) = %d results, want %d", tt.query, len(got), len(tt.want))
+			}
+			for i, id := range tt.want {
+				if got[i].ID != id {
+					t.Fatalf("filteredProviders(%q)[%d] = %q, want %q", tt.query, i, got[i].ID, id)
+				}
+			}
+		})
+	}
+}
+
+func TestProviderSearchResetsSelectedProviderOnEdit(t *testing.T) {
+	m := newModel(context.Background(), Options{})
+	m = openProviderWizardForTest(t, m)
+
+	// Move to a later provider, then type a search query.
+	m.providerWizard.selectedProvider = 3
+	updated, _ := m.Update(testKeyText("anth"))
+	next := updated.(model)
+	if next.providerWizard.selectedProvider != 0 {
+		t.Fatalf("selectedProvider after typing = %d, want 0 (reset on edit)", next.providerWizard.selectedProvider)
+	}
+}
+
+func TestProviderSearchFilteredAdvanceSelectsCorrectProvider(t *testing.T) {
+	wizard := &providerWizardState{
+		step: providerWizardStepProvider,
+		providers: []providercatalog.Descriptor{
+			{ID: "openai", Name: "OpenAI", AuthEnvVars: []string{"OPENAI_API_KEY"}, RequiresAuth: true},
+			{ID: "anthropic", Name: "Anthropic", AuthEnvVars: []string{"ANTHROPIC_API_KEY"}, RequiresAuth: true},
+			{ID: "google", Name: "Google", AuthEnvVars: []string{"GOOGLE_API_KEY"}, RequiresAuth: true},
+			{ID: "groq", Name: "Groq", AuthEnvVars: []string{"GROQ_API_KEY"}, RequiresAuth: true},
+		},
+		selectedProvider: 0,
+	}
+
+	// Type a search that matches exactly "groq".
+	wizard.providerSearch = "groq"
+	filtered := wizard.filteredProviders()
+	if len(filtered) != 1 || filtered[0].ID != "groq" {
+		t.Fatalf("expected exactly groq in filtered results, got %v", providerWizardIDs(filtered))
+	}
+
+	// currentProvider() via filtered list should be groq.
+	if got := wizard.currentProvider().ID; got != "groq" {
+		t.Fatalf("currentProvider() = %q, want groq", got)
+	}
+}
+
+func TestProviderSearchEmptyMatchEnterIsNoop(t *testing.T) {
+	m := newModel(context.Background(), Options{})
+	m = openProviderWizardForTest(t, m)
+
+	// Type a query that matches nothing.
+	updated, _ := m.Update(testKeyText("zzzzz"))
+	next := updated.(model)
+	if len(next.providerWizard.filteredProviders()) != 0 {
+		t.Fatal("expected zero filtered providers")
+	}
+
+	// Enter should be a no-op.
+	updated, _ = next.Update(testKey(tea.KeyEnter))
+	next = updated.(model)
+	if next.providerWizard.step != providerWizardStepProvider {
+		t.Fatalf("wizard step = %v, want provider (empty match Enter should be no-op)", next.providerWizard.step)
+	}
+	if next.providerWizard.providerSearch != "zzzzz" {
+		t.Fatalf("providerSearch = %q, want query preserved on noop", next.providerWizard.providerSearch)
+	}
+}
+
+func TestProviderSearchClearRestoresFullList(t *testing.T) {
+	m := newModel(context.Background(), Options{})
+	m = openProviderWizardForTest(t, m)
+
+	initialCount := len(m.providerWizard.filteredProviders())
+	if initialCount == 0 {
+		t.Fatal("expected providers in the wizard")
+	}
+
+	// Type a search query.
+	updated, _ := m.Update(testKeyText("open"))
+	next := updated.(model)
+	filtered := next.providerWizard.filteredProviders()
+	if len(filtered) >= initialCount {
+		t.Fatalf("search should narrow results: got %d, want < %d", len(filtered), initialCount)
+	}
+
+	// Ctrl+U clears the search.
+	updated, _ = next.Update(testKeyCtrl('u'))
+	next = updated.(model)
+	restored := next.providerWizard.filteredProviders()
+	if len(restored) != initialCount {
+		t.Fatalf("after clear, filtered count = %d, want %d", len(restored), initialCount)
+	}
+}
+
+func providerWizardIDs(descriptors []providercatalog.Descriptor) []string {
+	ids := make([]string, len(descriptors))
+	for i, d := range descriptors {
+		ids[i] = d.ID
+	}
+	return ids
+}

internal/tui/session.go

@@ -11,6 +11,7 @@ import (
 	"github.com/Gitlawb/zero/internal/sandbox"
 	"github.com/Gitlawb/zero/internal/sessions"
 	"github.com/Gitlawb/zero/internal/tools"
+	"github.com/Gitlawb/zero/internal/usage"
 )
 
 const tuiSessionTitleLimit = 80
@@ -39,6 +40,60 @@ func (m model) ensureActiveSession(prompt string) (model, error) {
 	return m, nil
 }
 
+// startNewSession abandons the visible conversation and the agent's in-context
+// history and begins a fresh session in place. The current session already lives
+// on disk (its events are persisted as they happen), so it stays resumable via
+// /resume; here we only clear the in-memory conversation and the per-session
+// usage/compaction counters, then let the next prompt lazily create a new session
+// through ensureActiveSession — the same seam a cold start uses. Model, provider,
+// permission mode, and response style are intentionally preserved: /new starts a
+// clean conversation, not a clean configuration.
+func (m model) startNewSession() model {
+	previousID := m.activeSession.SessionID
+
+	m.activeSession = sessions.Metadata{}
+	m.sessionEvents = nil
+
+	// Reset the per-session usage + compaction display so the new session starts
+	// from zero instead of inheriting the previous conversation's token/cost totals.
+	if m.usageTracker != nil {
+		m.usageTracker.Reset()
+	}
+	m.lastUsage = usage.Normalized{}
+	m.lastUsageSeen = false
+	m.unpricedRequests = 0
+	m.unpricedTokens = 0
+	m.compactRequests = 0
+	m.compactFrame = 0
+	m.lastCompactResult = nil
+	m.lastCompactError = ""
+	m.turnLatencySum = 0
+	m.turnLatencyCount = 0
+	m.turnTTFTSum = 0
+	m.turnTTFTCount = 0
+
+	// Staged input belongs to the previous conversation. Attachments and a queued
+	// message are only consumed at prompt-submit, so without clearing them here the
+	// fresh session's first prompt would silently inherit the old session's images,
+	// documents, or queued text.
+	m.pendingImages = nil
+	m.pendingImageLabels = nil
+	m.pendingDocuments = nil
+	m.queuedMessage = ""
+
+	note := "Started a new session."
+	if previousID != "" {
+		note = "New session started. Previous session saved as " + previousID +
+			" — resume it anytime with /resume " + previousID + "."
+	}
+	m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionClear})
+	m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionAppendSystem, text: note})
+	// Scrollback above can't be un-printed; a faint divider marks the boundary and
+	// the flush frontier restarts for the fresh transcript (mirrors /clear, /resume).
+	m.resetFlushFrontier("· new session ·")
+	return m
+}
+
 func (m model) appendSessionEvent(eventType sessions.EventType, payload any) (model, error) {
 	if m.activeSession.SessionID == "" {
 		return m, nil

internal/tui/session_controls.go

@@ -803,6 +803,25 @@ func (m model) usageSummaryText() string {
 	return usage.FormatSummary(summary) + "; " + formatUnpricedUsage(m.unpricedRequests, m.unpricedTokens)
 }
 
+// cacheEfficiencyText reports the session's prompt-cache hit rate for /context so a
+// user can see whether cache reads are actually saving work. A low rate across
+// several turns usually means the cacheable prefix is churning (e.g. a tool list
+// that shifts mid-session), so it flags that case to make slowness diagnosable.
+func (m model) cacheEfficiencyText() string {
+	if m.usageTracker == nil {
+		return "usage unavailable"
+	}
+	summary := m.usageTracker.Summary()
+	if summary.InputTokens <= 0 {
+		return "n/a"
+	}
+	text := usage.FormatCacheEfficiency(summary)
+	if summary.RecordCount > 5 && summary.CacheHitRate() < 0.5 {
+		text += " — low; prefix may be unstable"
+	}
+	return text
+}
+
 func formatUnpricedUsage(requests int, tokens int) string {
 	requestLabel := "requests"
 	if requests == 1 {

internal/tui/session_controls_test.go

@@ -148,21 +148,21 @@ func TestStyleCommandListsAndSetsSessionPreference(t *testing.T) {
 	if cmd != nil {
 		t.Fatal("expected /style to be handled without starting an agent run")
 	}
-	if !transcriptContains(next.transcript, "active style: balanced") || !transcriptContains(next.transcript, "concise") {
+	if !transcriptContains(next.transcript, "active style: concise") || !transcriptContains(next.transcript, "explanatory") {
 		t.Fatalf("expected style list transcript, got %#v", next.transcript)
 	}
 
-	next.input.SetValue("/style concise")
+	next.input.SetValue("/style explanatory")
 	updated, cmd = next.Update(testKey(tea.KeyEnter))
 	next = updated.(model)
 
 	if cmd != nil {
-		t.Fatal("expected /style concise to be handled without starting an agent run")
+		t.Fatal("expected /style explanatory to be handled without starting an agent run")
 	}
-	if next.responseStyle != "concise" {
-		t.Fatalf("expected concise style, got %q", next.responseStyle)
+	if next.responseStyle != "explanatory" {
+		t.Fatalf("expected explanatory style, got %q", next.responseStyle)
 	}
-	if !transcriptContains(next.transcript, "active style: concise") {
+	if !transcriptContains(next.transcript, "active style: explanatory") {
 		t.Fatalf("expected style switch transcript, got %#v", next.transcript)
 	}
 }
@@ -621,7 +621,7 @@ func TestUsageEventsUpdateFooterAndContext(t *testing.T) {
 	if cmd != nil {
 		t.Fatal("expected /context to be handled without starting an agent run")
 	}
-	for _, want := range []string{"usage      1 request, 120 tokens", "style      balanced", "effort     auto", "compaction  idle"} {
+	for _, want := range []string{"usage      1 request, 120 tokens", "style      concise", "effort     auto", "compaction  idle"} {
 		if !transcriptContains(next.transcript, want) {
 			t.Fatalf("expected context transcript to contain %q, got %#v", want, next.transcript)
 		}

internal/tui/sidebar.go

@@ -47,6 +47,34 @@ func (m model) sidebarActive() bool {
 	return !m.sidebarHidden && m.sidebarAvailable()
 }
 
+// sidebarToggleAllowed reports whether the toggle-sidebar keybinding should
+// respond. Unlike sidebarAvailable it OMITS the content check
+// (sidebarHasContent) so the user can toggle their show/hide preference even
+// when the sidebar auto-hid due to having nothing to show. The content gate
+// is still applied at render time (sidebarActive chains sidebarAvailable), so
+// toggling on when there's no content just records the preference for when
+// content arrives — the sidebar stays hidden until then.
+func (m model) sidebarToggleAllowed() bool {
+	if !m.altScreen || m.height <= 0 || m.subchat.active {
+		return false
+	}
+	if sidebarWidth(m.width) <= 0 {
+		return false
+	}
+	if widthTier(m.width) < tierMedium {
+		return false
+	}
+	if m.setup.visible || m.providerWizard != nil || m.mcpAddWizard != nil ||
+		m.mcpManager != nil || m.picker != nil || m.suggestionsActive() {
+		return false
+	}
+	// Home/welcome screen: stay single-column until there's real conversation.
+	if m.transcriptEmpty() {
+		return false
+	}
+	return true
+}
+
 // sidebarAvailable reports whether the two-column layout CAN render: only in
 // alt-screen managed mode, with a measured height, on a wide-enough terminal,
 // outside subchat/overlays, with real conversation. It ignores the user's Ctrl+B

internal/tui/view.go

@@ -153,16 +153,23 @@ func (m model) titlePRSegment() string {
 func (m model) titleModelSegment() string {
 	provider := strings.TrimSpace(m.providerDisplayName())
 	model := strings.TrimSpace(m.modelName)
+	var segment string
 	switch {
 	case provider == "" && model == "":
 		return zeroTheme.muted.Render("no provider")
 	case model == "":
 		return zeroTheme.ink.Render(provider)
 	case provider == "":
-		return zeroTheme.ink.Render(model)
+		segment = zeroTheme.ink.Render(model)
 	default:
-		return zeroTheme.ink.Render(provider + "/" + model)
+		segment = zeroTheme.ink.Render(provider + "/" + model)
 	}
+	// Mark the active model with a quiet "f" when a fast variant is available, so
+	// the user knows /fast is on offer here without opening a picker.
+	if _, ok := m.currentModelFastVariant(); ok {
+		segment += renderFastBadge(zeroTheme.accent)
+	}
+	return segment
 }
 
 func (m model) composerDividerLine(width int) string {
@@ -386,17 +393,24 @@ func (m model) contextWindowSegment() string {
 }
 
 // humanCount renders a token count the way the status line wants it: 999,
-// 12.4K, 200K.
+// 12.4K, 200K, 1M, 1.2M.
 func humanCount(n int) string {
 	if n < 0 {
 		n = 0
 	}
-	if n < 1000 {
+	switch {
+	case n < 1000:
 		return strconv.Itoa(n)
+	case n < 1_000_000:
+		return humanCountScaled(float64(n)/1000, "K")
+	default:
+		return humanCountScaled(float64(n)/1_000_000, "M")
 	}
-	value := float64(n) / 1000
-	text := fmt.Sprintf("%.1fK", value)
-	return strings.Replace(text, ".0K", "K", 1)
+}
+
+func humanCountScaled(value float64, suffix string) string {
+	text := fmt.Sprintf("%.1f%s", value, suffix)
+	return strings.Replace(text, ".0"+suffix, suffix, 1)
 }
 
 // formatContextWindow renders a model's context window for the title bar
@@ -859,6 +873,9 @@ func modelPickerOverlayWidth(terminalWidth int, picker *commandPicker) int {
 			if item.Favorite {
 				labelWidth += lipgloss.Width("* ")
 			}
+			if strings.TrimSpace(item.FastVariant) != "" {
+				labelWidth += lipgloss.Width(renderFastBadge(zeroTheme.accent))
+			}
 			target = maxInt(target, lipgloss.Width("❯ ")+labelWidth)
 			if detail := modelPickerItemDetail(item); detail != "" {
 				target = maxInt(target, lipgloss.Width("  "+detail))
@@ -895,6 +912,11 @@ func renderModelPickerRow(width int, selected bool, item pickerItem) string {
 		prefix = "* "
 	}
 	left := marker + surface(zeroTheme.ink).Render(prefix+label)
+	// A quiet "f" badge marks rows whose model has a fast variant; the focused-row
+	// detail line spells out the target and command.
+	if strings.TrimSpace(item.FastVariant) != "" {
+		left += renderFastBadge(surface(zeroTheme.accent))
+	}
 	// The provider is shown as a section header above each group, so rows no longer
 	// repeat it as a right-aligned tag (matches a grouped provider+model list).
 	return fillPaletteLine(left, width, surface)
@@ -910,6 +932,9 @@ func modelPickerItemDetail(item pickerItem) string {
 	if meta := strings.TrimSpace(item.Meta); meta != "" {
 		parts = append(parts, meta)
 	}
+	if hint := fastVariantHint(item.FastVariant); hint != "" {
+		parts = append(parts, hint)
+	}
 	return strings.Join(parts, " · ")
 }
 

internal/update/apply.go

@@ -0,0 +1,269 @@
+package update
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"time"
+
+	"github.com/Gitlawb/zero/internal/release"
+)
+
+// DefaultDownloadTimeout bounds the archive/checksum download phase of a
+// standalone Apply, separately from Options.Timeout (which only covers the
+// small release-metadata check), so a stalled connection can't hang forever.
+const DefaultDownloadTimeout = 5 * time.Minute
+
+// ApplyResult reports the outcome of Apply.
+type ApplyResult struct {
+	Result
+	Applied       bool          `json:"applied"`
+	InstallMethod InstallMethod `json:"installMethod,omitempty"`
+	BinaryPath    string        `json:"binaryPath,omitempty"`
+	Message       string        `json:"message,omitempty"`
+	Warnings      []string      `json:"warnings,omitempty"`
+}
+
+// windowsOptionalBinaries/linuxOptionalBinaries mirror the helper binary
+// names scripts/postinstall.mjs copies alongside the main binary when
+// present, so `zero upgrade` refreshes them too instead of leaving them stale.
+var (
+	windowsOptionalBinaries = []string{"zero-windows-command-runner.exe", "zero-windows-sandbox-setup.exe"}
+	linuxOptionalBinaries   = []string{"zero-linux-sandbox", "zero-seccomp"}
+)
+
+// Apply checks for an update and, if one is available, installs it: via
+// `npm install -g` for npm-managed installs, or by downloading, verifying,
+// and atomically replacing the binary for standalone installs.
+func Apply(ctx context.Context, options Options) (ApplyResult, error) {
+	checkResult, err := Check(ctx, options)
+	if err != nil {
+		return ApplyResult{}, err
+	}
+
+	executablePath, err := os.Executable()
+	if err != nil {
+		return ApplyResult{}, fmt.Errorf("resolve current executable: %w", err)
+	}
+	if resolved, err := filepath.EvalSymlinks(executablePath); err == nil {
+		executablePath = resolved
+	}
+	// Best-effort: remove a "<binary>.old" left behind by a previous Windows
+	// replaceBinary call now that enough time (a whole separate invocation)
+	// has passed for the old process to have released the file. Runs
+	// regardless of whether an update is available, so it isn't stuck waiting
+	// on a future upgrade that may never come.
+	CleanupStaleBinary(executablePath)
+
+	if !checkResult.UpdateAvailable {
+		return ApplyResult{Result: checkResult, Message: "already up to date"}, nil
+	}
+
+	method := DetectInstallMethod(executablePath)
+	switch method {
+	case InstallMethodNpm:
+		if err := applyNpmUpdate(ctx); err != nil {
+			return ApplyResult{}, err
+		}
+		return ApplyResult{
+			Result:        checkResult,
+			Applied:       true,
+			InstallMethod: method,
+			BinaryPath:    executablePath,
+			Message:       fmt.Sprintf("updated via npm to %s", checkResult.LatestVersion),
+		}, nil
+	default:
+		warnings, err := applyStandaloneUpdate(ctx, checkResult, executablePath)
+		if err != nil {
+			return ApplyResult{}, err
+		}
+		return ApplyResult{
+			Result:        checkResult,
+			Applied:       true,
+			InstallMethod: method,
+			BinaryPath:    executablePath,
+			Message:       fmt.Sprintf("updated to %s", checkResult.LatestVersion),
+			Warnings:      warnings,
+		}, nil
+	}
+}
+
+// FormatApply renders an ApplyResult as human-readable text.
+func FormatApply(result ApplyResult) string {
+	if !result.Applied {
+		return Format(result.Result)
+	}
+	lines := []string{
+		fmt.Sprintf("[zero] %s (%s -> %s)", result.Message, result.CurrentVersion, result.LatestVersion),
+		"Binary: " + result.BinaryPath,
+	}
+	for _, warning := range result.Warnings {
+		lines = append(lines, "Warning: "+warning)
+	}
+	return strings.Join(lines, "\n")
+}
+
+func applyNpmUpdate(ctx context.Context) error {
+	npmPath, err := exec.LookPath("npm")
+	if err != nil {
+		return fmt.Errorf("npm not found on PATH: reinstall with `npm install -g %s@latest`", npmPackageName)
+	}
+	command := exec.CommandContext(ctx, npmPath, "install", "-g", npmPackageName+"@latest")
+	command.Stdout = os.Stdout
+	command.Stderr = os.Stderr
+	if err := command.Run(); err != nil {
+		return fmt.Errorf("npm install -g %s@latest: %w", npmPackageName, err)
+	}
+	return nil
+}
+
+func applyStandaloneUpdate(ctx context.Context, result Result, executablePath string) ([]string, error) {
+	asset := result.ReleaseAsset
+	if !asset.Verified {
+		return nil, fmt.Errorf("release asset for %s-%s could not be verified", asset.Platform, asset.Arch)
+	}
+
+	tempDir, err := os.MkdirTemp("", "zero-update-*")
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		_ = os.RemoveAll(tempDir)
+	}()
+
+	downloadCtx, cancel := context.WithTimeout(ctx, DefaultDownloadTimeout)
+	defer cancel()
+
+	archivePath := filepath.Join(tempDir, asset.ArchiveName)
+	if err := downloadFile(downloadCtx, asset.ArchiveURL, archivePath); err != nil {
+		return nil, fmt.Errorf("download release archive: %w", err)
+	}
+	checksumPath := filepath.Join(tempDir, asset.ChecksumName)
+	if err := downloadFile(downloadCtx, asset.ChecksumURL, checksumPath); err != nil {
+		return nil, fmt.Errorf("download release checksum: %w", err)
+	}
+	if _, err := release.VerifySHA256Checksum(checksumPath); err != nil {
+		return nil, fmt.Errorf("verify release checksum: %w", err)
+	}
+
+	extractDir := filepath.Join(tempDir, "extracted")
+	if err := os.MkdirAll(extractDir, 0o755); err != nil {
+		return nil, err
+	}
+	if err := extractArchive(archivePath, extractDir); err != nil {
+		return nil, fmt.Errorf("extract release archive: %w", err)
+	}
+
+	binaryName := "zero"
+	optionalBinaries := linuxOptionalBinaries
+	if runtime.GOOS == "windows" {
+		binaryName = "zero.exe"
+		optionalBinaries = windowsOptionalBinaries
+	} else if runtime.GOOS == "darwin" {
+		optionalBinaries = nil
+	}
+
+	newBinaryPath, err := findByBasename(extractDir, binaryName)
+	if err != nil {
+		return nil, err
+	}
+	if newBinaryPath == "" {
+		return nil, fmt.Errorf("release archive did not contain %s", binaryName)
+	}
+
+	targetDir := filepath.Dir(executablePath)
+	if err := installBinary(newBinaryPath, executablePath); err != nil {
+		return nil, err
+	}
+
+	var warnings []string
+	for _, name := range optionalBinaries {
+		source, err := findByBasename(extractDir, name)
+		if err != nil || source == "" {
+			continue // optional: the sandbox degrades gracefully without it
+		}
+		destPath := filepath.Join(targetDir, name)
+		if _, err := os.Stat(destPath); err != nil {
+			continue // only refresh helpers this install already has
+		}
+		if err := installBinary(source, destPath); err != nil {
+			warnings = append(warnings, fmt.Sprintf("failed to update helper %s: %v", name, err))
+		}
+	}
+
+	return warnings, nil
+}
+
+// installBinary stages sourcePath next to targetPath (same directory, so the
+// final rename is atomic/same-filesystem) and then swaps it into place.
+func installBinary(sourcePath string, targetPath string) error {
+	stagedPath := targetPath + ".new"
+	if err := copyFile(sourcePath, stagedPath); err != nil {
+		return fmt.Errorf("stage %s: %w", filepath.Base(targetPath), err)
+	}
+	defer func() {
+		_ = os.Remove(stagedPath)
+	}()
+	if err := replaceBinary(targetPath, stagedPath); err != nil {
+		return fmt.Errorf("install %s: %w", filepath.Base(targetPath), err)
+	}
+	return nil
+}
+
+func copyFile(sourcePath string, destPath string) (retErr error) {
+	source, err := os.Open(sourcePath)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = source.Close()
+	}()
+	dest, err := os.OpenFile(destPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o755)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if closeErr := dest.Close(); closeErr != nil && retErr == nil {
+			retErr = closeErr
+		}
+	}()
+	_, retErr = io.Copy(dest, source)
+	return retErr
+}
+
+func downloadFile(ctx context.Context, url string, destPath string) error {
+	if url == "" {
+		return fmt.Errorf("missing download URL")
+	}
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("User-Agent", "zero/update")
+	response, err := http.DefaultClient.Do(request)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = response.Body.Close()
+	}()
+	if response.StatusCode < http.StatusOK || response.StatusCode >= http.StatusMultipleChoices {
+		return fmt.Errorf("download failed (%s): %s", response.Status, url)
+	}
+	out, err := os.Create(destPath)
+	if err != nil {
+		return err
+	}
+	_, copyErr := io.Copy(out, response.Body)
+	closeErr := out.Close()
+	if copyErr != nil {
+		return copyErr
+	}
+	return closeErr
+}

internal/update/apply_test.go

@@ -0,0 +1,302 @@
+package update
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/Gitlawb/zero/internal/release"
+)
+
+func TestApplyReturnsNoopWhenUpToDate(t *testing.T) {
+	result, err := Apply(context.Background(), Options{
+		CurrentVersion: "0.2.0",
+		GOOS:           "linux",
+		GOARCH:         "amd64",
+		Fetch: func(_ context.Context, endpoint string) (Release, error) {
+			return releaseForTarget(t, "v0.2.0", "linux", "amd64"), nil
+		},
+	})
+	if err != nil {
+		t.Fatalf("Apply returned error: %v", err)
+	}
+	if result.Applied {
+		t.Fatalf("expected Applied=false when already up to date, got %#v", result)
+	}
+}
+
+func TestApplyStandaloneUpdateReplacesBinary(t *testing.T) {
+	binaryName := "zero"
+	// macOS ships no optional helper binaries (matching scripts/postinstall.mjs),
+	// so there's nothing to refresh there; only linux/windows have one to check.
+	optionalName := ""
+	switch runtime.GOOS {
+	case "windows":
+		binaryName = "zero.exe"
+		optionalName = "zero-windows-command-runner.exe"
+	case "linux":
+		optionalName = "zero-seccomp"
+	}
+
+	installDir := t.TempDir()
+	executablePath := filepath.Join(installDir, binaryName)
+	if err := os.WriteFile(executablePath, []byte("old-binary"), 0o755); err != nil {
+		t.Fatalf("WriteFile executable: %v", err)
+	}
+	// Only pre-existing optional helpers should be refreshed; an absent one
+	// (e.g. the platform's other optional helper) must not be introduced.
+	var existingHelperPath string
+	if optionalName != "" {
+		existingHelperPath = filepath.Join(installDir, optionalName)
+		if err := os.WriteFile(existingHelperPath, []byte("old-helper"), 0o755); err != nil {
+			t.Fatalf("WriteFile helper: %v", err)
+		}
+	}
+
+	archiveName := "zero-v0.2.0-linux-x64.tar.gz"
+	archiveDir := t.TempDir()
+	archivePath := filepath.Join(archiveDir, archiveName)
+	writeTestTarGz(t, archivePath, map[string]string{
+		"zero":                            "new-binary",
+		"zero.exe":                        "new-binary-exe",
+		"zero-seccomp":                    "new-helper",
+		"zero-windows-command-runner.exe": "new-helper-exe",
+	})
+	checksum, err := release.SHA256File(archivePath)
+	if err != nil {
+		t.Fatalf("SHA256File: %v", err)
+	}
+	checksumText, err := release.FormatSHA256Checksum(checksum, archiveName)
+	if err != nil {
+		t.Fatalf("FormatSHA256Checksum: %v", err)
+	}
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/" + archiveName:
+			http.ServeFile(w, r, archivePath)
+		case "/" + archiveName + ".sha256":
+			_, _ = w.Write([]byte(checksumText))
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+
+	result := Result{
+		LatestVersion: "0.2.0",
+		ReleaseAsset: AssetCheck{
+			Platform:      "linux",
+			Arch:          "x64",
+			ArchiveName:   archiveName,
+			ArchiveURL:    server.URL + "/" + archiveName,
+			ChecksumName:  archiveName + ".sha256",
+			ChecksumURL:   server.URL + "/" + archiveName + ".sha256",
+			ArchiveFound:  true,
+			ChecksumFound: true,
+			Verified:      true,
+		},
+	}
+
+	if warnings, err := applyStandaloneUpdate(context.Background(), result, executablePath); err != nil {
+		t.Fatalf("applyStandaloneUpdate returned error: %v", err)
+	} else if len(warnings) != 0 {
+		t.Fatalf("unexpected warnings: %v", warnings)
+	}
+
+	data, err := os.ReadFile(executablePath)
+	if err != nil {
+		t.Fatalf("ReadFile executable: %v", err)
+	}
+	wantBinary := "new-binary"
+	if runtime.GOOS == "windows" {
+		wantBinary = "new-binary-exe"
+	}
+	if string(data) != wantBinary {
+		t.Fatalf("executable content = %q, want %q", data, wantBinary)
+	}
+
+	if optionalName != "" {
+		helperData, err := os.ReadFile(existingHelperPath)
+		if err != nil {
+			t.Fatalf("ReadFile helper: %v", err)
+		}
+		wantHelper := "new-helper"
+		if runtime.GOOS == "windows" {
+			wantHelper = "new-helper-exe"
+		}
+		if string(helperData) != wantHelper {
+			t.Fatalf("helper content = %q, want %q", helperData, wantHelper)
+		}
+	}
+
+	if entries, err := os.ReadDir(installDir); err == nil {
+		for _, entry := range entries {
+			name := entry.Name()
+			// On Windows, replaceBinary leaves "<name>.old" behind (the running
+			// binary is renamed aside, not deleted) for later best-effort cleanup.
+			if name == binaryName || (optionalName != "" && name == optionalName) || name == binaryName+".old" || (optionalName != "" && name == optionalName+".old") {
+				continue
+			}
+			t.Fatalf("unexpected extra file left in install dir: %s", name)
+		}
+	}
+}
+
+func TestApplyStandaloneUpdateWarnsWhenHelperRefreshFails(t *testing.T) {
+	binaryName := "zero"
+	optionalName := "zero-seccomp"
+	if runtime.GOOS == "windows" {
+		binaryName = "zero.exe"
+		optionalName = "zero-windows-command-runner.exe"
+	} else if runtime.GOOS == "darwin" {
+		t.Skip("macOS ships no optional helper binaries to refresh")
+	}
+
+	installDir := t.TempDir()
+	executablePath := filepath.Join(installDir, binaryName)
+	if err := os.WriteFile(executablePath, []byte("old-binary"), 0o755); err != nil {
+		t.Fatalf("WriteFile executable: %v", err)
+	}
+	// The helper must already exist for a refresh to be attempted at all.
+	existingHelperPath := filepath.Join(installDir, optionalName)
+	if err := os.WriteFile(existingHelperPath, []byte("old-helper"), 0o755); err != nil {
+		t.Fatalf("WriteFile helper: %v", err)
+	}
+	// Force installBinary's staging copy to fail by occupying its staged
+	// "<helper>.new" path with a directory instead of a file.
+	if err := os.MkdirAll(existingHelperPath+".new", 0o755); err != nil {
+		t.Fatalf("MkdirAll staged path: %v", err)
+	}
+
+	archiveName := "zero-v0.2.0-linux-x64.tar.gz"
+	archiveDir := t.TempDir()
+	archivePath := filepath.Join(archiveDir, archiveName)
+	writeTestTarGz(t, archivePath, map[string]string{
+		"zero":                            "new-binary",
+		"zero.exe":                        "new-binary-exe",
+		"zero-seccomp":                    "new-helper",
+		"zero-windows-command-runner.exe": "new-helper-exe",
+	})
+	checksum, err := release.SHA256File(archivePath)
+	if err != nil {
+		t.Fatalf("SHA256File: %v", err)
+	}
+	checksumText, err := release.FormatSHA256Checksum(checksum, archiveName)
+	if err != nil {
+		t.Fatalf("FormatSHA256Checksum: %v", err)
+	}
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/" + archiveName:
+			http.ServeFile(w, r, archivePath)
+		case "/" + archiveName + ".sha256":
+			_, _ = w.Write([]byte(checksumText))
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+
+	result := Result{
+		LatestVersion: "0.2.0",
+		ReleaseAsset: AssetCheck{
+			Platform:      "linux",
+			Arch:          "x64",
+			ArchiveName:   archiveName,
+			ArchiveURL:    server.URL + "/" + archiveName,
+			ChecksumName:  archiveName + ".sha256",
+			ChecksumURL:   server.URL + "/" + archiveName + ".sha256",
+			ArchiveFound:  true,
+			ChecksumFound: true,
+			Verified:      true,
+		},
+	}
+
+	warnings, err := applyStandaloneUpdate(context.Background(), result, executablePath)
+	if err != nil {
+		t.Fatalf("applyStandaloneUpdate returned error: %v", err)
+	}
+	if len(warnings) != 1 || !strings.Contains(warnings[0], optionalName) {
+		t.Fatalf("expected one warning mentioning %s, got %v", optionalName, warnings)
+	}
+
+	data, err := os.ReadFile(executablePath)
+	if err != nil {
+		t.Fatalf("ReadFile executable: %v", err)
+	}
+	wantBinary := "new-binary"
+	if runtime.GOOS == "windows" {
+		wantBinary = "new-binary-exe"
+	}
+	if string(data) != wantBinary {
+		t.Fatalf("main binary should still be updated despite helper failure: got %q, want %q", data, wantBinary)
+	}
+}
+
+func TestApplyStandaloneUpdateRejectsChecksumMismatch(t *testing.T) {
+	binaryName := "zero"
+	if runtime.GOOS == "windows" {
+		binaryName = "zero.exe"
+	}
+
+	installDir := t.TempDir()
+	executablePath := filepath.Join(installDir, binaryName)
+	if err := os.WriteFile(executablePath, []byte("old-binary"), 0o755); err != nil {
+		t.Fatalf("WriteFile executable: %v", err)
+	}
+
+	archiveName := "zero-v0.2.0-linux-x64.tar.gz"
+	archiveDir := t.TempDir()
+	archivePath := filepath.Join(archiveDir, archiveName)
+	writeTestTarGz(t, archivePath, map[string]string{"zero": "new-binary", "zero.exe": "new-binary-exe"})
+
+	badChecksumText, err := release.FormatSHA256Checksum("0000000000000000000000000000000000000000000000000000000000000000"[:64], archiveName)
+	if err != nil {
+		t.Fatalf("FormatSHA256Checksum: %v", err)
+	}
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/" + archiveName:
+			http.ServeFile(w, r, archivePath)
+		case "/" + archiveName + ".sha256":
+			_, _ = w.Write([]byte(badChecksumText))
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+
+	result := Result{
+		ReleaseAsset: AssetCheck{
+			Platform:      "linux",
+			Arch:          "x64",
+			ArchiveName:   archiveName,
+			ArchiveURL:    server.URL + "/" + archiveName,
+			ChecksumName:  archiveName + ".sha256",
+			ChecksumURL:   server.URL + "/" + archiveName + ".sha256",
+			ArchiveFound:  true,
+			ChecksumFound: true,
+			Verified:      true,
+		},
+	}
+
+	if _, err := applyStandaloneUpdate(context.Background(), result, executablePath); err == nil {
+		t.Fatal("expected checksum mismatch error")
+	}
+
+	data, err := os.ReadFile(executablePath)
+	if err != nil {
+		t.Fatalf("ReadFile executable: %v", err)
+	}
+	if string(data) != "old-binary" {
+		t.Fatalf("executable should be untouched after checksum failure, got %q", data)
+	}
+}

internal/update/extract.go

@@ -0,0 +1,165 @@
+package update
+
+import (
+	"archive/tar"
+	"archive/zip"
+	"compress/gzip"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// extractArchive extracts a .tar.gz or .zip release archive into destDir.
+func extractArchive(archivePath string, destDir string) error {
+	if strings.HasSuffix(archivePath, ".zip") {
+		return extractZip(archivePath, destDir)
+	}
+	return extractTarGz(archivePath, destDir)
+}
+
+func extractTarGz(archivePath string, destDir string) error {
+	file, err := os.Open(archivePath)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = file.Close()
+	}()
+	gzipReader, err := gzip.NewReader(file)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = gzipReader.Close()
+	}()
+	tarReader := tar.NewReader(gzipReader)
+	for {
+		header, err := tarReader.Next()
+		if err == io.EOF {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		target, err := safeExtractPath(destDir, header.Name)
+		if err != nil {
+			return err
+		}
+		switch header.Typeflag {
+		case tar.TypeDir:
+			if err := os.MkdirAll(target, 0o755); err != nil {
+				return err
+			}
+		case tar.TypeReg:
+			if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
+				return err
+			}
+			if err := writeExtractedFile(target, tarReader, fs.FileMode(header.Mode)); err != nil {
+				return err
+			}
+		default:
+			// Release archives only ever contain regular files and directories;
+			// reject anything else (symlinks, devices) rather than silently skip it.
+			return fmt.Errorf("unsupported archive entry type for %s", header.Name)
+		}
+	}
+}
+
+func extractZip(archivePath string, destDir string) error {
+	reader, err := zip.OpenReader(archivePath)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = reader.Close()
+	}()
+	for _, entry := range reader.File {
+		target, err := safeExtractPath(destDir, entry.Name)
+		if err != nil {
+			return err
+		}
+		if entry.FileInfo().IsDir() {
+			if err := os.MkdirAll(target, 0o755); err != nil {
+				return err
+			}
+			continue
+		}
+		if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
+			return err
+		}
+		if err := func() error {
+			entryReader, err := entry.Open()
+			if err != nil {
+				return err
+			}
+			defer func() {
+				_ = entryReader.Close()
+			}()
+			return writeExtractedFile(target, entryReader, entry.Mode())
+		}(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func writeExtractedFile(target string, source io.Reader, mode fs.FileMode) error {
+	if mode == 0 {
+		mode = 0o644
+	}
+	out, err := os.OpenFile(target, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, mode)
+	if err != nil {
+		return err
+	}
+	_, copyErr := io.Copy(out, source)
+	closeErr := out.Close()
+	if copyErr != nil {
+		return copyErr
+	}
+	return closeErr
+}
+
+// safeExtractPath resolves an archive entry name against destDir, rejecting
+// absolute paths or entries that would escape destDir via "..".
+func safeExtractPath(destDir string, name string) (string, error) {
+	cleanName := filepath.Clean(strings.ReplaceAll(name, "\\", "/"))
+	if cleanName == "." {
+		return destDir, nil
+	}
+	if filepath.IsAbs(cleanName) || cleanName == ".." || strings.HasPrefix(cleanName, "../") {
+		return "", fmt.Errorf("archive entry escapes destination: %s", name)
+	}
+	target := filepath.Join(destDir, cleanName)
+	destDirClean := filepath.Clean(destDir)
+	if target != destDirClean && !strings.HasPrefix(target, destDirClean+string(os.PathSeparator)) {
+		return "", fmt.Errorf("archive entry escapes destination: %s", name)
+	}
+	return target, nil
+}
+
+// findByBasename recursively searches root for the first regular file whose
+// basename matches name, mirroring scripts/postinstall.mjs's lookup so
+// helper binaries nested under archive subdirectories (e.g. helpers/) are
+// still found.
+func findByBasename(root string, name string) (string, error) {
+	var found string
+	err := filepath.WalkDir(root, func(path string, entry fs.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+		if found != "" {
+			return fs.SkipAll
+		}
+		if !entry.IsDir() && entry.Name() == name {
+			found = path
+		}
+		return nil
+	})
+	if err != nil {
+		return "", err
+	}
+	return found, nil
+}

internal/update/extract_test.go

@@ -0,0 +1,177 @@
+package update
+
+import (
+	"archive/tar"
+	"archive/zip"
+	"compress/gzip"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func writeTestTarGz(t *testing.T, archivePath string, entries map[string]string) {
+	t.Helper()
+	file, err := os.Create(archivePath)
+	if err != nil {
+		t.Fatalf("Create archive: %v", err)
+	}
+	defer func() { _ = file.Close() }()
+	gzipWriter := gzip.NewWriter(file)
+	tarWriter := tar.NewWriter(gzipWriter)
+	for name, content := range entries {
+		header := &tar.Header{Name: name, Mode: 0o755, Size: int64(len(content))}
+		if err := tarWriter.WriteHeader(header); err != nil {
+			t.Fatalf("WriteHeader %s: %v", name, err)
+		}
+		if _, err := tarWriter.Write([]byte(content)); err != nil {
+			t.Fatalf("Write %s: %v", name, err)
+		}
+	}
+	if err := tarWriter.Close(); err != nil {
+		t.Fatalf("close tar writer: %v", err)
+	}
+	if err := gzipWriter.Close(); err != nil {
+		t.Fatalf("close gzip writer: %v", err)
+	}
+}
+
+func writeTestZip(t *testing.T, archivePath string, entries map[string]string) {
+	t.Helper()
+	file, err := os.Create(archivePath)
+	if err != nil {
+		t.Fatalf("Create archive: %v", err)
+	}
+	defer func() { _ = file.Close() }()
+	zipWriter := zip.NewWriter(file)
+	for name, content := range entries {
+		writer, err := zipWriter.Create(name)
+		if err != nil {
+			t.Fatalf("Create entry %s: %v", name, err)
+		}
+		if _, err := writer.Write([]byte(content)); err != nil {
+			t.Fatalf("Write %s: %v", name, err)
+		}
+	}
+	if err := zipWriter.Close(); err != nil {
+		t.Fatalf("close zip writer: %v", err)
+	}
+}
+
+func TestExtractTarGzRoundTrip(t *testing.T) {
+	dir := t.TempDir()
+	archivePath := filepath.Join(dir, "archive.tar.gz")
+	writeTestTarGz(t, archivePath, map[string]string{
+		"zero":                 "main-binary",
+		"helpers/zero-seccomp": "helper-binary",
+	})
+
+	destDir := filepath.Join(dir, "extracted")
+	if err := os.MkdirAll(destDir, 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := extractArchive(archivePath, destDir); err != nil {
+		t.Fatalf("extractArchive: %v", err)
+	}
+
+	data, err := os.ReadFile(filepath.Join(destDir, "zero"))
+	if err != nil {
+		t.Fatalf("ReadFile zero: %v", err)
+	}
+	if string(data) != "main-binary" {
+		t.Fatalf("zero content = %q", data)
+	}
+	data, err = os.ReadFile(filepath.Join(destDir, "helpers", "zero-seccomp"))
+	if err != nil {
+		t.Fatalf("ReadFile helpers/zero-seccomp: %v", err)
+	}
+	if string(data) != "helper-binary" {
+		t.Fatalf("helpers/zero-seccomp content = %q", data)
+	}
+}
+
+func TestExtractZipRoundTrip(t *testing.T) {
+	dir := t.TempDir()
+	archivePath := filepath.Join(dir, "archive.zip")
+	writeTestZip(t, archivePath, map[string]string{
+		"zero.exe": "main-binary",
+	})
+
+	destDir := filepath.Join(dir, "extracted")
+	if err := os.MkdirAll(destDir, 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := extractArchive(archivePath, destDir); err != nil {
+		t.Fatalf("extractArchive: %v", err)
+	}
+
+	data, err := os.ReadFile(filepath.Join(destDir, "zero.exe"))
+	if err != nil {
+		t.Fatalf("ReadFile zero.exe: %v", err)
+	}
+	if string(data) != "main-binary" {
+		t.Fatalf("zero.exe content = %q", data)
+	}
+}
+
+func TestExtractTarGzRejectsPathTraversal(t *testing.T) {
+	dir := t.TempDir()
+	archivePath := filepath.Join(dir, "archive.tar.gz")
+	writeTestTarGz(t, archivePath, map[string]string{
+		"../escape": "malicious",
+	})
+
+	destDir := filepath.Join(dir, "extracted")
+	if err := os.MkdirAll(destDir, 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := extractArchive(archivePath, destDir); err == nil {
+		t.Fatal("expected extractArchive to reject a path-traversal entry")
+	}
+	if _, err := os.Stat(filepath.Join(dir, "escape")); err == nil {
+		t.Fatal("path traversal entry was written outside the destination directory")
+	}
+}
+
+func TestExtractZipRejectsPathTraversal(t *testing.T) {
+	dir := t.TempDir()
+	archivePath := filepath.Join(dir, "archive.zip")
+	writeTestZip(t, archivePath, map[string]string{
+		"../../escape.exe": "malicious",
+	})
+
+	destDir := filepath.Join(dir, "extracted")
+	if err := os.MkdirAll(destDir, 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := extractArchive(archivePath, destDir); err == nil {
+		t.Fatal("expected extractArchive to reject a path-traversal entry")
+	}
+}
+
+func TestFindByBasenameSearchesRecursively(t *testing.T) {
+	dir := t.TempDir()
+	nested := filepath.Join(dir, "helpers")
+	if err := os.MkdirAll(nested, 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	wantPath := filepath.Join(nested, "zero-seccomp")
+	if err := os.WriteFile(wantPath, []byte("helper"), 0o755); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	found, err := findByBasename(dir, "zero-seccomp")
+	if err != nil {
+		t.Fatalf("findByBasename: %v", err)
+	}
+	if found != wantPath {
+		t.Fatalf("findByBasename = %q, want %q", found, wantPath)
+	}
+
+	notFound, err := findByBasename(dir, "does-not-exist")
+	if err != nil {
+		t.Fatalf("findByBasename: %v", err)
+	}
+	if notFound != "" {
+		t.Fatalf("findByBasename = %q, want empty", notFound)
+	}
+}

internal/update/installmethod.go

@@ -0,0 +1,45 @@
+package update
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+)
+
+// npmPackageName is the published package name for the npm distribution of
+// zero (see package.json). scripts/postinstall.mjs downloads the native
+// binary into the same directory as package.json and leaves a
+// ".zero-binary-version" marker file next to it — both are reliable signals
+// that a given executable came from an npm install.
+const npmPackageName = "@gitlawb/zero"
+
+// InstallMethod identifies how the running zero binary was installed.
+type InstallMethod string
+
+const (
+	InstallMethodNpm        InstallMethod = "npm"
+	InstallMethodStandalone InstallMethod = "standalone"
+)
+
+// DetectInstallMethod inspects the directory containing executablePath for
+// npm-install markers left by scripts/postinstall.mjs.
+func DetectInstallMethod(executablePath string) InstallMethod {
+	dir := filepath.Dir(executablePath)
+	if _, err := os.Stat(filepath.Join(dir, ".zero-binary-version")); err == nil {
+		return InstallMethodNpm
+	}
+	data, err := os.ReadFile(filepath.Join(dir, "package.json"))
+	if err != nil {
+		return InstallMethodStandalone
+	}
+	var pkg struct {
+		Name string `json:"name"`
+	}
+	if err := json.Unmarshal(data, &pkg); err != nil {
+		return InstallMethodStandalone
+	}
+	if pkg.Name == npmPackageName {
+		return InstallMethodNpm
+	}
+	return InstallMethodStandalone
+}

internal/update/installmethod_test.go

@@ -0,0 +1,60 @@
+package update
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestDetectInstallMethodStandaloneByDefault(t *testing.T) {
+	dir := t.TempDir()
+	exePath := filepath.Join(dir, "zero")
+	if err := os.WriteFile(exePath, []byte("binary"), 0o755); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+	if method := DetectInstallMethod(exePath); method != InstallMethodStandalone {
+		t.Fatalf("DetectInstallMethod = %q, want standalone", method)
+	}
+}
+
+func TestDetectInstallMethodNpmViaMarkerFile(t *testing.T) {
+	dir := t.TempDir()
+	exePath := filepath.Join(dir, "zero")
+	if err := os.WriteFile(exePath, []byte("binary"), 0o755); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, ".zero-binary-version"), []byte("0.1.0\n"), 0o644); err != nil {
+		t.Fatalf("WriteFile marker: %v", err)
+	}
+	if method := DetectInstallMethod(exePath); method != InstallMethodNpm {
+		t.Fatalf("DetectInstallMethod = %q, want npm", method)
+	}
+}
+
+func TestDetectInstallMethodNpmViaPackageJSON(t *testing.T) {
+	dir := t.TempDir()
+	exePath := filepath.Join(dir, "zero")
+	if err := os.WriteFile(exePath, []byte("binary"), 0o755); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "package.json"), []byte(`{"name":"@gitlawb/zero"}`), 0o644); err != nil {
+		t.Fatalf("WriteFile package.json: %v", err)
+	}
+	if method := DetectInstallMethod(exePath); method != InstallMethodNpm {
+		t.Fatalf("DetectInstallMethod = %q, want npm", method)
+	}
+}
+
+func TestDetectInstallMethodIgnoresUnrelatedPackageJSON(t *testing.T) {
+	dir := t.TempDir()
+	exePath := filepath.Join(dir, "zero")
+	if err := os.WriteFile(exePath, []byte("binary"), 0o755); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "package.json"), []byte(`{"name":"some-other-package"}`), 0o644); err != nil {
+		t.Fatalf("WriteFile package.json: %v", err)
+	}
+	if method := DetectInstallMethod(exePath); method != InstallMethodStandalone {
+		t.Fatalf("DetectInstallMethod = %q, want standalone", method)
+	}
+}

internal/update/replace_other.go

@@ -0,0 +1,19 @@
+//go:build !windows
+
+package update
+
+import "os"
+
+// replaceBinary installs newPath over targetPath. On POSIX systems renaming
+// over a running executable is safe: the process currently executing it keeps
+// its open inode, and the rename is atomic within the same filesystem.
+func replaceBinary(targetPath string, newPath string) error {
+	if err := os.Chmod(newPath, 0o755); err != nil {
+		return err
+	}
+	return os.Rename(newPath, targetPath)
+}
+
+// CleanupStaleBinary is a no-op outside Windows, which is the only platform
+// that requires renaming a running binary aside instead of replacing it directly.
+func CleanupStaleBinary(targetPath string) {}

internal/update/replace_windows.go

@@ -0,0 +1,34 @@
+//go:build windows
+
+package update
+
+import (
+	"fmt"
+	"os"
+)
+
+// replaceBinary installs newPath over targetPath. Windows will not let a
+// running executable be overwritten or deleted directly, but NTFS does allow
+// renaming it aside — the same trick already used for locked config files in
+// internal/cli/mcp_config.go's replaceMCPWritableConfigFile.
+func replaceBinary(targetPath string, newPath string) error {
+	oldPath := targetPath + ".old"
+	_ = os.Remove(oldPath) // best-effort cleanup of a leftover from a previous upgrade
+	if err := os.Rename(targetPath, oldPath); err != nil {
+		return fmt.Errorf("rename running binary aside: %w", err)
+	}
+	if err := os.Rename(newPath, targetPath); err != nil {
+		if restoreErr := os.Rename(oldPath, targetPath); restoreErr != nil {
+			return fmt.Errorf("install new binary: %w; additionally failed to restore the original binary: %v (original preserved at %s)", err, restoreErr, oldPath)
+		}
+		return fmt.Errorf("install new binary: %w", err)
+	}
+	return nil
+}
+
+// CleanupStaleBinary best-effort removes a "<path>.old" file left behind by a
+// previous replaceBinary call once the old process holding it has exited.
+// Callers should invoke this once at startup for the current executable.
+func CleanupStaleBinary(targetPath string) {
+	_ = os.Remove(targetPath + ".old")
+}

internal/usage/cache_efficiency_test.go

@@ -0,0 +1,23 @@
+package usage
+
+import "testing"
+
+func TestSummaryCacheHitRate(t *testing.T) {
+	s := Summary{InputTokens: 13100, CachedInputTokens: 8200}
+	if got := s.CacheHitRate(); got < 0.62 || got > 0.63 {
+		t.Fatalf("CacheHitRate = %v, want ~0.626", got)
+	}
+	if got := (Summary{}).CacheHitRate(); got != 0 {
+		t.Fatalf("empty CacheHitRate = %v, want 0", got)
+	}
+}
+
+func TestFormatCacheEfficiency(t *testing.T) {
+	s := Summary{InputTokens: 13100, CachedInputTokens: 8200}
+	if got := FormatCacheEfficiency(s); got != "63% (8,200 cached / 13,100 input)" {
+		t.Fatalf("FormatCacheEfficiency = %q", got)
+	}
+	if got := FormatCacheEfficiency(Summary{}); got != "n/a" {
+		t.Fatalf("empty FormatCacheEfficiency = %q, want n/a", got)
+	}
+}

internal/usage/tracker.go

@@ -219,6 +219,29 @@ func FormatSummary(summary Summary) string {
 	return fmt.Sprintf("%s %s, %s tokens, %s", comma(summary.RecordCount), requestLabel, comma(summary.TotalTokens), summary.FormattedTotalCost)
 }
 
+// CacheHitRate is the fraction of input tokens served from the provider's prompt
+// cache. CachedInputTokens is clamped to InputTokens in Normalize, so the result is
+// always in [0,1]; it is 0 when no input has been recorded.
+func (summary Summary) CacheHitRate() float64 {
+	if summary.InputTokens <= 0 {
+		return 0
+	}
+	return float64(summary.CachedInputTokens) / float64(summary.InputTokens)
+}
+
+// FormatCacheEfficiency renders the prompt-cache hit rate for display, e.g.
+// "63% (8,200 cached / 13,100 input)", so a user can see whether cache reads are
+// actually saving work. Returns "n/a" until some input has been recorded.
+func FormatCacheEfficiency(summary Summary) string {
+	if summary.InputTokens <= 0 {
+		return "n/a"
+	}
+	return fmt.Sprintf("%.0f%% (%s cached / %s input)",
+		summary.CacheHitRate()*100,
+		comma(summary.CachedInputTokens),
+		comma(summary.InputTokens))
+}
+
 func addUsageToSummary(summary *Summary, usage Normalized) {
 	summary.InputTokens += usage.InputTokens
 	summary.CachedInputTokens += usage.CachedInputTokens

scripts/install.ps1

@@ -62,6 +62,19 @@ function Find-ZeroExtractedFile {
   throw "Release archive did not contain exactly one $FileName"
 }
 
+function Test-ZeroPathContainsDir {
+  param(
+    [string]$PathValue,
+    [string]$Dir
+  )
+
+  if ([string]::IsNullOrEmpty($PathValue)) {
+    return $false
+  }
+
+  return @($PathValue -split [System.IO.Path]::PathSeparator) -contains $Dir
+}
+
 function Find-ZeroOptionalExtractedDirectory {
   param(
     [string]$Root,
@@ -149,9 +162,20 @@ try {
   $targetPath = Join-Path $InstallDir "zero.exe"
   Write-Host "Installed $targetPath"
 
-  $pathEntries = $env:PATH -split [System.IO.Path]::PathSeparator
-  if ($pathEntries -notcontains $InstallDir) {
-    Write-Host "Add $InstallDir to PATH to run zero from any directory."
+  $userPath = [Environment]::GetEnvironmentVariable("PATH", "User")
+  if (-not (Test-ZeroPathContainsDir -PathValue $userPath -Dir $InstallDir)) {
+    try {
+      $newUserPath = if ([string]::IsNullOrEmpty($userPath)) { $InstallDir } else { "$userPath;$InstallDir" }
+      [Environment]::SetEnvironmentVariable("PATH", $newUserPath, "User")
+      Write-Host "Added $InstallDir to your user PATH. Restart your terminal to use 'zero'."
+    } catch {
+      Write-Warning "Could not update your user PATH automatically: $_"
+      Write-Warning "Add $InstallDir to PATH manually to run zero from any directory."
+    }
+  }
+
+  if (-not (Test-ZeroPathContainsDir -PathValue $env:PATH -Dir $InstallDir)) {
+    $env:PATH = "$env:PATH;$InstallDir"
   }
 } finally {
   if (Test-Path $tempDir) {