feat(grok): add Grok Build (xAI) as a seventh CLI run mode

SessionMode gains 'grok', a first-class backend alongside Claude Code,
shell, OpenCode, Codex, Gemini, Antigravity and Pi: its own PTY, tmux
session, charcoal tab identity ('gk' badge), welcome button, run-mode
entry, cron agentType, Docker and remote-SSH command defaults, and
clone-repo Brain option. Flag surface verified live against grok 1.0.5.

Grok mixes two existing shapes and the wiring follows from that:

- Codex-shaped on permissions: the bypass switch is GrokConfig.alwaysApprove
  (--always-approve, grok's bypassPermissions mode; config-level deny rules
  still apply on top). The Run button sends it true, like runAntigravity(),
  and clampExternalCliBypassForOwner() puts grok in the only-if-sent branch:
  a bare grok spawn is grok's own ask-mode default, which is already safe,
  so only a sent config needs the flag forced off. Cron needs nothing for
  the same reason.
- OpenCode-shaped on rendering: grok is a fullscreen alternate-screen TUI
  with mouse support, so it stays OUT of isAltScreenStripMode() and lands
  on the narrow tmux-attach strip and the 'buffer' local-echo fallthrough
  (unmeasured against an authenticated composer; documented fallback is the
  'off' branch).
- Pi-shaped on resolution: 'grok' has npm squatters (@vibe-kit/grok-cli
  also installs a grok bin), so grok-cli-resolver.ts version-probes every
  candidate (grok --version, killSignal SIGKILL, VITEST-gated) and
  GET /api/grok/status surfaces path AND version; GROK_VERSION_REGEX is
  shared with the dependency registry so doctor and run mode cannot drift.

Env allowlist gains GROK_* plus the XAI_* vendor namespace (XAI_API_KEY is
grok's documented headless auth var), the same narrow-vendor reasoning as
GOOGLE_* for gemini. Resume is id-regexed on purpose: grok's own --resume
also matches session titles, which are arbitrary user strings that must
never reach the bash -c spawn line.

Docker: grok is not on npm, so the agent image installs it in its own step
(xAI's installer has no --dir override; the binary is copied to
/usr/local/bin and root's ~/.grok dropped in the same layer), and
credentials are seeded per-file (auth.json, config.toml, pager.toml; the
dir also holds sessions/, memory/ and the ~160MB binary). Remote SSH routes
through the login-shell wrapper like the other agent CLIs.

Verified end to end on an isolated CODEMAN_INSTANCE with grok 1.0.5
installed: /api/grok/status resolves and reports the probed version,
quick-start spawns a pane whose command line ends in 'grok
--always-approve', the real TUI renders (OAuth device screen on an
unauthenticated box), and grokConfig round-trips through state.json.
Docs: docs/grok-integration.md (user guide) + docs/grok-integration-plan.md
(decisions, verification record, follow-ups).

Tests: test/grok-mode.test.ts, test/grok-cli-resolver.test.ts, plus
extended clamp/system-routes/render-index-html/run-mode-ui/mobile-overview/
local-echo-gating coverage. npm test (the CI gate) green: 5910 tests.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/architecture-invariants.md

@@ -18,9 +18,9 @@ Implementation detail extracted from `CLAUDE.md` so that file stays small enough
 
 ## Session launch modes
 
-### External CLI modes (OpenCode, Codex, Gemini, Antigravity, Pi)
+### External CLI modes (OpenCode, Codex, Gemini, Antigravity, Pi, Grok)
 
-**External CLI modes (OpenCode, Codex, Gemini, Antigravity, Pi)**: `isExternalCliMode()` in `session.ts` (`mode === 'opencode' || 'codex' || 'gemini' || 'antigravity' || 'pi'`) gates Claude-specific behavior — Ralph tracker, BashToolParser, token/CLI-info parsing, and ❯-prompt readiness detection are all skipped (these CLIs render their own TUIs; readiness = output stabilization instead). All five modes **require tmux — no direct PTY fallback** — because secrets are injected via `tmux setenv` (socket-scoped `${this.tmux()} setenv`, never on the spawn command line): OpenCode gets `OPENCODE_CONFIG_CONTENT` etc., Codex gets `OPENAI_API_KEY`/`CODEX_API_KEY`/`CODEX_HOME` (`setCodexEnvVars`), Gemini gets `GEMINI_API_KEY`/`GOOGLE_API_KEY`/`GOOGLE_CLOUD_PROJECT`/`GOOGLE_APPLICATION_CREDENTIALS`/`GOOGLE_GENAI_USE_VERTEXAI` etc. (`setGeminiEnvVars`, all in `tmux-manager.ts`). Codex specifics: command built by `buildCodexCommand()` (`--model`, `resume <id>`, `--dangerously-bypass-approvals-and-sandbox` from the `codexConfig` payload / `codexDangerouslyBypassApprovals` app setting; `renderMode` is schema-coerced to `'hybrid'`, the only supported mode). Gemini specifics: command built by `buildGeminiCommand()` (`--skip-trust` always, `--approval-mode <default|auto_edit|yolo|plan>` defaulting to `yolo` for parity with Claude's `--dangerously-skip-permissions`, `--model`, `--resume` from the `geminiConfig` payload); availability via `GET /api/gemini/status` — session/quick-start routes fail with `OPERATION_FAILED` + install hint (`npm install -g @google/gemini-cli`) when missing. Codex AND Gemini export `COLORTERM=truecolor` + unset `NO_COLOR` (other modes unset `COLORTERM`); Gemini joins `isAltScreenStripMode()` (Codex/Claude/Gemini are Ink TUIs that repaint inline → strip alt-screen/`3J` so scrollback survives). Codex availability via `GET /api/codex/status`. Antigravity specifics: command built by `buildAntigravityCommand()` (`--model`, `--conversation <id>` resume, `--dangerously-skip-permissions` from the `antigravityConfig` payload); availability via `GET /api/antigravity/status` — routes fail with `OPERATION_FAILED` + install hint (`curl -fsSL https://antigravity.google/cli/install.sh | bash`) when missing. Unlike the other three it is NOT an npm package (standalone binary, `~/.local/bin/agy`), which is why `docker/agent.Dockerfile` installs it with its own `--dir /usr/local/bin` step rather than in the `npm install -g` line, and why it does NOT join `isAltScreenStripMode()`. Frontend: run-mode dropdown → `runCodex()`/`runGemini()` in `session-ui.js` ("Run CX"/"Run GM" labels), App Settings → Agents & CLIs → Codex; Respawn/Ralph options are Claude-only, so session options open on the Session tab for external CLI sessions. ⚠️ `run*()` MUST unwrap the `{success,data}` envelope (`(await res.json()).data.available` / `data.data.sessionId`) — reading the raw shape silently breaks the run. Tests: `test/run-mode-ui.test.ts` + `test/gemini-mode.test.ts` (vm-sandbox harness, no real DOM).
+**External CLI modes (OpenCode, Codex, Gemini, Antigravity, Pi, Grok)**: `isExternalCliMode()` in `session.ts` (`mode === 'opencode' || 'codex' || 'gemini' || 'antigravity' || 'pi' || 'grok'`) gates Claude-specific behavior — Ralph tracker, BashToolParser, token/CLI-info parsing, and ❯-prompt readiness detection are all skipped (these CLIs render their own TUIs; readiness = output stabilization instead). All six modes **require tmux — no direct PTY fallback** — because secrets are injected via `tmux setenv` (socket-scoped `${this.tmux()} setenv`, never on the spawn command line): OpenCode gets `OPENCODE_CONFIG_CONTENT` etc., Codex gets `OPENAI_API_KEY`/`CODEX_API_KEY`/`CODEX_HOME` (`setCodexEnvVars`), Gemini gets `GEMINI_API_KEY`/`GOOGLE_API_KEY`/`GOOGLE_CLOUD_PROJECT`/`GOOGLE_APPLICATION_CREDENTIALS`/`GOOGLE_GENAI_USE_VERTEXAI` etc. (`setGeminiEnvVars`, all in `tmux-manager.ts`). Codex specifics: command built by `buildCodexCommand()` (`--model`, `resume <id>`, `--dangerously-bypass-approvals-and-sandbox` from the `codexConfig` payload / `codexDangerouslyBypassApprovals` app setting; `renderMode` is schema-coerced to `'hybrid'`, the only supported mode). Gemini specifics: command built by `buildGeminiCommand()` (`--skip-trust` always, `--approval-mode <default|auto_edit|yolo|plan>` defaulting to `yolo` for parity with Claude's `--dangerously-skip-permissions`, `--model`, `--resume` from the `geminiConfig` payload); availability via `GET /api/gemini/status` — session/quick-start routes fail with `OPERATION_FAILED` + install hint (`npm install -g @google/gemini-cli`) when missing. Codex AND Gemini export `COLORTERM=truecolor` + unset `NO_COLOR` (other modes unset `COLORTERM`); Gemini joins `isAltScreenStripMode()` (Codex/Claude/Gemini are Ink TUIs that repaint inline → strip alt-screen/`3J` so scrollback survives). Codex availability via `GET /api/codex/status`. Antigravity specifics: command built by `buildAntigravityCommand()` (`--model`, `--conversation <id>` resume, `--dangerously-skip-permissions` from the `antigravityConfig` payload); availability via `GET /api/antigravity/status` — routes fail with `OPERATION_FAILED` + install hint (`curl -fsSL https://antigravity.google/cli/install.sh | bash`) when missing. Unlike the other three it is NOT an npm package (standalone binary, `~/.local/bin/agy`), which is why `docker/agent.Dockerfile` installs it with its own `--dir /usr/local/bin` step rather than in the `npm install -g` line, and why it does NOT join `isAltScreenStripMode()`. Frontend: run-mode dropdown → `runCodex()`/`runGemini()` in `session-ui.js` ("Run CX"/"Run GM" labels), App Settings → Agents & CLIs → Codex; Respawn/Ralph options are Claude-only, so session options open on the Session tab for external CLI sessions. ⚠️ `run*()` MUST unwrap the `{success,data}` envelope (`(await res.json()).data.available` / `data.data.sessionId`) — reading the raw shape silently breaks the run. Tests: `test/run-mode-ui.test.ts` + `test/gemini-mode.test.ts` (vm-sandbox harness, no real DOM). Grok specifics: command built by `buildGrokCommand()` (`--always-approve` from `grokConfig.alwaysApprove` — grok's `bypassPermissions` permission mode, deny rules still apply; `--model`; `--resume <id>` / `--continue`, id-regexed so grok's resume-by-TITLE feature can never put an arbitrary string on the spawn line); availability via `GET /api/grok/status`, which carries `version` because the resolver version-probes candidates (`grok` has npm squatters, e.g. @vibe-kit/grok-cli — `GROK_VERSION_REGEX` is shared with the dependency registry so doctor and run mode agree). Like antigravity it is a standalone binary (xAI installer → `~/.grok/bin`, symlinked into `~/.local/bin`), so `docker/agent.Dockerfile` installs it in its own step (copy to `/usr/local/bin`, drop root's `~/.grok` in the same layer) and it stays OUT of `isAltScreenStripMode()` (fullscreen alt-screen TUI with mouse support — the opencode case, not the Ink case). Env allowlist: `GROK_*` plus the vendor namespace `XAI_*` (`XAI_API_KEY` is grok's documented headless auth var — the same narrow-vendor-namespace reasoning as `GOOGLE_*` for gemini). Docker cred seeding is per-file (`auth.json`, `config.toml`, `pager.toml` from `~/.grok` — the dir also holds `sessions/`, `memory/`, and the ~160MB binary under `downloads/`). Grok tests: `test/grok-mode.test.ts`, `test/grok-cli-resolver.test.ts`.
 
 **Pi specifics** (#206, `docs/pi-integration.md`): command built by `buildPiCommand()` (`--model` — the only builder whose model regex admits `:` and `/`, for `sonnet:high` and `openai/gpt-4o` — plus `--provider`, `--thinking`, `--session <id>` / `-c`, and the TRI-STATE `--approve`/`--no-approve`). ⚠️ **Pi has no permission prompts and no sandbox**, so there is no `--dangerously-skip-permissions` analog and Codeman must not invent one; the privilege-shaped knob is `approveProjectTrust`, which makes pi LOAD AND EXECUTE repo-local `.pi/extensions` TypeScript and npm-install missing project packages. It therefore joins `clampExternalCliBypassForOwner()`'s **materialize** branch (gemini's, not codex/antigravity's only-if-sent one): an absent config still yields `--no-approve` for a non-granted owner, because pi's own default is an interactive prompt the session user could answer themselves. ⚠️ `--api-key` is NEVER wired — it would put a provider secret on the spawn command line. ⚠️ Pi stays **out** of `isAltScreenStripMode()`: its default TUI renders into the main screen with terminal-owned scrollback (nothing to strip), and since 0.84.0 the user can flip to a fullscreen TUI at runtime via `/settings`, where the alt screen is load-bearing — being out of the list is exactly what makes that switch safe. ⚠️ Only the `PI_*` env prefix was added; pi's ~34 provider keys share no prefix and `ALLOWED_ENV_PREFIXES` is a single GLOBAL list with no mode context, so admitting them would widen the allowlist for every mode at once (a mode-aware allowlist is the tracked follow-up). ⚠️ `pi` is a short, GENERIC binary name, so unlike the sibling resolvers `pi-cli-resolver.ts` sanity-probes `pi --version` (cached, vitest-skipped) and requires semver-shaped output; `GET /api/pi/status` carries `version` on top of the sibling `{available, path}` shape so a misresolution is diagnosable. Local echo: pi lands on the `'buffer'` overlay via the fallthrough in `_updateLocalEchoState` (pinned in `test/local-echo-codex-gating.test.ts`); if pi's live composer turns out to fight it the way codex's did, the fallback is one `'off'` branch. Tests: `test/pi-mode.test.ts`, `test/routes/external-cli-bypass-clamp.test.ts` (first-ever coverage of the clamp).