feat(pi): add Pi (pi.dev) as a sixth CLI run mode (#206)

SessionMode gains 'pi', a first-class backend alongside Claude Code,
OpenCode, Codex, Gemini and Antigravity: its own PTY, tmux session, rose
tab identity, welcome button, run-mode entry, cron agentType, Docker and
remote-SSH command defaults, and clone-repo Brain option.

Pi is a different shape of CLI from the other four, and three decisions
follow from that:

- It has NO permission prompts and no sandbox, so there is no
  --dangerously-skip-permissions analog and none was invented. The
  privilege-shaped knob is the tri-state approveProjectTrust, which makes
  pi load and EXECUTE repo-local .pi/extensions TypeScript and install
  missing project packages. clampExternalCliBypassForOwner() therefore
  puts pi in the MATERIALIZE branch: a non-granted multi-user owner gets
  --no-approve even when no config was sent, because pi's own default is
  a prompt the session user could answer themselves. That helper had zero
  test coverage; it now has coverage for all four CLIs.
- Only the PI_ prefix joins the env allowlist. Pi's ~34 provider key vars
  share no prefix and ALLOWED_ENV_PREFIXES is one global list with no mode
  context, so admitting them would widen the allowlist for every mode at
  once. Auth goes through pi's /login or the server's own environment.
  --api-key is deliberately 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, and its 0.84.0 fullscreen
  mode is runtime-switchable via /settings; that flip was measured to put
  the pane into the alt screen, which the strip would have corrupted.

pi-cli-resolver.ts additionally sanity-probes `pi --version` and requires
semver-shaped output, because `pi` is a short generic name a stray binary
can shadow; GET /api/pi/status surfaces path and version so a
misresolution is diagnosable rather than presenting as a broken mode.

Docker installs pi in its own --ignore-scripts step so that flag cannot
affect the other four CLIs, and seeds its credentials per-file rather than
whole-dir (~/.pi/agent also holds sessions, extensions and package trees).

Verified end to end against pi 0.84.1 on an isolated instance: resolver
search-dir fallback, flag construction, piConfig persistence across a full
server restart, the trust prompt and its --no-approve suppression, the
rose Run button on the default daylight-blue skin (the nested skin block
eats per-mode gradients unless the rule lives inside it), and the buffer
local-echo policy, which pi tolerates where codex did not.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -80,7 +80,7 @@ CI runs `npm run check:lockfile` on every push/PR, so lockfile drift fails the b
 
 Codeman is a Claude Code session manager with web interface and autonomous Ralph Loop. Spawns Claude CLI via PTY, streams via SSE, supports respawn cycling for 24+ hour autonomous runs.
 
-**Tech Stack**: TypeScript (ES2022/NodeNext, strict mode), Node.js, Fastify, node-pty, xterm.js. Supports Claude Code, OpenCode, Codex (OpenAI), Gemini (Google, enterprise-only since Google's June 2026 consumer cutover), and Antigravity (`agy`, Google) CLIs via pluggable CLI resolvers (`SessionMode = 'claude' | 'shell' | 'opencode' | 'codex' | 'gemini' | 'antigravity'`).
+**Tech Stack**: TypeScript (ES2022/NodeNext, strict mode), Node.js, Fastify, node-pty, xterm.js. Supports Claude Code, OpenCode, Codex (OpenAI), Gemini (Google, enterprise-only since Google's June 2026 consumer cutover), Antigravity (`agy`, Google) and Pi (pi.dev) CLIs via pluggable CLI resolvers (`SessionMode = 'claude' | 'shell' | 'opencode' | 'codex' | 'gemini' | 'antigravity' | 'pi'`).
 
 **TypeScript Strictness** (see `tsconfig.json`): `noUnusedLocals`, `noUnusedParameters`, `noImplicitReturns`, `noImplicitOverride`, `noFallthroughCasesInSwitch`, `allowUnreachableCode: false`, `allowUnusedLabels: false`.
 
@@ -124,10 +124,10 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 - **ESM only** — Never `require()`, use `await import()`. `tsx` masks CJS/ESM issues in dev but production breaks
 - **Package ≠ product name** — npm: `aicodeman`, product: **Codeman**. Release renames tags accordingly. Both `aicodeman` and `codeman` bin aliases are installed (`package.json` `bin`)
 - **Global regex `lastIndex`** — Shared `g`-flag patterns in loops must reset `lastIndex = 0` first, or use the `execPattern()` helper in `utils/regex-patterns.ts` (resets automatically)
-- **`envOverrides` flow `CLAUDE_CODE_*` / `OPENCODE_*` / `CODEX_*` / `GEMINI_*` / `GOOGLE_*` / `ANTIGRAVITY_*` env vars, plus exact-key `CLAUDE_CONFIG_DIR`** — Set via `POST /api/sessions { envOverrides }`, stored on `Session._envOverrides`, exported by `tmux-manager.buildEnvExports()` at spawn time, persisted in `SessionState.envOverrides`. **Do NOT** write these to `<case>/.claude/settings.local.json` — that's the old path and creates UI/disk drift. (`GOOGLE_*` is the deliberately-broad Vertex-AI namespace for Gemini — see Multi-CLI prefix discipline.) `CLAUDE_CONFIG_DIR` (#255, exact match via `ALLOWED_ENV_KEYS` in `schemas.ts`) points a session at a separate Claude account/config dir for per-client subscriptions; it persists to state.json (a path, not a secret; losing it on restart would silently switch accounts). ⚠️ A relocated config dir writes transcripts outside `~/.claude/projects`, so the response viewer, subagent windows, ultracode panel and Read My Mind capture go blind for that session unless the user symlinks `projects` back into the shared tree (`ln -s ~/.claude/projects <configDir>/projects`). → [architecture-invariants#per-session-env-overrides-exact-key-allowlist-and-claude_config_dir](docs/architecture-invariants.md#per-session-env-overrides-exact-key-allowlist-and-claude_config_dir)
+- **`envOverrides` flow `CLAUDE_CODE_*` / `OPENCODE_*` / `CODEX_*` / `GEMINI_*` / `GOOGLE_*` / `ANTIGRAVITY_*` / `PI_*` env vars, plus exact-key `CLAUDE_CONFIG_DIR`** — Set via `POST /api/sessions { envOverrides }`, stored on `Session._envOverrides`, exported by `tmux-manager.buildEnvExports()` at spawn time, persisted in `SessionState.envOverrides`. **Do NOT** write these to `<case>/.claude/settings.local.json` — that's the old path and creates UI/disk drift. (`GOOGLE_*` is the deliberately-broad Vertex-AI namespace for Gemini — see Multi-CLI prefix discipline.) `CLAUDE_CONFIG_DIR` (#255, exact match via `ALLOWED_ENV_KEYS` in `schemas.ts`) points a session at a separate Claude account/config dir for per-client subscriptions; it persists to state.json (a path, not a secret; losing it on restart would silently switch accounts). ⚠️ A relocated config dir writes transcripts outside `~/.claude/projects`, so the response viewer, subagent windows, ultracode panel and Read My Mind capture go blind for that session unless the user symlinks `projects` back into the shared tree (`ln -s ~/.claude/projects <configDir>/projects`). → [architecture-invariants#per-session-env-overrides-exact-key-allowlist-and-claude_config_dir](docs/architecture-invariants.md#per-session-env-overrides-exact-key-allowlist-and-claude_config_dir)
 - **Effort is NOT an env var** — never carry effort as `CLAUDE_CODE_EFFORT_LEVEL`: the env var hard-locks effort and blocks in-session `/effort` switching (incl. ultracode). It flows as the dedicated `effort` payload field → `Session._effort` → `claude --effort <level>` for regular levels incl. `max` (the settings `effortLevel` key is `enum(["low","medium","high","xhigh"]).catch(undefined)` — `max` gets SILENTLY dropped there), or `claude --settings '{"ultracode":true}'` for ultracode (rejected by `--effort`). Both are soft defaults the user can override anytime. Legacy env-var entries are auto-migrated by the Session constructor and unset from tmux sessions in `applyEnvOverrides()`. See `buildEffortCliArgs()` in `session-cli-builder.ts`, tests in `test/effort-injection.test.ts`
 - **Model choice flows via `settings.local.json`, NOT `--model` or env** — the App Settings **Claude Model** picker (`claudeModel` in `settings.json`) is read by `session-ui.js` at session create (wins over the legacy 1M-Opus toggles `opusContext1m`/`opusContext1mEnabled`), sent as the `modelOverride` payload field, and `updateCaseModel()` (`hooks-config.ts`) writes/deletes the `model` key in `<case>/.claude/settings.local.json`. This is the intended exception to the envOverrides rule above: model legitimately lives in `settings.local.json` (a soft default — in-session `/model` still works); env vars do not
-- **Multi-CLI prefix discipline** — env-var prefix is CLI-specific (`CLAUDE_CODE_*` vs `OPENCODE_*` vs `CODEX_*` vs `GEMINI_*` vs `ANTIGRAVITY_*`) and the `ALLOWED_ENV_PREFIXES` allowlist in `schemas.ts` enforces this; non-prefix exceptions are exact keys in `ALLOWED_ENV_KEYS` (currently only `CLAUDE_CONFIG_DIR`), never a widened prefix. Gemini additionally allowlists the **broad `GOOGLE_*`** namespace (intentional: Vertex AI auth needs `GOOGLE_CLOUD_PROJECT`/`GOOGLE_APPLICATION_CREDENTIALS`/`GOOGLE_GENAI_USE_VERTEXAI`; it is the loosest allowlist entry, affecting only the user's own spawned CLI). When adding a setting, decide which CLI(s) it applies to and gate the env export accordingly. Never blanket-forward all prefixes. Resolver design pattern: `docs/opencode-integration.md`
+- **Multi-CLI prefix discipline** — env-var prefix is CLI-specific (`CLAUDE_CODE_*` vs `OPENCODE_*` vs `CODEX_*` vs `GEMINI_*` vs `ANTIGRAVITY_*` vs `PI_*`) and the `ALLOWED_ENV_PREFIXES` allowlist in `schemas.ts` enforces this; non-prefix exceptions are exact keys in `ALLOWED_ENV_KEYS` (currently only `CLAUDE_CONFIG_DIR`), never a widened prefix. Gemini additionally allowlists the **broad `GOOGLE_*`** namespace (intentional: Vertex AI auth needs `GOOGLE_CLOUD_PROJECT`/`GOOGLE_APPLICATION_CREDENTIALS`/`GOOGLE_GENAI_USE_VERTEXAI`; it is the loosest allowlist entry, affecting only the user's own spawned CLI). When adding a setting, decide which CLI(s) it applies to and gate the env export accordingly. Never blanket-forward all prefixes. ⚠️ Pi is the case that proves the rule: its ~34 provider keys (`ANTHROPIC_API_KEY`, `OPENAI_API_KEY`, `HF_TOKEN`, …) share NO prefix, and the allowlist is one GLOBAL list applied by a refine with no mode context, so admitting them for pi would widen it for every mode at once — they stay out, and pi users authenticate via `/login` or the server process's own env. Resolver design pattern: `docs/opencode-integration.md`, `docs/pi-integration.md`
 - **Zod `.optional()` rejects `null`** — accepts `undefined` only. When the frontend builds a request body with `JSON.stringify`, an explicit `null` field is preserved on the wire and fails validation with `INVALID_INPUT`. Convert `null` → `undefined` before stringifying (e.g. `field: value ?? undefined`), or declare the schema `.nullish()`. This has caused real shipped bugs twice
 - **`xterm-zerolag-input` is single-source** — BOTH echo addons live ONLY in `packages/xterm-zerolag-input/src/`, bundled into TWO **gitignored** vendor files: `vendor/xterm-zerolag-input.js` (buffer overlay, entry `zerolag-input-addon.ts`) and `vendor/xterm-predictive-echo.js` (codex write-through, entry `predictive-echo-addon.ts`) — dev by `scripts/postinstall.js`, prod by `scripts/build.mjs`. `app.js`/terminal-ui.js only **consume** them via `new LocalEchoOverlay(terminal)` / `new PredictiveEchoOverlay(terminal)`; there is no inline copy. So: change the package source, then rerun the bundle step (`npm install` for dev, `npm run build` for prod). **Never hand-edit `app.js` for overlay behavior, and never commit the gitignored vendor bundles.** Always test on mobile after touching it. → [architecture-invariants#xterm-zerolag-input-is-single-source](docs/architecture-invariants.md#xterm-zerolag-input-is-single-source), `docs/local-echo-overlay-plan.md`
 - **Default bind is loopback-only; non-loopback without a password starts but warns** — the server defaults to `--host 127.0.0.1`. Binding non-loopback (`--host`/`-H`/`CODEMAN_HOST`) without `CODEMAN_PASSWORD` starts anyway but prints a loud warning; `--allow-unauthenticated-network` / `CODEMAN_ALLOW_UNAUTHENTICATED_NETWORK=1` acknowledges it. ⚠️ The production systemd unit passes no `--host`, so prod binds **localhost only**: reach it via `tailscale serve`/tunnel to `127.0.0.1`. A loopback bind is reachable through a same-host tunnel but NOT by a browser hitting the box's LAN IP. `install.sh` is separate and prompts for the binding (defaulting to LAN + a password), and preserves the existing binding on re-runs. → [architecture-invariants#default-bind-and-the-non-loopback-warning-path](docs/architecture-invariants.md#default-bind-and-the-non-loopback-warning-path), `docs/security-architecture.md`
@@ -169,7 +169,7 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 **Config**: `src/config/` — 20 files, no barrel (`index.ts`) exists; import from the specific file.
 
-**Utilities**: `src/utils/` — re-exported via index. Key: `CleanupManager`, `LRUMap` (⚠ NOT in the barrel — import from `./utils/lru-map.js` directly), `StaleExpirationMap`, `BufferAccumulator`, `stripAnsi`, `Debouncer`, `KeyedDebouncer`. Also: `claude-cli-resolver`/`opencode-cli-resolver`/`codex-cli-resolver`/`gemini-cli-resolver` (CLI path resolution), `string-similarity` (fuzzy matching), `regex-patterns` (ANSI/token/spinner patterns), `assertNever` (exhaustive checks), `token-validation` (auth tokens), `nice-wrapper` (process priority).
+**Utilities**: `src/utils/` — re-exported via index. Key: `CleanupManager`, `LRUMap` (⚠ NOT in the barrel — import from `./utils/lru-map.js` directly), `StaleExpirationMap`, `BufferAccumulator`, `stripAnsi`, `Debouncer`, `KeyedDebouncer`. Also: `claude-cli-resolver`/`opencode-cli-resolver`/`codex-cli-resolver`/`gemini-cli-resolver`/`antigravity-cli-resolver`/`pi-cli-resolver` (CLI path resolution; ⚠ `pi-cli-resolver` additionally version-probes the binary, since `pi` is a generic name), `string-similarity` (fuzzy matching), `regex-patterns` (ANSI/token/spinner patterns), `assertNever` (exhaustive checks), `token-validation` (auth tokens), `nice-wrapper` (process priority).
 
 ### Data Flow
 
@@ -200,7 +200,7 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 **Docker cases**: a case can point at a **container**, with any of the five CLI backends running inside it. Like remote-SSH this is a **LOCATION OVERLAY on cases, never a sixth `SessionMode`**. Exactly one long-lived container **per case**, shared by all its sessions, so killing a session kills only that session's in-container tmux and **never** `docker stop` while siblings remain. The workspace is a real host dir bind-mounted at the **same absolute path**, which is what keeps file-routes/watchers on real host bytes and makes the in-container transcript projHash match the host. Credentials are **seeded** (RO mount, copied into the container once) rather than shared RW, so in-container CLIs never write refreshed tokens back to the host, and bind mounts are excluded from `docker commit` so exports stay secret-free. **NEVER a create-time `-e` for secrets, NEVER `--privileged`, NEVER the docker socket.** Config drift is detected via a label hash and a drifted launch is REFUSED rather than silently launched with stale config. ⚠️ On the loopback-only prod bind a container cannot reach 127.0.0.1, so in-container hooks need `CODEMAN_DOCKER_BRIDGE_HOOKS=1`; otherwise idle detection falls back to output-based. → [architecture-invariants#docker-cases](docs/architecture-invariants.md#docker-cases), `docs/docker-cases.md` (user guide), `docs/docker-cases-plan.md` (design)
 
-**External CLI modes (OpenCode, Codex, Gemini, Antigravity)**: `isExternalCliMode()` in `session.ts` gates Claude-specific behavior off (Ralph tracker, BashToolParser, token/CLI-info parsing, ❯-prompt readiness); these CLIs render their own TUIs, so readiness is output stabilization instead. All four **require tmux with no direct PTY fallback**, because secrets are injected via socket-scoped `tmux setenv` and never on the spawn command line. ⚠️ `run*()` in `session-ui.js` MUST unwrap the `{success,data}` envelope; reading the raw shape silently breaks the run. ⚠️ **Codex sessions use PREDICTIVE WRITE-THROUGH echo, never the buffer overlay** (`_localEchoPolicy` in `_updateLocalEchoState`, terminal-ui.js): codex's composer reacts per keystroke ("/" pops a live-filtering picker, arrows edit server-side state, the composer grows as it wraps), so buffer-until-Enter starved it into issues #218/#219/#220/#222 and stays disabled (`_localEchoEnabled` remains false for codex). Instead, `PredictiveEchoAddon` (separate `vendor/xterm-predictive-echo.js` bundle) paints each keystroke at the predicted cell while the wire path stays BYTE-IDENTICAL: the onData hook (`_predictHookOnData`) is a plain statement with no `return`, so control always falls through into the untouched send path — pinned by vm and E2E byte-identity tests. Predictions reconcile against the parsed buffer and only while the cursor sits on the measured composer row (`isCodexComposerRow`, `/^› /`). Codex also **drops keystrokes that share a PTY read with a bracketed paste**, so flushed text and the paste sequence must go out as separate delayed writes (mirroring the Enter branch's delayed `\r`). Tests: `test/local-echo-codex-gating.test.ts`, `test/codex-predictive-echo.test.ts` (E2E vs real codex), `packages/xterm-zerolag-input/test/codex-replay.test.ts`. → [architecture-invariants#external-cli-modes-opencode-codex-gemini](docs/architecture-invariants.md#external-cli-modes-opencode-codex-gemini-antigravity)
+**External CLI modes (OpenCode, Codex, Gemini, Antigravity, Pi)**: `isExternalCliMode()` in `session.ts` gates Claude-specific behavior off (Ralph tracker, BashToolParser, token/CLI-info parsing, ❯-prompt readiness); these CLIs render their own TUIs, so readiness is output stabilization instead. All five **require tmux with no direct PTY fallback**, because secrets are injected via socket-scoped `tmux setenv` and never on the spawn command line. ⚠️ `run*()` in `session-ui.js` MUST unwrap the `{success,data}` envelope; reading the raw shape silently breaks the run. ⚠️ **Codex sessions use PREDICTIVE WRITE-THROUGH echo, never the buffer overlay** (`_localEchoPolicy` in `_updateLocalEchoState`, terminal-ui.js): codex's composer reacts per keystroke ("/" pops a live-filtering picker, arrows edit server-side state, the composer grows as it wraps), so buffer-until-Enter starved it into issues #218/#219/#220/#222 and stays disabled (`_localEchoEnabled` remains false for codex). Instead, `PredictiveEchoAddon` (separate `vendor/xterm-predictive-echo.js` bundle) paints each keystroke at the predicted cell while the wire path stays BYTE-IDENTICAL: the onData hook (`_predictHookOnData`) is a plain statement with no `return`, so control always falls through into the untouched send path — pinned by vm and E2E byte-identity tests. Predictions reconcile against the parsed buffer and only while the cursor sits on the measured composer row (`isCodexComposerRow`, `/^› /`). Codex also **drops keystrokes that share a PTY read with a bracketed paste**, so flushed text and the paste sequence must go out as separate delayed writes (mirroring the Enter branch's delayed `\r`). Tests: `test/local-echo-codex-gating.test.ts`, `test/codex-predictive-echo.test.ts` (E2E vs real codex), `packages/xterm-zerolag-input/test/codex-replay.test.ts`. ⚠️ **Pi is the opposite kind of CLI and needs the opposite instincts**: it has NO permission prompts and no sandbox, so there is no bypass flag to send and Codeman must not invent one; its privileged knob is the tri-state `approveProjectTrust` (`--approve`/`--no-approve`), which makes pi EXECUTE repo-local `.pi/extensions` TypeScript, so the multi-user clamp puts pi in the **materialize** branch (an absent config still yields `--no-approve` for a non-granted owner) and `--api-key` is never wired. Pi stays OUT of `isAltScreenStripMode()` (main-screen TUI, and its 0.84.0 fullscreen mode is runtime-switchable via `/settings`, where the alt screen is load-bearing), and lands on the `'buffer'` echo policy via the `_updateLocalEchoState` fallthrough. Pi's own tests: `test/pi-mode.test.ts`, `test/routes/external-cli-bypass-clamp.test.ts`; user guide `docs/pi-integration.md`. → [architecture-invariants#external-cli-modes-opencode-codex-gemini-antigravity-pi](docs/architecture-invariants.md#external-cli-modes-opencode-codex-gemini-antigravity-pi)
 
 **Run launch synchronization**: the Run entrypoint holds an in-flight lock and disables `#runBtn` for the whole launch (≥500ms), so a double click cannot create duplicate sessions with the same `w<n>-<case>` name. `_ensureCreatedSessionVisible()` runs before `selectSession()`, and `_onSessionCreated()` stays an idempotent upsert, so POST-first and SSE-first ordering both produce exactly one rendered tab. → [architecture-invariants#run-launch-synchronization](docs/architecture-invariants.md#run-launch-synchronization)