fix: Project action terminal lifecycle (#3287)

* fix(terminal): make command sessions own action lifecycle

* fix(ui): reconcile project action terminal state

* feat(ui): show running project actions in terminal tabs

* feat(ui): run project actions from linked worktrees

* fix(ui): guard project action reconciliation

* fix(ui): scope project action preview fallback

* fix(ui): default project actions to worktrees

* fix(ui): reveal project action terminals

* fix(ui): retain terminal output after snapshot replay

* fix(ui): restore running action terminals on revisit

packages/web/server/lib/terminal/DOCUMENTATION.md

@@ -2,7 +2,7 @@
 
 ## Ownership
 
-`runtime.js` owns terminal identity, PTY processes, status, ordered output, bounded scrollback, WebSocket attachments, and lifecycle routes. `shells.js` discovers executable shell families and resolves the persisted shell ID without accepting command strings or arguments. Clients own tab arrangement and choose stable terminal IDs. Electron uses this same runtime in-process; VS Code returns an explicit unsupported error.
+`runtime.js` owns terminal identity, PTY processes, launch mode, session purpose, ordered output, bounded scrollback, WebSocket attachments, and lifecycle routes. `shells.js` discovers executable shell families, resolves the persisted shell ID, and builds the per-shell argv for interactive versus command launches. Clients own tab arrangement and choose stable terminal IDs. Electron uses this same runtime in-process; VS Code returns an explicit unsupported error.
 
 ## Protocol
 
@@ -19,21 +19,23 @@
 
 HTTP remains the authenticated command plane for create, resize, appearance updates, restart, close, and force-kill. There is no SSE output or HTTP input compatibility path.
 
-`GET /api/terminal/sessions` enumerates live sessions (optionally filtered by resolved `cwd`) so clients can adopt terminals their local tab projection does not know about — another device, a new browser tab, or cleared storage. `POST /api/terminal/touch` refreshes `lastActivity` for the listed session ids; open clients call it periodically so background tabs, which hold no WebSocket attachment, are not idle-reaped while a client still shows them.
+`GET /api/terminal/sessions` enumerates live sessions (optionally filtered by resolved `cwd`) so clients can adopt terminals their local tab projection does not know about — another device, a new browser tab, or cleared storage. Listings include the effective launch mode and the normalized purpose, but never the command text. `POST /api/terminal/touch` refreshes `lastActivity` for the listed session ids; open clients call it periodically so background tabs, which hold no WebSocket attachment, are not idle-reaped while a client still shows them.
 
 ## PTY Lifecycle
 
 - IDs are client-provided or generated with `randomUUID()`.
-- Concurrent creates for one ID are single-flight only when working directory and shell preference match. Existing IDs cannot be reused for another working directory.
+- Create defaults to interactive mode. Command mode requires a non-empty trimmed command no longer than the terminal input limit and launches the shell so the PTY exits when that command exits. Each session also carries a normalized purpose. Omitted purpose means `{ type: 'terminal' }`. Project actions use `{ type: 'project-action', actionId, executionId }`, and the server validates both IDs as non-empty bounded strings. Create responses and attach snapshots echo the effective mode and purpose.
+- Concurrent creates for one ID are single-flight only when working directory, shell preference, login mode, launch mode, and session purpose match. Command-mode creates must also match the command text, unless the purpose is a project action that is already running for the same resolved `(cwd, actionId)` pair. In that case the runtime returns the existing session and its existing execution identity, even when another client requested a different session ID. Existing IDs cannot be reused for another working directory or another purpose.
 - Dimensions are bounded to 1-1000 columns and 1-500 rows; input is capped at 64 KiB.
 - A client may create before its renderer has mounted. It derives an initial size from the container and font metrics (falling back to 80x24 when unavailable), then sends a resize once Ghostty reports its final dimensions. This allows shell startup and renderer initialization to overlap.
 - PTY children explicitly clear `NODE_CHANNEL_FD`; daemon IPC descriptors are host-private and invalid after PTY descriptor cleanup.
 - PTY children also strip AppImage `ARGV0` (and other host-private shell vars such as `ELECTRON_RUN_AS_NODE`, `BASH_ENV`, `ENV`, `BASH_XTRACEFD`). An exported `ARGV0` makes zsh rewrite argv[0] for every external command, which breaks Python venv detection and other argv[0]/$0 consumers while leaving `/proc/self/exe` correct. On Linux, PTY spawn is wrapped with `env -u ARGV0` because `bun-pty` merges the native OS environ and would otherwise reintroduce `ARGV0` after a JS-only delete.
-- `GET /api/terminal/shells` reports shell IDs available on the active server using the same augmented PATH provided to spawned PTYs, plus whether each executable has a supported login-mode argument. `auto` preserves environment/platform fallback order; an explicit unavailable shell fails creation instead of silently running a different shell. Login mode is opt-in and uses only built-in arguments for known shells. Preference changes affect new sessions and explicit restarts, not running PTYs.
-- PTY data and exit callbacks enter one FIFO queue. Stale callbacks from replaced processes are ignored.
+- `GET /api/terminal/shells` reports shell IDs available on the active server using the same augmented PATH provided to spawned PTYs, plus whether each executable has a supported login-mode argument. `auto` preserves environment/platform fallback order; an explicit unavailable shell fails creation instead of silently running a different shell. Login mode is opt-in and uses only built-in arguments for known shells. Interactive shells still launch as before. Command-mode launches reuse the same environment and login support, but switch argv by shell family: POSIX and Fish use interactive `-c`, Nushell uses `-c`, PowerShell uses `-Command`, and cmd uses `/d /s /c`. Preference changes affect new sessions and explicit restarts, not running PTYs.
+- PTY data and exit callbacks enter one FIFO queue. The runtime wires those listeners in the same synchronous turn that receives the PTY object. `node-pty` and `bun-pty` both expose the PTY before dispatching registered callbacks. If a backend emitted exit before listener registration, this layer could not recover it, so the wiring stays adjacent to PTY creation.
 - Scrollback is retained on the server and capped at 512 KiB with UTF-8-safe trimming. Device-status, device-attribute, cursor-position reply, and color-query exchanges are removed from replay history with incomplete control sequences carried across PTY chunks; live output remains byte-for-byte unchanged.
 - Exited sessions remain attachable until explicit close or idle cleanup.
-- Restarts are serialized per terminal. Each restart spawns and wires the replacement before terminating the old process, retaining the terminal ID.
+- Restarts are serialized per terminal. Each restart spawns and wires the replacement before terminating the old process, retaining the terminal ID. Command-mode sessions reject restart with HTTP 400 instead of silently turning into interactive shells with stale action metadata.
+- A delete that arrives while create is still pending leaves a cancellation tombstone. When the PTY arrives, the runtime terminates it immediately, never inserts the session into the live map, and returns a create error while the delete still succeeds.
 - Close uses SIGTERM with bounded SIGKILL escalation. Force-kill, idle cleanup, and runtime shutdown terminate process groups immediately where supported. Removal explicitly sends a fatal scoped closure and evicts client projections even when a PTY backend fails to emit `onExit`; attached terminals are not considered idle.
 
 ## Security And Relay