Merge pull request #466 from irisitymichaelgrundberg/feat/pane-exit-reporting

feat(tmux): report that a pane's agent has exited (#446, part 1)

docs/architecture-invariants.md

@@ -162,6 +162,10 @@ Tests: `test/docker-hosts.test.ts`, `test/docker-exec-options.test.ts`, `test/do
 
 **Circuit breaker**: Prevents respawn thrashing. States: `CLOSED` → `HALF_OPEN` → `OPEN`. Reset: `/api/sessions/:id/ralph-circuit-breaker/reset`. **Distinct: PTY-exit breaker** (COD-115/118/#147, `session-pty-exit-breaker.ts`) trips after repeated rapid PTY exits (crash loops on attach), blocks further auto-restarts, broadcasts SSE `session:respawnBreakerTripped` + push (in `PUSH_EVENT_MAP`). Reset ONLY via an explicit `{clearBreaker:true}` body on `POST /api/sessions/:id/interactive` (sent by the user-facing restart control) — the frontend's auto-reattach in `selectSession()` sends no body and must never clear it. Sessions also scrub inherited `TMUX`/`TMUX_PANE` env so Codeman-in-tmux doesn't nest. Tests: `test/respawn-pty-breaker.test.ts`.
 
+### An exited agent in a live pane (`paneExit`)
+
+**Codeman creates every pane with `remain-on-exit on`, so a session whose agent exited still looks alive.** `/exit` ends the CLI, tmux keeps the pane and the tmux session, and the `tmux attach-session` process Codeman records as `Session.pid` runs on, so no PTY exit handler fires and the record keeps its pid and `status: 'idle'` (Ark0N/Codeman#446). `SessionState.paneExit` (`{status?, signal?, at}`) is the fact tmux already knows, published through `toState()` so it rides `session:updated` and lands in `state.json` on the same persist — there is no SSE event for it. One batched `tmux list-panes -a` per tick fills it, from `TmuxManager.startPaneExitWatcher()`, which has its OWN always-on interval: the stats collector cannot carry it, because the browser arms and disarms that one with the Monitor panel (`panels-ui.js`) and boot skips it entirely when no session was recovered. ⚠️ **The field is TRI-STATE and its third state is absence**, meaning UNKNOWN, which renders as nothing and must NEVER read as alive; it covers a running pane, a session the read did not list, a failed probe, and every session shape a dead local pane does not describe. `Session.paneExitApplies` is the single place that scoping lives, and it fails closed for four shapes: a direct-PTY session (no pane), a remote SSH session (the local pane is the ssh client, whose death is a transport drop OR an exit — the whole of #355), a docker case (the local pane is a `docker exec` into the container's own tmux), and a session rebuilt from the socket (`MuxSession.discovered`: its synthetic `restored-<fragment>` id matches no `state.json` entry, so a remote session rediscovered after `mux-sessions.json` was lost would arrive looking local). ⚠️ **Never set `status: 'error'`** for an exited pane — that value is the PTY-exit breaker's and the browser answers it with a "restart it?" confirm — and **never null the `pid`**, which is what makes `selectSession()` re-attach and launch a fresh CLI. Local panes keep `remain-on-exit on`; flipping them to `failed` ends the tmux session, nulls the pid and reintroduces the auto-revive #355 removed. ⚠️ **An absent `#{pane_dead_status}` is not 0**: measured on tmux 3.2a a SIGKILLed pane reports neither a status nor a signal (`#{pane_dead_signal}` did not exist before tmux 3.4), so folding it into 0 would turn an unexplained death into a clean exit. A session answers only when the read listed EXACTLY ONE pane for it, since Codeman never splits a pane and a session the user split by hand has none that speaks for the agent. The three synchronous `isPaneDead()` callers (the `/wait` route, the TUI, the attach path) keep their own probes — this watcher is never fresh enough for them. ⚠️ **The always-on timer gates the READ, never the tick.** `hasObservablePaneSession()` (`tmux-manager.ts`) skips the tmux exec while every session on the manager is one of the shapes `paneExitApplies` forces to UNKNOWN, so an instance running only remote or Docker work keeps ticking and costs nothing; the two predicates are two copies of one rule, and `test/session-pane-exit.test.ts` pins them against each other for the four session shapes that exist today — a FIFTH condition added to one and not the other still fails nothing, so change them together. Skipping retracts nothing, for the same reason a failed read does not. ⚠️ **The muted status dot is a specificity fight, and it is fought on three surfaces.** The tab renders `status` as before, and `tab-agent-exited` only quiets the dot, so the rule excludes three states BY HAND: `.tab-alert-action` and `.tab-alert-idle` on the tab, and `.tab-status.error` on the dot itself. Each of those colours means "this needs you" — the two alerts because a human is blocked, `error` because the browser answers it with a "restart it?" confirm — and each must survive the exit. The rich tab rail needs a SECOND copy of the rule, because its own `tab-state-*` dot rules are (0,9,1) against the strip's (0,5,0) — measured, an exited session on a detailed rail kept a full green dot and the working halo beside a badge reading "exited". Its twin matches that specificity exactly and therefore must stay BELOW those rules in source order. mobile.css needs a THIRD copy, with `!important`, because the phone block enlarges a `busy` dot and gives it a green glow that way, and `status` stays `busy` for a pane whose agent died mid-turn — without it a phone renders a grey dot still wearing the green halo. `test/session-pane-exit-ui.test.ts` resolves the real stylesheets in jsdom rather than matching selector text — styles.css for the desktop cases and both files for the phone ones — so the ordering, the hand-written exclusions and a missing phone rule all fail there. Tests: `test/session-pane-exit.test.ts`, `test/tmux-manager.test.ts`, `test/session-pane-exit-ui.test.ts`.
+
 ## Features
 
 ### Attachments