daemon: playbook run is never reaped when the owning session never reports Running — including after it errors

[edwin-zvs]

Every stop signal for a Playbook run is gated on the run having been seen running:

SessionState::Done | SessionState::Errored => {
    if run.seen_running {
        clear = true;
    }
}
SessionState::AwaitingInput => {
    if run.seen_running && (!run.agent_managed || (…pending empty…)) {
        clear = true;
    }
}

(crates/daemon/src/session/playbook_run.rs ~lines 541–568 @ ad47152)

seen_running is only set from a SessionState::Running transition. A turn that ends before the busy detector ever reports Running never sets it, so no stop signal can fire and the run survives to the PLAYBOOK_RUN_MAX_MS backstop — 10 minutes of the whole document shimmering (crates/daemon/src/session.rs ~line 122).

The Done | Errored arm is the worse half: a terminal session can never settle anything, so there is nothing to protect by waiting.

Repro

A — fast turn, no Running transition. Run a Playbook on a shell session whose delivered prompt fails immediately (e.g. bash syntax error). Subscribed to subscribe.events for 20s afterwards: one playbook/state with seen_running: false, and no session/state status event at all. The session sits at awaiting input while all 9 blocks report shimmer: true, and stay that way.

B — session dies mid-run. Create a session, set a Playbook, playbook.execute, then kill the session:

=== after kill ===
● ✗ se01e3332a  shell    errored
  b0:0  shimmer=True  '# T'
  b1:0  shimmer=True  '- alpha'
  b2:0  shimmer=True  '- beta'

The owning agent is gone and the Playbook keeps shimmering.

Both reproduce with a shell harness, but the shape is general: any harness whose turn fails fast (crashed CLI, auth error, rejected prompt) lands in case A.

Expected

• Done / Errored: clear the run unconditionally. Nothing can settle those blocks.
• AwaitingInput with no Running ever observed: use a short post-dispatch grace (~10–20s) rather than the 10-minute backstop, so a failed dispatch stops shimmering promptly.

Per spec 0042, narrowing/stop remains best-effort and system-owned; this is about the backstop being the only signal in these cases.

Acceptance criteria

• A session reaching Done/Errored clears its active Playbook run regardless of seen_running.
• A run whose session goes idle without ever reporting Running clears within seconds, not 10 minutes.
• Tests cover both: terminate-before-Running, and idle-without-Running.

Found during a hands-on UX audit of the Playbook in the TUI and web UI.