Thread lifecycle: snooze (deferred) #527

Summary

Snooze: hide a thread from the active list until a chosen time, following T3 Code. Deferred: not part of the release in #535; nothing is reserved for it (no empty commands, UI or scheduler). Depends on #526 and #528.

Spec (from current upstream code)

• snoozed_until, snoozed_at. Snooze is an overlay that may sit over active, pinned or settled state. Expiry is computed from the clock; there is no host wake event or turn.
• Presets: 1 hour, 3 hours, this evening at 18:00 (only when more than an hour away), tomorrow 09:00, next Monday 09:00, custom; Sunday deduplicates tomorrow and next Monday. The time must be in the future. A pending approval or input, or a queued run, refuses; a running run is snoozable.
• Raise a hand (reappears in the active list without clearing the snooze): pending approval or input, a fresh failure, or a completed run ending after snoozed_at; interrupt or cancel does not.
• Cleared by message admission and by pin. Canonical settle retains snooze fields (upstream's optimistic client clears them; this discrepancy is decided when snooze is built).
• Sidebar: collapsed Snoozed section between active and settled, earliest wake first. Undo toast shared.
• Automatic settlement treats a parked snooze as a blocker unless it failed or completed after snoozed_at.
• Protocol: SnoozeSession {session_id, until}, UnsnoozeSession.

Reference

T3 Code 83a82a46b: Orchestrator.ts:2705, :2791; packages/client-runtime/src/state/threadSettled.ts:95–329; ThreadSettlementService.ts:152–192; docs/user/thread-sidebar.md.