skill: open-threads — sweep recent sessions, propose a consolidated spawn plan

[aarontrowbridge]

Important

Problem — The fleet's chat database holds weeks of sessions whose threads end in every possible way: interrupted mid-action, parked at a documented next step, blocked on a human decision, or green-awaiting-merge. None of that is visible anywhere — resuming work means manually re-reading sessions. With the session-spawn tool landing (#641), the natural move is a skill that sweeps recent sessions, classifies their open threads, and — on the user's confirmation — spools a small, consolidated set of fresh sessions to continue the work, each seeded with a prompt that carries the thread state.

Approach — A public skill: read-only sweep of the server's aggregated chat SQLite DB (top-level sessions in a window, last assistant message per session, pending todos), a classification pass (blocked-on-user / interrupted / parked-at-next-step / awaiting-review / stale), consolidation of spawnable threads into at most a few theme-scoped sessions (never one-per-thread), a human confirm gate, then one session-spawn call per confirmed theme with the pointers baked into the prompt. Graceful degradation when the spawn tool isn't deployed yet: report + inline offer.

Scope — in: one skill file, the tested DB recipe, classification + consolidation doctrine, spawn handoff via the session-spawn tool · out: any DB writes, background/automatic spawning, a dashboard widget, cross-server federation.

Acceptance Criteria

• The documented DB recipe runs verbatim (read-only) and returns the session list + last-message text for a given window.
• The skill never spawns without explicit user confirmation, and never proposes spawning threads that are blocked on a human decision.
• Spawn prompts are self-contained: the child session can act on paths, PR numbers, and parked next-steps without re-reading this conversation.
• When the spawn tool is unavailable, the skill still delivers the full report and offers inline continuation.