clarify.request is a one-shot blocking event: the gateway turn blocks on
clarify.respond. The desktop handler dropped it for any non-focused session
(`if (!isActiveEvent) return`) and stored at most one request in a single
global atom, so a background session that asked a clarifying question hung
forever and re-focusing it could never recover (the event was already gone).
- store/clarify.ts: key pending requests by runtime session id; expose the
active session's request via a focus-scoped computed view (ClarifyTool is
unchanged). clearClarifyRequest takes an optional session id for targeted
clears, with a request-id fallback.
- use-message-stream.ts: park every session's clarify (drop the isActiveEvent
early return); toast when one lands for a background session since the row
otherwise just keeps spinning like normal work.
- clarify-tool.tsx: clear by session id so answering one chat can't wipe
another's pending request.
- store/clarify.test.ts: concurrent independence, focus-scoped view,
targeted/stale/fallback clears.
