Claude reports a background subagent completed when its turn ends while its
own background shell still runs, then resumes it under its launch call once
that shell finishes. The launching run stopped listening at the interim
completion, so events emitted while the root was idle reached no run and the
card stayed Finished. Such a resume now requests a continuation, as a
notification does, and because Claude does not wake the root for it, the
continuation settles its root turn at once instead of holding it busy.

Replaces the idle reopen from the previous commit, whose events were never
persisted because no run subscribed to them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>