Follow-up to the #73728 normalization fix (supersedes the event-agnostic
fallback the maintainers flagged as incomplete):
- subagent.complete is terminal by definition — an unrecognized status on
it now renders as 'failed' instead of falling through to 'running',
which would recreate the immortal false-active row for any future
backend status (the keep_open request on #73859).
- Live events keep the lenient 'running' fallback.
- Synthesize a 'Timed out after Xs' summary from duration_seconds when
the backend completes with status 'timeout' and no summary, so the
failed row explains itself.
- Tests: timeout reason synthesis + pruning, event-aware fail-closed vs
lenient live fallback (13 total).
David Metcalfe
09b1726a1d