Starts server + sidebar-agent together with a mock claude binary (shell script
outputting canned stream-json). Verifies the full queue-based message flow:
- Full round-trip: POST /sidebar-command → queue → agent → mock claude → events → chat
- Claude crash recovery: mock exits 1, agent_error appears, status returns to idle
- Sequential queue drain: two rapid messages both process in order
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>