Root causes:
- Mock readline (EventEmitter) lacked .close() method, causing TypeError
that blocked extractDescriptionFromFile's Promise from ever resolving
- Mock stream lacked .destroy() method (same issue after .close() fix)
- Entry-processing tests shared one readline mock between description
extraction and tailing — events emitted before tailFile started were lost
- Liveness checker marked agents as 'completed' instead of 'idle' because
fixed stat timestamps became stale after fake timer advancement
Fixes:
- Add createMockRl() helper with .close() method
- Use { destroy: vi.fn() } for stream mocks
- Use mockReturnValueOnce() for two-readline pattern in 7 entry tests
- Use mockImplementation() for dynamic stat timestamps
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
