- Use separate mock functions for insert/select chain to enable per-test assertions
- Reset mock implementations in beforeEach after vi.clearAllMocks
- Mock returns {id:42} from select (calendar ID for event upsert)
- 6 tests: all-day DATE vs timed TIMESTAMP, allDay flag, upsert on dup UID, rawVevent blob, ctag update
- Mocks db singleton at module level with vi.mock hoisting pattern
- Uses SAMPLE_VEVENT_TIMED/ALLDAY fixtures from tests/helpers/db.ts
- RED gate: all fail (src/broker/sync.ts does not exist yet)