Add comprehensive tests for staged history loading
Unit tests:
- Staged loading (initial batch, background fetch, concurrent requests)
- Deduplication (by record ID, empty record sets)
- Event subscription (subscribe/unsubscribe, error handling)
- Pagination (max records limit, batch sizes)
Integration tests:
- Race conditions (concurrent requests, cache consistency, duplicate handling)
- Edge cases (empty history, single record, batch boundaries)
Tests verify:
- No records are missed during staged loading
- No duplicates are created
- Cache remains consistent during concurrent operations
- Background fetch doesn't interfere with concurrent user requests
gronod
05c9527189