# Refactoring Validation — TASK-966

## Summary

The backend file watcher was refactored from `watchdog` to `watchfiles` while preserving the `FileWatcher` public API and the emitted socket event contract.

## Files Updated

- `src/x_ipe/services/file_service.py`
- `pyproject.toml`
- `uv.lock`
- `README.md`

## Validation Results

### Passed

- `python3 -m pytest tests/test_live_refresh.py -q`
  - Result: `28 passed, 2 skipped`
- `python3 -m pytest tests/test_navigation.py -q -k filewatcher`
  - Result: `3 passed`

### Baseline / Unrelated Failures

- `python3 -m pytest tests/test_navigation.py -q`
  - Existing unrelated failure remains:
    - `tests/test_navigation.py::TestProjectService::test_get_structure_returns_five_sections`
    - Current behavior returns 6 sections, while the test still expects 5.
- `npm test`
  - Fails in unrelated frontend/sidebar test areas with mocked project-structure response issues such as:
    - `TypeError: sections is not iterable`
    - `TypeError: treeRes.value.json is not a function`
  - No watcher-related JavaScript files were changed in this refactor.

## Behavior Checks

- `FileWatcher.start()` still starts background monitoring.
- `FileWatcher.stop()` still stops monitoring cleanly.
- `FileWatcher.is_running` still reflects watcher lifecycle state.
- Socket events still emit:
  - `structure_changed`
  - `content_changed`
- Relative-path conversion and `.gitignore` filtering remain in place.
- `watchfiles` batch semantics are normalized so file actions continue to map to:
  - `created`
  - `modified`
  - `deleted`
- Added regression coverage for transient temp-file batches so files created and removed in the same watch batch do not emit spurious `deleted` events.

## Conclusion

TASK-966 is complete for the requested watcher-backend replacement. Remaining test failures observed during broader validation are outside the changed surface and were not introduced by this refactor.
