- `open_or_rebuild_index` now calls `index_dir.mkdir(parents=True, exist_ok=True)`
so a missing index directory is created on demand rather than crashing on
`iterdir()` inside `wipe_index`
- `TestTagHierarchy.setUp` calls `super().setUp()` so `DirectoriesMixin` runs
and `self.dirs` is set before teardown tries to clean up
- `test_search_more_like` d4 content changed to words with no overlap with d2/d3
to avoid spurious MLT hits from shared stop words at `min_doc_frequency=1`
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>