test-quality: tests/test_storage_vector.py 'vector refresh failed' assertion couples two exception layers

[aksOps]

Summary

`tests/test_storage_vector.py:114-115` (rc3 / PR #41) asserts both `"vector delete failed"` and `"vector refresh failed"` log messages when a fake vector store raises on both `delete()` and `add_documents()`. The first assertion is internal to `_refresh_vector()`; the second relies on the exception propagating up to `SessionStore.save()`'s outer `try/except`, which logs via the same helper with `operation="refresh"`.

Code-reviewer flagged: a future refactor that moves the `add_documents` catch inside `_refresh_vector` (which is the natural place for it) would silently break the second assertion's intent without changing production behavior.

Suggested fix

Either:

1. Add a comment to the test block explaining the two-layer coupling (`# 'vector refresh failed' originates from save()'s outer catch, not _refresh_vector — see PR feat: v2.0.0-rc3 — fix audit findings (finalizer, state_overrides, idempotency + 6 important) #41 review`).
2. Move the `add_documents` catch into `_refresh_vector` itself (cleaner), and update the test accordingly.

(1) is the minimal-touch path.

References

• PR feat: v2.0.0-rc3 — fix audit findings (finalizer, state_overrides, idempotency + 6 important) #41 review (independent code-reviewer agent verification)
• rc3 tag: `v2.0.0-rc3` @ `8be7ea2`