Backend:
- Deterministic SQLite connection cleanup. The RAG code used bare
`with get_connection() as conn:`, which commits but never closes, leaning
on GC to release handles (the rest of studio_db closes explicitly). Add a
closing_connection() context manager that commits/rolls back like sqlite3's
own manager and always closes, and route all 30 RAG call sites through it.
- filter_by_min_score no longer drops BM25-only and figure-ref hits. min_score
is a cosine floor, so it now gates only hits that carry a dense_score;
lexical and figure-ref hits (dense_score is None) pass through instead of
being silently discarded when the floor is raised.
- Fix two tests that could not pass against the production code: the RRF
fusion test asserted the wrong winner (c edges out b: 0.032266 vs 0.032258),
and two tool-handler scope tests stubbed retrieve_hybrid without accepting
the embedder_model kwarg the handler now passes (TypeError was swallowed,
leaving captured["scope"] unset).
Frontend:
- Removing an in-flight upload chip now routes through the teardown thunk
already registered for the aggregate-progress toast (abort, unsubscribe,
release the index slot, delete the backend doc with the correct kb/thread
scope key it closed over) and clears the toast entry. Deleting directly
leaked the concurrency slot and hardcoded the thread scope, mis-targeting
KB-scoped docs. Applied in both the composer hook and the compare-view
composer; drop the now-vestigial chip-scope-key tracking and unused
activeThreadId selectors. Add index-progress-store.remove(id).
Shorten and condense comments across the RAG backend, frontend, and
tests for readability. Comment text only; no code, strings, identifiers,
or logic changed. License headers and lint/type pragmas are preserved.
