Two pre-existing races in the loops routes, flagged by CodeRabbit on #839 (the
verbatim extraction moved them unchanged from server.py, so they correctly
weren't fixed there):
1. save_loop computed `COUNT(*)` OUTSIDE meta_db._lock, then inserted inside it.
Two simultaneous unnamed POSTs read the same count and both mint "Loop N".
Fix: one lock scope around COUNT + INSERT.
2. list_loops read the shared single connection (check_same_thread=False) with
no lock, so it could overlap a POST/DELETE commit. Fix: read under the lock,
like every writer.
Low severity in context — FeedBack is single-user (Principle I), so concurrent
unnamed-loop POSTs essentially can't happen — but each fix is one lock scope.
tests/test_loops_concurrency.py pins both with a threading.Barrier that releases
16 workers into save_loop at once. Negative-checked: reverting the COUNT back
outside the lock fails the uniqueness assertion 5/5 runs; the fix passes 3/3.
pytest 2400 passed; on-device two unnamed POSTs -> ['Loop 1','Loop 2'].
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
