bvandeusen
8d75ade1d5
Audit 2026-06-02 flagged three SELECT-then-INSERT sites that lost the race under concurrent writers / recovery-sweep replays, poisoning the outer transaction with an unrecoverable IntegrityError and crashing the calling task. Same shape as the banked 2026-05-26 ImageProvenance incident (see reference_scalar_one_or_none_duplicates memory). Mirrors the importer._get_or_create pattern in all three: savepoint via begin_nested + IntegrityError rollback to that savepoint + re- SELECT to grab the row the other worker committed first. - importer._capture_attachment: PostAttachment.sha256 UNIQUE. attachments.store is sha-addressed so both workers race to write the same on-disk path (shutil.copy2 + rename is idempotent), so no extra cleanup needed. - TagService.find_or_create: partial uniqueness index on (name, kind, COALESCE(fandom_id, -1)). The previous docstring claimed "INSERT ... ON CONFLICT" but the implementation was SELECT-then-INSERT with no recovery. - ArtistService.find_or_create: already had IntegrityError handling but did session.rollback() (unwinds the WHOLE transaction); now uses begin_nested + sp.rollback() so the surrounding request's progress isn't lost.