Adopt 8 PR-agent (Qodo) findings; 4 declined (concurrency already guarded by
the putSyncedRecord/markRecordSynced guards + RPC optimistic concurrency;
SQL-injection / won-equality / microtask-race are false positives — see PR reply).
- markRecordSynced: guard on updatedAt too — softDeleteStory doesn't bump rev,
so a same-rev newer local tombstone must not be marked synced by an older
push's ack (symmetric with putSyncedRecord's guard)
- recordToEnvelope: fallback timestamps to 0 not Date.now() (a corrupt record
should lose LWW, not win as "now")
- push/delete routes: validate rev/updatedAt as finite -> 400 (was silent 200);
push: Content-Length pre-check before buffering the body
- pushDeletion: idbGet a single record instead of a full-store scan
- manifest: Cache-Control private,no-store + client fetch cache:no-store
- cloudSyncClient: Array.isArray narrowing on items/blobs
- RPC: `if found` instead of `v_row.id is not null` after RETURNING INTO
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>