Extends the atomic_write suite with three write-path gaps:
- an app cannot exceed PICLOUD_APP_DOCS_MAX_ROWS (create-only, update
net-zero, delete frees a slot) via a real PostgresDocsWriter;
- concurrent writers cannot push a group past its docs total-bytes quota
(16 racers against a 450-byte ceiling under pg_advisory_xact_lock);
- a files create with a broken outbox leaves no row AND no blob on disk,
while a files delete with a broken outbox keeps both the row and the
readable blob (the disk-ordering invariant).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>