WriteAsAsync takes a shared Postgres advisory lock on the account (the key the chain trigger locks exclusively) across the standing read and the writer's save; CommitAsync takes the exclusive lock before it reduces. Votes, appraisals, sealed commit and reveal, patron events (RecordSupportEventAsync routes and journals in the same save, so the manual Ledger door obeys it too) and the Heimdall sign-in pass through it; SupportTargetAsync, MayWriteAsync and JournalIntakeAsync are deleted. A folded or frozen account's sign-in writes no membership. A retry of an event stranded on the folded account journals nothing. Tests: Down refuses in every merge state, Stripe journal prior owner and undo, the lock racing a freeze and a commit on live Postgres. Docs say what the lock guarantees and what it does not.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
