Lock idempotency keys alongside row ids in TryAppend so concurrent
duplicate keys cannot both succeed; return true from TryClearInstance
when the row is absent to match Postgres idempotent DELETE behavior.
Ensure instance schema before outcome DDL, require matching player/instance
on Postgres append, catch unique violations on concurrent duplicates, and
add parity plus concurrency integration tests.
Durable per-player contract instances (one active) and append-only
outcome audit rows, mirroring NEO-116/135 store patterns with V011/V012
migrations, AAA tests, README docs, and Bruno health smoke.
VinPropane