Mirrors stablyai/orca-cloud#471 (squash c3354e8), byte-identical under cloud/.
The relay's cell-inventory lock (SELECT ... FROM relay_cells FOR UPDATE over
all 23 rows) is one global critical section shared by the assignment hot path
and every director sweep; with the pool's 1s lock_timeout a blocked waiter held
a pooled client for a full second, producing ~690 55P03 retries per 5 minutes
in production. Request paths now bound the wait at 500ms with a SET LOCAL that
is restored to the pool default before the next statement; director-only sweeps
take the lock NOWAIT and skip the tick; sweep timers are jittered; hold time is
exported as additive runtime-metrics fields so the bound can be tuned.
Phase 6 of the relay split: the relay's deploy/operate surface moves under cloud/ with 24 cloud-* workflows gated on ORCA_CLOUD_OPERATIONS_ENABLED, the Cloud SQL rollout lease action, the relay Terraform root (dual-accept identities for both repositories), scripts, docs, CODEOWNERS, and a terraform validate job in Cloud Verify.