Return the completed record for a scoped key, or undefined on a miss.
Inspect a key without reserving, finalizing, or releasing it.
Finalize a key's record. token is the lease returned by an atomic
reserve(): when supplied, the store finalizes ONLY if the key still
belongs to that lease. A stale holder whose lease was taken over cannot
overwrite the new result. Omit the token on the legacy get/put path,
which upserts
unconditionally (same-isolate protection only).
Optionaltoken: string
Idempotency store that can distinguish an absent key from a pending claim without reserving it. Atomic stores need this capability during the v1-to-v2 composite-key transition so legacy pending work cannot be mistaken for a miss and executed again.