Return the completed record for a scoped key, or undefined on a miss.
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
Result storage keyed by
${connectorId}:${key}. The record wrapper distinguishes a stored undefined result from a miss.get/put plus the wrapper's in-flight dedup close same-isolate races only. Durable implementations (D1/KV) must implement AtomicIdempotencyStore — its reserve() claim is what stops two isolates racing one key from both missing get() and both executing. D1IdempotencyStore ships that shape.