@nestarc/idempotency

IETF-draft-compliant idempotency module for NestJS — one-line decorator API with pluggable storage and response replay.

Features

IETF draft compliant — implements httpapi-idempotency-key-header-07 semantics (400 / 409 / 422)
One-line decorator — @Idempotent() on any handler to enable exactly-once processing
Response replay — duplicate requests return the cached response without re-running the handler
Request fingerprint — SHA-256 body hashing detects key reuse with different payloads (422)
Pluggable storage — MemoryStorage for dev/test, RedisStorage for production (custom adapters supported)
Configurable scope — per-endpoint (default), global, or custom function (e.g. multi-tenant)
Token-based CAS — prevents TTL-expiry races from clobbering newer records
Per-handler overrides — ttl, required, fingerprint configurable per endpoint
Binary detection — Buffer, streams, typed arrays bypass caching with a warning (never corrupt replays)
NestJS lifecycle — storage adapters implement OnModuleDestroy for graceful shutdown