sequence-diagrams.md

# Sequence diagram

```mermaid
sequenceDiagram
  participant C as Client
  participant G as Gateway
  participant A as Antrian Service
  participant D as Antrian DB
  participant R as Outbox Relay
  participant B as Broker
  participant N as Notification Worker
  C->>G: POST antrian + token + idempotency key
  G->>A: Forward request + trace context
  A->>A: Validasi dan authorization
  A->>D: Transaksi antrian + idempotency + outbox
  D-->>A: Commit
  A-->>G: 201 + antrian_id
  G-->>C: 201 + antrian_id
  R->>D: Baca outbox pending
  R->>B: Publish AntrianCreated
  B->>N: Deliver event (dapat duplikat)
  N->>N: Deduplicate dan kirim notifikasi
  N-->>B: ACK setelah pemrosesan berhasil
```

Relay berjalan setelah commit; tidak harus menunggu response sampai ke client. Diagram menunjukkan happy path. Retry publish/delivery membutuhkan idempotency; kegagalan notifikasi dicatat terpisah.