Idempotent Inbox Pattern

Idempotent inbox pattern

Canonical guide: https://sendpromptly.com/docs/guides/webhook-idempotency-dedupe/

Minimal workflow

1) Verify signature 2) Insert a row with a UNIQUE key (prefer X-SP-Message-Id) 3) If UNIQUE violation → duplicate → return 2xx 4) Queue async processing 5) Mark completed / DLQ poison events

See Laravel migration + job stub:

• examples/laravel-drop-in/create_webhook_inbox_table.php
• examples/laravel-drop-in/ProcessSendPromptlyWebhook.php