Symfony Messenger (Symfony)

Use when

• Implementing asynchronous workflows with Messenger/Scheduler/Cache.
• Stabilizing retries and failure transports.

Default workflow

1. Define async contract and delivery semantics.
2. Implement idempotent handlers and routing strategy.
3. Configure retries, failure transport, and observability.
4. Validate success/failure replay scenarios.

Guardrails

• Assume at-least-once delivery, not exactly-once.
• Keep handlers deterministic and side-effect aware.
• Surface poison-message handling strategy.