Concepts

This service is small, but it still benefits from a shared vocabulary and a consistent mental model.

Key terms

Term	Definition
Message	A JSON payload published to Iron Messages for later consumption.
Message ID	Server-assigned identifier (e.g. msg_...) returned on publish.
Ack	An explicit acknowledgement that a consumer has successfully processed a message.
Visibility timeout	Time window where a claimed message is hidden from other consumers before it becomes available again (at-least-once delivery).
Idempotency key	Client-provided key that makes a publish request safe to retry without creating duplicates.
Sandbox	Non-production environment for development/testing.
Production	Live environment with higher limits and stricter operational expectations.

Mental model

• Producers publish messages.
• Consumers poll for messages.
• After processing, consumers ack the message.
• If a consumer crashes before ack, the message may reappear after the visibility timeout.

This implies at-least-once delivery: consumers must be safe to run the same message more than once.

Environment model

Environment	Base URL	Typical use
Sandbox	https://sandbox.api.iron.example	development, tests, CI
Production	https://api.iron.example	live workloads

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