Output JSON HTTP

How it fits

Typical backends

Caveats

• Hard constraintEvery entry in transports must be websocket, sse, or http; any other value aborts startup. An empty list emits nothing and binds no port.
• FallbackListing http while url is empty silently skips the POST per message; WebSocket and SSE delivery continue unaffected.
• I/O contractWith both websocket and sse active, dispatch is per request — a GET carrying an Upgrade websocket header opens the WebSocket, any other GET opens the SSE stream, both on the same path.
• FallbackHTTP delivery is asynchronous with exponential backoff from initial_retry_delay_ms to max_retry_delay_ms, retried up to max_retries times; once pending requests exceed queue_capacity the oldest queued request is dropped.
• LimitationWebSocket and SSE broadcast to all connected subscribers with no per-client filtering and no backfill, so clients connecting late see only frames produced after they subscribe; the Last-Event-ID header is ignored.
• Parameter interactionA non-empty sse_event_name is emitted as the SSE event line, so EventSource clients must use addEventListener rather than onmessage.
• State lifetimeOnly url and sse_event_name are hot-swappable at runtime; every other key is captured once at startup.