API reference

Parse response streams by `data.type`.

HarnessRouter streams Server-Sent Events in an OpenAI Responses-style wire format with `data:` frames only.

Wire format

There are no event: lines. Every frame arrives as a default SSE message, and the event name is the type field inside the JSON payload.

First frame

data: {"type":"response.created","sequence_number":0,"response":{"id":"resp_...","status":"in_progress","metadata":{"session_id":"hsess..."}}}

Important events

response.created: Save response.id and response.metadata.session_id immediately.
response.output_text.delta: Append visible answer text.
response.output_item.added: Show sanitized tool or activity progress.
response.completed: Finalize successful UI state.
response.incomplete: Show partial result and offer Continue when appropriate.
response.failed: Show the classified failure or cancellation state.

Open standard

Data-only SSE frames carrying type and sequence_number, ending in exactly one terminal event, are the wire rules that UHP's Streaming chapter makes normative for every conformant server. See the Streaming chapter of the Unified Harness Protocol.

Create API Key

Ready to run this against a live workspace? Keys take under a minute.