How a turn streams from backend to browser — Orb's SSE contract

A companion to docs/architecture/sse-stream.md. One POST opens a long-lived Server-Sent Events stream; handle_turn on the backend pushes a sequence of named events across it, and the frontend's dispatcher turns each one into a UI change. This walkthrough follows that wire.

Concept

Frontend (browser)

processSSEStream → handleSSEEvent

idle

Director

Writer

Editor

assistant bubblenot yet created

·idle

—

Backend (handle_turn)

POST /conversations/{cid}/send

0persist user message

1Director pass

2Writer pass (streams prose)

3Editor / feedback pass

4persist reply + log

Black box: what each pass does internally is out of scope here — see the KV-cache doc. This panel only shows which pass is emitting.

control / framing (FE→BE or lifecycle) meta event (phase, inspector, feedback) prose token (writer output)