Coexist Call

Operator joins an in-progress AGENT call as an additional publisher without taking over (does NOT flip mode, does NOT silence agent).

Use case: operator wants to speak briefly alongside agent ("hold on a sec, let me check that for you") without committing to taking over the call. Both agent and operator publish into the room; the bridge subscribes to all room audio so the caller hears both.

The agent's STT is bound to the bridge participant only via RoomOptions(participant_identity=...) at session.start (see entrypoint.py Part D), so operator's voice doesn't pollute the agent's chat_ctx. Bot toggle in the inbox header still works (silences agent in place via runtime hash agent_disabled).

Distinct from /rejoin (user_call recovery) and /takeover (mode flip

• agent silence). Returns publish-capable browser JWT.

Records metadata.operator_publisher_user_id for audit. Does not publish a WS event because frontend tracks this with local state after the POST returns.