75736cd3a4
The session chat stream registered its wrapper task in _active_run_tasks, but that turn is already counted by active_agent_work_count() via _inflight_agent_runs (_run_agent) — the drain saw 2 for one turn (test_session_chat_sse_turn_is_interrupted). Keep only the agent-ref registration; run-scoped steer control doesn't need the task entry.