handle.stop() intermittently leaves _stop_requested false, agent never exits its loop

[mp-orkes]

handle.stop() returns without raising but sometimes _stop_requested is never set to true.

In examples/agents/79_agent_message_bus.py the DoWhile condition is not flipped (1 of 3 runs), the agent stays blocked on PULL_WORKFLOW_MESSAGES, and the caller dies on join(timeout=30) → TimeoutError.

Repro

cd examples/agents
for i in 1 2 3; do uv run python 79_agent_message_bus.py; echo "exit=$?"; done

On a failing run, take the id from Writer started: <id>:

curl -s "http://localhost:8080/api/workflow/<id>" | jq '.status, .variables._stop_requested'
# RUNNING, false   <- stop() did not set the flag

curl -s -X POST "http://localhost:8080/api/agent/<id>/stop" -w '%{http_code}\n'   # 200
curl -s "http://localhost:8080/api/workflow/<id>" | jq '.variables._stop_requested'
# true             <- endpoint works when called by hand

Environment: conductor-oss server (agent runtime + WMQ enabled), python-sdk main.

Ruled out

• Endpoint itself — works by hand on the same stuck execution.
• Loop clobbering the flag — per-iteration SET_VARIABLE writes only _last_tool_results and _agent_state.
• stop() raising — it returned normally.
• The WMQ unblock message — sent after the flag write, so it can't produce a false flag.

Unexplained: why the POST didn't apply despite a 2xx. Server logs for a failing run would settle it.

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