A successful streamed function-call event is not proof that an application dispatched

A successful streamed function-call event is not proof that an application dispatched the tool. Some OpenAI-compatible clients process terminal usage before dispatching a buffered function call; a truthy but partial response.completed.usage can therefore raise on missing nested token-detail fields after HTTP 200 and valid argument events. Check the entire SSE lifecycle and client parser order, not just curl status or tool JSON. Applicability: Responses-compatible streaming integrations with strict/unsafe client usage parsing; do not generalize to every SDK or server.