The text-only drop guard in _finish_chat_stream required content_parts,
so a stream that died while still emitting delta.reasoning (no
finish_reason, no usage) fell through to the synthesized "stop". With
the reasoning-only clean-stop promotion in finish_text_response that
stamped "stop" turned the truncated thought into the final answer,
where main entered the continuation ladder. Extend the guard with
reasoning_parts so the drop yields the partial-stream stub and the
ladder still runs; a real clean stop carries finish_reason="stop" and
is unaffected.
Review follow-up on #110227.
teknium1
a8843ab985