The reasoning-box extraction loop in run_conversation() walked backwards
through the entire message history looking for any assistant message
with a non-empty 'reasoning' field. When the current turn produced
no reasoning (e.g. the provider returned reasoning_content=null for a
trivial response), the loop walked past the current turn and showed
reasoning from a prior turn — stale text from minutes or hours ago
displayed as if it belonged to the current reply.
Fix: stop the walk at the user message that started the current turn.
That picks the most recent reasoning WITHIN the turn (correct for
tool-calling turns where reasoning lands on the tool-call step and
the final-answer step has reasoning=None — common on Claude thinking,
DeepSeek v4, Codex Responses), and returns None cleanly when the
current turn genuinely had no reasoning.
Co-authored-by: happy5318 <happy5318@users.noreply.github.com>
