When the message tool is used to send a message to a different chat_id
than the current conversation, it was incorrectly including the default
message_id from the original context. This caused channels like Feishu
to send the message as a reply to the original chat instead of creating
a new message in the target chat.
Changes:
- Only use default message_id when chat_id matches the default context
- When targeting a different chat, set message_id to None to avoid
unintended reply behavior
