When the sender-name lookup fails with a Feishu permission error (code
99991672), the bot was dispatching two separate agent turns:
1. A dedicated permission-error notification turn
2. The regular inbound user message turn
This caused two bot replies for a single user message, degrading UX and
wasting tokens.
Fix: instead of a separate dispatch, append the permission error notice
directly to the main messageBody. The agent receives both the user's
message and the system notice in a single turn, and responds once.
Fixes#27372
736ec9690f