Tagging Chopin in the chat hides the tagged user

See screenshot. I did `@chopin, can you start making this plan` and got this output:

Also no messages after that, not even a progress indicator

EDIT:

Just took a while to get through it, feedback can be improved here as well:

No files or tests are named. Reproduce the chat interaction by tagging Chopin with a message such as “@chopin, can you start making this plan,” then inspect the chat flow around the hidden tag, missing progress indicator, and delayed feedback. Done means the tagged user remains visible and progress or clearer feedback appears while processing.

Written by the indexing model from the issue text.