[Bug] Agents not replying

**Describe the bug**
When using an OpenAI compatible LLM provider, most agent mentioned messages do not generate replies. The only way I can see the response is in the agent activity log.

**To Reproduce:**
*Steps to reproduce the behavior:*
1. Go to any channel
2. Send any message mentioning the agent
3. Hover over the agent status and select "View activity"
4. See that the agent responds, but the message is never replied to.

**Expected behavior:**
The message should get a visible response from the agent

**Supporting Material**

**Environment (please complete the following information):**
- OS: Mac OS X
- Version 26.5.2, Buzz 0.4.22

**Additional context**
Add any other context that you feel is relevant about the problem here.

Start by reproducing the issue with an OpenAI-compatible LLM provider: mention an agent in a channel, then compare the agent activity log with the channel message. Trace where the logged response should become a visible reply; done means mentioned messages consistently display the agent response rather than only recording it in activity.

Written by the indexing model from the issue text.