[Bug] `/reload-plugins` doesn't update agent context for new plugins

**Bug Description**
running /reload-plugins doesn't seem to trigger the agent that there's new context. i usually need to prompt it to carry on with the task

**Environment Info**
- Platform: darwin
- Terminal: xterm-256color
- Version: 2.1.266
- Feedback ID: 9c3415a8-93ee-4743-bf7f-2e396a754540

**Errors**
```json
[]
```

The issue identifies `/reload-plugins` as the entry point; reproduce it in a terminal by loading a plugin, running the command, and checking whether the agent recognizes the new context without another prompt. Trace the command's context-refresh path and its existing tests; done means the agent receives and acts on newly loaded plugin context immediately after `/reload-plugins`.

索引モデルが issue の本文から書いたものです。