Context compression capability will not be triggered automatically.

### What happened

The underlying system actually has "manual compression" and "context diagnostics" capabilities; the main problem is that these capabilities are not exposed in the sending area and are not automatically triggered during high water levels.

### How to reproduce

1、上下文窗口占满出现提示

### Environment

- source build

### Logs, screenshots, or additional context

_No response_

No files, tests, or entry points are named. Start by locating the sending area and the existing manual compression and context diagnostics capabilities, then reproduce the full-context condition; done means those capabilities are exposed there and compression triggers automatically at high water levels.

Written by the indexing model from the issue text.