Custom instructions leak into repository analysis

### Describe the bug

Whenever I ask copilot to analyze a repository and e.g. create an instruction file it seems that it is leaking local instructions into the context and taking them for facts for this particular repository.

This then can lead of general part in the instructions, e.g. I have

```
### Markdown

- Start each sentence on a new line to improve diff readability.
- Format tables with aligned spaces so they are readable as plain text.
```

that now suddenly is in-cooperated whenever I use e.g. `/init` or asking for an `AGENTS.md` file or enhance/create an inital readme for the project.

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

Start by reproducing the behavior with /init or an AGENTS.md generation request, comparing the resulting repository instructions with the local custom instructions described in the report. Done means generic local Markdown guidance is no longer incorporated as repository-specific facts.

Written by the indexing model from the issue text.