Plan Mode is Consistently Ignored

### Describe the bug

Despite having the chat set to plan mode, and stating in my COPILOT-INSTRUCTIONS.md to never dump code in plan mode, the chat window constantly ignores this and will spend a ton of tokens dumping code that I then have to stop and tell it you are in plan mode before "starting implementation." This works flawlessly in cursor and is a big annoyance, when planning the point is a back and forth and this workflow is broken (not to mention token costs)

usually it will spend some time trying to edit the files, notice that editing is disabled and then just dump hundreds of lines of code.

### Affected version

0.37.5

### Steps to reproduce the behavior

Its pretty consistent but can be reproduced every time by starting in agent mode and then switching to plan mode after some work has been done.

### Expected behavior

Plan mode should ideally never try to edit files, but when it notices it doesn't have the ability it should never start dumping hundreds of lines of code/multiple files worth.

### Additional context

_No response_