Path-specific custom instructions not working in Agent mode

[lorinbudaca-one]

When using Agent mode, the applyTo filter that can be setup for Path-specific custom copilot instructions doesn't work.
As far as I can tell, the only applyTo value that worked for me was **.

This doesn't seem to work, for example:

---
applyTo: '**/*.swift'
---
Instruction here

From what I can see, Path-specific custom instructions don't even appear in the documentation, under the Xcode tab, but they appear as a feature in the app.

Versions

• Copilot for Xcode: 0.45.0
• Xcode: 26.1
• macOS: 26.1

Steps to reproduce

1. Create a new project
2. In Github Copilot settings, go to Advanced -> Under Custom Instructions -> Create
3. Enter a file name
4. In the prompted file, under the applyTo field, type something like '**/*.swift'
5. Add some test instructions
6. Open chat in a swift file, select agent mode.
7. See the agent not considering the instructions given at step 5.

[lorinbudaca-one]

Oh, I'm now seeing that the custom instructions isn't a supported feature yet for Copilot coding agent : https://docs.github.com/en/copilot/concepts/prompting/response-customization#support-for-repository-custom-instructions-4.

The feature not being supported is not obvious from the Copilot for Xcode app. Would suggest adding something about this.

Is there any plan to support it?