Cannot select non-code files (.md, .txt) to include in chat window via 📎 file list button

Comienza en el manejo de la lista de archivos 📎 de la ventana de Copilot Chat y reproduce el problema con README.md y task_list.txt en un proyecto de Xcode en macOS. Compara su comportamiento con el de un archivo .md.swift renombrado; se considera terminado cuando los archivos .md y .txt compatibles aparecen en la lista y se pueden seleccionar como contexto del chat sin el workaround.

In the Chat window for GitHub Copilot for Xcode (v0.31.0), non-code files, specifically markdown and text files (.md and .txt files) are not listed in the file list when I tap the 📎 button.

It is therefore impossible for Copilot to access the contents of a README.md or task_list.txt file directly within the Copilot UI. Thanks for taking a look.

Versions

• Copilot for Xcode: 0.31.0
• Xcode: 16.2 (16C5032a)
• macOS: Sequoia 15.3.1 (24D70)

Steps to reproduce

1. Open an Xcode project that contains a .txt or .md file on macOS.
2. Select GitHub Copilot >> Open Chat from the macOS menubar (having installed GitHub Copilot for Xcode, of course—NOT the independently developed "Copilot for Xcode").
3. Attempt to select one of these non-code files (e.g. README.md or task_list.txt) from the 📎 file list to provide it as context in Copilot chat.

Results
Expected: Non-code files like README.md and task_list.txt are listed in the 📎 file list in the Copilot Chat window.
Actual: Non-code files do not appear in the 📎 file list and thus cannot be shared as context in Copilot Chat.

Impact
This limits users' ability to use GitHub Copilot for Xcode to maintain task lists, README, license files, release notes, and other non-code documents.

Workaround
Rename README.md to README.md.swift and the file now appears in the 📎 file list.

Screenshots
0 - project layout

1 - .md file missing from file list

2 - workaround by renaming files

Logs
N/A

Additional context
There is a problem in which DerivedData files are spuriously included in the 📎 file list menu (if the DerivedData is located in the project directory). I'll file a separate ticket for that, but these could probably both be addressed together.

ps. I'm open to full-time or contract work and would love to contribute if there is an opportunity. https://www.linkedin.com/in/billfeth Thanks!