Add support for assigning issues to Copilot via REST API

[MariusStorhaug]

Summary

GitHub has announced support for assigning issues to Copilot using the REST API (announced December 3, 2025). The PSModule/GitHub module should support this new functionality.

Background

As of December 3, 2025, GitHub now allows assigning issues to Copilot using the REST API. This enables automated workflows to assign issues to Copilot for automated resolution.

Announcement: https://github.blog/changelog/2025-12-03-assign-issues-to-copilot-using-the-api/

REST API Support

The following REST API endpoints now support assigning Copilot as an assignee:

1. Add assignees to an issue

   • Endpoint: POST /repos/{owner}/{repo}/issues/{issue_number}/assignees
   • Documentation: https://docs.github.com/rest/issues/assignees?apiVersion=2022-11-28#add-assignees-to-an-issue

2. Create an issue

   • Endpoint: POST /repos/{owner}/{repo}/issues
   • Documentation: https://docs.github.com/rest/issues/issues?apiVersion=2022-11-28#create-an-issue

3. Update an issue

   • Endpoint: PATCH /repos/{owner}/{repo}/issues/{issue_number}
   • Documentation: https://docs.github.com/rest/issues/issues?apiVersion=2022-11-28#update-an-issue

Implementation Details

All three endpoints accept an assignees parameter (array of strings) where you can now include Copilot as an assignee. The assignees parameter:

• Only works for users with push access
• Can assign up to 10 assignees to an issue
• Assignees are silently dropped if the user doesn't have push access

Proposed Changes

The PSModule/GitHub module should be updated to:

1. Document that Copilot can be assigned to issues via the existing issue management functions
2. Potentially add examples showing how to assign issues to Copilot
3. Consider adding helper functions or parameters specific to Copilot assignment workflows

Additional Information

While GraphQL support also exists (with a required header GraphQL-Features: issues_copilot_assignment_api_support), this issue focuses only on REST API support as requested.

Related documentation:

• https://docs.github.com/copilot/how-tos/use-copilot-agents/coding-agent/create-a-pr