Support GitHub Copilot style instructions and skills

[lurebat]

Hey, once again regarding to migration/using in tandem with GitHub Copilot.

I'm going to list several items for compatibility, if needed ill create a new issue for each, just let me know:

• Support custom dirs for skills discovery
• Specifically support .github/skills for project skill discovery, and ~/.copilot/skills for personal skill discovery.
• Support custom instruction files
• Discover .github/copilot-instructions.md by default like Claude.md
• Support globbing instruction files
• Support copilots path specific instruction format (https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/add-custom-instructions#creating-path-specific-custom-instructions)
• glob by default GitHub's custom path instructions (.github/instructions/**/*.instructions.md)

I'm willing to try to implement any or all as needed

[yogthos]

If you want to try giving this a shot, a PR is very welcome, and I can help review and get it merged in after.

[screenfluent]

Hi @yogthos, I checked the current GitHub Copilot documentation and also looked at how skill discovery works in Dirge.

I would like to start with a small, self-contained PR that only adds support for the official Copilot skill locations:

• .github/skills for project skills
• ~/.copilot/skills for personal skills
• tests for discovery and conflicts
• a small documentation update

I would leave custom skill directories and instruction files for separate PRs. Path-specific instruction files use the applyTo field, so supporting them properly looks like a bigger change than just loading another file at startup.

I have one question about precedence before I start. Copilot CLI documents first-found-wins with .github/skills before .agents/skills and .claude/skills. Dirge currently uses last-write-wins and has its own override order.

Would you prefer the new locations to follow the existing Dirge behavior or should this part match the Copilot CLI precedence?

If this scope sounds good, I can start with the skills-only PR.

[yogthos]

Yeah, sounds like a plan. I should have some time to review and merge it in tomorrrow.