Claude Code has its own file-based customization system, parallel to Copilot's. This page covers the files you commit to a repo so the whole team gets the same behavior: CLAUDE.md, skills, subagents, hooks, permission settings, and MCP configuration.
GitHub Copilot supports several file-based customization mechanisms beyond the global .github/copilot-instructions.md. This page covers the advanced file types — .instructions.md, .prompt.md, *.agent.md, and SKILL.md — that give teams scoped, reusable, and agent-discoverable customization. For the basics of .github/copilot-instructions.md, AGENTS.md, and CLAUDE.md, see Prompt Engineering → Workspace Instruction Files.