Answers
copilot-instructions.md vs CLAUDE.md: do you need both?
According to GitHub's documentation, Copilot reads .github/copilot-instructions.md for the whole repository, path-specific .instructions.md files that carry an applyTo pattern, AGENTS.md files (the nearest one in the directory tree takes precedence), and a single CLAUDE.md or GEMINI.md in the repository root as an alternative to AGENTS.md. So Copilot can read a CLAUDE.md on its own; what a CLAUDE.md does not give it is path-specific rules, which exist only in .instructions.md files, and the documentation says path-specific instructions are currently supported on GitHub.com only for the Copilot cloud agent and Copilot code review. When a repository-wide file and a path-specific file both match, Copilot uses both. Across personal, repository and organization instructions, all relevant sets are provided, and the documentation advises avoiding conflicts between them. Nothing in either file records who decided a line or when it stops holding. In Arroway, assistants write proposals, a person approves what becomes a rule, each rule carries the condition that ends it, and Copilot, Claude Code, Cursor or anything over MCP reads the current version before acting. The install page is the first step.
Last updated October 9, 2026
What each tool reads
The GitHub documentation I read lists the files Copilot takes as instructions: .github/copilot-instructions.md for the repository, .instructions.md files under .github/instructions with an applyTo pattern for specific paths, AGENTS.md anywhere in the repository, and a CLAUDE.md or GEMINI.md in the root. Different Copilot features read different sets: the cloud agent and code review read the path-specific files, and Copilot Chat uses the repository instructions when the repository is attached. I read only GitHub's documentation for this page, so what Claude Code does with .github/copilot-instructions.md is not described here.
Where it stops
The documentation says Copilot code review reads instructions from the pull request's head branch, not the base branch, so a branch that edits the instruction file is reviewed under its own edit. It also says that when instruction sets conflict, all of them are provided and the conflict is yours to avoid; it does not say how CLAUDE.md and AGENTS.md interact when both exist. A file shows who changed a line and when. It does not show who decided it, whether it still holds or what it replaced, and a person who works outside the repository has no file at all.
When to use Arroway
Use Arroway when a rule has to reach Copilot, Claude Code and the people who never open the repository, with someone answering for it. Each rule is recorded once, by whoever answers for it, with who approved it and the condition that ends it, and every connected assistant reads the current version at the start of a session. When the rule changes, the replacement names the one it retires, and everyone's next session opens with the new one. What holds goes there, and the files are left with nothing worth keeping. The first step is the install page.
What it looks like in practice
A six-person team uses Copilot code review on its pull requests and Claude Code for most of the writing. In June the tech lead adds a line to .github/copilot-instructions.md: every new endpoint needs an integration test. A developer adds a similar line to CLAUDE.md in a different wording. In September a developer opens a pull request that relaxes the line in copilot-instructions.md for one service. Copilot reviews that pull request using the head branch, so it reviews the change under the rule the change itself rewrote, while Claude Code in the next session still reads the June wording. Nobody can say which version the team meant, or who had the authority to relax it. In Arroway the rule is recorded once with the tech lead's name; the September exception is a proposal until the tech lead approves it as a replacement with its own end condition. Copilot and Claude Code open their next session with the current rule, and the history shows the old one, when it changed and who changed it. The team in this example is illustrative.
Questions people ask about this
- Does Copilot read CLAUDE.md?
- According to GitHub's documentation, yes: a single CLAUDE.md or GEMINI.md in the repository root is read as an alternative to AGENTS.md. Path-specific rules need .instructions.md files.
- Where should a rule that both tools follow live?
- Outside both files, in one place where someone sees it and approves it. In Arroway the rule is recorded once, with its approver and the condition that ends it, and both tools read it before acting.
- How do I try Arroway?
- Install it in the tool you already use — the install page has one route for Claude, ChatGPT, Codex, Cursor or any MCP tool — and sign in when the tool asks. From then on, sessions open by reading the project and close by recording what was decided.
Where this is verifiable
GitHub documentation on adding repository custom instructions for Copilot (docs.github.com/en/copilot/how-tos/configure-custom-instructions/add-repository-instructions), read on 9 October 2026 — Copilot is described only as that documentation describes it on that date, and it can change in any release. Product documentation on this site (How it works, Install), the answers on Cursor rules and CLAUDE.md in the same team and on keeping three instruction files in sync, and the sanction, supersession and expiry-condition rules in the sanctioned product spec. Everything described here about Arroway is behaviour the tools apply today, not roadmap. The team in the example is illustrative.
https://www.arroway.app/en/answers/copilot-instructions-and-claude-md-in-the-same-repo