AGENTS.md vs CLAUDE.md vs Copilot Instructions: Which File Should You Use?
Use this support matrix to decide whether CLAUDE.md, Copilot instructions, AGENTS.md, or Cursor rules should carry repository guidance for each tool surface.
AI coding agents are moving from autocomplete toward repository-aware systems that can inspect files, run tools, propose changes, and verify results. The useful question is no longer whether an agent can generate code. Teams need to know which instruction files it reads, how it handles context, what permissions it receives, and how its output is reviewed before changes reach production.
This hub connects evidence-led product updates with practical setup and comparison guides. Use the articles for dated vendor changes, then use the guides for durable decisions such as choosing repository instructions, comparing Codex and Claude Code, and creating reusable AGENTS.md policies. Pages remain separate when the search intent differs, while related updates point back to the evergreen guide that should accumulate long-term authority.
Dated vendor changes and implementation implications.
SpaceX signed a $60 billion all-stock agreement to acquire Cursor maker Anysphere, but the deal is not closed yet. Track the verified status, Q3 2026 timeline, and what Cursor users should review.
GitHub made the Copilot SDK generally available, giving teams a supported way to embed Copilot's agent runtime into apps, services, and developer tools.
OpenAI's June 2026 Codex update turns coding-agent workflows into role-specific plugins, shareable sites, and in-place annotations.
GitHub's June 3 changelog highlights the Agents window preview, BYOK controls, session sync, terminal safety, and integrated browser improvements in VS Code.
OpenAI's GPT-5.3-Codex release emphasizes faster agentic coding, frontend work, computer-use tasks, and stronger cybersecurity guardrails.