One AGENTS.md, six coding agents: where bridge files are still required
A compatibility-first way to keep repository instructions aligned across Codex, Claude Code, Cursor, Copilot, Gemini CLI, and Devin Desktop.
Practical takeaway
Treat AGENTS.md as the maintained source, then add only the native bridge files required by the exact tools and surfaces your team uses.
The drift problem is larger than the file count
A repository can contain AGENTS.md, CLAUDE.md, .github/copilot-instructions.md, GEMINI.md, and tool-specific rule folders while still giving agents contradictory guidance. The risk is not that there are several files. The risk is that several files become independently maintained sources of truth.
A smaller plan starts by choosing one maintained instruction source and treating every additional file as a compatibility bridge. For agent-heavy repositories, AGENTS.md is a useful center because several current tools read it directly and it can be scoped by directory where the tool supports that behavior.
Native support is surface-dependent
Codex can use AGENTS.md directly. Claude Code can keep a short root CLAUDE.md that imports AGENTS.md. Gemini CLI can import an AGENTS.md file or include it among configured context filenames. Cursor recognizes a root AGENTS.md, while scoped behavior belongs in its native rules directory.
GitHub Copilot needs more precise language because support differs across cloud agent, code review, editor, CLI, and chat surfaces. Some surfaces can consume AGENTS.md, while broader coverage may still require .github/copilot-instructions.md. A relative include supported by one CLI should not be presented as a universal bridge across every Copilot surface.
Devin Desktop, formerly Windsurf, now documents .devin/rules for native rules while older repositories may still contain the legacy .windsurf/rules path. Migration guidance should name both without treating the legacy path as the new default.
Generate the smallest honest plan
The right output depends on the selected tools, not on a fixed checklist. Start with AGENTS.md, add a native bridge only when the selected product needs it, and explain whether that bridge imports the source or repeats a minimal self-contained subset. The result should name each path, its scope, and the reason it exists.
This makes maintenance observable: edit the canonical file first, regenerate or review the bridges, and test the exact coding-agent surfaces your team relies on. Compatibility becomes a documented repository decision instead of a collection of copied prompts.