Support repo-level .codex customization

What feature would you like to see?

Having .codex/ customization live next to the code I am working on is more ergonomic and than placing everything at the root of my filesystem. Today, I use a monorepo-level AGENTS.md and package-level overrides, but a dedicated .codex/ directory would enable clearer structure, better modularity, and parity with tools like Cursor.

.codex/prompts/ Works exactly as currently supported. This is just a namespaced, repo-local location.

.codex/rules/ Equivalent to Cursor Rules, so file-based rules that are activated via glob patterns and are contextual and scoped. This lets Codex apply guidance where relevant, without polluting global context.

.codex/skills/ Instead of requiring one folder per skill, allow both files and folders. This keeps simple skills in a single file, while more complex ones can include specific data, files, or examples relevant to the skill.

.codex/skills/
  design-feature.md
  ci/
    README.md
    examples/
    skill.md

.codex/docs/
This is a lightweight alternative to docs-focused MCPs. There are two possible ways to support it: either a folder of relevant documentation files (e.g., the complete Convex rules file) or a single file that links to documentation pages and includes descriptions, hints, and usage context (like skills and prompts do right now).

Option 1 could go even further by including a description file (like Option 2), but using local files instead of web search. Both options would let Codex decide which docs to consult and load them selectively, based on descriptions or glob-based activation (similar to Cursor rules).

This would simplify documentation grounding without needing external tools.

Additional information

_No response_