Tools: How I Manage AI Coding Rules Across Claude Code, Cursor, and Codex With One CLI

If you use more than one AI coding assistant, you already know this pain: I had the same commit conventions, security policies, and React patterns written in 3 different formats. Every time I updated one, the others fell out of sync. On top of that, Claude Code loads every rule on every prompt -- 30 rules installed means 30 rules injected, even when you're just writing a commit message. I built https://github.com/JSK9999/ai-nexus -- a CLI that solves both problems: Write rules once in simple markdown: description: "Git commit message conventions and best practices" ai-nexus distributes them: Semantic Routing (Claude Code) A hook runs on every prompt and picks only the rules you actually need: $ npx ai-nexus test "write a commit message" Selected files (2): • rules/commit.md • commands/commit.md $ npx ai-nexus test "review this React component" Selected files (3): • rules/essential.md • skills/react.md • skills/review.md 30+ rules installed, but only 2-3 loaded per prompt. Cursor: Auto-Conversion ai-nexus converts .md rules to .mdc format, adding description and alwaysApply metadata automatically. After that, Cursor's built-in semantic search handles the filtering. Codex: Aggregated Rules Individual rule files are aggregated into a single AGENTS.md file, loaded at session start. Community Marketplace You don't have to write everything from scratch: npx ai-nexus search react npx ai-nexus get react.md npx ai-nexus browse https://raw.githubusercontent.com/JSK9999/ai-nexus/main/docs/nexus-marketplace.pn g Share rules across your team via Git: npx ai-nexus install --rules github.com/your-org/team-rules npx ai-nexus update Existing files are never overwritten. Only new rules are added. https://raw.githubusercontent.com/JSK9999/ai-nexus/main/docs/nexus-demo.gif Apache 2.0 licensed. Contributions welcome -- each rule is just a markdown file. If you have questions or feedback, drop a comment! Templates let you quickly answer FAQs or store snippets for re-use. Are you sure you want to hide this comment? It will become hidden in your post, but will still be visible via the comment's permalink. Hide child comments as well For further actions, you may consider blocking this person and/or reporting abuse - Claude Code wants rules in .claude/rules/*.md
- Cursor wants .cursor/rules/*.mdc with frontmatter
- Codex wants a single .codex/AGENTS.md - Write rules once, deploy to all three tools
- Smart rule loading so only relevant rules are used per prompt - Only relevant rules loaded -- 30+ rules installed, only 2-3 per prompt.
Semantic Router picks just the rules you need.
- Write once, deploy everywhere -- One .md file auto-converts to .mdc for Cursor
and AGENTS.md for Codex.
- AI-powered rule selection -- GPT-4o-mini or Claude Haiku picks rules
(~$0.50/month). Falls back to keyword matching for free.
- Team-wide consistency -- Everyone installs from the same Git repo. One command
to sync.
- Your edits are safe -- Install and update never overwrite local customizations.
- Community marketplace -- Browse, install, remove rules from a local web UI. - Title under 50 chars
- Body explains changes and reasons - Claude Code → .claude/rules/*.md with a semantic router hook
- Cursor → .cursor/rules/*.mdc with auto-converted frontmatter
- Codex → .codex/AGENTS.md aggregated into one file - AI routing -- GPT-4o-mini or Claude Haiku analyzes your prompt (~$0.50/month)
- Keyword matching -- zero cost fallback - GitHub: https://github.com/JSK9999/ai-nexus
- npm: https://www.npmjs.com/package/ai-nexus
- Docs: https://jsk9999.github.io/ai-nexus/