How to Give Your AI Coding Tool Domain Expertise in 30 Seconds

Every AI coding tool starts from zero context.

You open Claude Code or Cursor, and the AI has no idea what your project does, which patterns you follow, or what "good" looks like in your domain.

So you explain it. Every. Single. Session.

There's a better way.

The concept: persona configs

Both Claude Code and Cursor support project-level config files:

• .claude/rules/ — Claude Code reads every .md file here at session start

• .cursor/rules/ — Cursor reads every file here automatically

These are native features. No extensions. No API keys. Most developers don't know they exist.

What goes in the config?

Rules — always-on instructions that shape every response:

• "Always use type hints in Python"

• "Follow the Airbnb style guide for JavaScript"

• "Think about security implications before suggesting code"

Skills — domain knowledge docs that load when relevant:

• Your API schema

• Your deployment process

• Your testing conventions

cursor-claude-personas: 38 ready-made configs

Instead of writing these configs from scratch, I built a library of 38 pre-configured personas for different dev roles:

PersonaWhat it doessenior-python-developerType hints, FastAPI patterns, pytestsecurity-engineerThreat modeling, OWASP, blast radiusdevops-cloud-engineerTerraform, CI/CD, observabilitysenior-frontend-developerReact, TypeScript, a11ysystem-architectService boundaries, tradeoffs...33 more roles

How to use it

1. Clone the repo: git clone https://github.com/ratnesh-maurya/cursor-claude-personas

2. Copy the persona folder into your project: cp -R senior-python-developer/.claude/ your-project/

3. Reload your editor.

That's it. The AI reads the configs and behaves like a domain specialist.

Building your own persona

Fork the repo, pick the closest persona, and edit the rules to match your team's conventions. The structure is simple:
.claude/ rules/ your-rule.md # Always-on behavior skills/ your-skill/ SKILL.md # Domain knowledge

MIT licensed: https://github.com/ratnesh-maurya/cursor-claude-personas

Star it if it's useful. PRs welcome.