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 config