Keep your .env file away from AI agents
An update let the agent into .env, and every key had to be rotated · Reddit r/cursor · u/HistoricalFace1048 · Apr 2026
After an update, Cursor's agent edited .env files it hadn't touched before, so the builder treated the keys as exposed and rotated them.
Lesson
Add .env to your AI tool's ignore file (e.g. .cursorignore) and keep production keys out of your local .env.
Fix prompt
Copy this into your own AI tool (Cursor, Lovable, Claude Code, Bolt…). It's general guidance written by us. Review what the AI suggests before applying it.
I'm a beginner and want to make sure my API keys are safe in my Cursor project. 1) Search the code for hardcoded keys or tokens and for secrets in variables that ship to the browser (NEXT_PUBLIC_, VITE_, REACT_APP_). List the file and line, but don't print the values. 2) For each one, tell me whether it's meant to be public (like a Supabase anon key) or secret. 3) For secret ones, show me how to move them to server-side env vars and call the provider through a server route. 4) Give me the steps to rotate each exposed key in the provider's dashboard and set a spending limit. 5) Make sure .env is in .gitignore and in my AI tool's ignore file. Don't change anything until I've approved your plan. Never ask me to paste API keys, passwords or .env contents; tell me where to check them myself.
Source: Reddit r/cursor ↗