Protect Your Database from Cursor

I’ve been seeing a bunch of screenshots on twitter of horrified vibecoders realize Cursor did irreversible damage to their application e.g.

Personally, I think it’s fucking wild to give any AI agent read/write permission on anything important and without version control but out of curiosity/boredom I build something to mitigate these errors.

have your database defend itself

I called it pg_guard and it’s a Postgres proxy that sits between your app and your database and audits unusual or suspicious queries while rejecting potentially dangerous ones with a human readable error message designed for guiding whatever vibecoding tool you’re using.

Here's how it works:

• Query Interception: pg_guard analyzes every SQL query before it ever hits your database. It's like a bouncer for your data, checking every query to make sure it's not going to cause a problem.

• Row-Level Damage Limiting: Ever run a DELETE or UPDATE that affects way more rows than you intended? pg_guard will stop it in its tracks. You can configure a limit, and if a query would affect more rows than that, pg_guard will block it.

• Dangerous Query Blocking: pg_guard automatically blocks truly dangerous queries like DROP TABLE and TRUNCATE. It also prevents DELETE and UPDATE queries without a WHERE clause, which is a common source of disaster.

• Human-Readable Errors: One of my favorite features is that it provides helpful, human-readable error messages. If a query is blocked, pg_guard will tell you why, which is especially useful for tools like claude/cursor so they can correct their queries to be safe. I’ve been doing this with other tools as well based on a conversation I had with Armin, the creator of Flask, and it's something he wrote about in one of his blog posts: https://lucumr.pocoo.org/2025/6/12/agentic-coding/

I'm a big believer in building tools that are simple, focused, and solve a real problem. pg_guard isn't a replacement for proper database management, but it is a small, easy-to-use safety net that can prevent a lot of headaches. It's a "curse-proof" layer that lets me use the tools I love without worrying about a catastrophic accident.

You can check out the source code https://github.com/jonaylor89/pg_guard