Your API returns "200 OK".

Your PostgreSQL query executes successfully.

Your monitoring dashboard shows no errors.

And you might have just exposed another customer's data.

That's what makes cross-tenant data leaks dangerous.

They don't always crash your application. They don't necessarily trigger database errors. Sometimes, the query works exactly as written.

The dangerous query

Imagine a multi-tenant SaaS application running:

SELECT * FROM invoices WHERE id = 4821;

The query is valid. PostgreSQL executes it.

But where is the tenant boundary?

If authorization depends entirely on application code, one missing check could expose another customer's invoice.

Now imagine this happening across hundreds of endpoints.

How many queries would you need to trust?

What if tenant isolation had another enforcement boundary?

That's the engineering problem behind Agata Proxima.

I built an open-source Rust proxy that sits between PostgreSQL clients and an existing PostgreSQL database.

Instead of blindly…