Assistants like Copilot, Cursor, and Claude Code ship features fast and ship security holes at the same speed. Here are the flaws they reliably produce, with real before-and-after code, and how to use AI to catch them before an attacker does.
AI assistants can now scan your codebase for vulnerabilities and propose patches. Here is how to wire that into a real pipeline, why you still keep a deterministic scanner next to it, and the four places it will lie to you if you let it.
Row-Level Security is one layer, not the whole answer. Real tenant isolation is defense in depth across the data, the API, and the keys, so that no single mistake exposes another customer. Here are the layers and where each one earns its place.
Row-Level Security moves tenant isolation out of every developer's memory and into the database itself. Here is the exact Postgres pattern for a pooled multi-tenant app, plus the four footguns that leak data in production if you miss them.
The question is not which one wins, it is where you draw the isolation boundary. Here is how single and multi-tenant differ on cost, isolation, compliance, and ops, and why most SaaS that scales ends up running both at once.
Silo, pool, or bridge is one of the few architecture choices you cannot cheaply reverse. Here are the three models in plain terms, how they map to a real database, and a decision framework so you pick the one your customers and your margins actually need.
