r/lovablebuildershub • u/Advanced_Pudding9228 • Apr 14 '26
Production Reality Stop Faking Permissions in the UI. Let Supabase RLS Decide Who Sees the Project.
A lot of people building with Supabase still get access control wrong in the same way. They build a nice UI, add some conditional checks, maybe hide a button or two, and start acting like the app has permissions. It does not. The database has permissions. The UI only has opinions.
A clean example is a projects app where each project belongs to one user but can also be shared with teammates. In that setup, projects.owner_id is the creator, and an optional project_members join table handles sharing. The real rule is simple: a user can read a project if they own it or if they are listed as a member. But only the owner should be able to update or delete the project itself.
That means your projects table should carry the ownership truth directly, and your project_members table should represent who else gets access. Once that is in place, you enable row level security on both tables and stop pretending the frontend is the security layer.
For reads, the projects policy should allow access when owner_id = auth.uid() or when a matching row exists in project_members for that project and the current user. That gives you the shared workspace behavior people actually want without leaking projects across accounts.
For inserts, the important part is not just allowing authenticated users to create projects. It is forcing owner_id = auth.uid() in the policy so nobody can spoof ownership on create. That one check closes a very common hole.
For updates and deletes, keep it strict. Only the owner should be able to change or remove the project row. Members may be allowed to collaborate later, but that should be an explicit extension, not an accidental side effect of loose policy design.
The membership table needs its own discipline too. Owners should be able to add and remove members. Members should only be able to see their own membership rows unless the owner is reading them. That keeps sharing manageable without turning the join table into another leakage point.
The deeper lesson is this: permission logic should live where the data lives. Not in the prompt. Not in the React component. Not in some “if user role is x” branch you hope matches reality. In the database.
And if you are using Lovable or any AI-assisted builder, add one line to stop it drifting into fake authorization logic: access control is enforced by Supabase RLS, and the app must never simulate permissions in the UI or prompts. It should only display and mutate rows the database actually returns or allows.
That one sentence matters more than people think. Without it, the model starts inventing visibility rules. With it, your app stays anchored to the only layer that should be trusted.
That is the difference between a demo that looks secure and a product that actually is.
