Replit Clone — AI App Builder
The longest build on the channel: an AI app builder with workspaces, agent runs, subscription billing, and the auth boundary holding it all together.
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One request, end to end.
Select a stage to read what it decides.
The session decides everything below it
Better Auth resolves the request to an account once, at the edge, and every workspace, run and invoice further along hangs off that identity rather than re-deciding it per handler.
The unit of ownership
Files, history and runs belong to a workspace and a workspace belongs to exactly one account, which is what reduces every later permission check to a single comparison.
A run is a record, not a request
Sending a prompt creates a row with a status instead of an HTTP call that either returns or does not — which is what lets the interface show progress, survive a reload, and report a failure.
Generated code has to run somewhere
The output is only convincing once the reader can use it, which raises the question every AI builder has to answer: where code you did not write is allowed to execute.
The gate is a server check, not a badge
Stripe decides how much of the loop an account may use, and the check sits on the server in front of the expensive call rather than in the component that offers it.
Three things you can point at afterwards.
An auth boundary you can point at
One place that turns a request into an account, and a data model where ownership is a column rather than a convention.
Agent runs that survive a reload
Long work modelled as state with a status, so progress is readable and a failure is a value the interface can render.
A subscription that gates real work
Stripe wired to the thing it is selling: the plan is read on the server before the expensive call is made.
Where to go from here.
Closest to this one by what it teaches, then by what it is built on.
A document workspace where Claude answers only from the files in the chat, every claim opens the exact passage it quotes, and questions are metered by plan through Stripe.
A course marketplace in the shape of Udemy: instructors author courses that go live through an admin review, learners buy through Stripe and earn certificates anyone can verify, and every sale records the instructor's share.
A browser video editor for product videos: record or upload your app, let an AI director plan the camera, cuts and text, refine it on a multi-track timeline, then export an MP4 or share a link.