Classes 10–12 (I): Try the app

← (H) Deploy the Edge Functions and the Stripe webhook · All steps · (J) Save your work to GitHub →

Part of the task-app setup for Classes 10–12. Work through the parts in order, doing every step yourself; Start here has the worksheet, the screenshot log, how to ask Claude when you’re stuck, and the list of all parts.

Time: about 10–15 minutes.

As of Oct 22, 2026 · Official docs: Next.js · Stripe: Testing (test cards) · Supabase: Edge Function logs

Start the app. In VS Code’s terminal, first go into the app’s folder (harmless if you’re already there; this just makes sure):

cd ~/projects/full-stack-demo-app/task-app

Then type:

npm run dev

(Stop it later with Ctrl+C.) npm run runs a script listed in package.json, and dev is the script that starts Next.js’s development server: a web server on your own computer, at the address localhost:3000 (localhost means “this computer”, and 3000 is the port, a numbered door on your computer that the server listens at). It keeps running, and updates the page when the code changes, until you stop it. At http://localhost:3000:

Sign up with an email and password, or sign in with Google.
Create a task. After a moment, an AI label appears.
Open the task and attach an image.
On your profile page, upgrade to Premium. Pay with the test card 4242 4242 4242 4242, any future expiration date (such as 12/34), and any three-digit CVC. Your plan changes to Premium.
Click the button to manage your subscription, and look at Stripe’s customer portal.

If something fails, ask Claude (When you’re stuck): tell it exactly what you clicked and what you saw, and paste the last lines that npm run dev printed in the terminal. The Edge Function logs are in the Supabase dashboard under Edge Functions. See Step 12: Run the Application.

If the AI label or the upgrade fails

If creating a task or upgrading fails, open the function’s logs in the Supabase dashboard (Edge Functions) and show Claude what they say. One known fix, which Claude can explain: for an “Invalid JWT” (401) error, turn off Verify JWT with legacy secret for that function (Edge Functions > the function > Details). This is safe here: the functions check the user’s login themselves.