A demo app built with Elements.
Courses sold by card, lesson videos with notes and progress, live lesson questions, and revenue and completion stats.
Demo: Lecturemint
- Agent: Claude Code, Opus 5.5 Medium
- Time: 29 min
- Cost: $9.32 at API rates, September 2026
elements create lecturemint -scaffold=elementscode/demo-lecturemintThe seed creates the instructor, Iris Calder, and three published courses with watercolor covers: Wet-on-Wet Skies (6 lessons, $49), Botanical Watercolor (7 lessons, $79) and Loose Landscapes (8 lessons, $99). Every lesson has a short sample video of a painting coming together, and markdown notes. Four students own one to three courses each, with partial progress, and eight questions sit under lessons, some answered and two waiting for a reply.
The sign-in page lists every account and fills the form when you click one.
Students use the password paintalong; the instructor uses watercolor.
| Role | |
|---|---|
| iris@lecturemint.test | instructor (Studio) |
| maya@lecturemint.test | student, 2 courses |
| theo@lecturemint.test | student, 1 course |
| priya@lecturemint.test | student, 3 courses |
| sam@lecturemint.test | student, 1 course |
Students pay by card. Without a Stripe key, payments run through the built-in
test checkout: the Buy button opens an order summary inside the app, and its
Pay button grants the course the same way a real payment does. For real Stripe
Checkout, add a Stripe secret key (sandbox keys are free at
dashboard.stripe.com/register) as
STRIPE_SECRET_KEY in config/env/development.env, and test with card
4242 4242 4242 4242, any future date and any CVC. Production requires the
key and registers its own Stripe webhook on the first checkout.
Lecturemint needed course sales by card, video lessons with progress, a question thread under each lesson that the instructor answers live, and a studio for uploading lessons and reading the numbers. Each of those is a part of Elements, so the agent spent its 29 minutes on the course platform itself.
-
Live questions and replies. Lesson questions are a LiveTable, so a question appears on the lesson page and in the instructor's inbox the moment it is posted, and the reply shows up under it just as fast. Only students who bought the course can ask, and only the instructor replies.
-
Card payments. Buying a course is one
@rpccall that reads the price on the server and sends the student to Stripe. The course is granted once whether the return page or Stripe's webhook arrives first. Until a Stripe key is set, a test checkout inside the app takes the payment, and in production the app registers its own webhook. -
Video uploads. The instructor uploads lesson videos straight through a server call, and the app streams them so the player can jump to any point.
-
Progress as a function call. Marking a lesson complete is one server call that checks the student owns the course and returns the updated progress.
-
Data from SQL files. Migrations define the platform and seed the instructor, three courses with covers and six to eight lessons each with sample videos and notes, four students with purchases and progress, and eight questions.
-
Sessions and roles. Every studio page and server call shares one guard on the instructor role.
The project server runs alongside the agent and answers as soon as a file is saved: it type-checks the templates, TypeScript and SQL, applies migrations and reruns the tests, so every question came back right away and the agent kept building.
The app type-checks with zero errors and all 26 tests pass. Every page works on desktop and phone. A real sandbox payment went through Stripe end to end.
Demo: Lecturemint
MIT. See LICENSE.