Builds
Supper plans our dinners and fills the grocery cart
Supper plans dinner for the two of us. Every Saturday it picks five dinners from recipes we've saved, turns them into one shopping list, prices that list at No Frills, Superstore and Walmart, and fills the cheapest cart. Then it stops, and I check out myself. Supper never pays for anything.
I built it because we did all of that by hand: planning the week, writing the list, picking a store. Delivery apps charge more than the store does, so I wanted the store's own cart at the store's own prices, filled for me.
Play a week of dinners
Here's a pretend week you can tap through. It's seven steps and takes about a minute. The recipes, the household and the store totals are made up, and nothing leaves this page. Turn on Show who did what to see which steps use AI.
Step 1 of 7: add a recipe from a photo
Add a recipe from a photo
A photo of a recipe card. In the real app you take it with your phone and Supper reads it into the library.
Where I used AI
I started with one rule: a fixed set of steps with a few AI steps in them, and every bit of money math in plain code. Most of Supper ended up as plain code, which is how I like it when it's our grocery money.
- Sonnet plans the week. It suggests three plans and my code picks the best one.
- Haiku reads recipe photos and PDFs. At each store, it says which products in the search results match each line on our list.
- Plain code does everything with a number in it: the swap list, the shopping list, the totals and the cheapest product. It also fills the cart.
- I approve the list and check out. A guard on the Mac blocks checkout, payment and placing an order, so the robot can't check out even by mistake.
The real app on my phone
I recorded these and the clip at the top of the page on the real app, on a phone. The household is a demo one and the recipes are made up, so these aren't our actual dinners.
What went wrong
The robot that fills the cart runs on a Mac mini at home. I had a version working in the cloud too, and I dropped it. The Mac was already on and cost nothing extra.
One day I added a few extra page loads to debug something, and No Frills decided I was a bot. It locked us out for an hour. Now nothing loads store pages on top of the robot's own.
Walmart can win a price check and get its cart filled now, but we haven't placed a real Walmart order yet. Until we do, I don't know that part works.
How I keep building it
A lot of Supper's changes start as cards on my Agent Board. AI agents build them and I decide what merges. That's how the recipe filters got their counts. It's also where my first reviewer agent passed a Supper change while noting, almost in passing, that it would delete last week's meal plans along with a recipe.