Nine illustrations, each with a real state machine underneath

April gathered the scattered images into one place—nine of them, depicting how things work. There's an exploded view of a street, peeling from top to bottom through the road surface, brick layers, London clay, and subway tunnels; a baggage machine; a comic; a clock. Under each image sits a real statechart.

These images weren't just hand-drawn and delivered. The statecharts were checked with @poteto's skills; they were only released once the logic lined up.

First, some background. A statechart is a diagram describing a system's states and how it transitions between them; it's used in civil aviation, automotive electronics, protocol stacks, and other fields. It looks dry—boxes and arrows—and most people wouldn't stare at it for more than ten seconds.

April's approach flips it around. She first uses /statechart plus Colorfigures to generate isometric illustrations, then makes the visuals move. The subway station's floors fold like sheets of paper, a coffee bean travels from branch all the way into a cup, a Saturday gets stuffed into dice, and every animal on the farm can talk. Every object in the image is clickable.

Here's an easy-to-miss detail: the illustrations weren't generated out of thin air and shipped as-is. Each image has its corresponding state machine attached beneath it, effectively writing the manual for “how this thing operates” into the image itself. What you see is a cute little isometric picture; click it and you find a set of logic underneath that can be checked item by item.

Both skills are in pstack, installed at https://github.com/cursor/plugins/tree/main/pstack. April's work is at https://april-zhu.com/fieldnotes and https://april-zhu.com/colorfigures; all five images are clickable and playable. Someone in the comments asked her how she did it, and she replied with just one line: install these two skills and try it.

What's worth a closer look is where the tool is headed. Formal verification used to live deep inside engineering teams: when you got it right, no one praised you; when you got it wrong, you got called into a meeting. Now it's being used to draw subway stations and coffee beans—and after drawing them, they can move. The skill itself hasn't gotten smarter; what changed is who is using it and what they're using it for.

When lauren retweeted this post, she laid out all nine images together and asked which one looked best. The answer to that question doesn't really matter. What matters is the line of state machines underneath, reminding you: cute things can also be verified.