URL as an API (Scalar)

The viewer's URL described as an OpenAPI document, browsed with Scalar — every parameter with the right control for its type

The app has no HTTP API, but its URL behaves like one: a single GET / whose query parameters are the whole state. docs/scripts/build-url-params.mjs writes that as an OpenAPI 3.1 document, openapi.json, from the same source scan as the state reference, and Scalar renders it below. Booleans, numbers, enums and lists get the matching control; fill some in and copy the resulting URL from the request preview. The "send" button is meaningless here, and lists are comma-separated in one value unless the parameter is marked repeatable.