I did a system design interview awhile back using Excalidraw. I really enjoyed it (though I also frequently use it for normal work stuff, so was familiar with it).

I love excalidraw. But does it have an editable, diffable textual representation? Can it be generated with little ceremony, and laid out automatically?

The sibling submission about https://kroki.io has an Excalidraw in https://kroki.io/#examples and the input is the following, so presumably "yes" and "no"

  {
    "type": "excalidraw",
    "version": 2,
    "source": "https://excalidraw.com",
    "elements": [
        {
          "type": "rectangle",
          "version": 175,
          "versionNonce": 279344008,
          "isDeleted": false,
          "id": "2ZYh24ed28FJ0yE-S3YNY",

Yes, textual, but no, the diffs aren't going to mean anything. It'll be like diffing svg from Inkscape