I'd love some version of these tools that could reliably round-trip pure text. Some heuristic or model that can actually recognise boxes, lines with anchors, parent-child relationships etc, so you can paste in pure text and immediately start rearranging stuff. My experience with Monodraw was that you had to maintain the original file format to do this, so once a diagram was in a markdown file or whatever, you couldn't just cut and paste it and easily edit it. At that point it might as well be any file format rendered as an image.

This is surely possible.

You need to find the monospace whitespace characters (seems there's a few [0]). Then encode a compressed version of the logical diagram in the white space, steganography style.

Or do something with characters [1] to compress a lot of data into a tiny ball of hair at the end.

Draw.io smuggles the XML in a PNG which I've always admired.

[0] https://en.wikipedia.org/wiki/Whitespace_character

[1] https://en.wikipedia.org/wiki/Combining_character