[heleninboodler]

Suggestion: add some metadata at the top level, including a bounding box that includes all nodes so that you can encapsulate a canvas and include it within another context before having created all the elements within it. It's redundant information and it needs to be kept in sync with the nodes and edges, but it's very useful for applications working with your data.

Also, this is not very json-ish, but optimizing your serializer so your metadata is always written first is pretty handy for embedding, since it allows you to use a pull parser and do useful things before the entire doc is parsed. (e.g. picture a huge doc being embedded and starting out as just a box and having its elements filled in async. You can't do that well if you don't know the bounding box ahead of time)

[kijin]

+1 for bounding box. It would save a lot of computation when trying to determine the initial scale for the canvas, especially if text is involved. It would also make the format useful for fixed-size canvases, not only infinite ones.

[heleninboodler]

> not only infinite ones

I don't think this really has much to do with the "infinite" nature of the canvas. Individual instances of infinite canvases have a finite size. :)