I think they mean for seeding suiji.
I’m pretty sure that doesn’t exist, and I kinda question the usefulness. What is your usecase? I would guess you want to export the same document multiple times, each with their own variations. Then I assume you’re not pressing “download” multiple times in the web app, i.e. you have Typst installed locally. On the CLI, you can just use --input: Can I configure my document (e.g. draft/release version, color theme) when creating a PDF without modifying the Typst file directly?
I think that’s a sensible workaround, and I don’t think there is a lot of interest in adding now(): I barely use today() as I want my documents reproducible, and now() changes so often that I doubt people would really want to use it to get the time a document was created. There are of course documents that incorporate the creation time; those are generated automatically, so --input is again the solution.
The other use of now() is of course randomness as you describe. When previewing your document, that would decrease the benefits of incremental compilation while not really giving a benefit: in the end, you will only get one document anyway.
I’m of course open to being convinced otherwise, but that’s my current view on this matter 