Something to be careful about here is that browsers/proxies/etc have arbitrary length limits on URLs, and they can vary by quite a lot We did this once with a

Something to be careful about here is that browsers/proxies/etc have arbitrary length limits on URLs, and they can vary by quite a lot We did this once with a web-based REPL, where you could click a button to copy a link to something you'd previously eval'd and then send that to someone else and their buffer would be preloaded with it. It was super nifty, until someone tried it with a buffer that was a few hundred lines long and at least one browser just said "nope". It sounds like OP is doing some smart stuff to minimize URL length, which should help, but there's still a limit somewhere