• need to figure out how to indicate to user in those cases that they should click the share button.

Maybe a toast message that says something like "Auto-updating the app link is disabled. Please use the share button."?

• Maybe don't auto-update if the code is loaded from a gist? Not sure what the behavior should be for this case.

Can gist and code coexist in the URL? I think the expectation is that copying the current URL will give you a link to the app you're editing right then. So to me it makes sense that if you open a gist, update the code and then copy the URL, that URL would restore the edited app.

Keeping the gist provenance seems reasonable so you could delete code=... to reset, but if they're mutually exclusive then I think it's okay to drop gist from the URL.

• need to figure out how to indicate to user in those cases that they should click the share button.

Maybe a toast message that says something like "Auto-updating the app link is disabled. Please use the share button."?

That sounds reasonable -- I did think about that earlier and thought it would be too intrusive, but now that I think about it again, it would only happen in rare cases anyway.

• Maybe don't auto-update if the code is loaded from a gist? Not sure what the behavior should be for this case.

Can gist and code coexist in the URL? I think the expectation is that copying the current URL will give you a link to the app you're editing right then. So to me it makes sense that if you open a gist, update the code and then copy the URL, that URL would restore the edited app.

Keeping the gist provenance seems reasonable so you could delete code=... to reset, but if they're mutually exclusive then I think it's okay to drop gist from the URL.

gist and code can't coexist, so I suppose it does make sense to replace the gist= with code= if they re-run the app. Ideally it would only be replaced if the user actually modifies the files, and I'll look into making it work that way.