I just tried again now, opened two tabs, typed ‘hello’ in one of them and switched to the other, after a second or so it showed ‘hell’ so missing the final letter, it’s still missing now ~5 min after. If I keep switching between the two tabs I see ‘hello’ in one and ‘hell’ in hte other with the console empty on both.
I just tested collaborative editing using two Chrome (v.52.0.2743.116) tabs on Mac. I also opened Safari for good measure. I was able to reproduce the problem of ‘hello’ in the Chrome input browser but only ‘hell’ in the other Chrome and Safari browser if I typed ‘hello’ quickly. Upon resumption of typing (e.g. adding a space) that last ‘o’ and the space appeared in Chrome and Safari. When I typed ‘hello’ slowly it would appear correctly in all browsers.
Seems to be a timing issue. I was able to sporadically reproduce this when I typed really fast. Will look into it. (Note that the bug is in the demo’s implementation, not in ProseMirror’s algorithm.)