Check each thread for unread messages.

[clokep]

This is an attempt to fix (partially) element-hq/element-web#23907, instead of checking only the main timeline's events for unread messages we also check each thread timeline for unread messages.

I've been unable to successfully also propagate this information to the thread icon or the threads list, but this is still an improvement to show that you've had a reply in a room.

See element-hq/element-web#23907 for steps to reproduce.

Checklist

• Tests written for new code (and old code if feasible)
• Linter and other CI checks pass
• Sign-off given on the changes (see CONTRIBUTING.md)

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Here's what your changelog entry will look like:

🐛 Bug Fixes

• Check each thread for unread messages. (#9723).

[germain-gg]

I believe room.getThreads() is sorted by order of thread discovery in the client side.

room.threadsTimelineSets[0].getLiveTimeline().getEvents() is an array of root events sorted by thread last activity (last item is the newest).
We might want to use that to increase our chances to bail early

[clokep]

We need the actual Thread objects though (as they implement ReadReceipt), is there a way to get those ordered by activity?

[germain-gg]

you can call getThread() on a root event to get the Thread instance

[clokep]

Will threadTimelineSets always have a single element in it? Or what is a "timeline set"?

The following is giving undefined errors on all tests weirdly:

Suggested change

	for (const timeline of [room, ...room.getThreads()]) {
	for (const timeline of [
	room, ...room.threadsTimelineSets[0].getLiveTimeline().getEvents().map((ev) => ev.getThread()),
	]) {

[germain-gg]

We create different timelines when there's a gappy sync or if you follow a link to an event way in the past, and each of those timelines have their own pagination tokens.

Maybe the threads timeline sets are created asynchronously. I'll have a look into the code!

[clokep]

@gsouquet I think this is ready for another look? CI is a bit red, but not quite sure why.

[germain-gg]

That looks great to me 👏

CI seems to be failing on one flaky e2e test and has gone a bit crazy with the TS strict checks.
You should merge/rebase develop and that will get rid of most of those failures, becasue after glancing at the CI output, it looks like the failures are unrelated to your changes

[clokep]

Thanks for the review! 🎉