Experimental: Sliding Sync Issues

[Just-Insane]

This issue has a non-exhaustive list of known issues with sliding sync, and is linked to from the Use Sliding Sync (Experimental) in app.

Known Incompatibilities

These are known issues with sliding sync implementation in matrix-js-sdk

• Does not work with element-call/sable-call calls Fixed

Bugs in app

These are known to be bugs within Sable related to enabling sliding sync

• Activating sliding sync option results in blinking sidebar #185 - non-synapse servers seem to have... issues. Fixed

[alterNERDtive]

Since the release of 1.19 I have tried out Sliding Sync. I have noticed several issues, and I’m just going to document them here.

My homeserver is running Continuwuity (v26.6.1 at the time of writing).

• Display names don’t work correctly on first use; new users always display as their account name (most noticeable in combination with bridges, e.g. people being called discord_XXXXXXXXXX). Clearing cache fixes this for existing users.
  • This is probably also going to be an issue in case the display name changes.
• Something is also up with room names, though I am not exactly sure what; rooms created by mautrix-signal should be named after the contact, but with sliding sync they are “Signal bridge bot and ”, as if they had not been renamed.
  • Also missing the correct room icon.
• Room invites get “stuck”, accepting (or denying) them seemingly does not have any effect. Clearing cache fixes this for pending invites, they disappear and the rooms show up.
• Leaving rooms does not remove rooms from the room list. Clearing cache fixes this for pending leaves.
• When starting Sable, you can see it go through events and update everything in fast forward; I would have expected this to happen during the “Petting cats …” screen.
• Unread markers for rooms in pinned subspaces are inconsistent; I have bridged Discord guilds (subspaces in the bridge space) pinned, and sometimes the unread marker only applies to the top level space, not the pinned subspace.
• With “Show Hidden Events” and “Hide Member Events in Read-Only Rooms” both enabled, opening a read only room will replay all the hidden events since the last post, then hide them all once replay is done. This only happens once, and after clearing cache.
• When Sable has been running for a while without a cache clear (like … a good 10h in my case right now), clearing cache will have already read messages randomly appear as unread again.
• (only seen this on mobile PWA) Sometimes™ on load, spaces are not recognized correctly? Subspaces show up in the sidebar as spaces when the parent is “gone”, bare rooms in the room list instead of in a “gone” space.

There are probably more things that I have already forgotten (and some things I have not encountered yet <.<), so I will keep updating this.

[7w1]

When starting Sable, you can see it go through events and update everything in fast forward; I would have expected this to happen during the “Petting cats …” screen.

This is an intentional design with sliding sync, the goal is to make the UI accessible as fast as possible. Imo its more effort than its worth to try to cache data for rendering, having things load in ends up making the app feel faster and is preferable to a longer loading screen.

Room invites get “stuck”, accepting (or denying) them seemingly does not have any effect. Clearing cache fixes this for pending invites, they disappear and the rooms show up.

Doesn't seem like I can reproduce this beyond the normal c10y bug (779?) of stuff just not accepting. Testing on morg and I haven't had any issues. Regardless might still be able to find a work around, but not sliding sync related.

[alterNERDtive]

Room invites get “stuck”, accepting (or denying) them seemingly does not have any effect. Clearing cache fixes this for pending invites, they disappear and the rooms show up.

Doesn't seem like I can reproduce this beyond the normal c10y bug (779?) of stuff just not accepting. Testing on morg and I haven't had any issues. Regardless might still be able to find a work around, but not sliding sync related.

Well, doesn’t happen for me with sliding sync disabled 🤷🏿

779 symptom is the room appearing empty after joining. I don’t get that very often.

[7w1]

This is an intentional design with sliding sync, the goal is to make the UI accessible as fast as possible. Imo its more effort than its worth to try to cache data for rendering, having things load in ends up making the app feel faster and is preferable to a longer loading screen.

So anyway that was a lie i made it cache things, its pretty nice. Only the first load should have that in #1069

I think I've fixed many of the mentioned bugs too