Local echos disappear if you exit a room

[ara4n]

Steps to reproduce

1. Send some messages in a room
2. Switch room
3. Go back again
4. If the messages haven’t remote echoed yet, they will have entirely vanished
5. panic
6. “did i send them in the right room?”
7. “is EX dropping msgs?”
8. “did it send them at all?”
9. then the remote echos suddenly turn up, which is somewhat reassuring but not by much

Outcome

What did you expect?

Reliable local echoes

What happened instead?

A small heart attack

Your phone model

No response

Operating system version

No response

Application version

683

Homeserver

No response

Will you send logs?

No

[bnjbvr]

@ara4n can you provide a minimal rageshake with all logs set to trace where you reproduce this issue, please? Thanks!

[ara4n]

@bnjbvr Have done (at least with timeline trace logging; i really don't want to do trace on all log levels as it will make my logs enorrrrrrrmous, although i can if you really insist), and here's the accompanying video:

https://github.com/user-attachments/assets/ded31e65-776c-4212-9497-aeff2fca4d26

This example isn't too bad as the echo was fairly fast (~1s), but if the echo takes longer due to slower server or bad connectivity it's terrifying.

This is 100% reproduceable (and so doesn't need to be blocked on me ;)

[bnjbvr]

This is 100% reproduceable (and so doesn't need to be blocked on me ;)

Unfortunately, this is tied to the performance characteristics of your account ;)

Investigated as https://github.com/matrix-org/matrix-rust-sdk/issues/3941, will triage with others.