Timeline displays edits to state events incorrectly

Steps to reproduce

Suppose I send an m.room.topic event with this content:

{
  "topic":"spam spam spam spam", 
  "m.new_content": {"topic": "normal topic"},
  "m.relates_to": {"rel_type":"m.replace","event_id":"<previous topic event>"}
}

This changes the topic of the room to spam spam spam spam. However, the timeline replaces the previous topic change event with:

(it doesn’t even label it (edited) or allow you to view the edit history).

I feel like we probably shouldn’t process edits of state events (or indeed anything that’s not a (possibly encrypted) m.room.message).

Outcome

What did you expect?

The timeline should reflect reality. Since there were two separate topic changes, I think these should be shown as separate events, and the m.replace relation should be ignored.

What happened instead?

The timeline showed a state change that never happened

Operating system

No response

Browser information

No response

URL for webapp

develop.element.io

Application version

Element version: f46a6f2d920b-react-70cdd57a5c61-js-540514c805ea Olm version: 3.2.8

Homeserver

No response

Will you send logs?

No

[richvdh]

The MSC explicitly says not state events, but yes you’re right in that it doesn’t specify an allow set

yeah, tbh I’m treating that “edge cases” section as “a bunch of stuff we haven’t yet defined”. But fine, let’s do that.

Polls, stickers.

That’s super-helpful, thanks.

[richvdh]

I’m not entirely convinced this is fixed. It’s better, but not great. See #22280