Threaded message is missing my reaction

Steps to reproduce

1. Open a thread
2. Put a reaction on one of the messages
   • It’s probably related to the fact that the threaded message was edited but my client wasn’t showing the edit at the time and I reacted to the original message instead of the edit. In any case, it seems like the reaction should follow.
3. Come back to the room later and notice your reaction isn’t displayed

Related to https://github.com/vector-im/element-web/issues/21627

Thread information

mxMatrixClientPeg.matrixClient.getRoom("!xxx:matrix.org").findEventById("$threadRoot").getThread().events.length
28

When I look at the events in mxMatrixClientPeg.matrixClient.getRoom("!xxx:matrix.org").findEventById("$threadRoot").getThread().events, it does include my reaction. Full output in the rageshake issue.

Relevant events

Full uncensored screenshots, context, event_ids, etc in the rageshake log issue: https://github.com/matrix-org/element-web-rageshakes/issues/12869

The original message being reacted to:

{
    "content": {
        "algorithm": "m.megolm.v1.aes-sha2",
        "ciphertext": "...",
        "m.relates_to": {
            "event_id": "$E74-sH4t54_0GjTZDBiPdm7Wq1pb1_eHV_VdHUe6wac",
            "is_falling_back": true,
            "m.in_reply_to": {
                "event_id": "$UnyKkkxehyjqYR66zfb74F2OtnV7ts-L9fd83msrNnQ"
            },
            "rel_type": "m.thread"
        },
    },
    "origin_server_ts": 1652201438062,
    "room_id": "!xxx:matrix.org",
    "sender": "@alice",
    "type": "m.room.encrypted",
    "unsigned": {
        "age": 101777709,
        "m.relations": {
            "m.annotation": {
                "chunk": [
                    {
                        "type": "m.reaction",
                        "key": "😢",
                        "count": 1
                    }
                ]
            }
        }
    },
    "event_id": "$yYGxATPiCuhVCK1cKiCXB9MSXUyTZcXTVBjAZNT5fGM",
    "age": 101777709
},

The edit:

{
  "content": {
    "algorithm": "m.megolm.v1.aes-sha2",
    "ciphertext": "....",
    "m.relates_to": {
      "event_id": "$yYGxATPiCuhVCK1cKiCXB9MSXUyTZcXTVBjAZNT5fGM",
      "rel_type": "m.replace"
    },
  },
  "origin_server_ts": 1652201489856,
  "room_id": "!xxx:matrix.org",
  "sender": "@alice",
  "type": "m.room.encrypted",
  "unsigned": {
    "age": 101296010
  },
  "event_id": "$gEFlk0Jea101_sk8sI6Vq6NxSv21bXcT3ILaNn7al1Q",
  "age": 101296010
}

My reaction. Interestingly, my reaction comes after the edit in time, but applies to the original message. This probably means my client was showing me out of date information in the first place.

{
  "content": {
    "m.relates_to": {
      "event_id": "$yYGxATPiCuhVCK1cKiCXB9MSXUyTZcXTVBjAZNT5fGM",
      "key": "😢",
      "rel_type": "m.annotation"
    }
  },
  "origin_server_ts": 1652250027013,
  "room_id": "!xxx:matrix.org",
  "sender": "@madlittlemods:matrix.org",
  "type": "m.reaction",
  "unsigned": {
    "age": 52235505
  },
  "event_id": "$cQpsz6y51fHg9THifzRLG7ABAFODMVTnEuM1I3-11C8",
  "user_id": "@madlittlemods:matrix.org",
  "age": 52235505
}

Outcome

What did you expect?

Reaction is shown on the threaded message

What happened instead?

Threaded message is missing my reaction

Operating system

Windows 10

Browser information

Chrome Version 101.0.4951.64

URL for webapp

https://develop.element.io/

Application version

Element version: 479d4bf64d97-react-5348572439be-js-4d4d6e1411b6 Olm version: 3.2.8

Homeserver

matrix.org

Will you send logs?

Yes

[t3chguy]

This is https://github.com/vector-im/element-web/issues/9743

[t3chguy]

If we discover reactions from /sync or /messages, will the reactions be added to the target message even if it has unsigned? It feels like we will show reactions given that the reaction is showing today.

Yes

And from a few days ago, I could see the hidden reaction event in the timeline (which means it was discovered via /messages), while looking at the thread where the reaction was missing. This seems like a valid bug?

That should be the bug fixed by the async->sync js-sdk changes