Need a way to paginate forwards from the start of a room's timeline

[richvdh]

Sometimes paginating forwards from the very start of a room is a useful thing to do. It's possible if you have the event id of the create event, but otherwise is tricky.

[MadLittleMods]

As a cumbersome workaround, we can use MSC3030 to jump to the first event in the room:

1. GET /_matrix/client/v1/rooms/<roomID>/timestamp_to_event?ts=0&dir=f to get the first event in the room
2. GET /_matrix/client/r0/rooms/<roomId>/context/<eventId>?limit=0 to get a pagination token
3. Use /messages?dir=f to paginate forwards

[richvdh]

I think MSC3567 solves this?

[MadLittleMods]

In Synapse, GET /_matrix/client/v3/rooms/{roomId}/messages?dir=f doesn't seem to work to get the first messages in the room as MSC3567 mentions ❌. It looks like it's at the most recent position in the timeline looking forward.

{
    "chunk": [],
    "start": "s957_0_0_0_0_0_0_0_0",
    "end": "s957_0_0_0_0_0_0_0_0"
}

GET /_matrix/client/v3/rooms/{roomId}/messages?dir=b does get the latest events in the room as MSC3567 mentions though.

[richvdh]

GET /_matrix/client/v3/rooms/{roomId}/messages?dir=f doesn't seem to work to get the first messages in the room as MSC3567 mentions x.

That sounds like a synapse bug rather than a spec one, tbh.

(though it does make me wonder: what happens if the local server doesn't have the start of the room history?)

[MadLittleMods]

(though it does make me wonder: what happens if the local server doesn't have the start of the room history?)

👍 Can't backfill forwards. It's a weird scenario.

[richvdh]

ok, so it seems like we can close this? The spec at least has a way to do this. @MadLittleMods: if you find synapse doesn't implement it correctly, please can you file a bug over there.