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> A funding crunch since 2023 yet those features have been necessary for many years before 2023.

But before 2023, the funding was going to things like solving state resolution, a VoIP system that was not dependent on Jitsi, getting rid of "could not decrypt message" errors, and so on.

> It's specifically to increase the speed if state resolution. If it weren't for the convoluted state resolution system, there wouldn't be a need to store gigabytes worth of state groups in the database.

No, it's specifically to increase the speed of state retrieval. One of the uses for that is state resolution, but it could equally well just be calling the /messages API or any other point you need to know historical state. But what do I know :)

> it could equally well just be calling the /messages API or any other point you need to know historical state.

State groups aren't really a thing for messages in a timeline, there are many easier ways of doing it, for example, simply storing the message sequentially (impossible in matrix though, due to the convoluted tree structure it uses)

But when it comes to state (where state groups are actually needed) who actually needs a snapshot of the state at literally every point in history? Any other messaging app just needs to know the current state and maybe also an audit log of the change history for audit log purposes.

In any sane messaging app (e.g. discord, slack, telegram etc.) there is exactly zero relevance in knowing the member list, room configuration, permissions and room title at exactly 2024-06-19T15:23:45Z. Who the heck cares??? Yet the design of matrix somehow makes this an integral part of every single operation.

Perhaps just watch the video and see that the proposed solution is just doing a temporal state table - just as Slack and Discord etc must have in order to know what the state of a room was at some point in time.

Slack and discord don't know the state of the room at any given time in the past. Show me anywhere in slack or discord where you can see the membership of a room at 2024-06-19T15:23:45Z. Or anywhere where you can see the historical profile picture and nickname of everyone in the room at 2024-06-19T15:23:45Z. You can't, because they don't know.

I am pretty confident that slack and discord know who has permission to read a message at a given point in time, which is all that state groups are achieving here.

I am pretty confident they only know who has permission to read it right now.

No, they all need to know who had permission to read a message which was sent at a given point in the timeline. This is all state groups is: a track of the room state at the point a message was sent: e.g. who has permission to read it.

I repeat: I am pretty confident they only know who has permission to read it right now.

It works like this: their server gets a request to read messages, and checks if the client currently has permission to read messages. If so, it reads the messages. If not, it returns a permission error. If you don't have permission, it doesn't attempt to analyze history to figure out whether you had permission in the past.

In fact, Discord is pretty explicit about not letting you have any interaction with things you don't have permission to view. It doesn't even tell you you don't have permission. It just silently removes them from your menu, and if you try to access them with a link, it tells you "unknown error".

The room state is cached to not need to recompute the current room state from the beginning of time.

You probably would do that even if there was no state resolution at all

> Simply fixes some of the many ways that rooms can explode or be bricked.

How many other ways are there? Afaik none is known

> Afaik none is known

Before project hydra people didn't know about the room exploit either. They just knew that rooms exploded somehow every once in a while.

Most people actually working on Matrix have been aware of state resets for quite a while. Hydra is just the name of the project which addresses them. There are 3 phases, of which the 1st covers the most serious ones; the 2nd and 3rd phases should drop next year.

As an analogy, it's not dissimilar to how Git has added various different merge resolution approaches over the years in order to come up with more predictable and more "do what i mean" algorithms (resolve, recursive, ORT, octopus, etc). It's slightly different in that a bad merge in Matrix feels very unexpected and problematic, whereas manually unpicking collisions in a VCS is just part of the territory.