matrix-spec/content/client-server-api/modules/room_upgrades.md
Travis Ralston f97d2944ae
Some checks failed
Spec / 🔎 Validate OpenAPI specifications (push) Has been cancelled
Spec / 🔎 Check Event schema examples (push) Has been cancelled
Spec / 🔎 Check OpenAPI definitions examples (push) Has been cancelled
Spec / 🔎 Check JSON Schemas inline examples (push) Has been cancelled
Spec / ⚙️ Calculate baseURL for later jobs (push) Has been cancelled
Spec / 📢 Run towncrier for changelog (push) Has been cancelled
Spell Check / Spell Check with Typos (push) Has been cancelled
Spec / 🐍 Build OpenAPI definitions (push) Has been cancelled
Spec / 📖 Build the spec (push) Has been cancelled
Spec / 🔎 Validate generated HTML (push) Has been cancelled
Spec / 📖 Build the historical backup spec (push) Has been cancelled
Room version 12 (#2193)
* Placeholder

* i++

* Room version 12

Template out a v12 room version

Make v12 default, per MSC4304

Update PDU checks and auth event selection per MSC4291

Describe new room_id format per MSC4291

Move v6 depth definition to a component for easier referencing

Move room_id to a component to prep for v12, per MSC4291

Create and use a new room_id component for v12+ per MSC4291

Reflect auth events selection change onto all room versions per MSC4291

The MSC asks the `description` of `auth_events` to be adjusted, however this feels like a better representation of the change.

Add `room_id` format rules and renumber per MSC4291

Reflect change to rule 1.2 per MSC4291

Insert same room_id check to v1-12 auth rules per MSC4307 and MSC4291

Deprecate `predecessor.event_id` per MSC4291

Insert auth rule to validate `additional_creators` per MSC4289

Insert rule for `users` validation of creators and renumber per MSC4289

Define "room creator(s)" per MSC4289

Spec `additional_creators` on create events per MSC4289

Spec `additional_creators` on `/upgrade` per MSC4289

The MSC doesn't mention how to handle unsupported room versions, but the Synapse implementation used for FCP ignores the field in such room versions. This feels like a good approach, and will need clarifying in the MSC too (if accepted at the spec level).

Add notes to `/upgrade` behaviour per MSC4289 and MSC4291

Describe how additional creators work during room creation per MSC4289

Fix default user power level descriptions per MSC4289

Describe tombstone power level changes per MSC4289

Warn clients about event format changes in v12 per MSC4289 and MSC4291

Flag additional room creators support for client reference per MSC4289

Remove TODO now that it's fully addressed

Copy state res into v12 as-is for modification

Apply Modification 1 to SR2.1 per MSC4297

Apply Modification 2 to SR2.1 per MSC4297

Add summary box to the top of SR2.1 for ease of developer reference

Modification 2 was split into items 2 and 3 for further ease of understanding.

Add all the changelogs

`x` is used until a real PR number can be assigned.

Some changelogs are duplicated to the Client-Server API to increase visibility of the changes to v12.

Review: Minor phrasing adjustments in changelogs

Review: Clarify that v12 isn't quite the default yet in the changelog

Review: Clarify to clients that creators are immutable

Review: Improve 'how to parse a domain' advice for legacy apps

Review: Add a bit more detail as to why a room ID might be required

Apply suggestions from code review

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

Clarify that clients can override the tombstone default

Mention creatorship UI label by finishing the Permissions section

We probably should have removed the WIP note in v1.0, but alas.

Add changelog for tombstone changes

Use assigned spec PR number in changelogs

(cherry picked from commit ec81eea7e4532fd398b8013071d6981c97117d9e)
2025-08-14 11:16:00 -06:00

84 lines
3.2 KiB
Markdown

### Room Upgrades
From time to time, a room may need to be upgraded to a different room
version for a variety of reasons. This module defines a way for rooms
to upgrade to a different room version when needed.
#### Events
{{% event event="m.room.tombstone" %}}
#### Client behaviour
Clients which understand `m.room.tombstone` events and the `predecessor`
field on `m.room.create` events should communicate to the user that the
room was upgraded. One way of accomplishing this would be hiding the old
room from the user's room list and showing banners linking between the
old and new room - ensuring that permalinks work when referencing the
old room. Another approach may be to virtually merge the rooms such that
the old room's timeline seamlessly continues into the new timeline
without the user having to jump between the rooms.
{{% http-api spec="client-server" api="room_upgrades" %}}
#### Server behaviour
When the client requests to upgrade a known room to a known version, the
server:
1. Checks that the user has permission to send `m.room.tombstone`
events in the room.
2. {{% changed-in v="1.4" %}} Creates a replacement room with a `m.room.create` event containing a
`predecessor` field, the applicable `room_version`, and a `type` field
which is copied from the `predecessor` room. If no `type` is set on the
previous room, no `type` is specified on the new room's create event
either.
{{% boxes/note %}}
{{% added-in v="1.16" %}} If both the new and old [room version](/rooms) support
additional creators, the server will not transfer those additional creators automatically.
They must be explicitly set during the `/upgrade` call.
{{% /boxes/note %}}
{{% boxes/note %}}
{{% added-in v="1.16" %}} When upgrading to room version 12 or later, the `predecessor` field MAY NOT contain
an `event_id`.
{{% /boxes/note %}}
3. Replicates transferable state events to the new room. The exact
details for what is transferred is left as an implementation detail,
however the recommended state events to transfer are:
- `m.room.server_acl`
- `m.room.encryption`
- `m.room.name`
- `m.room.avatar`
- `m.room.topic`
- `m.room.guest_access`
- `m.room.history_visibility`
- `m.room.join_rules`
- `m.room.power_levels`
Membership events should not be transferred to the new room due to
technical limitations of servers not being able to impersonate
people from other homeservers. Additionally, servers should not
transfer state events which are sensitive to who sent them, such as
events outside of the Matrix namespace where clients may rely on the
sender to match certain criteria.
4. Moves any local aliases to the new room.
5. Sends a `m.room.tombstone` event to the old room to indicate that it
is not intended to be used any further.
6. If possible, the power levels in the old room should also be
modified to prevent sending of events and inviting new users. For
example, setting `events_default` and `invite` to the greater of
`50` and `users_default + 1`.
When a user joins the new room, the server should automatically
transfer/replicate some of the user's personalized settings such as
notifications, tags, etc.