MSC: Using the create event as the room ID

proposals/4051-create-event-as-room-id.md

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+# MSC4051: Using the create event as the room ID
+
+Matrix has a dedicated [room ID grammar](https://spec.matrix.org/v1.8/appendices/#room-ids) which
+aims to ensure there is a single identifier representing the room. This is done by using the origin
+server's name in the ID, which often leads to confusion among users and admins that the listed server
+"owns" the room.
+
+**TODO(TR): Insert security context.**
+
+This proposal uses the create event's event ID as the room ID instead, ensuring there is a fully
+unique value that can be used.
+
+## Proposal
+
+A new room version is established to accomodate the event format, redaction, and identifier changes
+from this proposal.
+
+The `room_id` field is removed from events, and no longer protected from redaction. The create event's
+reference hash is used and prefixed with `!` when a room ID is needed (such as in API endpoints).
+
+The create event is already selected as an auth event for all events in the room, allowing servers to
+easily determine which room ID the sent event belongs.
+
+Events served over the client-server API MUST still include a `room_id`. Clients should already be
+treating the value as opaque, and therefore should not break when encountering the serverless value.
+
+**TODO(TR): Maybe go into *a bit* more detail...**
+
+## Potential issues
+
+**TODO(TR): This**
+
+## Alternatives
+
+**TODO(TR): This**
+
+## Security considerations
+
+**TODO(TR): This**
+
+## Unstable prefix
+
+**TODO(TR): This**
+
+## Dependencies
+
+As of writing, this MSC is being evaluated as a potential feature for use in the MIMI working group at
+the IETF through the Spec Core Team's efforts.