From 22f4f2004fa140b66dee2216d82dbe646d546c60 Mon Sep 17 00:00:00 2001
From: Eric Eastwood <erice@element.io>
Date: Mon, 4 May 2026 18:24:39 -0500
Subject: [PATCH] Updated comment

---
 rust/src/room_versions.rs              | 12 ++++++++----
 synapse/synapse_rust/room_versions.pyi | 21 ++++++++++++++++-----
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/rust/src/room_versions.rs b/rust/src/room_versions.rs
index 2dc7350194..7728f02c23 100644
--- a/rust/src/room_versions.rs
+++ b/rust/src/room_versions.rs
@@ -157,11 +157,11 @@ pub struct RoomVersion {
     /// This is similar to how doubly-linked lists can potentially not refer to previous items correctly
     /// without verifying the list's integrity, but doing it on every insert is too expensive.
     pub msc4242_state_dags: bool,
-    /// Whether the `m.room.create` event is required in the
-    /// `invite_state`/`knock_state` and `invite_room_state`/`knock_room_state` in the
-    /// client and federation API's.
+    /// Whether the `m.room.create` event is required in
+    /// `invite_room_state`/`knock_room_state` when receiving invites/knocks over the
+    /// federation API's.
     ///
-    /// Also determines whether full PDU's are returned in the
+    /// Also determines whether we expect full PDU's in the
     /// `invite_room_state`/`knock_room_state` in the federation API. The client API
     /// still uses stripped state.
     ///
@@ -171,6 +171,10 @@ pub struct RoomVersion {
     /// > server MAY respond to invites with a `400 M_MISSING_PARAM` standard Matrix
     /// > error (new to the endpoint). For invites to room version 12+ rooms, servers
     /// > SHOULD rather than MAY respond to such requests with `400 M_MISSING_PARAM`.
+    ///
+    /// This does *not* determine whether we should include the `m.room.create` event in
+    /// stripped state or use full PDU's in stripped state over federation. We should
+    /// always do this.
     pub msc4311_stripped_state: bool,
 }
 
diff --git a/synapse/synapse_rust/room_versions.pyi b/synapse/synapse_rust/room_versions.pyi
index 593b8a1d34..0bd56ebda9 100644
--- a/synapse/synapse_rust/room_versions.pyi
+++ b/synapse/synapse_rust/room_versions.pyi
@@ -125,13 +125,24 @@ class RoomVersion:
     without verifying the list's integrity, but doing it on every insert is too expensive."""
     msc4311_stripped_state: bool
     """
-    Whether the `m.room.create` event is required in the
-    `invite_state`/`knock_state` and `invite_room_state`/`knock_room_state` in the
-    client and federation API's.
-    ///
-    Also determines whether full PDU's are returned in the
+    Whether the `m.room.create` event is required in
+    `invite_room_state`/`knock_room_state` when receiving invites/knocks over the
+    federation API's.
+
+    Also determines whether we expect full PDU's in the
     `invite_room_state`/`knock_room_state` in the federation API. The client API
     still uses stripped state.
+
+    According to MSC4311:
+    > If any of the events are not a PDU, not for the room ID specified, or fail
+    > signature checks, or the `m.room.create` event is missing, the receiving
+    > server MAY respond to invites with a `400 M_MISSING_PARAM` standard Matrix
+    > error (new to the endpoint). For invites to room version 12+ rooms, servers
+    > SHOULD rather than MAY respond to such requests with `400 M_MISSING_PARAM`.
+
+    This does *not* determine whether we should include the `m.room.create` event in
+    stripped state or use full PDU's in stripped state over federation. We should
+    always do this.
     """
 
 class RoomVersions: