From 579efd9e1edc2517d428d9cd6ea1a30370a260e5 Mon Sep 17 00:00:00 2001
From: David Baker <dbkr@users.noreply.github.com>
Date: Fri, 8 Aug 2025 14:19:51 +0100
Subject: [PATCH] Support v12 rooms in maySendEvent (#4955)

Follows on from https://github.com/matrix-org/matrix-js-sdk/pull/4937

(cherry picked from commit dea184e9ec3888d0b6d17108262b94abb7275c4d)
---
 spec/unit/room-state.spec.ts | 40 ++++++++++++++++++++++++++++++++++--
 src/models/room-state.ts     | 14 +++++--------
 2 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/spec/unit/room-state.spec.ts b/spec/unit/room-state.spec.ts
index da3f5de6ca1..481833ee5f5 100644
--- a/spec/unit/room-state.spec.ts
+++ b/spec/unit/room-state.spec.ts
@@ -38,10 +38,10 @@ describe("RoomState", function () {
     const userLazy = "@lazy:bar";
 
     let state = new RoomState(roomId);
+    let statev12 = new RoomState(roomId);
 
     beforeEach(function () {
-        state = new RoomState(roomId);
-        state.setStateEvents([
+        const commonEvents = [
             utils.mkMembership({
                 // userA joined
                 event: true,
@@ -66,6 +66,11 @@ describe("RoomState", function () {
                     name: "Room name goes here",
                 },
             }),
+        ];
+
+        state = new RoomState(roomId);
+        state.setStateEvents([
+            ...commonEvents,
             utils.mkEvent({
                 // Room creation
                 type: "m.room.create",
@@ -75,6 +80,19 @@ describe("RoomState", function () {
                 content: {},
             }),
         ]);
+
+        statev12 = new RoomState(roomId);
+        statev12.setStateEvents([
+            ...commonEvents,
+            utils.mkEvent({
+                // Room creation (v12 version)
+                type: "m.room.create",
+                user: userA,
+                room: roomId,
+                event: true,
+                content: { room_version: "12" },
+            }),
+        ]);
     });
 
     describe("getMembers", function () {
@@ -851,6 +869,24 @@ describe("RoomState", function () {
             expect(state.maySendEvent("m.room.other_thing", userA)).toEqual(true);
             expect(state.maySendEvent("m.room.other_thing", userB)).toEqual(false);
         });
+
+        it("should recognise power level of room creators in v12 rooms", function () {
+            const powerLevelEvent = new MatrixEvent({
+                type: "m.room.power_levels",
+                room_id: roomId,
+                sender: userA,
+                state_key: "",
+                content: {
+                    users_default: 0,
+                    state_default: 100,
+                    events_default: 100,
+                    users: {},
+                },
+            });
+            statev12.setStateEvents([powerLevelEvent]);
+
+            expect(statev12.maySendEvent("m.room.name", userA)).toEqual(true);
+        });
     });
 
     describe("processBeaconEvents", () => {
diff --git a/src/models/room-state.ts b/src/models/room-state.ts
index a2f97bf9759..8dee3bc4d4d 100644
--- a/src/models/room-state.ts
+++ b/src/models/room-state.ts
@@ -904,7 +904,6 @@ export class RoomState extends TypedEventEmitter<EmittedEvents, EventHandlerMap>
 
         let stateDefault = 0;
         let eventsDefault = 0;
-        let powerLevel = 0;
         if (powerLevelsEvent) {
             powerLevels = powerLevelsEvent.getContent();
             eventsLevels = powerLevels.events || {};
@@ -915,13 +914,6 @@ export class RoomState extends TypedEventEmitter<EmittedEvents, EventHandlerMap>
                 stateDefault = 50;
             }
 
-            const userPowerLevel = powerLevels.users && powerLevels.users[userId];
-            if (Number.isSafeInteger(userPowerLevel)) {
-                powerLevel = userPowerLevel!;
-            } else if (Number.isSafeInteger(powerLevels.users_default)) {
-                powerLevel = powerLevels.users_default!;
-            }
-
             if (Number.isSafeInteger(powerLevels.events_default)) {
                 eventsDefault = powerLevels.events_default!;
             }
@@ -931,7 +923,11 @@ export class RoomState extends TypedEventEmitter<EmittedEvents, EventHandlerMap>
         if (Number.isSafeInteger(eventsLevels[eventType])) {
             requiredLevel = eventsLevels[eventType];
         }
-        return powerLevel >= requiredLevel;
+
+        const roomMember = this.getMember(userId);
+        const userPowerLevel = roomMember?.powerLevel ?? 0;
+
+        return userPowerLevel >= requiredLevel;
     }
 
     /**