review. Dont pass full vm to developer settings

src/room/InCallView.test.tsx

@@ -122,12 +122,13 @@ function createInCallView(args: CreateInCallViewArgs = {}): RenderResult & {
       remoteParticipants$: of([remoteParticipant]),
     },
   );
-  const { vm, footerVm, rtcSession } = getBasicCallViewModelEnvironment(
-    [local, alice],
-    undefined,
-    mediaDevices,
-    args.callViewModelOptions,
-  );
+  const { vm, footerVm, developerSettingsVm, rtcSession } =
+    getBasicCallViewModelEnvironment(
+      [local, alice],
+      undefined,
+      mediaDevices,
+      args.callViewModelOptions,
+    );
 
   rtcSession.joined = true;
   const room = rtcSession.room;
@@ -140,6 +141,7 @@ function createInCallView(args: CreateInCallViewArgs = {}): RenderResult & {
       muteStates={muteState}
       vm={vm}
       footerVm={footerVm}
+      developerSettingsVm={developerSettingsVm}
       matrixInfo={{
         userId: "",
         displayName: "",

src/room/InCallView.tsx

@@ -83,6 +83,8 @@ import { ObservableScope } from "../state/ObservableScope.ts";
 import { CallFooter, type FooterSnapshot } from "../components/CallFooter.tsx";
 import { SettingsIconButton } from "../button/Button.tsx";
 import { createCallFooterViewModel } from "../components/CallFooterViewModel.tsx";
+import { createDeveloperSettingsTabViewModel } from "../settings/DeveloperSettingsTabViewModel.ts";
+import { type DeveloperSettingsSnapshot } from "../settings/DeveloperSettingsTab.tsx";
 import { type ViewModel } from "../state/ViewModel.ts";
 import { RingingStatus } from "../tile/RingingStatus.tsx";
 import { RingingAudioRenderer } from "./RingingAudioRenderer.tsx";
@@ -96,7 +98,7 @@ declare module "react" {
 
 export interface ActiveCallProps extends Omit<
   InCallViewProps,
-  "vm" | "livekitRoom" | "connState" | "footerVm"
+  "vm" | "livekitRoom" | "connState" | "footerVm" | "developerSettingsVm"
 > {
   e2eeSystem: EncryptionSystem;
   // TODO refactor those reasons into an enum
@@ -110,6 +112,9 @@ export const ActiveCall: FC<ActiveCallProps> = (props) => {
   const [footerVm, setFooterVm] = useState<ViewModel<FooterSnapshot> | null>(
     null,
   );
+  const [developerSettingsVm, setDeveloperSettingsVm] =
+    useState<ViewModel<DeveloperSettingsSnapshot> | null>(null);
+
   const urlParams = useUrlParams();
   const mediaDevices = useMediaDevices();
   const trackProcessorState$ = useTrackProcessorObservable$();
@@ -168,7 +173,9 @@ export const ActiveCall: FC<ActiveCallProps> = (props) => {
       mediaDevices,
       `${props.client.getUserId()}:${props.client.getDeviceId()}`,
     );
+    const developerSettingsVm = createDeveloperSettingsTabViewModel(scope, vm);
     setFooterVm(footerVm);
+    setDeveloperSettingsVm(developerSettingsVm);
 
     return (): void => {
       scope.end();
@@ -188,10 +195,16 @@ export const ActiveCall: FC<ActiveCallProps> = (props) => {
 
   if (vm === null) return null;
   if (footerVm === null) return null;
+  if (developerSettingsVm === null) return null;
 
   return (
     <ReactionsSenderProvider vm={vm} rtcSession={props.rtcSession}>
-      <InCallView {...props} vm={vm} footerVm={footerVm} />
+      <InCallView
+        {...props}
+        vm={vm}
+        footerVm={footerVm}
+        developerSettingsVm={developerSettingsVm}
+      />
     </ReactionsSenderProvider>
   );
 };
@@ -200,6 +213,7 @@ export interface InCallViewProps {
   client: MatrixClient;
   vm: CallViewModel;
   footerVm: ViewModel<FooterSnapshot>;
+  developerSettingsVm: ViewModel<DeveloperSettingsSnapshot>;
   matrixInfo: MatrixInfo;
   rtcSession: MatrixRTCSession;
   matrixRoom: MatrixRoom;
@@ -211,6 +225,7 @@ export const InCallView: FC<InCallViewProps> = ({
   client,
   vm,
   footerVm,
+  developerSettingsVm,
   matrixInfo,
   matrixRoom,
   muteStates,
@@ -632,7 +647,7 @@ export const InCallView: FC<InCallViewProps> = ({
             onDismiss={(): void => setSettingsOpen(false)}
             tab={settingsTab}
             onTabChange={setSettingsTab}
-            vm={vm}
+            developerSettingsVm={developerSettingsVm}
             livekitRooms={allConnections
               .getConnections()
               .map((connectionItem) => ({

src/settings/DeveloperSettingsTab.test.tsx

@@ -9,11 +9,15 @@ import { afterEach, describe, expect, it, type Mock, vi } from "vitest";
 import { render, waitFor, screen } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
 import { TooltipProvider } from "@vector-im/compound-web";
-import { BehaviorSubject } from "rxjs";
 
 import type { MatrixClient } from "matrix-js-sdk";
 import type { Room as LivekitRoom } from "livekit-client";
-import { DeveloperSettingsTab } from "./DeveloperSettingsTab";
+import {
+  DeveloperSettingsTab,
+  type DeveloperSettingsSnapshot,
+} from "./DeveloperSettingsTab";
+import { outOfCallDeveloperSettingsTabViewModel } from "./DeveloperSettingsTabViewModel";
+import { createStaticViewModel } from "../state/ViewModel";
 import { getSFUConfigWithOpenID } from "../livekit/openIDSFU";
 import {
   customLivekitUrl as customLivekitUrlSetting,
@@ -108,6 +112,7 @@ describe("DeveloperSettingsTab", () => {
         roomId={"#room:example.org"}
         livekitRooms={livekitRooms}
         env={{ MY_MOCK_ENV: 10, ENV: "test" } as unknown as ImportMetaEnv}
+        vm={outOfCallDeveloperSettingsTabViewModel}
       />,
     );
 
@@ -137,6 +142,7 @@ describe("DeveloperSettingsTab", () => {
           <DeveloperSettingsTab
             client={client}
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );
@@ -160,6 +166,7 @@ describe("DeveloperSettingsTab", () => {
             client={client}
             roomId="#testRoom"
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );
@@ -182,6 +189,7 @@ describe("DeveloperSettingsTab", () => {
             client={client}
             roomId="#testRoom"
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );
@@ -207,6 +215,7 @@ describe("DeveloperSettingsTab", () => {
             client={client}
             roomId="#testRoom"
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );
@@ -237,6 +246,7 @@ describe("DeveloperSettingsTab", () => {
             client={client}
             roomId="#testRoom"
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );
@@ -274,6 +284,7 @@ describe("DeveloperSettingsTab", () => {
           <DeveloperSettingsTab
             client={client}
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );
@@ -306,6 +317,7 @@ describe("DeveloperSettingsTab", () => {
           <DeveloperSettingsTab
             client={client}
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );
@@ -350,6 +362,7 @@ describe("DeveloperSettingsTab", () => {
           <DeveloperSettingsTab
             client={client}
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );
@@ -389,6 +402,7 @@ describe("DeveloperSettingsTab", () => {
             <DeveloperSettingsTab
               client={client}
               env={{} as unknown as ImportMetaEnv}
+              vm={outOfCallDeveloperSettingsTabViewModel}
             />
           </TooltipProvider>,
         );
@@ -417,17 +431,16 @@ describe("DeveloperSettingsTab", () => {
   describe("KeyRotationStatus", () => {
     it("displays active status when key rotation is not suppressed", async () => {
       const client = createMockMatrixClient();
-      const mockVm = {
-        keyRotationSuppressed$: new BehaviorSubject(false),
-        participantCount$: new BehaviorSubject(5),
-      } as unknown as any;
+      const vm = createStaticViewModel<DeveloperSettingsSnapshot>({
+        keyRotation: { suppressed: false, participantCount: 5 },
+      });
 
       render(
         <TooltipProvider>
           <DeveloperSettingsTab
             client={client}
             env={{} as unknown as ImportMetaEnv}
-            vm={mockVm}
+            vm={vm}
           />
         </TooltipProvider>,
       );
@@ -443,17 +456,16 @@ describe("DeveloperSettingsTab", () => {
 
     it("displays suppressed status when key rotation is suppressed", async () => {
       const client = createMockMatrixClient();
-      const mockVm = {
-        keyRotationSuppressed$: new BehaviorSubject(true),
-        participantCount$: new BehaviorSubject(50),
-      } as unknown as any;
+      const vm = createStaticViewModel<DeveloperSettingsSnapshot>({
+        keyRotation: { suppressed: true, participantCount: 50 },
+      });
 
       render(
         <TooltipProvider>
           <DeveloperSettingsTab
             client={client}
             env={{} as unknown as ImportMetaEnv}
-            vm={mockVm}
+            vm={vm}
           />
         </TooltipProvider>,
       );
@@ -469,7 +481,7 @@ describe("DeveloperSettingsTab", () => {
       ).toBeInTheDocument();
     });
 
-    it("does not render KeyRotationStatus when vm is not provided", async () => {
+    it("does not render KeyRotationStatus when not in a call", async () => {
       const client = createMockMatrixClient();
 
       render(
@@ -477,6 +489,7 @@ describe("DeveloperSettingsTab", () => {
           <DeveloperSettingsTab
             client={client}
             env={{} as unknown as ImportMetaEnv}
+            vm={outOfCallDeveloperSettingsTabViewModel}
           />
         </TooltipProvider>,
       );

src/settings/DeveloperSettingsTab.tsx

@@ -67,25 +67,40 @@ import styles from "./DeveloperSettingsTab.module.css";
 import settingsStyles from "./SettingsModal.module.css";
 import { Slider } from "../Slider";
 import { useUrlParams } from "../UrlParams";
-import { type CallViewModel } from "../state/CallViewModel/CallViewModel.ts";
 import { getSFUConfigWithOpenID } from "../livekit/openIDSFU";
 import { useBehavior } from "../useBehavior";
+import { type ViewModel } from "../state/ViewModel.ts";
+
+/**
+ * The state of MatrixRTC's media key rotation.
+ */
+export interface KeyRotationInfo {
+  /** Whether the call is large enough that MatrixRTC has stopped rotating the media key. */
+  suppressed: boolean;
+  participantCount: number;
+}
+
+/**
+ * The Snapshot combines all fields the developer settings tab needs from the
+ * surrounding call. Everything else in this tab is read from the settings store
+ * or the environment directly.
+ */
+export interface DeveloperSettingsSnapshot {
+  /** The media key rotation state, or `null` when we are not in a call. */
+  keyRotation: KeyRotationInfo | null;
+}
 
 /**
  * Shows whether the call is large enough that MatrixRTC has stopped rotating the media key.
  */
-const KeyRotationStatus: FC<{ vm: CallViewModel }> = ({ vm }) => {
-  const suppressed = useBehavior(vm.keyRotationSuppressed$);
-  const participantCount = useBehavior(vm.participantCount$);
-  return (
-    <p>
-      Media key rotation:{" "}
-      {suppressed
-        ? `suppressed, participant limit reached (${participantCount} participants)`
-        : `active (${participantCount} participants)`}
-    </p>
-  );
-};
+const KeyRotationStatus: FC<{ info: KeyRotationInfo }> = ({ info }) => (
+  <p>
+    Media key rotation:{" "}
+    {info.suppressed
+      ? `suppressed, participant limit reached (${info.participantCount} participants)`
+      : `active (${info.participantCount} participants)`}
+  </p>
+);
 
 interface Props {
   client: MatrixClient;
@@ -97,8 +112,7 @@ interface Props {
     livekitAlias?: string;
   }[];
   env: ImportMetaEnv;
-  /** Only available while in a call. */
-  vm?: CallViewModel;
+  vm: ViewModel<DeveloperSettingsSnapshot>;
 }
 
 export const DeveloperSettingsTab: FC<Props> = ({
@@ -109,6 +123,7 @@ export const DeveloperSettingsTab: FC<Props> = ({
   vm,
 }) => {
   const { t } = useTranslation();
+  const keyRotation = useBehavior(vm.keyRotation$);
   const [duplicateTiles, setDuplicateTiles] = useSetting(duplicateTilesSetting);
   const [debugTileLayout, setDebugTileLayout] = useSetting(
     debugTileLayoutSetting,
@@ -385,7 +400,7 @@ export const DeveloperSettingsTab: FC<Props> = ({
           id: client.getDeviceId() || "unknown",
         })}
       </p>
-      {vm && <KeyRotationStatus vm={vm} />}
+      {keyRotation !== null && <KeyRotationStatus info={keyRotation} />}
       <Separator />
       <FieldRow>
         <InputField

src/settings/DeveloperSettingsTabViewModel.test.ts

@@ -0,0 +1,48 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { describe, expect, it } from "vitest";
+import { BehaviorSubject } from "rxjs";
+
+import { testScope } from "../utils/test";
+import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
+import {
+  createDeveloperSettingsTabViewModel,
+  outOfCallDeveloperSettingsTabViewModel,
+} from "./DeveloperSettingsTabViewModel";
+
+describe("createDeveloperSettingsTabViewModel", () => {
+  it("projects the key rotation state of the call", () => {
+    const keyRotationSuppressed$ = new BehaviorSubject(false);
+    const participantCount$ = new BehaviorSubject(5);
+    const vm = createDeveloperSettingsTabViewModel(testScope(), {
+      keyRotationSuppressed$,
+      participantCount$,
+    } as unknown as CallViewModel);
+
+    expect(vm.keyRotation$.value).toEqual({
+      suppressed: false,
+      participantCount: 5,
+    });
+
+    participantCount$.next(50);
+    keyRotationSuppressed$.next(true);
+
+    expect(vm.keyRotation$.value).toEqual({
+      suppressed: true,
+      participantCount: 50,
+    });
+  });
+});
+
+describe("outOfCallDeveloperSettingsTabViewModel", () => {
+  it("has no key rotation state", () => {
+    expect(outOfCallDeveloperSettingsTabViewModel.keyRotation$.value).toBe(
+      null,
+    );
+  });
+});

src/settings/DeveloperSettingsTabViewModel.ts

@@ -0,0 +1,43 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { combineLatest } from "rxjs";
+
+import { type CallViewModel } from "../state/CallViewModel/CallViewModel.ts";
+import { type ObservableScope } from "../state/ObservableScope.ts";
+import { createStaticViewModel, type ViewModel } from "../state/ViewModel.ts";
+import { type DeveloperSettingsSnapshot } from "./DeveloperSettingsTab.tsx";
+
+/**
+ * Creates the ViewModel for the developer settings tab while in a call.
+ *
+ * Only the call state the tab actually renders is projected here, so that the
+ * tab does not need to know about the CallViewModel.
+ *
+ * @param scope - ObservableScope that bounds the lifetime of derived behaviors.
+ * @param callModel - The root CallViewModel; provides the key rotation state.
+ */
+export function createDeveloperSettingsTabViewModel(
+  scope: ObservableScope,
+  callModel: CallViewModel,
+): ViewModel<DeveloperSettingsSnapshot> {
+  return {
+    keyRotation$: scope.behavior(
+      combineLatest(
+        [callModel.keyRotationSuppressed$, callModel.participantCount$],
+        (suppressed, participantCount) => ({ suppressed, participantCount }),
+      ),
+    ),
+  };
+}
+
+/**
+ * The ViewModel for the developer settings tab outside of a call (lobby, user
+ * menu), where no call state exists. All call specific fields are `null`.
+ */
+export const outOfCallDeveloperSettingsTabViewModel: ViewModel<DeveloperSettingsSnapshot> =
+  createStaticViewModel<DeveloperSettingsSnapshot>({ keyRotation: null });

src/settings/SettingsModal.tsx

@@ -29,12 +29,16 @@ import { PreferencesSettingsTab } from "./PreferencesSettingsTab";
 import { Slider } from "../Slider";
 import { DeviceSelection } from "./DeviceSelection";
 import { useTrackProcessor } from "../livekit/TrackProcessorContext";
-import { DeveloperSettingsTab } from "./DeveloperSettingsTab";
+import {
+  DeveloperSettingsTab,
+  type DeveloperSettingsSnapshot,
+} from "./DeveloperSettingsTab";
 import { FieldRow, InputField } from "../input/Input";
 import { useSubmitRageshake } from "./submit-rageshake";
 import { useUrlParams } from "../UrlParams";
 import { useBehavior } from "../useBehavior";
-import { type CallViewModel } from "../state/CallViewModel/CallViewModel.ts";
+import { type ViewModel } from "../state/ViewModel.ts";
+import { outOfCallDeveloperSettingsTabViewModel } from "./DeveloperSettingsTabViewModel";
 
 type SettingsTab =
   | "audio"
@@ -58,7 +62,7 @@ interface Props {
     isLocal?: boolean;
   }[];
   /** Only available while in a call. Used by the developer tab. */
-  vm?: CallViewModel;
+  developerSettingsVm?: ViewModel<DeveloperSettingsSnapshot>;
 }
 
 export const defaultSettingsTab: SettingsTab = "audio";
@@ -71,7 +75,7 @@ export const SettingsModal: FC<Props> = ({
   client,
   roomId,
   livekitRooms,
-  vm,
+  developerSettingsVm,
 }) => {
   const { t } = useTranslation();
 
@@ -224,7 +228,7 @@ export const SettingsModal: FC<Props> = ({
         client={client}
         livekitRooms={livekitRooms}
         roomId={roomId}
-        vm={vm}
+        vm={developerSettingsVm ?? outOfCallDeveloperSettingsTabViewModel}
       />
     ),
   };

src/utils/test-viewmodel.ts

@@ -42,6 +42,8 @@ import { MatrixRTCMode } from "../config/ConfigOptions";
 import { createCallFooterViewModel } from "../components/CallFooterViewModel";
 import { type FooterSnapshot } from "../components/CallFooter";
 import { type ViewModel } from "../state/ViewModel";
+import { createDeveloperSettingsTabViewModel } from "../settings/DeveloperSettingsTabViewModel";
+import { type DeveloperSettingsSnapshot } from "../settings/DeveloperSettingsTab";
 
 mockConfig({ livekit: { livekit_service_url: "https://example.com" } });
 
@@ -140,6 +142,7 @@ export function getBasicCallViewModelEnvironment(
 ): {
   vm: CallViewModel;
   footerVm: ViewModel<FooterSnapshot>;
+  developerSettingsVm: ViewModel<DeveloperSettingsSnapshot>;
   rtcMemberships$: BehaviorSubject<CallMembership[]>;
   rtcSession: MockRTCSession;
   handRaisedSubject$: BehaviorSubject<Record<string, RaisedHandInfo>>;
@@ -188,6 +191,7 @@ export function getBasicCallViewModelEnvironment(
   return {
     vm,
     footerVm,
+    developerSettingsVm: createDeveloperSettingsTabViewModel(testScope(), vm),
     rtcMemberships$,
     rtcSession,
     handRaisedSubject$: handRaisedSubject$,