feat: Disable session lock when running in element-desktop (#30643)

* feat: Disable session lock when running in element-desktop

* feat: Use Platform abstractions over direct invocation for session lock.

* fix: Remove window.electron checks from session lock methods.

* docs: Remove extraneous doc comments.

* feat: Convert BasePlatform session methods to abstract methods.

* fix: Check for PlatformPeg instance in session lock.

* fix: Remove async marker from checkSessionLockFree

Author: kaylendog

src/BasePlatform.ts

@@ -508,4 +508,19 @@ export default abstract class BasePlatform {
      * Begin update polling, if applicable
      */
     public startUpdater(): void {}
+
+    /**
+     * Checks if the current session is lock-free, i.e., no other instance is holding the session lock.
+     * Platforms that support session locking should override this method.
+     * @returns {boolean} True if the session is lock-free, false otherwise.
+     */
+    public abstract checkSessionLockFree(): boolean;
+    /**
+     * Attempts to acquire a session lock for this instance.
+     * If another instance is detected, calls the provided callback.
+     * Platforms that support session locking should override this method.
+     * @param _onNewInstance Callback to invoke if a new instance is detected.
+     * @returns {Promise<boolean>} True if the lock was acquired, false otherwise.
+     */
+    public abstract getSessionLock(_onNewInstance: () => Promise<void>): Promise<boolean>;
 }

src/components/structures/MatrixChat.tsx

@@ -130,7 +130,6 @@ import { NotificationLevel } from "../../stores/notifications/NotificationLevel"
 import { type UserTab } from "../views/dialogs/UserTab";
 import { shouldSkipSetupEncryption } from "../../utils/crypto/shouldSkipSetupEncryption";
 import { Filter } from "../views/dialogs/spotlight/Filter";
-import { checkSessionLockFree, getSessionLock } from "../../utils/SessionLock";
 import { SessionLockStolenView } from "./auth/SessionLockStolenView";
 import { ConfirmSessionLockTheftView } from "./auth/ConfirmSessionLockTheftView";
 import { LoginSplashView } from "./auth/LoginSplashView";
@@ -314,7 +313,8 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
     private async initSession(): Promise<void> {
         // The Rust Crypto SDK will break if two Element instances try to use the same datastore at once, so
         // make sure we are the only Element instance in town (on this browser/domain).
-        if (!(await getSessionLock(() => this.onSessionLockStolen()))) {
+        const platform = PlatformPeg.get();
+        if (platform && !(await platform.getSessionLock(() => this.onSessionLockStolen()))) {
             // we failed to get the lock. onSessionLockStolen should already have been called, so nothing left to do.
             return;
         }
@@ -479,7 +479,8 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         // mounted.
         if (!this.sessionLoadStarted) {
             this.sessionLoadStarted = true;
-            if (!checkSessionLockFree()) {
+            const platform = PlatformPeg.get();
+            if (platform && !platform.checkSessionLockFree()) {
                 // another instance holds the lock; confirm its theft before proceeding
                 setTimeout(() => this.setState({ view: Views.CONFIRM_LOCK_THEFT }), 0);
             } else {

src/vector/platform/ElectronPlatform.tsx

@@ -558,4 +558,12 @@ export default class ElectronPlatform extends BasePlatform {
         }
         return url;
     }
+
+    public checkSessionLockFree(): boolean {
+        return true;
+    }
+
+    public async getSessionLock(_onNewInstance: () => Promise<void>): Promise<boolean> {
+        return true;
+    }
 }

src/vector/platform/WebPlatform.ts

@@ -22,6 +22,7 @@ import ToastStore from "../../stores/ToastStore.ts";
 import GenericToast from "../../components/views/toasts/GenericToast.tsx";
 import SdkConfig from "../../SdkConfig.ts";
 import type { ActionPayload } from "../../dispatcher/payloads.ts";
+import * as SessionLock from "../../utils/SessionLock.ts";
 
 const POKE_RATE_MS = 10 * 60 * 1000; // 10 min
 
@@ -268,4 +269,12 @@ export default class WebPlatform extends BasePlatform {
     public reload(): void {
         window.location.reload();
     }
+
+    public checkSessionLockFree(): boolean {
+        return SessionLock.checkSessionLockFree();
+    }
+
+    public async getSessionLock(onNewInstance: () => Promise<void>): Promise<boolean> {
+        return SessionLock.getSessionLock(onNewInstance);
+    }
 }

test/test-utils/platform.ts

@@ -10,6 +10,7 @@ import { type MethodLikeKeys, mocked, type MockedObject } from "jest-mock";
 
 import BasePlatform from "../../src/BasePlatform";
 import PlatformPeg from "../../src/PlatformPeg";
+import * as SessionLock from "../../src/utils/SessionLock";
 
 // doesn't implement abstract
 // @ts-ignore
@@ -18,6 +19,14 @@ class MockPlatform extends BasePlatform {
         super();
         Object.assign(this, platformMocks);
     }
+
+    public checkSessionLockFree(): boolean {
+        return SessionLock.checkSessionLockFree();
+    }
+
+    public async getSessionLock(onNewInstance: () => Promise<void>): Promise<boolean> {
+        return SessionLock.getSessionLock(onNewInstance);
+    }
 }
 /**
  * Mock Platform Peg

test/unit-tests/components/structures/MatrixChat-test.tsx

@@ -1632,6 +1632,10 @@ describe("<MatrixChat />", () => {
     });
 
     describe("Multi-tab lockout", () => {
+        beforeEach(() => {
+            mockPlatformPeg();
+        });
+
         afterEach(() => {
             Lifecycle.setSessionLockNotStolen();
         });
@@ -1677,6 +1681,8 @@ describe("<MatrixChat />", () => {
             beforeEach(() => {
                 // make sure we start from a clean DOM for each of these tests
                 document.body.replaceChildren();
+                // use the MockPlatform
+                mockPlatformPeg();
             });
 
             function simulateSessionLockClaim() {