refactor: replace the lock screen with a native privacy cover

android/app/src/main/java/io/metamask/MainActivity.kt

@@ -11,9 +11,33 @@ import com.facebook.react.defaults.DefaultReactActivityDelegate
 import expo.modules.ReactActivityDelegateWrapper
 import io.branch.rnbranch.RNBranchModule
 import io.metamask.nativeModules.NotificationModule
+import io.metamask.nativeModules.PrivacyCover
 import com.braze.reactbridge.BrazeReactUtils
 
 class MainActivity : ReactActivity() {
+    override fun onPause() {
+        PrivacyCover.markAuthenticationUnavailable()
+        PrivacyCover.show(this)
+        super.onPause()
+    }
+
+    override fun onPostResume() {
+        super.onPostResume()
+        PrivacyCover.markAuthenticationReady()
+    }
+
+    /**
+     * Predictive back calls this from React Native's dispatcher callback.
+     * Swallow it while the cover is up so it cannot pop the screen underneath.
+     */
+    @Suppress("OVERRIDE_DEPRECATION")
+    override fun onBackPressed() {
+        if (PrivacyCover.isShown()) {
+            return
+        }
+        super.onBackPressed()
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         // Capture Notification Intent
         NotificationModule.saveNotificationIntent(intent)
@@ -24,6 +48,12 @@ class MainActivity : ReactActivity() {
         // This is required for expo-splash-screen.
         setTheme(R.style.AppTheme)
         super.onCreate(null)
+        // Android 13+ can suppress the Recents thumbnail without FLAG_SECURE, so
+        // screenshots keep working while the app is open. Older versions hold
+        // FLAG_SECURE for the wallet session instead (see AppLockService).
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            setRecentsScreenshotEnabled(false)
+        }
     }
 
     /**

android/app/src/main/java/io/metamask/MainApplication.kt

@@ -24,6 +24,7 @@ import io.metamask.nativeModules.RCTMinimizerPackage
 import io.metamask.nativeModules.RNTar.RNTarPackage
 import io.metamask.nativeModules.BrazePushPackage
 import io.metamask.nativeModules.NotificationPackage
+import io.metamask.nativeModules.PrivacyCoverPackage
 import io.metamask.nativeModules.HermesProfiler.HermesProfilerPackage
 import com.braze.BrazeActivityLifecycleCallbackListener
 import com.margelo.nitro.nitrofetch.AutoPrefetcher
@@ -46,6 +47,7 @@ class MainApplication : Application(), ShareApplication, ReactApplication {
                 add(RCTMinimizerPackage())
                 add(RNTarPackage())
                 add(NotificationPackage())
+                add(PrivacyCoverPackage())
                 add(BrazePushPackage())
                 if (BuildConfig.IS_PERFORMANCE_TEST) {
                     add(HermesProfilerPackage())

android/app/src/main/java/io/metamask/nativeModules/PrivacyCover.kt

@@ -0,0 +1,129 @@
+package io.metamask.nativeModules
+
+import android.app.Activity
+import android.view.View
+import android.view.ViewGroup
+import android.widget.FrameLayout
+import androidx.activity.ComponentActivity
+import androidx.activity.OnBackPressedCallback
+import com.facebook.react.bridge.Promise
+import io.metamask.R
+
+/**
+ * The Android privacy cover. [io.metamask.MainActivity] shows it from `onPause`
+ * and [PrivacyCoverModule] hides it once resume routing resolves.
+ *
+ * Theme fill plus the centered splash fox, matching the iOS cover. Recents stays
+ * a blank card: Android 13+ uses `setRecentsScreenshotEnabled`, older versions
+ * hold FLAG_SECURE from login until logout. The snapshot is taken before
+ * `onPause`, so this view is what the user sees on the way back in.
+ */
+internal object PrivacyCover {
+    private var overlay: View? = null
+    /** Consumes system back while the cover is visible so the screen underneath stays put. */
+    private var backCallback: OnBackPressedCallback? = null
+    private var backCallbackActivity: Activity? = null
+    /** Bumped on every pause so a stale resume cannot start authentication. */
+    private var authenticationEpoch = 0
+    /** Set to [authenticationEpoch] only while `onPostResume` is the latest lifecycle event. */
+    private var resumedEpoch: Int? = null
+    private val authenticationWaiters = mutableListOf<Pair<Int, Promise>>()
+
+    fun show(activity: Activity) {
+        val decor = activity.window.decorView as? ViewGroup ?: return
+        val existing = overlay
+        val cover = if (existing != null && existing.context === activity) {
+            existing
+        } else {
+            View(activity).apply {
+                setBackgroundResource(R.drawable.app_background)
+                isClickable = true
+                importantForAccessibility = View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS
+            }.also { overlay = it }
+        }
+
+        if (cover.parent !== decor) {
+            (cover.parent as? ViewGroup)?.removeView(cover)
+            decor.addView(
+                cover,
+                FrameLayout.LayoutParams(
+                    ViewGroup.LayoutParams.MATCH_PARENT,
+                    ViewGroup.LayoutParams.MATCH_PARENT,
+                ),
+            )
+        }
+        cover.bringToFront()
+        cover.visibility = View.VISIBLE
+        blockBack(activity)
+    }
+
+    fun isShown(): Boolean = overlay?.visibility == View.VISIBLE
+
+    fun hide() {
+        // A dismiss queued while the activity is pausing belongs to a resume
+        // that is no longer current. Dropping it here keeps the cover up.
+        if (resumedEpoch == null) {
+            return
+        }
+        overlay?.visibility = View.GONE
+        backCallback?.isEnabled = false
+    }
+
+    /**
+     * Registered after React Native's own back callback, so while it is enabled
+     * the dispatcher delivers back here first and the screen underneath does not move.
+     */
+    private fun blockBack(activity: Activity) {
+        val componentActivity = activity as? ComponentActivity ?: return
+        if (backCallback == null || backCallbackActivity !== componentActivity) {
+            backCallback?.remove()
+            val callback = object : OnBackPressedCallback(true) {
+                override fun handleOnBackPressed() {
+                    // The privacy cover is up. Drop the press.
+                }
+            }
+            componentActivity.onBackPressedDispatcher.addCallback(componentActivity, callback)
+            backCallback = callback
+            backCallbackActivity = componentActivity
+        } else {
+            backCallback?.isEnabled = true
+        }
+    }
+
+    /**
+     * Authentication may start. Resolves waiters for this resume only.
+     * Call from [android.app.Activity.onPostResume].
+     */
+    fun markAuthenticationReady() {
+        resumedEpoch = authenticationEpoch
+        val ready = authenticationWaiters.filter { it.first == authenticationEpoch }
+        authenticationWaiters.removeAll { it.first == authenticationEpoch }
+        ready.forEach { it.second.resolve(null) }
+    }
+
+    /**
+     * Invalidates the current resume. Pending authentication waits fail and
+     * must be requested again after the next [markAuthenticationReady].
+     * Call from [android.app.Activity.onPause] before `super.onPause()`.
+     */
+    fun markAuthenticationUnavailable() {
+        resumedEpoch = null
+        authenticationEpoch += 1
+        val waiting = authenticationWaiters.toList()
+        authenticationWaiters.clear()
+        waiting.forEach { (_, promise) ->
+            promise.reject(
+                "ACTIVITY_PAUSED",
+                "The activity paused before authentication could start",
+            )
+        }
+    }
+
+    fun waitUntilAuthenticationReady(promise: Promise) {
+        if (resumedEpoch == authenticationEpoch) {
+            promise.resolve(null)
+            return
+        }
+        authenticationWaiters.add(authenticationEpoch to promise)
+    }
+}

android/app/src/main/java/io/metamask/nativeModules/PrivacyCoverModule.kt

@@ -0,0 +1,33 @@
+package io.metamask.nativeModules
+
+import com.facebook.react.bridge.Promise
+import com.facebook.react.bridge.ReactApplicationContext
+import com.facebook.react.bridge.ReactContextBaseJavaModule
+import com.facebook.react.bridge.ReactMethod
+import com.facebook.react.bridge.UiThreadUtil
+
+/**
+ * Native bridge for [PrivacyCover]. `hide` dismisses the cover once JavaScript
+ * resume routing has resolved. `waitUntilAuthenticationReady` resolves after
+ * `onPostResume`, which is when Android will accept a biometric prompt.
+ * Showing the cover stays on the activity lifecycle.
+ */
+class PrivacyCoverModule(context: ReactApplicationContext) : ReactContextBaseJavaModule(context) {
+
+    override fun getName(): String = "PrivacyCoverModule"
+
+    @ReactMethod
+    fun hide() {
+        UiThreadUtil.runOnUiThread { PrivacyCover.hide() }
+    }
+
+    /**
+     * Resolves once [android.app.Activity.onPostResume] has run for the
+     * current resume. Rejects if [android.app.Activity.onPause] invalidates
+     * that resume first.
+     */
+    @ReactMethod
+    fun waitUntilAuthenticationReady(promise: Promise) {
+        UiThreadUtil.runOnUiThread { PrivacyCover.waitUntilAuthenticationReady(promise) }
+    }
+}

android/app/src/main/java/io/metamask/nativeModules/PrivacyCoverPackage.kt

@@ -0,0 +1,16 @@
+package io.metamask.nativeModules
+
+import com.facebook.react.ReactPackage
+import com.facebook.react.bridge.NativeModule
+import com.facebook.react.bridge.ReactApplicationContext
+import com.facebook.react.uimanager.ViewManager
+
+class PrivacyCoverPackage : ReactPackage {
+
+    override fun createViewManagers(reactContext: ReactApplicationContext): List<ViewManager<*, *>> =
+        emptyList()
+
+    @Suppress("OVERRIDE_DEPRECATION")
+    override fun createNativeModules(reactContext: ReactApplicationContext): List<NativeModule> =
+        listOf(PrivacyCoverModule(reactContext))
+}

app/components/Nav/App/App.test.tsx

@@ -239,9 +239,6 @@ jest.mock('../../Views/ProHub/screens/Earned', () => () => (
 jest.mock('../../Views/ProHub/screens/CancelMembership', () => () => (
   <MockView testID="mock-pro-hub-cancel-membership" />
 ));
-jest.mock('../../Views/LockScreen', () => () => (
-  <MockView testID="mock-lock-screen" />
-));
 jest.mock('../../Views/MultichainAccounts/AddressList', () => ({
   AddressList: () => <MockView testID="mock-address-list" />,
 }));
@@ -710,10 +707,6 @@ describe('App', () => {
       expect(Routes.EDIT_NETWORK).toBeDefined();
     });
 
-    it('has lock screen route defined', () => {
-      expect(Routes.LOCK_SCREEN).toBeDefined();
-    });
-
     it('has confirmation routes defined', () => {
       expect(Routes.CONFIRMATION_REQUEST_MODAL).toBeDefined();
       expect(Routes.CONFIRMATION_SWITCH_ACCOUNT_TYPE).toBeDefined();
@@ -857,19 +850,6 @@ describe('App', () => {
         expect(getByTestId(MOCK_FOX_LOADER_ID)).toBeTruthy();
       });
     });
-
-    it('renders the lock screen route', async () => {
-      const routeState = {
-        index: 0,
-        routes: [{ name: Routes.LOCK_SCREEN }],
-      };
-
-      const { toJSON } = renderAppWithDefaultState(routeState);
-
-      await waitFor(() => {
-        expect(toJSON()).toBeTruthy();
-      });
-    });
   });
 
   describe('Onboarding navigation', () => {
@@ -2237,19 +2217,6 @@ describe('App', () => {
         expect(getByTestId('mock-pk-list')).toBeOnTheScreen();
       });
     });
-
-    it('renders the LockScreen route', async () => {
-      const routeState = {
-        index: 0,
-        routes: [{ name: Routes.LOCK_SCREEN }],
-      };
-
-      const { getByTestId } = renderAppAtRoute(routeState);
-
-      await waitFor(() => {
-        expect(getByTestId('mock-lock-screen')).toBeTruthy();
-      });
-    });
   });
 
   describe('isNetworkUiRedesignEnabled conditional rendering', () => {

app/components/Nav/App/App.tsx

@@ -103,7 +103,6 @@ import ReturnToAppNotification from '../../Views/ReturnToAppNotification';
 import EditAccountName from '../../Views/EditAccountName/EditAccountName';
 import LegacyEditMultichainAccountName from '../../Views/MultichainAccounts/sheets/EditAccountName';
 import { EditMultichainAccountName } from '../../Views/MultichainAccounts/sheets/EditMultichainAccountName';
-import LockScreen from '../../Views/LockScreen';
 import StorageWrapper from '../../../store/storage-wrapper';
 import ShowIpfsGatewaySheet from '../../Views/ShowIpfsGatewaySheet/ShowIpfsGatewaySheet';
 import ShowDisplayNftMediaSheet from '../../Views/ShowDisplayMediaNFTSheet/ShowDisplayNFTMediaSheet';
@@ -1353,11 +1352,6 @@ const AppFlow = () => {
           />
         ) : null}
       </NativeStack.Group>
-      <NativeStack.Screen
-        name={Routes.LOCK_SCREEN}
-        component={LockScreen}
-        options={{ gestureEnabled: false }}
-      />
       <NativeStack.Screen
         name={Routes.CONFIRMATION_REQUEST_MODAL}
         options={{

app/components/UI/Card/routes/OnboardingNavigator.test.tsx

@@ -78,11 +78,11 @@ jest.mock('@react-navigation/native-stack', () => {
   };
 });
 
-jest.mock('../../../../core/LockManagerService', () => ({
+jest.mock('../../../../core/AppLock/AppLockService', () => ({
   __esModule: true,
   default: {
-    stopListening: jest.fn(),
-    startListening: jest.fn(),
+    dangerousPauseAutoLock: jest.fn(),
+    dangerousResumeAutoLock: jest.fn(),
   },
 }));