fix(mobile): restore Android create-channel and new-DM actions

mobile/lib/features/channels/channels_page/quick_actions_launcher.dart

@@ -5,6 +5,40 @@ const _kQuickActionsTabMotionCurve = Cubic(0.77, 0, 0.175, 1);
 const _kQuickActionsHiddenOverlap = Grid.half;
 const _kQuickActionsHiddenScale = 0.8;
 
+/// Keeps the closed quick-action button beside the tab bar without overlapping
+/// the centered pill on compact phone widths.
+double _effectiveQuickActionsRightInset({
+  required double screenWidth,
+  required double navigationBarWidth,
+  required double rightInset,
+}) {
+  final tabBarLeft = (screenWidth - navigationBarWidth) / 2;
+  final defaultFabRight = screenWidth - rightInset;
+  final defaultFabLeft = defaultFabRight - _kMorphClosedSize;
+  final tabBarRight = tabBarLeft + navigationBarWidth;
+  final overlapsTabBar =
+      defaultFabRight > tabBarLeft && defaultFabLeft < tabBarRight;
+  if (!overlapsTabBar) {
+    return rightInset;
+  }
+
+  final clearanceGap = Grid.half;
+  final shiftedFabRight = tabBarLeft - clearanceGap;
+  final shiftedRightInset = screenWidth - shiftedFabRight;
+  final shiftedFabLeft = shiftedFabRight - _kMorphClosedSize;
+  if (shiftedFabLeft >= 0) {
+    return shiftedRightInset;
+  }
+
+  final flushRightInset = screenWidth - tabBarLeft;
+  final flushFabLeft = tabBarLeft - _kMorphClosedSize;
+  if (flushFabLeft >= 0) {
+    return flushRightInset;
+  }
+
+  return (screenWidth - _kMorphClosedSize).clamp(rightInset, double.infinity);
+}
+
 /// Places the channel quick-actions button beside mobile navigation.
 ///
 /// The button remains available only on Home and moves behind the navigation
@@ -55,8 +89,13 @@ class ChannelQuickActionsLauncher extends HookConsumerWidget {
         ((navigationBarHeight - _kMorphClosedSize) / 2);
     final effectiveOpen = visible && quickActionsOpen.value;
     final screenWidth = MediaQuery.sizeOf(context).width;
+    final effectiveRightInset = _effectiveQuickActionsRightInset(
+      screenWidth: screenWidth,
+      navigationBarWidth: navigationBarWidth,
+      rightInset: rightInset,
+    );
     final navigationBarRight = (screenWidth + navigationBarWidth) / 2;
-    final launcherRight = screenWidth - rightInset;
+    final launcherRight = screenWidth - effectiveRightInset;
     final hiddenHorizontalOffset =
         navigationBarRight - launcherRight - _kQuickActionsHiddenOverlap;
 
@@ -141,7 +180,7 @@ class ChannelQuickActionsLauncher extends HookConsumerWidget {
               ? Duration.zero
               : _kQuickActionsTabMotionDuration,
           curve: _kQuickActionsTabMotionCurve,
-          right: rightInset,
+          right: effectiveRightInset,
           bottom: closedBottomInset + (effectiveOpen ? openLift : 0),
           child: IgnorePointer(
             ignoring: !visible,
@@ -171,7 +210,7 @@ class ChannelQuickActionsLauncher extends HookConsumerWidget {
                 ),
                 child: _MorphingQuickActionsButton(
                   open: effectiveOpen,
-                  openEdgeOffset: rightInset - Grid.gutter,
+                  openEdgeOffset: effectiveRightInset - Grid.gutter,
                   onToggle: () {
                     unawaited(HapticFeedback.lightImpact());
                     quickActionsOpen.value = !quickActionsOpen.value;

mobile/test/features/home/home_page_test.dart

@@ -13,6 +13,7 @@ void main() {
     int unreadInboxCount = 0,
     bool disableAnimations = false,
     Gradient? topSectionGradient,
+    double bottomViewPadding = 0,
   }) async {
     SharedPreferences.setMockInitialValues({});
     final prefs = await SharedPreferences.getInstance();
@@ -21,9 +22,11 @@ void main() {
       child: MaterialApp(
         theme: AppTheme.light(topSectionGradient: topSectionGradient),
         builder: (context, child) => MediaQuery(
-          data: MediaQuery.of(
-            context,
-          ).copyWith(disableAnimations: disableAnimations),
+          data: MediaQuery.of(context).copyWith(
+            disableAnimations: disableAnimations,
+            viewPadding: EdgeInsets.only(bottom: bottomViewPadding),
+            padding: EdgeInsets.only(bottom: bottomViewPadding),
+          ),
           child: child!,
         ),
         home: HomePage(
@@ -34,6 +37,69 @@ void main() {
     );
   }
 
+  Future<void> pumpHomeOnPhoneSurface(
+    WidgetTester tester, {
+    required Size surfaceSize,
+    required double bottomViewPadding,
+  }) async {
+    tester.view.devicePixelRatio = 1;
+    tester.view.physicalSize = surfaceSize;
+    tester.view.viewPadding = FakeViewPadding(bottom: bottomViewPadding);
+    addTearDown(tester.view.reset);
+    await tester.pumpWidget(
+      await buildHome(bottomViewPadding: bottomViewPadding),
+    );
+    await tester.pumpAndSettle();
+  }
+
+  void expectQuickActionClearOfHomeTab({required WidgetTester tester}) {
+    final surfaceSize = tester.view.physicalSize / tester.view.devicePixelRatio;
+    final quickAction = find.byTooltip('Create or start conversation');
+    expect(quickAction, findsOneWidget);
+
+    final quickActionRect = tester.getRect(
+      find.byKey(const Key('channel-quick-actions-motion')),
+    );
+    expect(quickActionRect.left, greaterThanOrEqualTo(0));
+    expect(quickActionRect.top, greaterThanOrEqualTo(0));
+    expect(quickActionRect.right, lessThanOrEqualTo(surfaceSize.width));
+    expect(quickActionRect.bottom, lessThanOrEqualTo(surfaceSize.height));
+
+    final homeDestinationRect = tester.getRect(find.bySemanticsLabel('Home'));
+    expect(quickActionRect.overlaps(homeDestinationRect), isFalse);
+  }
+
+  group('phone quick action layout', () {
+    const phoneSurfaces = [Size(360, 800), Size(412, 915)];
+    const bottomInsets = [0.0, 48.0];
+
+    for (final surfaceSize in phoneSurfaces) {
+      for (final bottomInset in bottomInsets) {
+        testWidgets(
+          'keeps the quick action on-screen on ${surfaceSize.width.toInt()}x'
+          '${surfaceSize.height.toInt()} with bottom inset $bottomInset',
+          (tester) async {
+            await pumpHomeOnPhoneSurface(
+              tester,
+              surfaceSize: surfaceSize,
+              bottomViewPadding: bottomInset,
+            );
+
+            expectQuickActionClearOfHomeTab(tester: tester);
+
+            await tester.tap(
+              find.byKey(const Key('channel-quick-actions-motion')),
+            );
+            await tester.pumpAndSettle();
+
+            expect(find.text('Create channel'), findsOneWidget);
+            expect(find.text('New direct message'), findsOneWidget);
+          },
+        );
+      }
+    }
+  });
+
   testWidgets('shows icon-only navigation and an aligned quick action', (
     tester,
   ) async {