fix(iOS, Tabs): make bottom accessory content switching robust and survive window detach

ios/tabs/bottom-accessory/RNSTabsBottomAccessoryComponentView.mm

@@ -49,9 +49,37 @@ - (void)initState
 - (void)didMoveToWindow
 {
   if (self.window != nil) {
+    // The helper & shadow proxy are torn down below whenever the accessory
+    // leaves the window (e.g. a full-screen push covering the tab bar), so
+    // they must be recreated on re-entry — previously
+    // `registerForAccessoryFrameChanges` was messaged at nil here and all
+    // trait/frame callbacks and content-view switching stayed permanently
+    // dead after the first full-screen push, freezing the accessory on
+    // whichever content copy was last visible. The content views' own
+    // `didMoveToWindow` runs after this one (window changes propagate
+    // top-down), so they re-register into the fresh helper.
+    if (@available(iOS 26, *)) {
+      if (_helper == nil) {
+        _helper = [[RNSTabsBottomAccessoryHelper alloc] initWithBottomAccessoryView:self];
+      }
+      if (_shadowStateProxy == nil) {
+        _shadowStateProxy = [[RNSTabsBottomAccessoryShadowStateProxy alloc] initWithBottomAccessoryView:self];
+      }
+    }
     [_helper registerForAccessoryFrameChanges];
   } else {
-    [self invalidate];
+    // Lighter teardown than `invalidate` — keep the Fabric `_state` alive
+    // across a detach/reattach cycle. Only React can re-deliver the state
+    // (via `updateState` on a commit), so resetting it on a mere window
+    // detach would leave the recreated shadow proxy unable to publish
+    // accessory frame updates until an unrelated commit happens to arrive.
+    // True unmount still fully invalidates via RNSTabsHostComponentView.
+    if (@available(iOS 26, *)) {
+      [_helper invalidate];
+      _helper = nil;
+      [_shadowStateProxy invalidate];
+      _shadowStateProxy = nil;
+    }
   }
 }
 

ios/tabs/bottom-accessory/RNSTabsBottomAccessoryHelper.mm

@@ -39,11 +39,6 @@ - (void)initState
 
 #pragma mark - Content view switching workaround
 
-- (BOOL)isContentViewSwitchingWorkaroundActive
-{
-  return _regularContentView != nil && _inlineContentView != nil;
-}
-
 - (void)setContentView:(RNSTabsBottomAccessoryContentComponentView *)contentView
         forEnvironment:(RNSTabsBottomAccessoryEnvironment)environment
 {
@@ -65,20 +60,29 @@ - (void)setContentView:(RNSTabsBottomAccessoryContentComponentView *)contentView
 
 - (void)handleContentViewVisibilityForEnvironmentIfNeeded
 {
-  if (!self.isContentViewSwitchingWorkaroundActive) {
-    return;
-  }
-
-  switch (self->_bottomAccessoryView.traitCollection.tabAccessoryEnvironment) {
-    case UITabAccessoryEnvironmentInline:
-      _regularContentView.layer.opacity = 0.0;
-      _inlineContentView.layer.opacity = 1.0;
-      break;
-    default:
-      _regularContentView.layer.opacity = 1.0;
-      _inlineContentView.layer.opacity = 0.0;
-      break;
-  }
+  // `hidden` is used as the sole carrier of invisibility, with alpha
+  // normalized to 1.0 on both content views:
+  // - `RCTViewComponentView.invalidateLayer` unconditionally resets
+  //   `layer.opacity` to the React props value on arbitrary commits, which
+  //   used to re-show the off-environment copy. It never touches `hidden`,
+  //   and with alpha kept at 1.0 the reset becomes a no-op by construction.
+  // - The off-environment copy is mounted absoluteFill ON TOP of the active
+  //   one (later sibling); when it regained opacity it also captured all
+  //   hit-testing, making the accessory unresponsive to taps. Hidden views
+  //   are excluded from hit-testing.
+  // Applied to whichever content views are registered (messages to nil are
+  // no-ops) — the previous both-registered early-return left a lone
+  // registered view fully visible until its sibling registered.
+  BOOL isInline =
+      self->_bottomAccessoryView.traitCollection.tabAccessoryEnvironment == UITabAccessoryEnvironmentInline;
+
+  UIView *viewToShow = isInline ? _inlineContentView : _regularContentView;
+  UIView *viewToHide = isInline ? _regularContentView : _inlineContentView;
+
+  viewToShow.hidden = NO;
+  viewToShow.alpha = 1.0;
+  viewToHide.hidden = YES;
+  viewToHide.alpha = 1.0;
 }
 
 #pragma mark - Observing environment changes
@@ -149,6 +153,15 @@ - (void)notifyWrapperViewFrameHasChanged
   // We use self.nativeWrapperView because it has both the size and the origin
   // that we want to send to the ShadowNode.
   [_bottomAccessoryView.shadowStateProxy updateShadowStateWithFrame:self.nativeWrapperView.frame];
+
+  // The wrapper frame changes on every regular <-> inline move, so re-evaluate
+  // content-view visibility here as well. The one-shot
+  // UITraitTabAccessoryEnvironment registration callback is occasionally
+  // missed during the minimize transition, which left the wrong copy visible
+  // inside the inline accessory (or vice versa); this KVO fires reliably on
+  // each transition (and once on registration via
+  // NSKeyValueObservingOptionInitial) and self-corrects that.
+  [self handleContentViewVisibilityForEnvironmentIfNeeded];
 }
 
 #pragma mark - Invalidation