fix(bottom-tabs): report tab bar height on placement change

native-views/react-native-bottom-tabs/docs/SPEC.md

@@ -104,6 +104,11 @@ height: a rendered custom bar's own measured height takes precedence; otherwise
 `tabBarHidden` forces zero. Native hide measurements MUST NOT overwrite a custom
 bar's height, including across native/custom presentation switches.
 
+The iOS drawer MUST NOT receive touches inside the native tab bar at any
+placement, because a vertical bar reports no bottom height. That covers
+everything under the tab controller's view outside tab content, including the
+floating item platter and side accessory.
+
 With opening swipes enabled, a one-finger rightward gesture may start anywhere
 in the foreground content. At the first confirmed direction, the actual native
 touch target and its ancestor chain determine ownership. A horizontal scroll
@@ -326,6 +331,12 @@ placement and can draw one round accessory button above the vertical bar.
   tab bar controller. It fires once after the bar is created and again on every
   change (rotation, folding, window resizing). Builds without the iOS 27.1 SDK
   and earlier systems always report `bottom`. Android never fires it.
+- **Height on placement change:** every placement event is followed by
+  `onTabBarMeasured` with the bar's current height, because the height reported
+  for the previous placement no longer applies. A vertical bar reports its full
+  column height, so `BottomTabs` MUST expose 0 through
+  `BottomTabBarHeightContext` and the drawer's `bottomBarHeight` for `leading`
+  and `trailing` placement, and the measured height only for `bottom`.
 - **Side accessory:** `sideAccessoryIcon` (an image source, loaded with the
   React image loader and drawn as a template tinted with `inactiveTintColor`),
   `sideAccessoryLabel` (accessibility label), and `onSideAccessoryPress`. The

native-views/react-native-bottom-tabs/ios/RCTBottomTabsContainerView.swift

@@ -344,6 +344,9 @@ class RCTBottomTabsContainerView: UIView {
     if placement != reportedTabBarPlacement {
       reportedTabBarPlacement = placement
       onTabBarPlacementChange?(["placement": placement])
+      // The bar's frame follows its placement, so the height reported for the
+      // previous placement is stale.
+      onTabBarMeasured?(["height": tabBarHidden ? 0 : Double(tbc.tabBar.frame.size.height)])
     }
 
     guard placement != "bottom",

native-views/react-native-bottom-tabs/ios/RCTBottomTabsDrawerContainerView.swift

@@ -135,6 +135,7 @@ final class RCTBottomTabsDrawerContainerView: UIView, UIGestureRecognizerDelegat
     guard enabled else { return false }
     let start = touch.location(in: self)
     guard start.y < bounds.height - CGFloat(max(0, bottomBarHeight)) else { return false }
+    guard !isInsideNativeTabBar(touch.view) else { return false }
     touchTarget = touch.view
     if progress > 0 { return start.x >= bounds.width * 0.78 * progress }
     return swipeEnabled && !touchPathContainsExclusiveControl()
@@ -171,6 +172,24 @@ final class RCTBottomTabsDrawerContainerView: UIView, UIGestureRecognizerDelegat
     return other is UIScreenEdgePanGestureRecognizer
   }
 
+  // A vertical bar reports no bottom height, and UIKit draws its items in a
+  // floating platter outside UITabBar, so match anything under the tab
+  // controller's view that is not tab content.
+  private func isInsideNativeTabBar(_ target: UIView?) -> Bool {
+    var path: [UIView] = []
+    var view = target
+    while let current = view, current !== self {
+      if current is UITabBar { return true }
+      if let tabs = current.next as? UITabBarController {
+        let content = (tabs.viewControllers ?? []).compactMap { $0.viewIfLoaded }
+        return !path.contains { step in content.contains { $0 === step } }
+      }
+      path.append(current)
+      view = current.superview
+    }
+    return false
+  }
+
   private func touchPathContainsExclusiveControl() -> Bool {
     var view = touchTarget
     while let current = view, current !== self {

native-views/react-native-bottom-tabs/src/BottomTabs.tsx

@@ -399,9 +399,12 @@ const BottomTabs = <Route extends BaseRoute>({
     useRef<React.ElementRef<typeof NativeBottomTabs>>(null);
   const [nativeTabBarHeight, setNativeTabBarHeight] = React.useState(0);
   const [customTabBarHeight, setCustomTabBarHeight] = React.useState(0);
+  const [tabBarPlacement, setTabBarPlacement] =
+    React.useState<TabBarPlacement>("bottom");
+  // A vertical bar measures its full column height but takes no bottom space.
   const tabBarHeight = renderCustomTabBar
     ? customTabBarHeight
-    : props.tabBarHidden
+    : props.tabBarHidden || tabBarPlacement !== "bottom"
     ? 0
     : nativeTabBarHeight;
   const [measuredDimensions, setMeasuredDimensions] = React.useState<
@@ -566,7 +569,9 @@ const BottomTabs = <Route extends BaseRoute>({
 
   const handleTabBarPlacementChange = React.useCallback(
     (event: NativeSyntheticEvent<{ placement: string }>) => {
-      onTabBarPlacementChange?.(event.nativeEvent.placement as TabBarPlacement);
+      const placement = event.nativeEvent.placement as TabBarPlacement;
+      setTabBarPlacement(placement);
+      onTabBarPlacementChange?.(placement);
     },
     [onTabBarPlacementChange]
   );