refactor lightbox orientation transform

src/view/com/lightbox/ImageViewing/index.tsx

@@ -59,6 +59,10 @@ type Rect = {x: number; y: number; width: number; height: number}
 const PORTRAIT_UP = ScreenOrientation.OrientationLock.PORTRAIT_UP
 const PIXEL_RATIO = PixelRatio.get()
 
+function lockOrientationToPortrait() {
+  void ScreenOrientation.lockAsync(PORTRAIT_UP)
+}
+
 const SLOW_SPRING: WithSpringConfig = {
   mass: IS_IOS ? 1.25 : 0.75,
   damping: 300,
@@ -137,23 +141,38 @@ export default function ImageViewRoot({
   )
 
   // Delay the unlock until after we've finished the scale up animation.
-  // It's complicated to do the same for locking it back so we don't attempt that.
   useAnimatedReaction(
     () => openProgress.get() === 1,
     (isOpen, wasOpen) => {
       if (isOpen && !wasOpen) {
         runOnJS(ScreenOrientation.unlockAsync)()
-      } else if (!isOpen && wasOpen) {
-        // default is PORTRAIT_UP - set via config plugin in app.config.js -sfn
-        runOnJS(ScreenOrientation.lockAsync)(PORTRAIT_UP)
       }
     },
   )
 
+  // Lock orientation back to portrait BEFORE triggering the close animation.
+  // This ensures the feed re-layouts while the lightbox is still fully opaque,
+  // preventing the scroll-to-top issue caused by orientation change.
+  const lockAndClose = useCallback(() => {
+    if (orientation === 'landscape') {
+      void ScreenOrientation.lockAsync(PORTRAIT_UP).then(() => {
+        // Give the layout time to settle behind the lightbox.
+        setTimeout(onRequestClose, 500)
+      })
+    } else {
+      void ScreenOrientation.lockAsync(PORTRAIT_UP)
+      onRequestClose()
+    }
+  }, [orientation, onRequestClose])
+
   const onFlyAway = useCallback(() => {
     'worklet'
+    // Fly-away: image is already off-screen, dismiss immediately.
+    // Lock orientation after — the fast swipe makes any brief scroll
+    // glitch less noticeable than the close button path.
     openProgress.set(0)
     runOnJS(onRequestClose)()
+    runOnJS(lockOrientationToPortrait)()
   }, [onRequestClose, openProgress])
 
   return (
@@ -178,7 +197,7 @@ export default function ImageViewRoot({
             key={activeLightbox.id + '-' + orientation}
             lightbox={activeLightbox}
             orientation={orientation}
-            onRequestClose={onRequestClose}
+            onRequestClose={lockAndClose}
             onPressSave={onPressSave}
             onPressShare={onPressShare}
             onFlyAway={onFlyAway}

src/view/com/util/List.tsx

@@ -1,4 +1,11 @@
-import {forwardRef, memo, useDeferredValue, useMemo} from 'react'
+import {
+  forwardRef,
+  memo,
+  useDeferredValue,
+  useEffect,
+  useMemo,
+  useRef,
+} from 'react'
 import {RefreshControl, type ViewToken} from 'react-native'
 import {
   type FlatListPropsWithLayout,
@@ -60,9 +67,12 @@ let List = forwardRef<ListMethods, ListProps>(
     ref,
   ): React.ReactElement<any> => {
     const isScrolledDown = useSharedValue(false)
+    const scrollOffsetY = useSharedValue(0)
+    const localRef = useRef<FlatList_INTERNAL | null>(null)
     const t = useTheme()
     const dedupe = useDedupe(400)
     const scrollsToTop = useAllowScrollToTop()
+    useSaveScrollOnLightbox(localRef, scrollOffsetY)
 
     const handleScrolledDownChange = useNonReactiveCallback(
       (didScrollDown: boolean) => {
@@ -88,6 +98,7 @@ let List = forwardRef<ListMethods, ListProps>(
       },
       onScroll(e, ctx) {
         onScrollFromContext?.(e, ctx)
+        scrollOffsetY.set(e.contentOffset.y)
 
         const didScrollDown = e.contentOffset.y > SCROLLED_DOWN_LIMIT
         if (isScrolledDown.get() !== didScrollDown) {
@@ -174,8 +185,11 @@ let List = forwardRef<ListMethods, ListProps>(
         scrollsToTop={scrollsToTop}
         scrollEventThrottle={1}
         style={style}
-        // @ts-expect-error FlatList_INTERNAL ref type is wrong -sfn
-        ref={ref}
+        ref={node => {
+          localRef.current = node
+          if (typeof ref === 'function') ref(node)
+          else if (ref) (ref as React.MutableRefObject<any>).current = node
+        }}
       />
     )
   },
@@ -192,3 +206,26 @@ function useAllowScrollToTopIOS() {
   const {activeLightbox} = useLightbox()
   return useDeferredValue(!activeLightbox)
 }
+
+// Save scroll position when lightbox opens, restore it when it closes.
+// This prevents the scroll-to-top caused by orientation changes during lightbox viewing.
+function useSaveScrollOnLightbox(
+  listRef: React.RefObject<FlatList_INTERNAL | null>,
+  scrollOffsetY: {get(): number},
+) {
+  const {activeLightbox} = useLightbox()
+  const savedOffset = useRef<number | null>(null)
+
+  useEffect(() => {
+    if (activeLightbox) {
+      savedOffset.current = scrollOffsetY.get()
+    } else if (savedOffset.current !== null) {
+      const offset = savedOffset.current
+      savedOffset.current = null
+      // Restore after layout settles from any orientation change.
+      requestAnimationFrame(() => {
+        listRef.current?.scrollToOffset({offset, animated: false})
+      })
+    }
+  }, [activeLightbox, listRef, scrollOffsetY])
+}