(fix): Pinch to close doesn't navigate back

Changelog: fix

Author: markharding

apps/polycentric/src/features/post/ImageViewer/ImageViewer.tsx

@@ -176,7 +176,9 @@ export function ImageViewer({
           if (scale.value > 1) {
             translateX.value = savedTranslateX.value + e.translationX;
             translateY.value = savedTranslateY.value + e.translationY;
-          } else {
+          } else if (scale.value === 1) {
+            // Only drag-to-dismiss at natural size; ignore the centroid
+            // drift while a pinch is shrinking the image.
             dismissY.value = e.translationY;
           }
         })
@@ -186,6 +188,13 @@ export function ImageViewer({
             savedTranslateY.value = translateY.value;
             return;
           }
+          if (scale.value < 1) {
+            // A pinch-to-close is in progress; let the pinch decide
+            // whether to dismiss, so we don't double-fire onClose (which
+            // on Android popped an extra screen).
+            dismissY.value = withTiming(0, { duration: 150 });
+            return;
+          }
           const dismiss =
             Math.abs(e.translationY) > CLOSE_DISTANCE ||
             Math.abs(e.velocityY) > CLOSE_VELOCITY;

apps/polycentric/src/features/post/ImageViewer/ImageViewerScreen.tsx

@@ -1,5 +1,5 @@
 import { router } from 'expo-router';
-import { useCallback } from 'react';
+import { useCallback, useRef } from 'react';
 import { ImageViewer } from './ImageViewer';
 import { useImageViewerStore } from './useImageViewerStore';
 
@@ -13,7 +13,13 @@ export default function ImageViewerScreen() {
   const images = useImageViewerStore((s) => s.images);
   const index = useImageViewerStore((s) => s.index);
 
+  // Guard against double-dismiss: simultaneous pinch + pan can both fire
+  // close, and `router.canGoBack()` may still read true before the first
+  // back() settles — popping an extra screen (notably on Android).
+  const closing = useRef(false);
   const onClose = useCallback(() => {
+    if (closing.current) return;
+    closing.current = true;
     if (router.canGoBack()) router.back();
   }, []);