diff --git a/docker/frontend/src/App.tsx b/docker/frontend/src/App.tsx
index 77060c9..f09d2ba 100644
--- a/docker/frontend/src/App.tsx
+++ b/docker/frontend/src/App.tsx
@@ -589,11 +589,19 @@ export function Workspace() {
   // and the whole photo is shown), and applied (the crop alone is rendered).
   // What the stage says it is painting at; PREVIEW_MAX until it reports.
   const [zoomNeedPx, setZoomNeedPx] = useState(PREVIEW_MAX);
+  // What the stage may be asked for, in device pixels: the photo's own longest
+  // edge once that is bigger than the cap. `resizedJpeg` never grows a photo,
+  // so at this size it hands the original bytes straight back — a frame zoomed
+  // past 3200 is then the frame itself rather than a 3200px copy stretched over
+  // the screen, which is the blur a reader reads as the thumbnail having been
+  // opened. The copy still only grows when the stage says it needs it: at
+  // fitting size the 1600px one stands, and the edit keeps its old cost.
+  const previewCeiling = Math.max(PREVIEW_HARD_MAX, photoDims ? Math.max(photoDims.w, photoDims.h) : 0);
   const onStageZoom = useCallback((longDevicePx: number) => {
     setZoomNeedPx(
-      Math.max(PREVIEW_MAX, Math.min(PREVIEW_HARD_MAX, Math.ceil(longDevicePx / PREVIEW_QUANTUM) * PREVIEW_QUANTUM))
+      Math.max(PREVIEW_MAX, Math.min(previewCeiling, Math.ceil(longDevicePx / PREVIEW_QUANTUM) * PREVIEW_QUANTUM))
     );
-  }, []);
+  }, [previewCeiling]);
   const cropEditing = crop !== 'none' && !cropApplied;
   const cropLive = crop !== 'none' && cropApplied;
   // A committed crop keeps only part of the photo, so the 1600px copy leaves
@@ -636,7 +644,7 @@ export function Workspace() {
   })();
   const cropWH = crop !== 'none' && crop !== 'free' ? CROP_W_H[crop] : null;
   const previewMax = Math.min(
-    PREVIEW_HARD_MAX,
+    previewCeiling,
     Math.max(
       zoomNeedPx,
       cropLive