fix: resize gallery thumbnails for current high density cards

pigway_frame_flow/api/app.py

@@ -421,12 +421,19 @@ def create_app(settings=None, start_worker=True):
                 raise FlowError(E.INVALID_REQUEST, "Invalid cloud image") from None
         if thumbnail:
             thumb = cached.with_name(cached.stem + "-thumb.jpg")
-            if not thumb.exists():
-                from PIL import Image
+            from PIL import Image
 
-                with Image.open(cached) as img:
-                    img.thumbnail((300, 400))
-                    img.save(thumb, "JPEG")
+            with Image.open(cached) as img:
+                # The 430px cards need up to 860px on 2x displays. Replace the
+                # existing cache in place so old 300px previews are upgraded.
+                expected_edge = min(860, max(img.size))
+                regenerate = not thumb.exists()
+                if not regenerate:
+                    with Image.open(thumb) as existing:
+                        regenerate = max(existing.size) != expected_edge
+                if regenerate:
+                    img.thumbnail((860, 860), Image.Resampling.LANCZOS)
+                    img.convert("RGB").save(thumb, "JPEG", quality=88, optimize=True)
             return FileResponse(thumb, media_type="image/jpeg")
         from PIL import Image