Fix

app.py

@@ -1,4 +1,5 @@
 from functools import lru_cache
+import re
 import traceback
 from typing import Optional
 
@@ -18,6 +19,8 @@ IMAGE_EXTENSIONS = (
     ".tif",
     ".tiff",
 )
+INIT_SCREENSHOT_NAMES = {"intial_screenshot", "initial_screenshot"}
+STEP_FILENAME_PATTERN = re.compile(r"^step_(\d+)(?:\.[^.]+)?$", re.IGNORECASE)
 
 
 api = HfApi()
@@ -71,12 +74,28 @@ def _get_image_urls(repo_id: str, directory: str) -> list[str]:
         and path.lower().endswith(IMAGE_EXTENSIONS)
     ]
 
+    sorted_files = sorted(image_files, key=_image_sort_key)
+
     return [
         hf_hub_url(repo_id=repo_id, filename=path, repo_type="dataset")
-        for path in sorted(image_files)
+        for path in sorted_files
     ]
 
 
+def _image_sort_key(path: str):
+    filename = path.rsplit("/", 1)[-1]
+    lower_name = filename.lower()
+
+    if any(lower_name.startswith(name) for name in INIT_SCREENSHOT_NAMES):
+        return (0, 0)
+
+    match = STEP_FILENAME_PATTERN.match(lower_name)
+    if match:
+        return (1, int(match.group(1)))
+
+    return (2, lower_name)
+
+
 def _dropdown_update(
     *,
     choices: list[str],