Validation: skip pairs with missing image paths; docs: add Updates section describing pairing/scheduling, storage, fairness, and config (AGENTS.md updated but intentionally ignored)

app.py

@@ -46,6 +46,12 @@ def _resolve_image_path(path: str) -> str:
     return path if os.path.isabs(path) else os.path.join(BASE_DIR, path)
 
 
+def _file_exists_under_base(rel_or_abs_path: str) -> bool:
+    """Check if file exists, resolving relative paths under BASE_DIR."""
+    check_path = rel_or_abs_path if os.path.isabs(rel_or_abs_path) else os.path.join(BASE_DIR, rel_or_abs_path)
+    return os.path.exists(check_path)
+
+
 def _load_task_rows(task_name: str) -> List[Dict[str, str]]:
     csv_path = _csv_path_for_task(task_name, "results.csv")
     if not os.path.exists(csv_path):
@@ -70,15 +76,31 @@ def _build_image_pairs(rows: List[Dict[str, str]], task_name: str) -> List[Dict[
             if model_a["model_name"] == model_b["model_name"]:
                 continue
 
+            org_path = os.path.join(folder, org_img)
+            path_a = os.path.join(folder, model_a["path"])
+            path_b = os.path.join(folder, model_b["path"])
+
+            # Validate existence to avoid UI errors
+            if not (_file_exists_under_base(org_path) and _file_exists_under_base(path_a) and _file_exists_under_base(path_b)):
+                try:
+                    print("[VisArena] Skipping invalid paths for test_id=", test_id, {
+                        "org": org_path,
+                        "a": path_a,
+                        "b": path_b,
+                    })
+                except Exception:
+                    pass
+                continue
+
             pair = {
                 "test_id": test_id,
-                "org_img": os.path.join(folder, org_img),
+                "org_img": org_path,
                 "model1_name": model_a["model_name"],
                 "model1_res": model_a["res"],
-                "model1_path": os.path.join(folder, model_a["path"]),
+                "model1_path": path_a,
                 "model2_name": model_b["model_name"],
                 "model2_res": model_b["res"],
-                "model2_path": os.path.join(folder, model_b["path"]),
+                "model2_path": path_b,
             }
             pairs.append(pair)