Upload app.py

app.py

@@ -392,10 +392,9 @@ def load_all_data(folder_path):
             # 1. Read CSV without parsing dates yet (load as strings to be safe)
             df = pd.read_csv(file_path, header=0, index_col=0, encoding='utf-8')
             
-            # 2. ROBUST DATE PARSING (The "Zig-Zag" Fix)
-            # We explicitly force dayfirst=True here on the index object.
-            # 'coerce' turns invalid formats into NaT so we can drop them.
-            df.index = pd.to_datetime(df.index, dayfirst=True, errors='coerce')
+            # 2. FORCE ISO PARSING (YYYY-MM-DD)
+            # We disable 'dayfirst' because ISO puts Year first.
+            df.index = pd.to_datetime(df.index, format='%Y-%m-%d', errors='coerce')
             
             # 3. Drop rows with invalid dates
             df = df[df.index.notna()]