calendar: fix _days_until to handle Unix timestamps from todoman --porcelain

skills/calendar/scripts/cal_tool.py

@@ -413,15 +413,23 @@ def _todoman_list_json(*extra_args):
     return json.loads(result.stdout)
 
 
-def _days_until(due_str):
+def _days_until(due_val):
-    """Days from today until due date string. Negative means overdue."""
+    """Days from today until due date (string or Unix timestamp). Negative means overdue."""
-    if not due_str:
+    if not due_val:
         return None
+    # Unix timestamp (int/float) from todoman --porcelain
+    if isinstance(due_val, (int, float)):
+        try:
+            due_date = datetime.fromtimestamp(due_val, tz=timezone.utc).date()
+        except (ValueError, TypeError, OSError):
+            return None
+        return (due_date - date.today()).days
+    # String formats (ISO or YYYY-MM-DD)
     try:
-        due_date = datetime.fromisoformat(due_str).date()
+        due_date = datetime.fromisoformat(due_val).date()
     except (ValueError, TypeError):
         try:
-            due_date = _parse_date(due_str)
+            due_date = _parse_date(due_val)
         except ValueError:
             return None
     return (due_date - date.today()).days