update picked data strucures

hbd/server/threshold.py

@@ -120,8 +120,11 @@ class AlertState:
         
         # Helper to sanitize numeric values for JSON (handle inf/nan)
         def sanitize_value(val):
-            if isinstance(val, float) and (math.isinf(val) or math.isnan(val)):
-                return None
+            if isinstance(val, float):
+                if math.isinf(val):
+                    return "overdue"
+                if math.isnan(val):
+                    return None
             return val
         
         result = {
@@ -148,6 +151,12 @@ class AlertState:
         
         return result
     
+    def __setstate__(self, state):
+        """Restore from pickle, backfilling fields added after the pickle was written."""
+        self.__dict__.update(state)
+        if not hasattr(self, 'consecutive_count'):
+            self.consecutive_count = 0
+
     def acknowledge(self):
         """Acknowledge this alert to stop reminder notifications."""
         self.acknowledged = True