diff --git a/services/agent-system/webui/web.py b/services/agent-system/webui/web.py
index d6a7fae..6833da5 100644
--- a/services/agent-system/webui/web.py
+++ b/services/agent-system/webui/web.py
@@ -68,12 +68,22 @@ def current_recommendations():
 
 
 def current_summary():
-    summary = read_json_file(WORLD_DIR / "runtime-summary.json", default={})
+    path = WORLD_DIR / "runtime-summary.json"
+    summary = read_json_file(path, default={})
     if summary:
-        # Check for staleness
-        mtime = os.path.getmtime(WORLD_DIR / "runtime-summary.json")
-        summary["last_update"] = mtime
-        summary["stale"] = (time.time() - mtime) > 60  # Stale if older than 60s
+        last_update_val = summary.get("last_update")
+        if last_update_val:
+            try:
+                if isinstance(last_update_val, str):
+                    last_update = datetime.fromisoformat(last_update_val.replace('Z', '+00:00')).timestamp()
+                else:
+                    last_update = float(last_update_val)
+            except Exception:
+                last_update = os.path.getmtime(path)
+        else:
+            last_update = os.path.getmtime(path)
+        summary["last_update"] = last_update
+        summary["stale"] = (time.time() - last_update) > 60
     return summary
 
 
diff --git a/services/control-plane/src/operator_ui.py b/services/control-plane/src/operator_ui.py
index 67ced90..ce5def3 100644
--- a/services/control-plane/src/operator_ui.py
+++ b/services/control-plane/src/operator_ui.py
@@ -164,22 +164,22 @@ def current_recommendations():
 
 
 def current_summary():
-    summary = read_json_file(WORLD_DIR / "runtime-summary.json", default={})
+    path = WORLD_DIR / "runtime-summary.json"
+    summary = read_json_file(path, default={})
     if summary:
-        # Check for staleness from the summary's own timestamp if available
-        # otherwise use file mtime
-        last_update_str = summary.get("last_update")
-        if last_update_str:
+        last_update_val = summary.get("last_update")
+        if last_update_val:
             try:
-                # Assuming ISO format from observer.py
-                last_update = datetime.fromisoformat(last_update_str.replace('Z', '+00:00')).timestamp()
+                if isinstance(last_update_val, str):
+                    last_update = datetime.fromisoformat(last_update_val.replace('Z', '+00:00')).timestamp()
+                else:
+                    last_update = float(last_update_val)
             except Exception:
-                last_update = os.path.getmtime(WORLD_DIR / "runtime-summary.json")
+                last_update = os.path.getmtime(path)
         else:
-            last_update = os.path.getmtime(WORLD_DIR / "runtime-summary.json")
-            
+            last_update = os.path.getmtime(path)
         summary["last_update"] = last_update
-        summary["stale"] = (time.time() - last_update) > 60  # Stale if older than 60s
+        summary["stale"] = (time.time() - last_update) > 60
     return summary