fix: unstuck agent after tool calls, display completed streams

backend/src/utils.py

@@ -20,7 +20,10 @@ def encode_value(value):
             json['result'] = encode_value(value.result),
         return json
     elif isinstance(value, Stream):
-        return {'streamId': value.id}
+        if value.open:
+            return {'streamId': value.id}
+        else:
+            return value.content
     else:
         return value