Constant MALFORMED_SEARCH_OUTPUT_TRIGGER 

const MALFORMED_SEARCH_OUTPUT_TRIGGER: &str = "!MOCK_MALFORMED_SEARCH_OUTPUT!";

Drives a search round whose completed output fails to parse as the chatbot’s search-output schema: the same plain-text failure shape a real search backend can return, but on a completed item rather than the in-progress placeholder every other scenario here uses.