Function run_strict_tw 

pub fn run_strict_tw(source: &str) -> EngineOutcome

Run source STRICTLY on the tree-walker. Identical pipeline to tw_outcome (same front-end, same oracle engine — concurrency runs on the tree-walker’s deterministic scheduler), plus the honest engine identity: engine_ran is Some(TreeWalker) whenever the program executed, None for a parse failure (nothing ran on any engine).