Function compile_to_tenstorrent_fanout 

pub fn compile_to_tenstorrent_fanout(
    source: &str,
) -> Result<MeshLowering<FanoutSpec>, String>

Recognize a fan-out program (N distinct tasks each send one value into a shared pipe; main folds all N) and lower its concurrency onto the Tensix mesh — one core per task, main folding via a NoC + semaphore barrier. The commutative fold makes the mesh’s arrival order irrelevant, so it is ≡VM. Errors if the program is not the fan-out pattern (the caller falls back to the sound refusal).