Function plan_host_grid_sync_segment_programs 

pub fn plan_host_grid_sync_segment_programs(
    program: &Program,
) -> Result<Vec<Program>, BackendError>

Diagnostics: the host-split segment programs (post buffer-rewrite) that the fallback dispatch path (dispatch_with_grid_sync_split*) validates and launches when the backend lacks native grid-sync. Exposed so tooling and tests can inspect or validate each segment without a live backend — the raw try_split_on_grid_sync output omits the per-segment buffer access/role rewrite, so it is not what the backend actually sees.

Errors

Propagates any BackendError from splitting or buffer rewriting.