Function validate_frontier_queue_batch 

pub fn validate_frontier_queue_batch(
    node_count: u32,
    frontiers: &[&[u32]],
    queue_capacity: u32,
) -> Result<usize, String>

Validate a batch of packed frontiers for queue-driven CSR traversal.

Returns the exact packed frontier word count implied by node_count, so dispatch wrappers can size resident scratch without duplicating the primitive’s batch-shape contract.

Errors

Returns an actionable diagnostic for zero-node graphs, empty batches, zero queue capacity, or any query frontier whose packed bitset width does not match node_count.