Function kv_len_ptr_table_range 

pub fn kv_len_ptr_table_range(
    e: &Engine,
    cache: &Cache,
    layers: Range<usize>,
    pos_ctr: Option<&CudaSlice<i32>>,
) -> Result<CudaSlice<u64>, Box<dyn Error>>

Stage-local twin of kv_len_ptr_table. Only pointers owned by layers enter the table, so a reconcile kernel launched through a PP stage’s engine never dereferences another device’s len_d. The returned table is dense over the requested range; callers pass layers.len() to the matching kernel.