Function route 

pub fn route(
    m: u32,
    n: u32,
    k: u32,
    enabled: bool,
    have: [bool; 3],
) -> Option<DtcKind>

2026-09-25: Pure routing decision; None keeps the caller’s kernel.

have says which of [tc8, tc16, tc32] resolved. The narrowest resolved entry that covers m wins; a wider one is also correct, because a token tile past M is skipped. Declines when enabled is false, m < MIN_M, n == 0, k == 0 or k is not a multiple of K_STEP. Any other N routes: the kernel loads zeros for weight rows past N and never stores them.