// Module B authors a DIFFERENT same-name chain: `M :: 10`, `K :: M + 1` (= 11).
// A shadow of A's `M`/`K`. Pre-fix the dimension fold collapsed to B's `M` for
// BOTH modules via the global last-wins map; now each `K`'s RHS leaf resolves to
// its own source's `M`.
M :: 10;
K :: M + 1;
b_val :: () -> s64 { return K; }
b_len :: () -> s64 {
    arr : [K]u8 = ---;
    return arr.len;
}