Exact void percolation in D_9^+: two equally deep holes with different escapes

The packing D_9^+, the union of the checkerboard lattice D_9 with its shift by (1/2,...,1/2), has two inequivalent deepest holes, both at squared distance 17/16 from the sites. As hiding places they are equal. As places to escape from they are not. Grow a ball of squared radius t around every site: one deepest hole joins an infinite network of clear passages as soon as t ≤ 33/32, while the other stays a sealed pocket until t ≤ 213/224. The whole void becomes one connected region exactly when t ≤ 8/9, and the last pockets to join are the holes at squared distance 1, which are neither the deepest nor the shallowest. The paper proves both thresholds exactly, with attainment, for closed and open levels, and determines the attachment level of each of the six hole types. Depth is the circumradius of a hole's contact configuration; the barrier to escape is set by its inradius, and the two deepest holes share the first and differ in the second. The critical network carries every translation of D_9. The deposit contains the paper and its TeX source, the exact rational certificate with its replay programs, an independent exact reconstruction of the principal values written from the manuscript alone, and a second independent computation of the Voronoi cell.