const SCATTER_SLOTS: 1024
Candidate slots per region: a 32 by 32 lattice.
The o: index runs 0 to this, and every slot is a fixed question — does this
region hold a rock at slot 837 — rather than a counter over the rocks that
exist. That is what makes an address stable: adding a density term changes
whether slot 837 is occupied and never which rock it is.
A power of two so the lattice is exact, and this large because rock abundance
is the one thing in this milestone a person standing on the ground reads
immediately. It is also what makes slots exist: resolving a candidate is a
field sample, so a whole region is 2.6 to 5.8 ms across the zoo and
cannot be paid inside one frame.