FR-DEV-8 is the last develop requirement with nothing behind it. The
pipeline it lands on already has most of the parts — the neighbourhood
stage, the mask crate's normalised coordinates, the gradient handles'
canvas drags, the merge-by-id rule — so the spec is mostly about the four
things that are genuinely new, and about the two places where the obvious
implementation is the wrong one: a Poisson solve is sixty dispatches per
spot, and a per-frame readback to find out what colour a sky is would undo
ARCH §6.1.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
