The Decoder named the elements under my hot tiles and had to test both coordinate
readings, because design space and the comparison frame differ by the capture
transform. I did not need the transform: the port has a mod tree, so shadowing a
sprite with a transparent PNG and diffing my own two renders measures the
element's footprint directly, in the comparison frame, assuming no convention.
Ranked by residual density on each element's own visible pixels: ptframe1 22.72
(9.47x the frame mean), ptframe2 13.09, ptmsg 8.46, pteff12 4.98, ptbase 3.34.
That refutes the hypothesis I came in with. I predicted the EFFECT element, since
blend mode is recorded as undecoded in screen.rs and a miscomposited effect would
be tonal and displace nothing. It is the frames; pteff12's ratio is largely
inherited from containing ptframe1. The mechanism may still be right, the element
was wrong, and only ranking rather than confirming showed it.
And it is not an edge effect: ptframe1 and ptframe2 are the only elements whose
residual is higher on FLAT pixels (25.41, 16.54) than on edges (19.85, 9.82).
Signed, ptframe1 renders 88.4 against the capture's 129.1 with 0.1 % of pixels
render-brighter. Body intensity, one direction, after a global tone LUT.
Filed in BLOCKED.md against HANDOFF 5a7f34d as an ask for the blend/alpha bits. I
am not brightening them to match.
Also: suppressing the FOCUSED button changed zero pixels, opaque magenta included,
while ptbtn02/03 change thousands. That looked like a defect and is not --
screen_view.gd:746 documents that a focused button draws its record instead of its
base, covering it at 100.0 %. The null re-derives that claim at a stricter
standard than the measurement behind it.
93d36f0f3b