5d02d5cd60
residual is smaller than I said Testing the candidate I raised last iteration rather than carrying it. Blending bit-0x02 sprites additively moves every measure the wrong way -- whole-frame mean diff +0.55 to +1.04, swoosh-band mean +1.83 to +3.98, band edge-correlation 0.6971 down to 0.5578. So the bit is real and independent but does not select an additive blend. I reverted the experiment and kept the word as T8adImage::flags, documented and not acted on; the render is byte-identical to before. Second refutation: the swoosh is not displaced. Shifting the band over plus or minus 80 by 8 pixels peaks sharply at zero, 0.7342, falling to 0.22 at 24 px. So the pivot story is dead twice over -- inert at scale 100, and no displacement to explain anyway. And I have restated the residual, because earlier sections overstated it. The +16 to +34 band tiles I quoted were measured WITHOUT --primitives. With the dim drawn the band's average is nearly right at +1.83; what is wrong is its structure, tiles running -38.6 then +33.8 and cancelling. Six candidates eliminated now and none confirmed. One caveat I owe the port agent about the capture I gave them: it is at t=4.0s, roughly 174 keyframe units into a screen whose elements have keyframes out to t=600. I judged "settled" from mean luminance, which cannot see a thin sprite still moving. It is settled for the bulk of the screen and not proven settled for every element -- which is a live alternative explanation for a structural difference in exactly the band the sweeps cross. METHOD: cargo build passing does not mean cargo test compiles. Adding the field built the library in 1.48s and broke two test-only struct literals; cargo test failed with exit 101.