[wingleeio]

Several callers asked Scene::world for the clip a node paints within (.2) and threw away the rest:

• shown_context, which damage runs for every subtree damaged alone;
• damage_node's parent clip, for a box painting past its own clip;
• two places in resolve_moves.

world sums the node's translation and opacity over every ancestor before it works out the clip.

world_clip is world's clip loop alone, in the same shape: each clipping ancestor is taken at its box, translated by its own and its ancestors' translations summed from it upwards, with no storage. world is its translation and effects plus world_clip. The clip-only callers call world_clip. The clip is bit-for-bit what it was, so damage is unchanged.

The speed-of-light lane handed this over after #587 (one damage context shared between a setter's two damage calls). It found world at 21% of script-layout, from animated rows under clipping ancestors.

Exactness: a hash of every frame's damage rects and scroll moves over 480 frames of heavy both, stream, scroll and animate matches main.

Numbers. Exact instruction counts (arm64 cachegrind, gate flags, against main 542ad4d, which includes #587):

scene	change
script-layout	−7.24%
style	−3.79%
anime	−3.72%
animate	−0.95%
heavy both / stream / scroll	−0.43% / −0.41% / −0.19%
lab stream / scroll	−0.02% / −0.41%
micro state / vscroll fixed / variable	−0.10% / −0.29% / −0.10%
script-update	−0.18%
widgets	−0.03%
mount	+0.02%

Mount varies by about ±0.15 M between runs of the same binary, and no zgx function in it changes.

Checks: fmt, clippy 1.99 -D warnings, and the zgx, zgx-gpu and zgx-desktop tests (1,341 passed).

🤖 Generated with Claude Code

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[github-actions]

Instruction counts (cachegrind, exact) against aaf35528; the gate fails above +1%.

scene	base	head	change
heavy-both	1,415.7 M	1,411.8 M	-0.27%
heavy-stream	1,359.3 M	1,355.8 M	-0.26%
heavy-scroll	80.4 M	80.3 M	-0.09%
lab-stream	462.1 M	462.3 M	+0.04%
lab-scroll	70.3 M	70.1 M	-0.27%
animate	397.6 M	394.8 M	-0.71%
micro-state	59.7 M	59.7 M	-0.06%
micro-vscroll-fixed	48.8 M	48.7 M	-0.17%
micro-vscroll-variable	89.0 M	89.0 M	-0.03%
micro-state-luau	82.9 M	82.9 M	-0.07%
micro-vscroll-fixed-luau	66.3 M	66.2 M	-0.13%
micro-vscroll-variable-luau	134.6 M	134.5 M	-0.07%
mount	327.2 M	327.6 M	+0.13%
script-update	1,700.2 M	1,698.2 M	-0.12%
anime	4,791.6 M	4,672.7 M	-2.48%
script-layout	4,001.4 M	3,767.1 M	-5.85%
list-state	893.8 M	893.8 M	-0.00%
style	2,146.7 M	2,084.3 M	-2.91%
widgets	2,685.2 M	2,684.5 M	-0.02%
app-mail	318.5 M	318.5 M	-0.01%
app-chat	53.2 M	53.2 M	-0.01%
app-dashboard	189.8 M	189.4 M	-0.20%
app-dashboard-sort	126.5 M	126.3 M	-0.18%
app-sketch	48.5 M	48.5 M	-0.02%
app-code	100.0 M	99.9 M	-0.10%
app-code-search	87.7 M	87.6 M	-0.02%