Add grid item justification and child margin mode, alignment, fixed/fill
sizing, size limits, absolute position and stacking order. Sample optional
asymmetric margins before copying. Keep existing input indexes and fixture
defaults, with explicit target eligibility and independent authored groups.
Check companion values, propagation, preserved overrides, reset, update
main, detach and exact undo/redo. Replay the histories through the real
frontend layout events and retain corrupt-result controls.
Correct F239's full-sync comparison to wait for layout on both routes.
The reduced add-child/absolute-child history stays settled, while the
negative control still rejects a real 0.25 px absolute-child displacement.
No geometry tolerance or golden data changes.
Validate the final continuation on common JVM (2004 tests / 32919
assertions), common JS (1940 / 31522), frontend (1745 / 13569), backend
(1793 / 9007) and exporter (16 / 40). All four modules pass lint and format.
All six generated properties pass 40 programs at seed 712 in both runtimes.
Golden data is unchanged.
The final continuation benchmark passes with no regression flags. Lower
quantile ratios against Phase 1e: main 10/100/1000 0.51/0.58/0.57, three
levels 0.57, chain 0.53, library 0.57, many shapes 0.45, variant switch 0.66.
Machine/JVM differences make these rough comparisons; baseline unchanged.
AI-assisted-by: gpt-6
a086fd9657