Store cumulative content scale as an optional shape attribute, default 1.
Sync scales the main's styles by the copy/main ratio separately from
constraint resizing. Keep descendants untouched and allow later main style
edits to propagate (F109). Both renderer modifier paths use this field.
Cover a later sync, repeated scaling, main radius edits, reset and its undo.
The original stroke regression failed before the fix. Common JVM/JS and
frontend suites, backend and exporter tests, lint and format checks pass.
Historical scale gestures cannot be reconstructed from old file data.
Benchmark vs Phase 1e (lower quantile, ms):
world baseline now ratio
main-10 1.790 0.993 0.55
main-100 15.415 9.038 0.59
main-1000 153.086 90.145 0.59
three-levels 35.215 18.989 0.54
chain 68.931 35.045 0.51
library-500 83.083 85.830 1.03
many-shapes 4.837 3.344 0.69
variant-100 32.052 33.586 1.05
All worlds pass the 10% regression threshold.
AI-assisted-by: GPT-6
e2740f3be7