Stored layout frames may omit padding. The padding helpers returned nil
sides, so padding totals and full flex/grid layout calculation crashed on
the JVM. Default absent padding to zero and share that reader between
horizontal and vertical totals.
Add portable regressions that prove the inputs pass the shape schema,
then compare their layout calculation with explicit zero padding. Both
regressions fail before the fix; existing simple/multiple checks stay green.
Validate common JVM (1997 tests) and JS (1933), frontend (1742), backend
(1793) and exporter (16), plus lint and formatting for all four modules.
All six generated properties pass 40 programs at seed 712 in both runtimes.
Golden data is unchanged.
The benchmark passes with no regression flags against the existing baseline.
Lower-quantile ratios: main 10/100/1000 copies 0.51/0.58/0.60, three levels
0.56, chain 0.52, library 0.53, many shapes 0.43, variant switch 0.64.
The tool warns that machine/JVM differences make these rough comparisons.
No performance baseline changed.
AI-assisted-by: gpt-6
78feb03b83