alonso.torres 90138f14c6 🐛 Compose child flip flags from the roots during geometry sync
Keep the roots' relative flip state when placing the source subtree.
Several small rotations must give the same child flags after a full sync;
recomputing one large turn could toggle both axes. Fix F139.

The direct regression failed nil/nil to true/true before the fix. Focused
geometry and oracle suites pass 20 tests, 88 assertions.
Benchmark ratios against Phase 1e: main 10/100/1000 0.57/0.64/0.60;
three levels 0.67; chain 0.56; library 0.60; many shapes 0.50;
variant switch 0.64. No regression flag.

AI-assisted-by: GPT-6
2026-10-28 15:53:08 +01:00
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