A switch places the new root in the old orientation before carrying
attributes. When rotation is already equal, the carry step emits no
write and drops its geometry group. Preserve that group for retained
authored root orientation so later sync keeps the visible result.
Extend the rotation regression to check touched and later sync: two
assertions fail before the fix. Focused checks pass 43 tests and 166
assertions, including the two previously shrunk generated regressions.
Benchmark vs Phase 1e: main 10/100/1000 0.64/0.65/0.97; levels 0.49;
chain 0.59; library 0.58; many shapes 0.89; switch 0.60. No flags.
AI-assisted-by: GPT-6
9f10e5e7c3