forked from 1b-agent/opencadstudio-upstream
11 tests in tests/flatten_regression.rs: projection goldens (line/circle/polyline3d/polyline2d/text/solid), None cases, locked-layer/selection/space collection filters, plan/apply invariants, legacy-loop differential. Adds 2 ring-depth tests in src/scene/mod.rs pinning update_entities' collapsed block-sentinel delta (legacy 2 vs batch 1, final-state equality).