solid.move takes copy: true to keep the source bodies and transform a new copy of each, with a Create Copy box in the Move dialog. Designs without it save and load exactly as before.
A profile traced over a face sketch's projected boundary left the extrude's caps and sides without an exact planar source, so a sketch or offset plane on the new top face was refused. The drawn curve is now the edge's source where it covers a projection. Clearer fixed-plane message; regression tests in the engine, UI harness and design corpus, plus a corpus-wide flat-face attachment check (known gaps under #491-#495).
Fixes#489
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>