The floor grab-offset comment claimed floorStrategy.move reads localPosition
"under Alt (free place)"; it reads event.position with mode-governed snapToGrid
and has no Alt branch (Alt is force-place-only). Describe the real reason both
frames carry the offset: it's computed local-space but the strategy consumes the
world point.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>