Profiles picked by index are kept by the curves around them: add_feature turns profile indices into the curve ids of each profile's outer loop (Extrude, Revolve, Sweep, Loft, Emboss, Sheet Base, Patch), so a face sketch whose projected outline is rebuilt still extrudes the picked region; a profile that is gone is an error on the feature, never another pick

Fixes #30

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RjGw4gA5ZvKrU8MQP6sBgT

crates/engine/src/lib.rs

@@ -433,6 +433,8 @@ mod delete_face_tests;
 #[cfg(test)]
 mod extent_tests;
 #[cfg(test)]
+mod profile_refs_tests;
+#[cfg(test)]
 mod split_face_tests;
 #[cfg(test)]
 mod tests;