Intersection edge nodes advance along the curve at fine display qualities (#1615)

Thanks @jyviko.

crates/engine/src/boolean_regression_tests.rs

@@ -288,3 +288,27 @@ fn cut_of_a_whole_face_beside_round_corners_after_a_chamfer() {
     let top = mesh.bounds().max.z;
     assert!((top - 15.0).abs() < 1e-6, "top at {top}");
 }
+
+/// The display tessellation of loft bodies joined into a bike frame plans at every display
+/// quality and every refinement step. The edge nodes on an intersection of two lofts once
+/// stepped back along the curve (the edge's fit rang where truck's parameter changes speed, and
+/// took a leader point off the curve past a vertex), so a face's boundary crossed itself and
+/// the body fell back to the reference mesher, which drew a sheet across the down tube.
+#[test]
+fn joined_loft_frames_plan_their_display_at_every_quality() {
+    use solidcraft_doc::display_quality::{DisplayQuality, MAX_REFINE};
+    for (script, name) in [
+        (include_str!("../../../examples/regressions/loft_join_bracket_hull_triangle.json"), "DT2"),
+        (include_str!("../../../examples/regressions/front_triangle_hull_triangle.json"), "FrontTriangle"),
+    ] {
+        let s = replay(script);
+        let state = s.model.state();
+        let body = &state.body(name).unwrap().body;
+        for q in DisplayQuality::ALL {
+            for k in 0..=MAX_REFINE {
+                let plan = body.display_plan_angular(q.refined_chord(body.size(), k), q.refined_angle(k));
+                assert!(plan.is_ok(), "{name} at {} + {k}: {:?}", q.id(), plan.err());
+            }
+        }
+    }
+}