fix(kernel): a small overlap is not taken for bodies apart or inside (#484)

When sample points say two bodies are apart or one is inside the other, the facetings are now checked for surfaces passing through each other; if they do, the boolean is computed instead of shortcut. If it still can't be intersected, the sampled answer is kept as a flagged, unverified result, and Interference lists such pairs as "could not be checked" with the reason. Fixes #442 and #443.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/features_more_tests.rs

@@ -602,3 +602,26 @@ fn cylinder_auto_inference_refuses_ambiguity_curves_and_seam_crossing_atomically
         assert_eq!(exact_cylinder_volume(&s), volume);
     }
 }
+
+/// A cone that takes only a 1 mm chamfer off a cylinder's top edge leaves nearly all of the
+/// cylinder inside it; the intersection is still the chamfered cylinder (#443).
+#[test]
+fn loft_intersect_that_trims_one_edge_changes_the_body() {
+    let mut s = Session::default();
+    run(&mut s, "sketch.create", json!({"plane": "XY"}));
+    run(&mut s, "sketch.circle.center", json!({"center": [0, 0], "radius": 35}));
+    run(&mut s, "sketch.finish", json!({}));
+    run(&mut s, "solid.extrude", json!({"distance": 10, "body_name": "Body"}));
+    for (name, offset, radius) in [("A", -1, 45), ("B", 11, 33)] {
+        run(&mut s, "sketch.create", json!({"plane": "XY", "offset": offset, "name": name}));
+        run(&mut s, "sketch.circle.center", json!({"center": [0, 0], "radius": radius}));
+        run(&mut s, "sketch.finish", json!({}));
+    }
+    run(&mut s, "solid.loft", json!({"sections": [{"sketch": "A"}, {"sketch": "B"}], "operation": "intersect"}));
+    // r 35 up to z = 9, then a frustum to r 34 at z = 10.
+    let want = std::f64::consts::PI * (35.0 * 35.0 * 9.0 + (35.0 * 35.0 + 35.0 * 34.0 + 34.0 * 34.0) / 3.0);
+    let got = volume(&mut s);
+    assert!((got - want).abs() < want * 2e-4, "{got} vs {want}");
+    let m = measure(&mut s);
+    assert_eq!(m["bodies"][0]["face_types"]["cone"], 1, "{m}");
+}