diff --git a/app-proto/src/add_remove.rs b/app-proto/src/add_remove.rs
index d23a849..bf48546 100644
--- a/app-proto/src/add_remove.rs
+++ b/app-proto/src/add_remove.rs
@@ -300,6 +300,41 @@ fn load_balanced_assemb(assembly: &Assembly) {
     }
 }
 
+/* DEBUG */
+// the initial configuration of this test assembly deliberately violates the
+// constraints, so loading the assembly will trigger a non-trivial realization
+fn load_off_center_assemb(assembly: &Assembly) {
+    // create a point almost at the origin and a sphere centered on the origin
+    let _ = assembly.try_insert_element(
+        Point::new(
+            "point".to_string(),
+            "Point".to_string(),
+            [0.75_f32, 0.75_f32, 0.75_f32],
+            engine::point(1e-9, 0.0, 0.0)
+        ),
+    );
+    let _ = assembly.try_insert_element(
+        Sphere::new(
+            "sphere".to_string(),
+            "Sphere".to_string(),
+            [0.75_f32, 0.75_f32, 0.75_f32],
+            engine::sphere(0.0, 0.0, 0.0, 1.0)
+        ),
+    );
+    
+    // get references to the elements
+    let point_and_sphere = ["point", "sphere"].map(
+        |id| assembly.elements_by_id.with_untracked(
+            |elts_by_id| elts_by_id[id].clone()
+        )
+    );
+    
+    // put the point on the sphere
+    let incidence = InversiveDistanceRegulator::new(point_and_sphere);
+    incidence.set_point.set(SpecifiedValue::try_from("0".to_string()).unwrap());
+    assembly.insert_regulator(Rc::new(incidence));
+}
+
 // setting the inversive distances between the vertices to -2 gives a regular
 // tetrahedron with side length 1, whose insphere and circumsphere have radii
 // sqrt(1/6) and sqrt(3/2), respectively. to measure those radii, set an
@@ -570,6 +605,7 @@ pub fn AddRemove() -> View {
                 "low-curv" => load_low_curv_assemb(assembly),
                 "pointed" => load_pointed_assemb(assembly),
                 "balanced" => load_balanced_assemb(assembly),
+                "off-center" => load_off_center_assemb(assembly),
                 "radius-ratio" => load_radius_ratio_assemb(assembly),
                 "irisawa-hexlet" => load_irisawa_hexlet_assemb(assembly),
                 _ => ()
@@ -624,6 +660,7 @@ pub fn AddRemove() -> View {
                 option(value="low-curv") { "Low-curvature" }
                 option(value="pointed") { "Pointed" }
                 option(value="balanced") { "Balanced" }
+                option(value="off-center") { "Off-center" }
                 option(value="radius-ratio") { "Radius ratio" }
                 option(value="irisawa-hexlet") { "Irisawa hexlet" }
                 option(value="empty") { "Empty" }