- Basic operations

src/fluency/geometry_occ/kernel.py

@@ -180,12 +180,31 @@ class OCGeometryKernel(GeometryKernel):
         from OCP.BRepAlgoAPI import BRepAlgoAPI_Fuse
         from OCP.TopoDS import TopoDS_Shape
 
-        face = self._get_shape(sketch)
+        # Defensive: figure out the actual shape from whatever the caller
+        # hands us, and surface a clear error if we can't get one.
+        #  - If it's an OCCGeometryObject wrapper, unwrap via _get_shape.
+        #  - If it's already a TopoDS_Shape (raw face/wire/etc.), use it.
+        #  - If it's a cadquery Workplane, unwrap that too.
+        #  - If it's a cadquery Shape (cq.Shape), unwrap to TopoDS_Shape.
+        if isinstance(sketch, OCCGeometryObject):
+            face = self._get_shape(sketch)
+        elif isinstance(sketch, TopoDS_Shape):
+            face = sketch
+        else:
+            face = self._get_shape(sketch)
         if face is None:
             raise ValueError(
                 "Cannot extrude: sketch has no geometry. "
                 "Draw a closed profile before extruding."
             )
+        # If the wrapper class itself leaked through somehow, surface a
+        # clear error instead of letting BRepPrimAPI_MakePrism raise an
+        # opaque TypeError.
+        if isinstance(face, OCCGeometryObject):
+            raise ValueError(
+                "Cannot extrude: sketch geometry is a wrapper, not a shape. "
+                "This is a bug — please report it."
+            )
         # ``face`` may be a TopoDS_Face (new path) or a compound/wire from
         # legacy cadquery objects.  If it's not already a face, build one.
         face = self._ensure_face(face)