feat(cadfs): expand selector provenance coverage

backend/tests/test_engine_extent_trim_contract.py

@@ -57,7 +57,7 @@ from cdsl_engine.runtime import rebuild_cdsl  # noqa: E402
 
 
 try:
-    from build123d import Face, Plane, Vector  # noqa: F401
+    from build123d import Face, Plane, Solid, Vector  # noqa: F401
     _HAS_BUILD123D = True
 except ImportError:
     _HAS_BUILD123D = False
@@ -137,6 +137,39 @@ class ExtentTrimContractTests(unittest.TestCase):
 
         self.assertAlmostEqual(trimmed.volume, 500.0, places=5)
 
+    @unittest.skipUnless(_HAS_BUILD123D, "build123d is not available")
+    def test_planar_supporting_surface_accepts_only_a_complete_forward_profile(self) -> None:
+        """A wholly unreachable planar face may supply its support plane.
+
+        The finite target is deliberately outside the profile's x/y range,
+        so no ray intersects its trim.  The underlying z=5 plane still gives
+        one exact +z termination distance.  This is distinct from the
+        partial-hit trim contract below.
+        """
+        profile = Face.make_rect(2, 2, Plane(origin=(8, 0, 0)))
+        target = Face.make_rect(2, 2, Plane(origin=(0, 0, 5)))
+
+        self.assertTrue(all(
+            Build123dGeometryAdapter._forward_intersection_distance(target, point, Vector(0, 0, 1)) is None
+            for point in Build123dGeometryAdapter.profile_sample_points(profile)
+        ))
+        self.assertAlmostEqual(
+            Build123dGeometryAdapter.uniform_planar_supporting_surface_distance(target, [profile], (0, 0, 1)),
+            5.0,
+            places=6,
+        )
+
+    @unittest.skipUnless(_HAS_BUILD123D, "build123d is not available")
+    def test_planar_supporting_surface_rejects_parallel_and_non_planar_targets(self) -> None:
+        profile = Face.make_rect(2, 2)
+        parallel = Face.make_rect(2, 2, Plane(origin=(0, 0, 5), z_dir=(1, 0, 0)))
+        cylindrical = next(face for face in Solid.make_cylinder(2, 4).faces() if face.geom_type != Face.make_rect(1, 1).geom_type)
+
+        with self.assertRaisesRegex(ValueError, "parallel"):
+            Build123dGeometryAdapter.uniform_planar_supporting_surface_distance(parallel, [profile], (0, 0, 1))
+        with self.assertRaisesRegex(ValueError, "planar"):
+            Build123dGeometryAdapter.uniform_planar_supporting_surface_distance(cylindrical, [profile], (0, 0, 1))
+
     @unittest.skipUnless(_HAS_BUILD123D, "build123d is not available")
     def test_up_to_surface_hanging_profile_is_trimmed_not_rejected(self) -> None:
         """集成裁剪契约：profile 悬空超出目标面时不再拒绝，悬空部分被切掉。