Simulation._validate_boundary_spec_symmetry() now ignores 'name' attribute.

Author: jewettaijfc

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- Giving opposite boundaries different names no longer causes a symmetry validator failure.
+
 ## [2.9.0rc2] - 2025-07-17
 
 ### Added

tests/test_components/test_simulation.py

@@ -595,24 +595,28 @@ def test_validate_symmetry_boundaries():
     # simulation with symmetry along an axis should have the same boundaries defined on both sides
     td.Simulation(
         size=(1, 1, 1),
-        symmetry=(0, 1, 0),
+        symmetry=(1, 1, 1),
         grid_spec=td.GridSpec.uniform(dl=0.1),
         run_time=1e-12,
         boundary_spec=td.BoundarySpec(
             x=td.Boundary.periodic(),
-            y=td.Boundary.periodic(),
+            y=td.Boundary(
+                # Now give the plus and minus boundaries different names to confirm it does not matter.
+                plus=td.PML(name="b1"),
+                minus=td.PML(name="b2"),
+            ),
             z=td.Boundary.pml(),
         ),
     )
-    with pytest.raises(pydantic.ValidationError):
+    with pytest.raises(pydantic.ValidationError, match="Symmetry"):
         td.Simulation(
             size=(1, 1, 1),
-            symmetry=(0, 1, 0),
+            symmetry=(1, 1, 1),
             grid_spec=td.GridSpec.uniform(dl=0.1),
             run_time=1e-12,
             boundary_spec=td.BoundarySpec(
                 x=td.Boundary.periodic(),
-                y=td.Boundary(plus=td.Boundary.pml(), minus=td.Boundary.periodic()),
+                y=td.Boundary(plus=td.PML(num_layers=10), minus=td.PML(num_layers=20)),
                 z=td.Boundary.pml(),
             ),
         )

tidy3d/components/simulation.py

@@ -420,9 +420,17 @@ def num_cells_in_monitor(monitor: Monitor) -> int:
     def _validate_boundary_spec_symmetry(cls, val, values):
         """Error if symmetry is imposed along an axis but the boundary conditions are not the same
         on both sides."""
+
+        def equivalent(plus: BoundarySpec, minus: BoundarySpec) -> bool:
+            """Returns whether two boundary conditions are physically identical."""
+            # Make copies of `plus` and `minus` with the `name` attribute set to "".
+            plus_cpy = plus.updated_copy(name="")
+            minus_cpy = minus.updated_copy(name="")
+            return plus_cpy == minus_cpy
+
         boundaries = [val.x, val.y, val.z]
         for ax, symmetry, ax_bounds in zip("xyz", values.get("symmetry"), boundaries):
-            if symmetry != 0 and ax_bounds.plus != ax_bounds.minus:
+            if symmetry != 0 and not equivalent(ax_bounds.plus, ax_bounds.minus):
                 raise ValidationError(
                     f"Symmetry '{symmetry}' along axis {ax} requires the same boundary "
                     f"condition on both sides of the axis."