From 311f217bdd8bcd6c886c10f8734f0e703565c647 Mon Sep 17 00:00:00 2001
From: Ben <106089368+benflexcompute@users.noreply.github.com>
Date: Thu, 9 Apr 2026 14:38:23 -0400
Subject: [PATCH] fix(): Fix coordinate transformation writes to frozen BETDisk
 fields (#1979)

---
 .../component/simulation/translator/utils.py  | 16 +++-
 .../translator/test_translation_utils.py      | 87 +++++++++++++++++++
 2 files changed, 100 insertions(+), 3 deletions(-)
 create mode 100644 tests/simulation/translator/test_translation_utils.py

diff --git a/flow360/component/simulation/translator/utils.py b/flow360/component/simulation/translator/utils.py
index 534a5fe65..133a4645e 100644
--- a/flow360/component/simulation/translator/utils.py
+++ b/flow360/component/simulation/translator/utils.py
@@ -123,9 +123,19 @@ def _apply_transformations_to_model(
                 setattr(model, field_name, new_entity_list)
 
         elif isinstance(field_value, (list, tuple)):
-            new_items = [_transform_sequence_item(item, manager) for item in field_value]
-            new_value = new_items if isinstance(field_value, list) else tuple(new_items)
-            setattr(model, field_name, new_value)
+            transformed_items = None
+            for index, item in enumerate(field_value):
+                transformed = _transform_sequence_item(item, manager)
+                if transformed is not item:
+                    if transformed_items is None:
+                        transformed_items = list(field_value)
+                    transformed_items[index] = transformed
+
+            if transformed_items is not None:
+                new_value = (
+                    transformed_items if isinstance(field_value, list) else tuple(transformed_items)
+                )
+                setattr(model, field_name, new_value)
 
         elif isinstance(field_value, Flow360BaseModel):
             _apply_transformations_to_model(field_value, manager)
diff --git a/tests/simulation/translator/test_translation_utils.py b/tests/simulation/translator/test_translation_utils.py
new file mode 100644
index 000000000..8066314b6
--- /dev/null
+++ b/tests/simulation/translator/test_translation_utils.py
@@ -0,0 +1,87 @@
+import flow360.component.simulation.units as u
+from flow360.component.simulation.draft_context.coordinate_system_manager import (
+    CoordinateSystemAssignmentGroup,
+    CoordinateSystemEntityRef,
+    CoordinateSystemStatus,
+)
+from flow360.component.simulation.entity_operation import CoordinateSystem
+from flow360.component.simulation.framework.param_utils import AssetCache
+from flow360.component.simulation.models.volume_models import (
+    BETDisk,
+    BETDiskChord,
+    BETDiskSectionalPolar,
+    BETDiskTwist,
+)
+from flow360.component.simulation.primitives import Cylinder
+from flow360.component.simulation.simulation_params import SimulationParams
+from flow360.component.simulation.translator.utils import (
+    apply_coordinate_system_transformations,
+)
+from flow360.component.simulation.unit_system import SI_unit_system
+
+
+def test_apply_coordinate_system_transformations_skips_frozen_non_entity_sequences():
+    with SI_unit_system:
+        cylinder = Cylinder(
+            name="bet_disk",
+            center=(0, 0, 0) * u.m,
+            axis=(0, 0, 1),
+            height=1 * u.m,
+            outer_radius=1 * u.m,
+        )
+        bet_disk = BETDisk(
+            entities=cylinder,
+            rotation_direction_rule="leftHand",
+            number_of_blades=3,
+            omega=100 * u.rpm,
+            chord_ref=1 * u.m,
+            n_loading_nodes=20,
+            mach_numbers=[0],
+            reynolds_numbers=[1000000],
+            twists=[BETDiskTwist(radius=0 * u.m, twist=0 * u.deg)],
+            chords=[BETDiskChord(radius=0 * u.m, chord=1 * u.m)],
+            alphas=[-2, 0, 2] * u.deg,
+            sectional_radiuses=[0.25, 0.5] * u.m,
+            sectional_polars=[
+                BETDiskSectionalPolar(
+                    lift_coeffs=[[[0.1, 0.2, 0.3]]],
+                    drag_coeffs=[[[0.01, 0.02, 0.03]]],
+                ),
+                BETDiskSectionalPolar(
+                    lift_coeffs=[[[0.15, 0.25, 0.35]]],
+                    drag_coeffs=[[[0.015, 0.025, 0.035]]],
+                ),
+            ],
+        )
+        coordinate_system = CoordinateSystem(name="cs", translation=(1, 2, 3) * u.m)
+        coordinate_system_status = CoordinateSystemStatus(
+            coordinate_systems=[coordinate_system],
+            parents=[],
+            assignments=[
+                CoordinateSystemAssignmentGroup(
+                    coordinate_system_id=coordinate_system.private_attribute_id,
+                    entities=[
+                        CoordinateSystemEntityRef(
+                            entity_type="Cylinder",
+                            entity_id=cylinder.private_attribute_id,
+                        )
+                    ],
+                )
+            ],
+        )
+        params = SimulationParams(
+            models=[bet_disk],
+            private_attribute_asset_cache=AssetCache(
+                coordinate_system_status=coordinate_system_status,
+            ),
+        )
+
+    apply_coordinate_system_transformations(params)
+
+    transformed_bet_disk = params.models[0]
+    transformed_cylinder = transformed_bet_disk.entities.stored_entities[0]
+
+    assert all(transformed_cylinder.center == [1, 2, 3] * u.m)
+    assert transformed_bet_disk.mach_numbers == [0]
+    assert transformed_bet_disk.twists[0].radius == 0 * u.m
+    assert transformed_bet_disk.chords[0].chord == 1 * u.m