diff --git a/comfy_extras/nodes_trellis2.py b/comfy_extras/nodes_trellis2.py
index 3479d5410..61d3532a1 100644
--- a/comfy_extras/nodes_trellis2.py
+++ b/comfy_extras/nodes_trellis2.py
@@ -256,6 +256,8 @@ def run_conditioning(model, cropped_img_tensor, include_1024=True):
     model_internal = model.model
     device = comfy.model_management.intermediate_device()
     torch_device = comfy.model_management.get_torch_device()
+    had_image_size = hasattr(model_internal, "image_size")
+    original_image_size = getattr(model_internal, "image_size", None)
 
     def prepare_tensor(pil_img, size):
         resized_pil = pil_img.resize((size, size), Image.Resampling.LANCZOS)
@@ -263,15 +265,21 @@ def run_conditioning(model, cropped_img_tensor, include_1024=True):
         img_t = torch.from_numpy(img_np).permute(2, 0, 1).unsqueeze(0).to(torch_device)
         return (img_t - dino_mean.to(torch_device)) / dino_std.to(torch_device)
 
-    model_internal.image_size = 512
-    input_512 = prepare_tensor(cropped_img_tensor, 512)
-    cond_512 = model_internal(input_512, skip_norm_elementwise=True)[0]
-
     cond_1024 = None
-    if include_1024:
-        model_internal.image_size = 1024
-        input_1024 = prepare_tensor(cropped_img_tensor, 1024)
-        cond_1024 = model_internal(input_1024, skip_norm_elementwise=True)[0]
+    try:
+        model_internal.image_size = 512
+        input_512 = prepare_tensor(cropped_img_tensor, 512)
+        cond_512 = model_internal(input_512, skip_norm_elementwise=True)[0]
+
+        if include_1024:
+            model_internal.image_size = 1024
+            input_1024 = prepare_tensor(cropped_img_tensor, 1024)
+            cond_1024 = model_internal(input_1024, skip_norm_elementwise=True)[0]
+    finally:
+        if not had_image_size:
+            delattr(model_internal, "image_size")
+        else:
+            model_internal.image_size = original_image_size
 
     conditioning = {
         'cond_512': cond_512.to(device),
diff --git a/tests-unit/comfy_extras_test/nodes_trellis2_test.py b/tests-unit/comfy_extras_test/nodes_trellis2_test.py
new file mode 100644
index 000000000..920eca471
--- /dev/null
+++ b/tests-unit/comfy_extras_test/nodes_trellis2_test.py
@@ -0,0 +1,127 @@
+import importlib
+import sys
+import types
+import unittest
+from unittest.mock import patch
+
+import torch
+from PIL import Image
+
+
+class _DummyPort:
+    @staticmethod
+    def Input(*args, **kwargs):
+        return None
+
+    @staticmethod
+    def Output(*args, **kwargs):
+        return None
+
+
+class _DummyIO:
+    ComfyNode = object
+
+    @staticmethod
+    def Schema(*args, **kwargs):
+        return None
+
+    @staticmethod
+    def NodeOutput(*args, **kwargs):
+        return args
+
+    def __getattr__(self, name):
+        return _DummyPort
+
+
+class _DummyTypes:
+    def __getattr__(self, name):
+        return lambda *args, **kwargs: None
+
+
+dummy_comfy_api_latest = types.SimpleNamespace(
+    ComfyExtension=object,
+    IO=_DummyIO(),
+    Types=_DummyTypes(),
+)
+
+dummy_sparse_tensor = type("SparseTensor", (), {})
+dummy_trellis_vae = types.SimpleNamespace(SparseTensor=dummy_sparse_tensor)
+
+with patch.dict(sys.modules, {
+    "comfy_api.latest": dummy_comfy_api_latest,
+    "comfy.ldm.trellis2.vae": dummy_trellis_vae,
+}):
+    nodes_trellis2 = importlib.import_module("comfy_extras.nodes_trellis2")
+
+
+class DummyInnerModel:
+    def __init__(self, image_size=..., fail_on_call=None):
+        self.call_count = 0
+        self.fail_on_call = fail_on_call
+        if image_size is not ...:
+            self.image_size = image_size
+
+    def __call__(self, input_tensor, skip_norm_elementwise=True):
+        self.call_count += 1
+        if self.fail_on_call == self.call_count:
+            raise RuntimeError("expected conditioning failure")
+        return (torch.ones((1, 4), dtype=torch.float32),)
+
+
+class DummyModel:
+    def __init__(self, inner_model):
+        self.model = inner_model
+
+
+class TestRunConditioningRestore(unittest.TestCase):
+    def setUp(self):
+        self.intermediate_patch = patch.object(
+            nodes_trellis2.comfy.model_management, "intermediate_device", lambda: "cpu"
+        )
+        self.torch_device_patch = patch.object(
+            nodes_trellis2.comfy.model_management, "get_torch_device", lambda: "cpu"
+        )
+        self.intermediate_patch.start()
+        self.torch_device_patch.start()
+
+    def tearDown(self):
+        self.intermediate_patch.stop()
+        self.torch_device_patch.stop()
+
+    @staticmethod
+    def make_test_image():
+        return Image.new("RGB", (8, 8), color="white")
+
+    def test_restores_existing_image_size_after_success(self):
+        inner_model = DummyInnerModel(image_size=777)
+
+        nodes_trellis2.run_conditioning(DummyModel(inner_model), self.make_test_image(), include_1024=True)
+
+        self.assertEqual(inner_model.image_size, 777)
+
+    def test_deletes_missing_image_size_after_success(self):
+        inner_model = DummyInnerModel()
+
+        nodes_trellis2.run_conditioning(DummyModel(inner_model), self.make_test_image(), include_1024=True)
+
+        self.assertFalse(hasattr(inner_model, "image_size"))
+
+    def test_restores_existing_image_size_after_512_failure(self):
+        inner_model = DummyInnerModel(image_size=777, fail_on_call=1)
+
+        with self.assertRaisesRegex(RuntimeError, "expected conditioning failure"):
+            nodes_trellis2.run_conditioning(DummyModel(inner_model), self.make_test_image(), include_1024=True)
+
+        self.assertEqual(inner_model.image_size, 777)
+
+    def test_deletes_missing_image_size_after_1024_failure(self):
+        inner_model = DummyInnerModel(fail_on_call=2)
+
+        with self.assertRaisesRegex(RuntimeError, "expected conditioning failure"):
+            nodes_trellis2.run_conditioning(DummyModel(inner_model), self.make_test_image(), include_1024=True)
+
+        self.assertFalse(hasattr(inner_model, "image_size"))
+
+
+if __name__ == "__main__":
+    unittest.main()