fix: support headless rollout on remote training hosts

tests/test_train_vla_transformer_optimizer.py

@@ -246,6 +246,35 @@ class TrainVLATransformerOptimizerTest(unittest.TestCase):
             module.torch.backends.cudnn.enabled = original
 
 
+    def test_resolve_run_output_dir_prefers_hydra_runtime_output_dir(self):
+        module = self._load_train_vla_module()
+        hydra_core_module = types.ModuleType('hydra.core')
+        hydra_hydra_config_module = types.ModuleType('hydra.core.hydra_config')
+
+        class _Runtime:
+            output_dir = '/tmp/hydra-output'
+
+        class _Cfg:
+            runtime = _Runtime()
+
+        class HydraConfigStub:
+            @staticmethod
+            def initialized():
+                return True
+            @staticmethod
+            def get():
+                return _Cfg()
+
+        hydra_hydra_config_module.HydraConfig = HydraConfigStub
+        with mock.patch.dict(sys.modules, {
+            'hydra.core': hydra_core_module,
+            'hydra.core.hydra_config': hydra_hydra_config_module,
+        }):
+            output_dir = module._resolve_run_output_dir()
+
+        self.assertEqual(Path(output_dir).resolve(), Path('/tmp/hydra-output').resolve())
+
+
     def test_train_script_uses_file_based_repo_root_on_sys_path(self):
         module = self._load_train_vla_module()