feat: Add a cloneable protocol for Reasoning Engine.

PiperOrigin-RevId: 638428830

tests/unit/vertex_langchain/test_reasoning_engine_templates_langchain.py

@@ -135,6 +135,20 @@ def test_set_up(self, vertexai_init_mock):
         agent.set_up()
         assert agent._runnable is not None
 
+    def test_clone(self, vertexai_init_mock):
+        agent = reasoning_engines.LangchainAgent(
+            model=_TEST_MODEL,
+            prompt=self.prompt,
+            output_parser=self.output_parser,
+        )
+        agent.set_up()
+        assert agent._runnable is not None
+        agent_clone = agent.clone()
+        assert agent._runnable is not None
+        assert agent_clone._runnable is None
+        agent_clone.set_up()
+        assert agent_clone._runnable is not None
+
     def test_query(self, langchain_dump_mock):
         agent = reasoning_engines.LangchainAgent(
             model=_TEST_MODEL,

tests/unit/vertex_langchain/test_reasoning_engines.py

@@ -46,6 +46,9 @@ def query(self, unused_arbitrary_string_name: str) -> str:
         """Runs the engine."""
         return unused_arbitrary_string_name.upper()
 
+    def clone(self):
+        return self
+
 
 _TEST_RETRY = base._DEFAULT_RETRY
 _TEST_CREDENTIALS = mock.Mock(spec=auth_credentials.AnonymousCredentials())

vertexai/preview/reasoning_engines/templates/langchain.py

@@ -13,17 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-import json
 from typing import (
     TYPE_CHECKING,
     Any,
     Callable,
     Dict,
-    List,
     Mapping,
     Optional,
     Sequence,
-    Tuple,
     Union,
 )
 
@@ -390,6 +387,24 @@ def set_up(self):
             runnable_kwargs=self._runnable_kwargs,
         )
 
+    def clone(self) -> "LangchainAgent":
+        """Returns a clone of the LangchainAgent."""
+        import copy
+
+        return LangchainAgent(
+            model=self._model_name,
+            prompt=copy.deepcopy(self._prompt),
+            tools=copy.deepcopy(self._tools),
+            output_parser=copy.deepcopy(self._output_parser),
+            chat_history=copy.deepcopy(self._chat_history),
+            model_kwargs=copy.deepcopy(self._model_kwargs),
+            model_tool_kwargs=copy.deepcopy(self._model_tool_kwargs),
+            agent_executor_kwargs=copy.deepcopy(self._agent_executor_kwargs),
+            runnable_kwargs=copy.deepcopy(self._runnable_kwargs),
+            model_builder=self._model_builder,
+            runnable_builder=self._runnable_builder,
+        )
+
     def query(
         self,
         *,

vertexai/reasoning_engines/_reasoning_engines.py

@@ -46,6 +46,15 @@ def query(self, **kwargs):
         """Runs the Reasoning Engine to serve the user query."""
 
 
+@typing.runtime_checkable
+class Cloneable(Protocol):
+    """Protocol for Reasoning Engine applications that can be cloned."""
+
+    @abc.abstractmethod
+    def clone(self):
+        """Return a clone of the object."""
+
+
 class ReasoningEngine(base.VertexAiResourceNounWithFutureManager, Queryable):
     """Represents a Vertex AI Reasoning Engine resource."""
 
@@ -214,6 +223,9 @@ def create(
                 "Invalid query signature. This might be due to a missing "
                 "`self` argument in the reasoning_engine.query method."
             ) from err
+        if isinstance(reasoning_engine, Cloneable):
+            # Avoid undeployable ReasoningChain states.
+            reasoning_engine = reasoning_engine.clone()
         if isinstance(requirements, str):
             try:
                 _LOGGER.info(f"Reading requirements from {requirements=}")