diff --git a/openhands/experiments/experiment_manager.py b/openhands/experiments/experiment_manager.py
index 39c6af6284..2e84542e9a 100644
--- a/openhands/experiments/experiment_manager.py
+++ b/openhands/experiments/experiment_manager.py
@@ -1,5 +1,7 @@
 import os
 
+from openhands.core.config.openhands_config import OpenHandsConfig
+from openhands.core.logger import openhands_logger as logger
 from openhands.server.session.conversation_init_data import ConversationInitData
 from openhands.utils.import_utils import get_impl
 
@@ -11,6 +13,15 @@ class ExperimentManager:
     ) -> ConversationInitData:
         return conversation_settings
 
+    @staticmethod
+    def run_config_variant_test(
+        user_id: str, conversation_id: str, config: OpenHandsConfig
+    ) -> OpenHandsConfig:
+        logger.debug(
+            f'Running agent config variant test for user_id={user_id}, conversation_id={conversation_id}'
+        )
+        return config
+
 
 experiment_manager_cls = os.environ.get(
     'OPENHANDS_EXPERIMENT_MANAGER_CLS',
diff --git a/openhands/server/conversation_manager/docker_nested_conversation_manager.py b/openhands/server/conversation_manager/docker_nested_conversation_manager.py
index bbd9366e7a..275e9a4a8d 100644
--- a/openhands/server/conversation_manager/docker_nested_conversation_manager.py
+++ b/openhands/server/conversation_manager/docker_nested_conversation_manager.py
@@ -19,6 +19,7 @@ from openhands.core.logger import openhands_logger as logger
 from openhands.events.action import MessageAction
 from openhands.events.nested_event_store import NestedEventStore
 from openhands.events.stream import EventStream
+from openhands.experiments.experiment_manager import ExperimentManagerImpl
 from openhands.integrations.provider import PROVIDER_TOKEN_TYPE, ProviderHandler
 from openhands.llm.llm import LLM
 from openhands.runtime import get_runtime_cls
@@ -468,24 +469,30 @@ class DockerNestedConversationManager(ConversationManager):
     ) -> DockerRuntime:
         # This session is created here only because it is the easiest way to get a runtime, which
         # is the easiest way to create the needed docker container
+
+        # Run experiment manager variant test before creating session
+        config: OpenHandsConfig = ExperimentManagerImpl.run_config_variant_test(
+            user_id, sid, self.config
+        )
+
         session = Session(
             sid=sid,
             file_store=self.file_store,
-            config=self.config,
+            config=config,
             sio=self.sio,
             user_id=user_id,
         )
-        agent_cls = settings.agent or self.config.default_agent
+        agent_cls = settings.agent or config.default_agent
         agent_name = agent_cls if agent_cls is not None else 'agent'
         llm = LLM(
-            config=self.config.get_llm_config_from_agent(agent_name),
+            config=config.get_llm_config_from_agent(agent_name),
             retry_listener=session._notify_on_llm_retry,
         )
         llm = session._create_llm(agent_cls)
-        agent_config = self.config.get_agent_config(agent_cls)
+        agent_config = config.get_agent_config(agent_cls)
         agent = Agent.get_cls(agent_cls)(llm, agent_config)
 
-        config = self.config.model_copy(deep=True)
+        config = config.model_copy(deep=True)
         env_vars = config.sandbox.runtime_startup_env_vars
         env_vars['CONVERSATION_MANAGER_CLASS'] = (
             'openhands.server.conversation_manager.standalone_conversation_manager.StandaloneConversationManager'
diff --git a/openhands/server/session/session.py b/openhands/server/session/session.py
index 566b3f0b5c..9ad93f2360 100644
--- a/openhands/server/session/session.py
+++ b/openhands/server/session/session.py
@@ -28,6 +28,7 @@ from openhands.events.observation.agent import RecallObservation
 from openhands.events.observation.error import ErrorObservation
 from openhands.events.serialization import event_from_dict, event_to_dict
 from openhands.events.stream import EventStreamSubscriber
+from openhands.experiments.experiment_manager import ExperimentManagerImpl
 from openhands.llm.llm import LLM
 from openhands.runtime.runtime_status import RuntimeStatus
 from openhands.server.session.agent_session import AgentSession
@@ -74,6 +75,9 @@ class Session:
         )
         # Copying this means that when we update variables they are not applied to the shared global configuration!
         self.config = deepcopy(config)
+        self.config = ExperimentManagerImpl.run_config_variant_test(
+            user_id, sid, self.config
+        )
         self.loop = asyncio.get_event_loop()
         self.user_id = user_id