feat: added ability to disable the initial message sequence during agent creation

letta/agent.py

@@ -235,6 +235,7 @@ def __init__(
         # extras
         messages_total: Optional[int] = None,  # TODO remove?
         first_message_verify_mono: bool = True,  # TODO move to config?
+        initial_message_sequence: Optional[List[Message]] = None,
     ):
         assert isinstance(agent_state.memory, Memory), f"Memory object is not of type Memory: {type(agent_state.memory)}"
         # Hold a copy of the state that was used to init the agent
@@ -294,6 +295,7 @@ def __init__(
 
         else:
             printd(f"Agent.__init__ :: creating, state={agent_state.message_ids}")
+            assert self.agent_state.id is not None and self.agent_state.user_id is not None
 
             # Generate a sequence of initial messages to put in the buffer
             init_messages = initialize_message_sequence(
@@ -306,14 +308,40 @@ def __init__(
                 include_initial_boot_message=True,
             )
 
-            # Cast the messages to actual Message objects to be synced to the DB
-            init_messages_objs = []
-            for msg in init_messages:
-                init_messages_objs.append(
+            if initial_message_sequence is not None:
+                # We always need the system prompt up front
+                system_message_obj = Message.dict_to_message(
+                    agent_id=self.agent_state.id,
+                    user_id=self.agent_state.user_id,
+                    model=self.model,
+                    openai_message_dict=init_messages[0],
+                )
+                # Don't use anything else in the pregen sequence, instead use the provided sequence
+                init_messages = [system_message_obj] + initial_message_sequence
+
+            else:
+                # Basic "more human than human" initial message sequence
+                init_messages = initialize_message_sequence(
+                    model=self.model,
+                    system=self.system,
+                    memory=self.memory,
+                    archival_memory=None,
+                    recall_memory=None,
+                    memory_edit_timestamp=get_utc_time(),
+                    include_initial_boot_message=True,
+                )
+                # Cast to Message objects
+                init_messages = [
                     Message.dict_to_message(
                         agent_id=self.agent_state.id, user_id=self.agent_state.user_id, model=self.model, openai_message_dict=msg
                     )
-                )
+                    for msg in init_messages
+                ]
+
+            # Cast the messages to actual Message objects to be synced to the DB
+            init_messages_objs = []
+            for msg in init_messages:
+                init_messages_objs.append(msg)
             assert all([isinstance(msg, Message) for msg in init_messages_objs]), (init_messages_objs, init_messages)
 
             # Put the messages inside the message buffer

letta/client/client.py

@@ -376,6 +376,7 @@ def create_agent(
         # metadata
         metadata: Optional[Dict] = {"human:": DEFAULT_HUMAN, "persona": DEFAULT_PERSONA},
         description: Optional[str] = None,
+        initial_message_sequence: Optional[List[Message]] = None,
     ) -> AgentState:
         """Create an agent
 
@@ -428,9 +429,18 @@ def create_agent(
             agent_type=agent_type,
             llm_config=llm_config if llm_config else self._default_llm_config,
             embedding_config=embedding_config if embedding_config else self._default_embedding_config,
+            initial_message_sequence=initial_message_sequence,
+        )
+
+        # Use model_dump_json() instead of model_dump()
+        # If we use model_dump(), the datetime objects will not be serialized correctly
+        # response = requests.post(f"{self.base_url}/{self.api_prefix}/agents", json=request.model_dump(), headers=self.headers)
+        response = requests.post(
+            f"{self.base_url}/{self.api_prefix}/agents",
+            data=request.model_dump_json(),  # Use model_dump_json() instead of json=model_dump()
+            headers={"Content-Type": "application/json", **self.headers},
         )
 
-        response = requests.post(f"{self.base_url}/{self.api_prefix}/agents", json=request.model_dump(), headers=self.headers)
         if response.status_code != 200:
             raise ValueError(f"Status {response.status_code} - Failed to create agent: {response.text}")
         return AgentState(**response.json())
@@ -1648,6 +1658,7 @@ def create_agent(
         # metadata
         metadata: Optional[Dict] = {"human:": DEFAULT_HUMAN, "persona": DEFAULT_PERSONA},
         description: Optional[str] = None,
+        initial_message_sequence: Optional[List[Message]] = None,
     ) -> AgentState:
         """Create an agent
 
@@ -1702,6 +1713,7 @@ def create_agent(
                 agent_type=agent_type,
                 llm_config=llm_config if llm_config else self._default_llm_config,
                 embedding_config=embedding_config if embedding_config else self._default_embedding_config,
+                initial_message_sequence=initial_message_sequence,
             ),
             actor=self.user,
         )

letta/schemas/agent.py

@@ -1,4 +1,3 @@
-import uuid
 from datetime import datetime
 from enum import Enum
 from typing import Dict, List, Optional
@@ -105,14 +104,19 @@ class Config:
 class CreateAgent(BaseAgent):
     # all optional as server can generate defaults
     name: Optional[str] = Field(None, description="The name of the agent.")
-    message_ids: Optional[List[uuid.UUID]] = Field(None, description="The ids of the messages in the agent's in-context memory.")
+    message_ids: Optional[List[str]] = Field(None, description="The ids of the messages in the agent's in-context memory.")
     memory: Optional[Memory] = Field(None, description="The in-context memory of the agent.")
     tools: Optional[List[str]] = Field(None, description="The tools used by the agent.")
     tool_rules: Optional[List[BaseToolRule]] = Field(None, description="The tool rules governing the agent.")
     system: Optional[str] = Field(None, description="The system prompt used by the agent.")
     agent_type: Optional[AgentType] = Field(None, description="The type of agent.")
     llm_config: Optional[LLMConfig] = Field(None, description="The LLM configuration used by the agent.")
     embedding_config: Optional[EmbeddingConfig] = Field(None, description="The embedding configuration used by the agent.")
+    # Note: if this is None, then we'll populate with the standard "more human than human" initial message sequence
+    # If the client wants to make this empty, then the client can set the arg to an empty list
+    initial_message_sequence: Optional[List[Message]] = Field(
+        None, description="The initial set of messages to put in the agent's in-context memory."
+    )
 
     @field_validator("name")
     @classmethod

letta/schemas/letta_base.py

@@ -1,4 +1,5 @@
 import uuid
+from datetime import datetime, timezone
 from logging import getLogger
 from typing import Optional
 from uuid import UUID
@@ -21,6 +22,8 @@ class LettaBase(BaseModel):
         from_attributes=True,
         # throw errors if attributes are given that don't belong
         extra="forbid",
+        # handle datetime serialization consistently across all models
+        json_encoders={datetime: lambda dt: (dt.replace(tzinfo=timezone.utc) if dt.tzinfo is None else dt).isoformat()},
     )
 
     # def __id_prefix__(self):

letta/server/server.py

@@ -857,15 +857,20 @@ def create_agent(
                     agent_state=agent_state,
                     tools=tool_objs,
                     # gpt-3.5-turbo tends to omit inner monologue, relax this requirement for now
-                    first_message_verify_mono=True if (llm_config.model is not None and "gpt-4" in llm_config.model) else False,
+                    first_message_verify_mono=(
+                        True if (llm_config and llm_config.model is not None and "gpt-4" in llm_config.model) else False
+                    ),
+                    initial_message_sequence=request.initial_message_sequence,
                 )
             elif request.agent_type == AgentType.o1_agent:
                 agent = O1Agent(
                     interface=interface,
                     agent_state=agent_state,
                     tools=tool_objs,
                     # gpt-3.5-turbo tends to omit inner monologue, relax this requirement for now
-                    first_message_verify_mono=True if (llm_config.model is not None and "gpt-4" in llm_config.model) else False,
+                    first_message_verify_mono=(
+                        True if (llm_config and llm_config.model is not None and "gpt-4" in llm_config.model) else False
+                    ),
                 )
             # rebuilding agent memory on agent create in case shared memory blocks
             # were specified in the new agent's memory config. we're doing this for two reasons:

tests/test_client.py

@@ -8,11 +8,12 @@
 from dotenv import load_dotenv
 
 from letta import create_client
+from letta.agent import initialize_message_sequence
 from letta.client.client import LocalClient, RESTClient
 from letta.constants import DEFAULT_PRESET
 from letta.schemas.agent import AgentState
 from letta.schemas.embedding_config import EmbeddingConfig
-from letta.schemas.enums import MessageStreamStatus
+from letta.schemas.enums import MessageRole, MessageStreamStatus
 from letta.schemas.letta_message import (
     AssistantMessage,
     FunctionCallMessage,
@@ -28,6 +29,7 @@
 from letta.schemas.usage import LettaUsageStatistics
 from letta.services.tool_manager import ToolManager
 from letta.settings import model_settings
+from letta.utils import get_utc_time
 from tests.helpers.client_helper import upload_file_using_client
 
 # from tests.utils import create_config
@@ -598,3 +600,75 @@ def test_shared_blocks(client: Union[LocalClient, RESTClient], agent: AgentState
     # cleanup
     client.delete_agent(agent_state1.id)
     client.delete_agent(agent_state2.id)
+
+
+@pytest.fixture
+def cleanup_agents():
+    created_agents = []
+    yield created_agents
+    # Cleanup will run even if test fails
+    for agent_id in created_agents:
+        try:
+            client.delete_agent(agent_id)
+        except Exception as e:
+            print(f"Failed to delete agent {agent_id}: {e}")
+
+
+def test_initial_message_sequence(client: Union[LocalClient, RESTClient], agent: AgentState, cleanup_agents: List[str]):
+    """Test that we can set an initial message sequence
+
+    If we pass in None, we should get a "default" message sequence
+    If we pass in a non-empty list, we should get that sequence
+    If we pass in an empty list, we should get an empty sequence
+    """
+
+    # The reference initial message sequence:
+    reference_init_messages = initialize_message_sequence(
+        model=agent.llm_config.model,
+        system=agent.system,
+        memory=agent.memory,
+        archival_memory=None,
+        recall_memory=None,
+        memory_edit_timestamp=get_utc_time(),
+        include_initial_boot_message=True,
+    )
+
+    # system, login message, send_message test, send_message receipt
+    assert len(reference_init_messages) > 0
+    assert len(reference_init_messages) == 4, f"Expected 4 messages, got {len(reference_init_messages)}"
+
+    # Test with default sequence
+    default_agent_state = client.create_agent(name="test-default-message-sequence", initial_message_sequence=None)
+    cleanup_agents.append(default_agent_state.id)
+    assert default_agent_state.message_ids is not None
+    assert len(default_agent_state.message_ids) > 0
+    assert len(default_agent_state.message_ids) == len(
+        reference_init_messages
+    ), f"Expected {len(reference_init_messages)} messages, got {len(default_agent_state.message_ids)}"
+
+    # Test with empty sequence
+    empty_agent_state = client.create_agent(name="test-empty-message-sequence", initial_message_sequence=[])
+    cleanup_agents.append(empty_agent_state.id)
+    assert empty_agent_state.message_ids is not None
+    assert len(empty_agent_state.message_ids) == 1, f"Expected 0 messages, got {len(empty_agent_state.message_ids)}"
+
+    # Test with custom sequence
+    custom_sequence = [
+        Message(
+            role=MessageRole.user,
+            text="Hello, how are you?",
+            user_id=agent.user_id,
+            agent_id=agent.id,
+            model=agent.llm_config.model,
+            name=None,
+            tool_calls=None,
+            tool_call_id=None,
+        ),
+    ]
+    custom_agent_state = client.create_agent(name="test-custom-message-sequence", initial_message_sequence=custom_sequence)
+    cleanup_agents.append(custom_agent_state.id)
+    assert custom_agent_state.message_ids is not None
+    assert (
+        len(custom_agent_state.message_ids) == len(custom_sequence) + 1
+    ), f"Expected {len(custom_sequence) + 1} messages, got {len(custom_agent_state.message_ids)}"
+    assert custom_agent_state.message_ids[1:] == [msg.id for msg in custom_sequence]