letta-memory 0.1.5

An experimental SDK for using Letta subagents for pluggable memory management

Memory SDK

An experimental SDK for adding agentic memory and learning in a pluggable way. When messages are added, subconsious memory agents process them to generate learned context that can be plugged into your system prompt, such as a user profile or a conversational summary.

+========================================+
|         SYSTEM PROMPT                  |
+========================================+
|      LEARNED CONTEXT (HUMAN)           | <- memory agent (learning from message history)
+========================================+
|           MESSAGES                     |
|  * User -> Assistant                   |
|  * User -> Assistant                   |
|  * User -> Assistant                   |
|  * ...                                 |
+========================================+

For a specific user, the memory agent will learn a summary block and a human block, formatted as follows:

<conversation_summary>
Sarah introduced herself and asked the assistant to tell about itself. The assistant provided a brief self-description and offered further help.
</conversation_summary>

<human description="Details about the human user you are speaking to.">
Name: Sarah
Interests: Likes cats (2025-09-03)
</human>

You can customize the prompt format by getting the raw summary or user block string with prompt_formatted=False.

Quickstart

1. Create a Letta API key
2. Run export LETTA_API_KEY=...
3. Install: pip install letta-memory

Usage: Conversational Memory

You can save conversation histories using the Memory SDK, and later retrieve the learned context block to place into your system prompt. This allows your agents to have an evolving understand of the user. Example: Create a basic OpenAI gpt-4o-mini chat agent with memory

from openai import OpenAI
from letta_memory import Memory

openai_client = OpenAI()
memory = Memory()

def chat_with_memories(message: str, user_id: str = "default_user") -> str:

    # get the user memory 
    user_memory = memory.get_user_memory(user_id)
    if not user_memory:
        memory.initialize_user_memory(user_id, reset=True)
        user_memory = memory.get_user_memory(user_id)
    
    # format the user memory 
    user_memory_prompt= memory.get_user_memory(user_id, prompt_formatted=True)

    # generate the assistant response
    system_prompt = f"<system>You are a helpful AI assistant</system>"
    system_prompt += f"\n{user_memory_prompt}"
    messages = [{"role": "system", "content": system_prompt}, {"role": "user", "content": message}]
    response = openai_client.chat.completions.create(model="gpt-4o-mini", messages=messages)
    assistant_response = response.choices[0].message.content

    # Create new memories from the conversation
    messages.append({"role": "assistant", "content": assistant_response})
    memory.add_messages(user_id, messages)

    return assistant_response

def main():
    print("Chat with AI (type 'exit' to quit)")
    while True:
        user_input = input("You: ").strip()
        if user_input.lower() == 'exit':
            print("Goodbye!")
            break
        print(f"AI: {chat_with_memories(user_input)}")

if __name__ == "__main__":
    main()

SDK Reference

You can initialize the memory SDK with:

from letta_memory import Memory

memory = Memory()

Adding memories

Save messages by adding them to memory:

run = memory.add_messages("user_id", [{"role": "user", "content": "hi"}])

The memory agent will process the messages asynchronously, tracked by the run.

[!WARNING] Each each call to add_messages(...) will invoke the memory agent. To reduce costs, you may want to send messages in batches (recommended 5-10) or only when messages are evicted from context.

Waiting for learning to complete

Messages are processed asynchronously, so to ensure all memory updates are reflected you should wait for the agent learning to complete.

memory.wait_for_run(run)

This will block until the memory agent has completed processing.

Retrieving memories for a user

You can retrieve the summary and/or user memory for a given user with:

summary = memory.get_summary("user_id", prompt_formatted=True)
user_memory = memory.get_user_memory("user_id", prompt_formatted=True)

Retrieving the memory agent

Memories are formed by Letta agents using the sleeptime architecture. You can get the agent's ID with:

agent_id = memory.get_memory_agent_id("user_id")

The agent can be viewed at https://app.letta.com/agents/<AGENT_ID>.

Deleting user memories

All memories and data associated with a user can be deleted with:

memory.delete_user("user_id")

Roadmap

• TypeScript support
• Learning from files
• Query historical messages
• Save messages as archival memories
• Query archival memory
• Add "sleep" (offline collective revisioning of all data)