# FSM-based LLM Conversational Agents
This project provides a package framework for creating conversational agents using a Finite State Machine (FSM) powered by Large Language Models (LLMs). It integrates with OpenAI's API and provides an easy way to define states, transitions, and interactions.

This is currently an experimental setup, and also part of a research project I am doing for university. For now it is meant for developers and experimenters mainly. Requires an OpenAI API key (currently tested on gpt-4o-mini and gpt-4o).


## Features

- Define states and transitions for your agent using a simple decorator.
- Handle dynamic conversation flow with flexible state management.
- Integrates with GPT models to generate responses based on state context.


## Installation

1. Install the package directly from PyPI:
   ```
   pip install fsm-llm
   ```


2. Set up environment variables:
   Create a `.env` file and add your OpenAI API key:
     ```
     OPENAI_API_KEY=your-api-key
     OPENAI_ORGANIZATION=your-organization-id
     ```

## Usage Example (On/Off Switch)

### 0. What is an FSM?
A Finite State Machine (FSM) is a computational model used to design systems that can exist in one of a finite number of states at any given time. The system transitions from one state to another based on specific conditions or inputs.

![on and off fsm](https://github.com/user-attachments/assets/a804de3d-47c4-4b02-a461-4f95340eab9f)

In the example ```examples/switch_agent.py```, the FSM transitions between two states (OFF and ON) based on the input (user pressing the switch). If the user presses the switch while the light is already in the desired state (e.g., turning the light off when it’s already off), the FSM remains in the same state but can trigger additional responses.




### 1. **Creating the FSM (Finite State Machine)**
The `LLMStateMachine` class is the core of the framework. It handles state transitions based on user input.
```python
from fsm_llm import LLMStateMachine

# Create the FSM
fsm = LLMStateMachine(initial_state="START", end_state="END")
```


### 2. **Defining States with the `@fsm.define_state` Decorator**

The main feature of this framework is the ability to define states using the `@fsm.define_state` decorator. Each state has a unique key, a prompt that will be used for the LLM, and possible transitions to other states based on user input.

#### `START` State

```python
@fsm.define_state(
    state_key="START",
    prompt_template="You are an on-off switcher. Ask the user if they want to turn the switch on or off.",
    transitions={"STATE_ON": "If user wants to turn on the switch", "END": "If user wants to end the conversation"},
)
async def start_state(fsm: LLMStateMachine, response: str, will_transition: bool):
    global SWITCH_STATE
    if will_transition and fsm.get_next_state() == "STATE_ON":
        SWITCH_STATE = "ON"
        print("SWITCH TURNED ON")
    elif will_transition and fsm.get_next_state() == "END":
        return "Goodbye!"
    return response
```

- **`state_key="START"`**: The name of the state in the FSM.
- **`prompt_template`**: The message that will be used to prompt the LLM. In this case, the agent asks the user if they want to turn the switch on or off.
- **`transitions`**: This defines what happens next based on user input. For example:
  - If the user wants to turn the switch on, the FSM transitions to the `STATE_ON` state.
  - If the user wants to end the conversation, the FSM will transition to the `END` state.

Inside the function `start_state`, we check whether the FSM will transition to the `STATE_ON` or `END` state. If the transition happens, we update the `SWITCH_STATE` to `"ON"`.

#### `STATE_ON` State

```python
@fsm.define_state(
    state_key="STATE_ON",
    prompt_template="The switch is now on. Ask the user if they want to turn off the switch or end the conversation.",
    transitions={"START": "If user wants to turn off the switch", "END": "If user wants to end the conversation"},
)
async def state_on(fsm: LLMStateMachine, response: str, will_transition: bool):
    global SWITCH_STATE
    if will_transition and fsm.get_next_state() == "START":
        SWITCH_STATE = "OFF"
        print("SWITCH TURNED OFF")
    elif will_transition and fsm.get_next_state() == "END":
        return "Goodbye!"
    return response
```

The logic inside `state_on` checks the transition. If the FSM is transitioning back to the `START` state, it sets the `SWITCH_STATE` to `"OFF"`.

#### `END` State

```python
@fsm.define_state(
    state_key="END",
    prompt_template="Goodbye!",
)
async def end_state(fsm: LLMStateMachine, response: str, will_transition: bool):
    return "Goodbye!"
```


### 3. **Running the Agent**

To run the FSM-based agent, we use an asynchronous loop to interact with the user and process their input.
```python
from fsm_llm.state_models import FSMRun
```

```python
async def main():
    """Example of a simple on-off switch FSM using LLMStateMachine"""
    # Create the OpenAI client
    openai_client = openai.AsyncOpenAI()

    print("Agent: Hi. I am an on-off switch manager.")
    while not fsm.is_completed():  # Run until FSM reaches the END state
        user_input = input("Your input: ")
        if user_input.lower() in ["quit", "exit"]:
            fsm.set_next_state("END")
            break
        run_state: FSMRun = await fsm.run_state_machine(openai_client, user_input=user_input)
        print(f"Agent: {run_state.response}")
        print("CURRENT SWITCH STATE:", SWITCH_STATE)

    print("Agent: Goodbye.")
```

- **`while not fsm.is_completed()`**: The loop continues running until the FSM reaches the `END` state.
- **`user_input`**: The user provides input, which the FSM processes.
- **`fsm.run_state_machine`**: This method processes the current state and transitions based on the user's input. The OpenAI client is used to get the response.
- **`SWITCH_STATE`**: After each interaction, the current state of the switch (on or off) is printed.




## Examples

- **Light Switch Agent**: A simple agent that asks the user whether they want to turn a switch on or off. ```switch_agent.py```
- **Customer Support Agent**: A bot that collects user details and assists with customer queries. ```support_agent.py```
- **Medical Triage Agent**: A complex agent that helps assess if a medical situation is an emergency and collects patient data. ```medical_agent.py```

<!-- ## Contributing
Feel free to fork, star, and create pull requests. Contributions are welcome! -->
