ask_candid/tools/question_reformulation.py

from langchain_core.prompts import ChatPromptTemplate
from langchain_core.output_parsers import StrOutputParser
from langchain_core.language_models.llms import LLM

from ask_candid.agents.schema import AgentState


def reformulate_question_using_history(
    state: AgentState,
    llm: LLM,
    focus_on_recommendations: bool = False
) -> AgentState:
    """Transform the query to produce a better query with details from previous messages and emphasize aspects important
    for recommendations if needed.

    Parameters
    ----------
    state : AgentState
        The current state
    llm : LLM
    focus_on_recommendations : bool, optional
        Flag to determine if the reformulation should emphasize recommendation-relevant aspects such as geographies,
        cause areas, etc., by default False

    Returns
    -------
    AgentState
        The updated state
    """

    print("---REFORMULATE THE USER INPUT---")
    messages = state["messages"]
    question = messages[-1].content

    if len(messages[:-1]) > 1:  # need to skip the system message
        if focus_on_recommendations:
            prompt_text = """Given a chat history and the latest user input which might reference context in the chat
            history, especially geographic locations, cause areas and/or population groups, formulate a standalone input
            which can be understood without the chat history.
            Chat history: ```{chat_history}```
            User input: ```{question}```

            Reformulate the question without adding implications or assumptions about the user's needs or intentions. 
            Focus solely on clarifying any contextual details present in the original input."""
        else:
            prompt_text = """Given a chat history and the latest user input which might reference context in the chat
            history, formulate a standalone input which can be understood without the chat history. Include hints as to
            what the user is getting at given the context in the chat history.
            Chat history: ```{chat_history}```
            User input: ```{question}```

            Do NOT answer the question, just reformulate it if needed and otherwise return it as is.
            """

        contextualize_q_prompt = ChatPromptTemplate([
            ("system", prompt_text),
            ("human", question),
        ])

        rag_chain = contextualize_q_prompt | llm | StrOutputParser()
        # new_question = rag_chain.invoke({"chat_history": messages, "question": question})
        new_question = rag_chain.invoke({
            "chat_history": '\n'.join(f"{m.type.upper()}: {m.content}" for m in messages[1:]),
            "question": question
        })
        print(f"user asked: '{question}', agent reformulated the question basing on the chat history: {new_question}")
        return {"messages": [new_question], "user_input" : question}
    return {"messages": [question], "user_input" : question}