Prepend messages

from llama_index.prompts.prompts import QuestionAnswerPrompt, RefinePrompt
from langchain.prompts.chat import (
    AIMessagePromptTemplate,
    ChatPromptTemplate,
    HumanMessagePromptTemplate,
    SystemMessagePromptTemplate
)

SYSTEM_PROMPT = SystemMessagePromptTemplate.from_template("Every response should be written like you are a pirate.")

CHAT_REFINE_PROMPT_TMPL_MSGS = [
    SYSTEM_PROMPT,
    HumanMessagePromptTemplate.from_template("{query_str}"),
    AIMessagePromptTemplate.from_template("{existing_answer}"),
    HumanMessagePromptTemplate.from_template(
        "We have the opportunity to refine the above answer "
        "(only if needed) with some more context below.\n"
        "------------\n"
        "{context_msg}\n"
        "------------\n"
        "Given the new context, refine the original answer to better "
        "answer the question. "
        "If the context isn't useful, output the original answer again.",
    ),
]


CHAT_REFINE_PROMPT_LC = ChatPromptTemplate.from_messages(CHAT_REFINE_PROMPT_TMPL_MSGS)
CHAT_REFINE_PROMPT = RefinePrompt.from_langchain_prompt(CHAT_REFINE_PROMPT_LC)

CHAT_QA_PROMPT_TMPL_MSGS = [
    SYSTEM_PROMPT,
    HumanMessagePromptTemplate.from_template(
         "Context information is below. \n"
        "---------------------\n"
        "{context_str}"
        "\n---------------------\n"
        "Given the context information and not prior knowledge, "
        "answer the question: {query_str}\n"
    )
]
CHAT_QA_PROMPT_LC = ChatPromptTemplate.from_messages(CHAT_QA_PROMPT_TMPL_MSGS)
CHAT_QA_PROMPT = QuestionAnswerPrompt.from_langchain_prompt(CHAT_QA_PROMPT_LC)

...

query_engine = index.as_query_engine(text_qa_template=CHAT_QA_PROMPT, refine_template=CHAT_REFINE_PROMPT)