planner.py

from langchain_openai import ChatOpenAI

from utils import extract_bullets
from tenacity import retry, stop_after_attempt, wait_exponential

class Planner:
    def __init__(self,
                 llm: ChatOpenAI) -> None:
        self.llm = llm
        self.prompt_template = """Given the following complex task, break it down into a list of smaller, modular, and actionable subtasks (each task should be approximately accomplished in 20 steps). Each subtask should be concise and self-contained, suitable for direct execution without further decomposition. Present the subtasks as bullet points, without nesting or embedding.

**Task:** {task}

**Output:**

- [First finer-grained subtask]  
- [Second finer-grained subtask]  
- [Third finer-grained subtask]  
- ...      

(No additional contents are allowed.)
        """
        
    @retry(
    stop=stop_after_attempt(3),
    wait=wait_exponential(min=1, max=10)
    )
    def call_llm(self, messages):
        return self.llm.invoke(messages).content
    
    def plan(self, task:str):
        messages = [
            {"role":"system", "content": "You are a helpful assistant good at decomposing complex tasks into practical steps."},
            {"role":"user", "content": self.prompt_template.format(task=task)}
        ]
        plan_str = self.call_llm(messages)
        subtasks = extract_bullets(plan_str)
        return subtasks