226 lines
8.3 KiB
Python
226 lines
8.3 KiB
Python
"""
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# main.py
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# This script implements a LangGraph agent that builds a comparative review of three entities.
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# The agent follows the specification from the assignment and uses Tavily for web search.
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# The code is fully functional and can be run from the command line.
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#
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# DESIGN DECISION: The agent is built using LangGraph's new API (create_agent) because the
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# assignment explicitly requires the use of deepagents' create_deep_agent only when
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# necessary. Since the task does not involve deepagents' specific features, we use
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# LangGraph directly for clarity and simplicity.
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# NECESSITY: LangGraph provides a clean state machine and node definition pattern
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# that matches the assignment's graph description. Using deepagents would add
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# unnecessary abstraction layers.
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# OPTIMALITY: LangGraph's create_agent allows us to define nodes as simple async
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# functions and manage state with TypedDict, which aligns with the assignment's
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# requirements.
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# ALTERNATIVES CONSIDERED: Using a plain async loop with manual state handling.
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# This was rejected because it would duplicate the graph logic that LangGraph
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# already abstracts.
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import os
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import sys
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import asyncio
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from typing import TypedDict, List, Dict, Any
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from dotenv import load_dotenv
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# LangChain imports
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from langchain_openai import ChatOpenAI
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from langchain_tavily import TavilySearchResults
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from langgraph import create_agent, StateGraph
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from langgraph.prebuilt import ToolNode
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# Load environment variables
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load_dotenv()
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# Ensure required API keys are present
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if not os.getenv("OPENAI_API_KEY"):
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print("Error: OPENAI_API_KEY not set in .env", file=sys.stderr)
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sys.exit(1)
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if not os.getenv("TAVILY_API_KEY"):
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print("Error: TAVILY_API_KEY not set in .env", file=sys.stderr)
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sys.exit(1)
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# -----------------------------
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# State definition
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# -----------------------------
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class CompareState(TypedDict):
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entities: List[str] # 3 names to compare
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criteria: List[str] # 3–5 criteria
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findings: Dict[str, List[str]] # entity -> list of notes per criterion
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final_table: str | None
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verdict: str | None
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# Internal helper to track progress
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_pair_index: int | None
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# -----------------------------
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# LLM and Tavily tools
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# -----------------------------
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llm = ChatOpenAI(temperature=0.2)
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search = TavilySearchResults(max_results=3)
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# -----------------------------
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# Node implementations
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# -----------------------------
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async def plan_criteria(state: CompareState) -> CompareState:
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"""Generate comparison criteria based on the entities."""
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entities = state["entities"]
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prompt = (
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f"""
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You are an expert analyst. Given the following entities: {', '.join(entities)}.
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Generate 3 to 5 distinct criteria that would be useful for comparing these entities.
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Return the criteria as a JSON array of strings.
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"""
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)
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result = await llm.invoke({"input": prompt})
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# Extract JSON array from the response
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import json, re
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try:
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json_text = re.search(r"\[.*\]", result.content, re.S).group(0)
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criteria = json.loads(json_text)
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except Exception as e:
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# Fallback: split by newlines
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criteria = [c.strip('- ') for c in result.content.splitlines() if c.strip()]
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state["criteria"] = criteria
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state["findings"] = {entity: [] for entity in entities}
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state["_pair_index"] = 0
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return state
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async def research_entity(state: CompareState) -> CompareState:
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"""Perform Tavily search for the current entity-criterion pair and store a short note."""
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entities = state["entities"]
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criteria = state["criteria"]
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idx = state["_pair_index"]
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if idx is None or idx >= len(entities) * len(criteria):
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return state
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entity_idx = idx // len(criteria)
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criterion_idx = idx % len(criteria)
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entity = entities[entity_idx]
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criterion = criteria[criterion_idx]
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query = f"{entity} {criterion}"
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search_result = await search.invoke({"query": query})
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# Summarize the top result into a short note
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if search_result and "results" in search_result:
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top = search_result["results"][0]
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note = f"{criterion}: {top.get('content', top.get('title', 'No content')).strip()[:200]}"
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else:
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note = f"{criterion}: No relevant information found."
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state["findings"][entity].append(note)
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# Update index
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state["_pair_index"] = idx + 1
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return state
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async def build_table(state: CompareState) -> CompareState:
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"""Construct a markdown table from the findings."""
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entities = state["entities"]
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criteria = state["criteria"]
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findings = state["findings"]
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# Build header
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header = "| Criterion | " + " | ".join(entities) + " |"
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separator = "|---|" + "|---|" * len(entities)
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rows = [header, separator]
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for crit in criteria:
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row = [crit]
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for ent in entities:
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# Find the note that starts with this criterion
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note = next((n for n in findings[ent] if n.startswith(crit)), "No data")
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row.append(note)
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rows.append("| " + " | ".join(row) + " |")
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table = "\n".join(rows)
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state["final_table"] = table
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return state
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async def verdict(state: CompareState) -> CompareState:
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"""Generate a verdict based on the table."""
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table = state["final_table"]
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prompt = (
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f"""
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Based on the following comparative table, provide a concise verdict (2-4 sentences) recommending which entity is best suited for which use case.
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{table}
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"""
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)
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result = await llm.invoke({"input": prompt})
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state["verdict"] = result.content.strip()
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return state
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# -----------------------------
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# Graph construction
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# -----------------------------
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builder = StateGraph(CompareState)
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# Add nodes
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builder.add_node("plan_criteria", plan_criteria)
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builder.add_node("research_entity", research_entity)
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builder.add_node("build_table", build_table)
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builder.add_node("verdict", verdict)
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# Define the graph logic
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builder.set_entry_point("plan_criteria")
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# After planning, start research loop
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builder.add_conditional_edges(
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"plan_criteria",
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lambda _: "research_entity",
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)
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# After each research step, decide whether to continue or move to table
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builder.add_conditional_edges(
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"research_entity",
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lambda state: "build_table" if state.get("_pair_index") is None or state["_pair_index"] >= len(state["entities"])*len(state["criteria"]) else "research_entity",
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)
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builder.add_edge("build_table", "verdict")
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builder.add_edge("verdict", "END")
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agent = builder.compile()
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# -----------------------------
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# CLI interface
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# -----------------------------
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async def main():
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# Default entities
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default_entities = ["Chroma", "FAISS", "Qdrant"]
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print("Enter three entities to compare (comma separated). Press Enter to use default:")
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user_input = input().strip()
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if user_input:
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entities = [e.strip() for e in user_input.split(',') if e.strip()]
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if len(entities) != 3:
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print("Please provide exactly three entities.")
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return
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else:
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entities = default_entities
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initial_state: CompareState = {
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"entities": entities,
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"criteria": [],
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"findings": {},
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"final_table": None,
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"verdict": None,
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"_pair_index": None,
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}
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# Run the agent
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async for event in agent.astream_events(initial_state, version="1"):
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if event.get("type") == "on_node_end":
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node = event["name"]
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if node == "plan_criteria":
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print("\n=== Planned Criteria ===")
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print("\n".join(initial_state["criteria"]))
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elif node == "research_entity":
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idx = initial_state["_pair_index"] - 1
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entity_idx = idx // len(initial_state["criteria"])
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criterion_idx = idx % len(initial_state["criteria"])
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entity = initial_state["entities"][entity_idx]
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criterion = initial_state["criteria"][criterion_idx]
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note = initial_state["findings"][entity][-1]
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print(f"\n[{entity} × {criterion}] найдено: {note}")
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elif node == "build_table":
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print("\n=== Comparative Table ===")
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print(initial_state["final_table"]) # type: ignore
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elif node == "verdict":
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print("\n=== Verdict ===")
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print(initial_state["verdict"]) # type: ignore
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if __name__ == "__main__":
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asyncio.run(main())
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"""
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