Add main.py implementing LangGraph code review agent

This commit is contained in:
2026-06-11 16:07:20 +00:00
parent e5f863da4f
commit 98dd596291
+120 -81
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@@ -1,105 +1,135 @@
import asyncio
import os
import asyncio
from typing import TypedDict, Dict
from langchain_openai import ChatOpenAI
from langchain_core.messages import HumanMessage
from langchain.tools import tool
from langgraph.graph import StateGraph, START, END
from typing import TypedDict, Annotated
from langgraph.graph.message import add_messages
from pydantic import BaseModel, Field
from langchain_core.output_parsers import PydanticOutputParser
# LLM setup
llm = ChatOpenAI(
model="openai/gpt-4o-mini",
model="openai/gpt-oss-20b:free",
base_url="https://openrouter.ai/api/v1",
api_key=os.getenv("OPENAI_API_KEY"),
temperature=0.0,
)
# Pydantic models for reflection
class CriteriaScores(BaseModel):
pep8: int
type_hints: int
edge_cases: int
naming: int
class ReviewResult(BaseModel):
scores: CriteriaScores
weakest: str
verdict: str
# Tool to run shell commands
@tool
def run_command(command: str) -> str:
"""Execute a shell command and return its output."""
try:
result = os.popen(command).read()
return result.strip() or "(no output)"
except Exception as e:
return f"Error: {e}"
# Draft review node
async def draft_review(state: dict):
code = state["code"]
prompt = f"Write a concise code review for the following Python function. Provide 3-6 bullet points highlighting strengths and areas for improvement.\n\n{code}"
response = llm.invoke([HumanMessage(content=prompt)])
state["draft_review"] = response.content
return state
# Reflect node
async def reflect(state: dict):
review = state["draft_review"]
prompt = f"Score the following code review on 4 criteria: PEP8, type hints, edge cases, naming. Return JSON with keys pep8, type_hints, edge_cases, naming (0-10). Also provide the weakest criterion and verdict ('ok' if all >=7 else 'needs_revision').\n\n{review}"
response = llm.invoke([HumanMessage(content=prompt)])
try:
data = ReviewResult.parse_raw(response.content)
except Exception:
# fallback simple parse
data = ReviewResult(scores=CriteriaScores(pep8=5,type_hints=5,edge_cases=5,naming=5),weakest="pep8",verdict="needs_revision")
state["criteria_scores"] = data.scores.dict()
state["weakest_criterion"] = data.weakest
state["verdict"] = data.verdict
return state
# Rewrite node
async def rewrite(state: dict):
weakest = state["weakest_criterion"]
review = state["draft_review"]
prompt = f"Improve the code review focusing on the {weakest} aspect. Keep the rest unchanged.\n\n{review}"
response = llm.invoke([HumanMessage(content=prompt)])
state["draft_review"] = response.content
state["round"] += 1
return state
# Graph definition
# State definition
class CodeReviewState(TypedDict):
code: str
draft_review: str
criteria_scores: dict
criteria_scores: Dict[str, int]
weakest_criterion: str
verdict: str
round: int
max_rounds: int
workflow = StateGraph(CodeReviewState)
workflow.add_node("draft", draft_review)
workflow.add_node("reflect", reflect)
workflow.add_node("rewrite", rewrite)
workflow.add_conditional_edges(START, lambda _: "draft")
workflow.add_conditional_edges("draft", lambda _: "reflect")
workflow.add_conditional_edges("reflect", lambda s: "rewrite" if s["verdict"]=="needs_revision" and s["round"]<s["max_rounds"] else "END")
workflow.add_conditional_edges("rewrite", lambda _: "reflect")
graph = workflow.compile()
# Reflect output model
class ReflectOutput(BaseModel):
pep8: int = Field(description="Score 0-10 for PEP8 compliance")
type_hints: int = Field(description="Score 0-10 for type hints usage")
edge_cases: int = Field(description="Score 0-10 for edge case coverage")
naming: int = Field(description="Score 0-10 for naming conventions")
weakest_criterion: str = Field(description="Criterion with lowest score")
verdict: str = Field(description="'ok' or 'needs_revision'")
reflect_parser = PydanticOutputParser(pydantic_object=ReflectOutput)
# Dummy tool for agent
@tool
def echo_tool(query: str) -> str:
return query
# Agent creation
from deepagents import create_deep_agent
from deepagents.backends import FilesystemBackend, LocalShellBackend, CompositeBackend
backend = CompositeBackend(
default=LocalShellBackend(root_dir="./workspace", virtual_mode=True, inherit_env=True),
routes={},
)
agent = create_deep_agent(
model=llm,
tools=[echo_tool],
backend=backend,
system_prompt="You are a code review assistant.",
)
# Node functions
async def draft_review(state: CodeReviewState) -> CodeReviewState:
prompt = f"""Write a concise code review (3-6 points) for the following Python function. Focus on style, correctness, and potential improvements.
```python
{state['code']}
```
Return only the review text."""
response = await agent.ainvoke({"messages": [HumanMessage(content=prompt)]}, {"configurable": {"thread_id": "draft-review"}})
review_text = response["messages"][-1].content
state["draft_review"] = review_text
return state
async def reflect(state: CodeReviewState) -> CodeReviewState:
prompt = f"""You are a senior reviewer. Evaluate the following review text against four criteria: PEP8, type hints, edge cases, naming. Assign each a score 0-10. Identify the weakest criterion and give a verdict: 'ok' if all scores >=7, else 'needs_revision'. Return a JSON with keys: pep8, type_hints, edge_cases, naming, weakest_criterion, verdict.
Review:
{state['draft_review']}"""
response = await agent.ainvoke({"messages": [HumanMessage(content=prompt)]}, {"configurable": {"thread_id": "reflect"}})
json_text = response["messages"][-1].content
try:
parsed = reflect_parser.parse(json_text)
except Exception:
parsed = ReflectOutput(pep8=5, type_hints=5, edge_cases=5, naming=5, weakest_criterion="pep8", verdict="needs_revision")
state["criteria_scores"] = {
"pep8": parsed.pep8,
"type_hints": parsed.type_hints,
"edge_cases": parsed.edge_cases,
"naming": parsed.naming,
}
state["weakest_criterion"] = parsed.weakest_criterion
state["verdict"] = parsed.verdict
return state
async def rewrite(state: CodeReviewState) -> CodeReviewState:
crit = state["weakest_criterion"]
prompt = f"""Improve the review section that addresses the weakest criterion '{crit}'. Provide a more detailed point for that criterion. Keep the rest of the review unchanged.
Current review:
{state['draft_review']}"""
response = await agent.ainvoke({"messages": [HumanMessage(content=prompt)]}, {"configurable": {"thread_id": "rewrite"}})
new_review = response["messages"][-1].content
state["draft_review"] = new_review
state["round"] += 1
return state
# Graph definition
from langgraph.graph import StateGraph
graph = StateGraph(CodeReviewState)
graph.add_node("draft_review", draft_review)
graph.add_node("reflect", reflect)
graph.add_node("rewrite", rewrite)
graph.set_entry_point("draft_review")
graph.add_edge("draft_review", "reflect")
graph.add_conditional_edges(
"reflect",
lambda x: "END" if x["verdict"] == "ok" else "rewrite" if x["round"] < x["max_rounds"] else "END",
)
graph.add_edge("rewrite", "reflect")
app = graph.compile()
# Demo function
async def run_demo():
code = """
def sort_numbers(arr):
return sorted(arr)
"""
state: CodeReviewState = {
"code": code,
async def demo():
sample_code = """def sort_numbers(arr):
return sorted(arr)"""
init_state: CodeReviewState = {
"code": sample_code,
"draft_review": "",
"criteria_scores": {},
"weakest_criterion": "",
@@ -107,9 +137,18 @@ def sort_numbers(arr):
"round": 0,
"max_rounds": 2,
}
final = await graph.ainvoke(state)
print("Final review:\n", final["draft_review"])
print("Scores:", final["criteria_scores"])
result = await app.ainvoke(init_state)
print("--- Draft Review ---")
print(result["draft_review"])
print("\n--- Scores ---")
print(result["criteria_scores"])
print("\n--- Verdict ---")
print(result["verdict"])
if result["verdict"] == "needs_revision":
print("\n--- Final Review After Rewrite ---")
print(result["draft_review"])
print("\n--- Final Scores ---")
print(result["criteria_scores"])
if __name__ == "__main__":
asyncio.run(run_demo())
asyncio.run(demo())