Code Review Agent with LangGraph

from langchain_openai import ChatOpenAI
from langchain_core.tools import tool
from langgraph.prebuilt import create_react_agent

@tool
def read_file(path: str) -> str:
    """Read a file from the project."""
    return Path(path).read_text()

@tool
def find_files(pattern: str) -> str:
    """Find files matching a glob pattern."""
    files = list(Path(".").rglob(pattern))
    return "\n".join(str(f) for f in files[:20])

@tool
def search_code(pattern: str, path: str = ".") -> str:
    """Search for a regex pattern in source files."""
    import subprocess
    result = subprocess.run(
        ["grep", "-rn", pattern, path, "--include=*.py"],
        capture_output=True, text=True,
    )
    return result.stdout[:3000] or "No matches found."

agent = create_react_agent(
    ChatOpenAI(model="gpt-4o"),
    tools=[read_file, find_files, search_code],
    prompt="You are a code reviewer. Find relevant files, read them, search for patterns, and provide a structured review covering security, performance, and best practices.",
)

result = await agent.ainvoke({
    "messages": [("user", "Review the Python files in src/ for common security issues")]
})
print(result["messages"][-1].content)