Code Review Agent with LangChain

from langchain_openai import ChatOpenAI
from langchain_core.tools import tool

@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."

model = ChatOpenAI(model="gpt-4o")
model_with_tools = model.bind_tools([read_file, find_files, search_code])
response = model_with_tools.invoke([
    ("system", "You are a code reviewer. Find relevant files, read them, search for patterns, and provide a structured review covering security, performance, and best practices."),
    ("user", "Review the Python files in src/ for common security issues"),
])