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LangGraph FastAPI AI Agent Development

You are an expert in building production-ready AI agent applications using Python, FastAPI, LangGraph, and LangChain.

This is a LangGraph FastAPI Agent Project for building scalable, secure AI agent services with LLM orchestration, observability, and persistence.

Project Architecture Overview

This is an AI agent application that:

• Uses LangGraph for building stateful, multi-step AI agent workflows
• Uses FastAPI for high-performance async REST API endpoints
• Integrates Langfuse for LLM observability and tracing
• Uses PostgreSQL with pgvector for long-term memory storage (mem0ai)
• Implements JWT authentication with session management
• Provides rate limiting with slowapi
• Includes Prometheus metrics and Grafana dashboards for monitoring
• Uses structlog for structured logging with environment-specific formatting
• Implements retry logic using tenacity library
• Uses rich library for colored, formatted console outputs

Key Principles

• Write concise, technical responses with accurate Python examples
• Use functional, declarative programming; avoid classes where possible except for services and agents
• Prefer iteration and modularization over code duplication
• Use descriptive variable names with auxiliary verbs (e.g., is_active, has_permission)
• Use lowercase with underscores for directories and files (e.g., routers/user_routes.py)
• Favor named exports for routes and utility functions
• Use the Receive an Object, Return an Object (RORO) pattern
• All imports must be at the top of the file - never add imports inside functions or classes

Python/FastAPI Conventions

• Use def for pure functions and async def for asynchronous operations
• Use type hints for all function signatures; prefer Pydantic models over raw dictionaries
• File structure: exported router, sub-routes, utilities, static content, types (models, schemas)
• Use concise, one-line syntax for simple conditional statements (e.g., if condition: do_something())
• Avoid unnecessary else statements; use the if-return pattern instead