Customer Support Agent

An AI-powered customer support agent built with LangGraph, LangChain, FastAPI, and LangSmith.

Architecture

POST /chat  (UserInput JSON)
    │
    ▼
input_guard.py          ← blocks injection / abuse before graph starts
    │
    ▼
graph/builder.py        ← StateGraph kicks off
    │
    ├─▶  enrich_query.py      LLM structured-output call
    │         UserInput  ──►  CustomerQuery  (validated by Pydantic)
    │
    ├─▶  route_priority.py    conditional edge
    │         priority == "high"  ──►  create_ticket.py  ──►  SupportTicket
    │         priority != "high"  ──►  faq_lookup.py     ──►  List[FAQResult]
    │
    └─▶  compose_response.py  final LLM call, builds plain-English reply
    │
    ▼
output_guard.py         ← scrub PII, tone check
    │
    ▼
Response JSON  →  caller

Quick Start

Prerequisites

• Python 3.11+
• uv installed

Setup

# Clone the repo
git clone <repo-url>
cd customer-support-agent

# Install dependencies with uv
make install

# Copy and fill in environment variables
cp .env.example .env
# Edit .env with your OPENAI_API_KEY etc.

# Run the server
make run

The API will be available at http://localhost:8000.

API Endpoints

Method	Path	Description
POST	/chat	Submit a support query
GET	/health	Liveness probe
GET	/ready	Readiness probe
POST	/feedback	Submit run feedback

Example Request

curl -X POST http://localhost:8000/chat \
  -H "Content-Type: application/json" \
  -H "X-API-Key: changeme-secret-key" \
  -d '{
    "message": "My order has not arrived and it has been 2 weeks!",
    "user_id": "user_123",
    "session_id": "sess_abc"
  }'

Example Response

{
  "response": "I'm sorry to hear your order hasn't arrived...",
  "priority": "high",
  "ticket_id": "TICKET-20240101-abc123",
  "run_id": "uuid-...",
  "session_id": "sess_abc"
}

Development

# Run tests
make test

# Lint
make lint

# Format code
make format

# Type check
make typecheck

Environment Variables

Variable	Required	Description
OPENAI_API_KEY	Yes	OpenAI API key
API_KEY	Yes	Bearer token for API authentication
LANGCHAIN_API_KEY	No	LangSmith API key for tracing
LANGCHAIN_TRACING_V2	No	Enable LangSmith tracing
MODEL_NAME	No	OpenAI model (default: gpt-4o-mini)
POSTGRES_DSN	No	PostgreSQL DSN for persistent checkpointing