LangGraph

Prerequisites: Basic understanding of LangGraph and completed Deploy Your First Agent tutorial

Overview

LangGraph is a powerful framework for building stateful, multi-step AI agents with complex workflows. RunAgent makes it easy to deploy LangGraph agents and access them from any programming language.

Quick Start

1. Create a LangGraph Agent

runagent init my-langgraph-agent --framework langgraph
cd my-langgraph-agent

2. Install Dependencies

pip install -r requirements.txt

3. Configure Your Agent

The generated runagent.config.json will be pre-configured for LangGraph:

{
  "agent_name": "my-langgraph-agent",
  "description": "LangGraph agent with stateful workflows",
  "framework": "langgraph",
  "agent_architecture": {
    "entrypoints": [
      {
        "file": "agents.py",
        "module": "langgraph_agent",
        "tag": "main"
      }
    ]
  }
}

Basic LangGraph Agent

Here’s a simple LangGraph agent that demonstrates the core concepts:

agents.py

from typing import Dict, Any, List
from langgraph import StateGraph, END
from langgraph.graph import StateGraph
from langchain_core.messages import HumanMessage, AIMessage
from langchain_openai import ChatOpenAI

# Define the state structure
class AgentState:
    messages: List[Any]
    user_input: str
    response: str
    step_count: int

# Initialize the LLM
llm = ChatOpenAI(model="gpt-4", temperature=0.7)

def process_input(state: AgentState) -> AgentState:
    """Process the user input and prepare for reasoning"""
    state.step_count = 0
    state.messages = [HumanMessage(content=state.user_input)]
    return state

def reason_step(state: AgentState) -> AgentState:
    """Perform reasoning step"""
    state.step_count += 1
    
    # Add reasoning message
    reasoning = f"Step {state.step_count}: Analyzing the user's request..."
    state.messages.append(AIMessage(content=reasoning))
    
    return state

def generate_response(state: AgentState) -> AgentState:
    """Generate the final response"""
    # Get response from LLM
    response = llm.invoke(state.messages)
    state.response = response.content
    state.messages.append(response)
    
    return state

def should_continue(state: AgentState) -> str:
    """Decide whether to continue reasoning or finish"""
    if state.step_count >= 3:  # Max 3 reasoning steps
        return "finish"
    elif "complex" in state.user_input.lower():
        return "reason"
    else:
        return "finish"

# Build the graph
workflow = StateGraph(AgentState)

# Add nodes
workflow.add_node("process_input", process_input)
workflow.add_node("reason", reason_step)
workflow.add_node("generate_response", generate_response)

# Add edges
workflow.add_edge("process_input", "reason")
workflow.add_conditional_edges(
    "reason",
    should_continue,
    {
        "reason": "reason",
        "finish": "generate_response"
    }
)
workflow.add_edge("generate_response", END)

# Compile the graph
app = workflow.compile()

def langgraph_agent(user_input: str) -> Dict[str, Any]:
    """Main entrypoint for the LangGraph agent"""
    try:
        # Initialize state
        initial_state = AgentState(
            messages=[],
            user_input=user_input,
            response="",
            step_count=0
        )
        
        # Run the workflow
        result = app.invoke(initial_state)
        
        return {
            "response": result.response,
            "step_count": result.step_count,
            "messages": [msg.content for msg in result.messages],
            "status": "success"
        }
        
    except Exception as e:
        return {
            "response": f"Error: {str(e)}",
            "step_count": 0,
            "messages": [],
            "status": "error"
        }

Advanced LangGraph Patterns

1. Multi-Agent Workflows

multi_agent.py

from typing import Dict, Any, List
from langgraph import StateGraph, END
from langchain_core.messages import HumanMessage, AIMessage, SystemMessage

class MultiAgentState:
    messages: List[Any]
    user_input: str
    researcher_output: str
    writer_output: str
    final_response: str

def researcher_agent(state: MultiAgentState) -> MultiAgentState:
    """Research agent that gathers information"""
    research_prompt = f"""
    Research the following topic: {state.user_input}
    Provide key facts and insights.
    """
    
    # Simulate research (in real app, use web search, databases, etc.)
    state.researcher_output = f"Research findings for: {state.user_input}"
    return state

def writer_agent(state: MultiAgentState) -> MultiAgentState:
    """Writer agent that creates content"""
    writer_prompt = f"""
    Based on this research: {state.researcher_output}
    Create a comprehensive response to: {state.user_input}
    """
    
    # Simulate writing (in real app, use LLM)
    state.writer_output = f"Written content based on: {state.researcher_output}"
    return state

def coordinator_agent(state: MultiAgentState) -> MultiAgentState:
    """Coordinator that combines outputs"""
    state.final_response = f"""
    Research: {state.researcher_output}
    
    Content: {state.writer_output}
    
    Final Response: Based on the research and writing, here's the complete answer.
    """
    return state

# Build multi-agent workflow
multi_workflow = StateGraph(MultiAgentState)

multi_workflow.add_node("researcher", researcher_agent)
multi_workflow.add_node("writer", writer_agent)
multi_workflow.add_node("coordinator", coordinator_agent)

multi_workflow.add_edge("researcher", "writer")
multi_workflow.add_edge("writer", "coordinator")
multi_workflow.add_edge("coordinator", END)

multi_app = multi_workflow.compile()

def multi_agent_workflow(user_input: str) -> Dict[str, Any]:
    """Multi-agent workflow entrypoint"""
    initial_state = MultiAgentState(
        messages=[],
        user_input=user_input,
        researcher_output="",
        writer_output="",
        final_response=""
    )
    
    result = multi_app.invoke(initial_state)
    
    return {
        "response": result.final_response,
        "research": result.researcher_output,
        "writing": result.writer_output,
        "status": "success"
    }

2. Conditional Workflows

conditional_workflow.py

from typing import Dict, Any, List
from langgraph import StateGraph, END

class ConditionalState:
    user_input: str
    intent: str
    response: str
    confidence: float

def classify_intent(state: ConditionalState) -> ConditionalState:
    """Classify user intent"""
    input_lower = state.user_input.lower()
    
    if any(word in input_lower for word in ["question", "what", "how", "why"]):
        state.intent = "question"
        state.confidence = 0.9
    elif any(word in input_lower for word in ["task", "do", "help", "assist"]):
        state.intent = "task"
        state.confidence = 0.8
    else:
        state.intent = "general"
        state.confidence = 0.5
    
    return state

def handle_question(state: ConditionalState) -> ConditionalState:
    """Handle question intent"""
    state.response = f"Answering your question: {state.user_input}"
    return state

def handle_task(state: ConditionalState) -> ConditionalState:
    """Handle task intent"""
    state.response = f"Helping you with this task: {state.user_input}"
    return state

def handle_general(state: ConditionalState) -> ConditionalState:
    """Handle general intent"""
    state.response = f"General response to: {state.user_input}"
    return state

def route_intent(state: ConditionalState) -> str:
    """Route based on intent"""
    return state.intent

# Build conditional workflow
conditional_workflow = StateGraph(ConditionalState)

conditional_workflow.add_node("classify", classify_intent)
conditional_workflow.add_node("question_handler", handle_question)
conditional_workflow.add_node("task_handler", handle_task)
conditional_workflow.add_node("general_handler", handle_general)

conditional_workflow.add_edge("classify", "route")
conditional_workflow.add_conditional_edges(
    "classify",
    route_intent,
    {
        "question": "question_handler",
        "task": "task_handler",
        "general": "general_handler"
    }
)
conditional_workflow.add_edge("question_handler", END)
conditional_workflow.add_edge("task_handler", END)
conditional_workflow.add_edge("general_handler", END)

conditional_app = conditional_workflow.compile()

def conditional_agent(user_input: str) -> Dict[str, Any]:
    """Conditional workflow entrypoint"""
    initial_state = ConditionalState(
        user_input=user_input,
        intent="",
        response="",
        confidence=0.0
    )
    
    result = conditional_app.invoke(initial_state)
    
    return {
        "response": result.response,
        "intent": result.intent,
        "confidence": result.confidence,
        "status": "success"
    }

Streaming with LangGraph

LangGraph agents can also provide streaming responses:

streaming_agent.py

from typing import Iterator, Dict, Any
from langgraph import StateGraph, END

def streaming_langgraph_agent(user_input: str) -> Iterator[str]:
    """Streaming LangGraph agent"""
    yield f"🤖 Starting LangGraph workflow for: {user_input}\n\n"
    
    # Simulate workflow steps
    steps = [
        "📝 Processing input...",
        "🧠 Analyzing context...",
        "🔍 Gathering information...",
        "💭 Reasoning through solution...",
        "✍️ Generating response...",
        "✅ Finalizing output..."
    ]
    
    for i, step in enumerate(steps):
        yield f"Step {i+1}: {step}\n"
        # Simulate processing time
        import time
        time.sleep(0.5)
    
    yield f"\n🎉 Workflow complete! Response: {user_input} processed successfully."

Configuration for Multiple Entrypoints

Update your runagent.config.json to include multiple LangGraph workflows:

{
  "agent_name": "advanced-langgraph-agent",
  "description": "Advanced LangGraph agent with multiple workflows",
  "framework": "langgraph",
  "agent_architecture": {
    "entrypoints": [
      {
        "file": "agents.py",
        "module": "langgraph_agent",
        "tag": "basic"
      },
      {
        "file": "multi_agent.py",
        "module": "multi_agent_workflow",
        "tag": "multi_agent"
      },
      {
        "file": "conditional_workflow.py",
        "module": "conditional_agent",
        "tag": "conditional"
      },
      {
        "file": "streaming_agent.py",
        "module": "streaming_langgraph_agent",
        "tag": "streaming"
      }
    ]
  }
}

Testing Your LangGraph Agent

Python Client

test_langgraph.py

from runagent import RunAgentClient

# Connect to your LangGraph agent
client = RunAgentClient(
    agent_id="your_agent_id_here",
    entrypoint_tag="basic",
    local=True
)

# Test basic workflow
result = client.run(user_input="What is the capital of France?")
print(f"Response: {result['response']}")
print(f"Steps: {result['step_count']}")

# Test multi-agent workflow
multi_client = RunAgentClient(
    agent_id="your_agent_id_here",
    entrypoint_tag="multi_agent",
    local=True
)

multi_result = multi_client.run(user_input="Explain quantum computing")
print(f"Multi-agent response: {multi_result['response']}")

# Test streaming
stream_client = RunAgentClient(
    agent_id="your_agent_id_here",
    entrypoint_tag="streaming",
    local=True
)

print("Streaming response:")
for chunk in stream_client.run(user_input="Process this data"):
    print(chunk, end="", flush=True)

JavaScript Client

test_langgraph.js

import { RunAgentClient } from 'runagent';

const client = new RunAgentClient({
    agentId: 'your_agent_id_here',
    entrypointTag: 'basic',
    local: true
});

await client.initialize();

const result = await client.run({
    user_input: 'What is the capital of France?'
});

console.log('Response:', result.response);
console.log('Steps:', result.step_count);

Best Practices

1. State Management

Keep state objects simple and focused
Use clear naming conventions
Avoid deep nesting in state

2. Error Handling

Wrap workflow execution in try-catch blocks
Provide meaningful error messages
Log errors for debugging

3. Performance Optimization

Use conditional edges to avoid unnecessary steps
Implement early termination when possible
Cache expensive operations

4. Testing

Test each node independently
Test the complete workflow
Use mock data for testing

Common Patterns

Research and Writing Workflow

Use LangGraph to create agents that research topics and then write about them.

Multi-Step Problem Solving

Break complex problems into smaller steps with conditional logic.

Agent Collaboration

Create multiple specialized agents that work together.

Human-in-the-Loop

Add human approval steps for critical decisions.

Troubleshooting

Common Issues

State Serialization Errors
- Ensure all state fields are serializable
- Use simple data types when possible
Graph Compilation Errors
- Check that all nodes are properly defined
- Verify edge connections are correct
Memory Issues
- Limit the number of messages in state
- Implement state cleanup for long conversations

Debug Tips

# Add debugging to your workflows
def debug_node(state: AgentState) -> AgentState:
    print(f"Debug: Current state = {state}")
    return state

# Add debug node to your workflow
workflow.add_node("debug", debug_node)

Next Steps

Advanced Patterns

Learn advanced LangGraph patterns and techniques

Production Deployment

Deploy your LangGraph agent to production

Multi-Language Access

Access your LangGraph agent from different languages

Performance Tuning

Optimize your LangGraph workflows for production

🎉 Great job! You’ve learned how to deploy LangGraph agents with RunAgent. LangGraph’s powerful workflow capabilities combined with RunAgent’s multi-language access make for a powerful combination!

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How-to Guides

Frameworks

Call from Different Languages

Deployment

Advanced Tasks

Overview

Quick Start

1. Create a LangGraph Agent

2. Install Dependencies

3. Configure Your Agent

Basic LangGraph Agent

Advanced LangGraph Patterns

1. Multi-Agent Workflows

2. Conditional Workflows

Streaming with LangGraph

Configuration for Multiple Entrypoints

Testing Your LangGraph Agent

Python Client

JavaScript Client

Best Practices

1. State Management

2. Error Handling

3. Performance Optimization

4. Testing

Common Patterns

Troubleshooting

Common Issues

Debug Tips

Next Steps

Advanced Patterns

Production Deployment

Multi-Language Access

Performance Tuning

How-to Guides

Frameworks

Call from Different Languages

Deployment

Advanced Tasks

​Overview

​Quick Start

​1. Create a LangGraph Agent

​2. Install Dependencies

​3. Configure Your Agent

​Basic LangGraph Agent

​Advanced LangGraph Patterns

​1. Multi-Agent Workflows

​2. Conditional Workflows

​Streaming with LangGraph

​Configuration for Multiple Entrypoints

​Testing Your LangGraph Agent

​Python Client

​JavaScript Client

​Best Practices

​1. State Management

​2. Error Handling

​3. Performance Optimization

​4. Testing

​Common Patterns

​Troubleshooting

​Common Issues

​Debug Tips

​Next Steps

Advanced Patterns

Production Deployment

Multi-Language Access

Performance Tuning

Still have a question?

Overview

Quick Start

1. Create a LangGraph Agent

2. Install Dependencies

3. Configure Your Agent

Basic LangGraph Agent

Advanced LangGraph Patterns

1. Multi-Agent Workflows

2. Conditional Workflows

Streaming with LangGraph

Configuration for Multiple Entrypoints

Testing Your LangGraph Agent

Python Client

JavaScript Client

Best Practices

1. State Management

2. Error Handling

3. Performance Optimization

4. Testing

Common Patterns

Troubleshooting

Common Issues

Debug Tips

Next Steps