Ctrip-Style AI Travel Assistant

An advanced, multi-agent intelligent service system based on LangChain and LangGraph, designed to simulate a professional travel agency (Ctrip-style). The system handles complex, multi-turn dialogues and dynamic task execution across flight booking, hotel reservations, car rentals, and tour planning.

Project Background

Traditional chatbot systems often struggle with state management in long-running conversations and the safe execution of sensitive operations. This project implements a Stateful Multi-Agent Orchestration architecture that manages task delegation, tool-calling permissions, and human-in-the-loop (HITL) verification.

Architecture Overview

The system is built on a "Hub-and-Spoke" architecture:

• Primary Assistant: The central router that identifies intent and delegates tasks.
• Specialized Sub-Agents: Dedicated agents for Flights, Hotels, Car Rentals, and Excursions.
• Unified State Management: A shared state tracking message history, user information, and a dialogue stack.

Key Components

1. Multi-Agent Dispatcher: Uses dynamic routing via add_conditional_edges and a dialog_stack to manage sub-agent lifecycle.
2. Permission Control: Implements a strict distinction between Safe Tools (Read-only) and Sensitive Tools (Write/Modify).
3. Human-in-the-Loop: Automated workflow interruption (interrupt_before) for sensitive operations, requiring user confirmation before database modification.
4. Context Persistence: Utilizes MemorySaver to ensure seamless dialogue recovery across different sessions or interruptions.

Detailed Tool Modules

Category	Safe Tools (Read)	Sensitive Tools (Write)
Flights	search_flights, fetch_user_flight_info	update_ticket_to_new_flight, cancel_ticket
Hotels	search_hotels	book_hotel, update_hotel, cancel_hotel
Car Rental	search_car_rentals	book_car_rental, cancel_car_rental
Activities	search_trip_recommendations	book_excursion, cancel_excursion
General	tavily_tool, lookup_policy	-

State Machine Implementation

Dialogue Stack Management

We use a custom update_dialog_stack function to manage the focus of the conversation. When a sub-agent completes its task or the user changes context, the stack "pops," returning control to the Primary Assistant.

def update_dialog_stack(left: list[str], right: Optional[str]) -> list[str]:
    if right is None: return left
    if right == "pop": return left[:-1]
    return left + [right]

The CompleteOrEscalate Pattern

Sub-agents are equipped with a CompleteOrEscalate tool. This allows them to gracefully exit their specialized loop when:

• The task is successfully finished.
• The user requests something outside the sub-agent's domain.

🔧 Installation & Setup

1. Clone the Repository

   git clone https://github.com/your-username/ctrip-ai-assistant.git
   cd ctrip-ai-assistant
   

2. Environment Configuration Create a .env file and add your API keys:

   OPENAI_API_KEY=your_openai_key
   TAVILY_API_KEY=your_tavily_key
   

3. Install Dependencies

   pip install -r requirements.txt
   

Usage

Run the main script to start the interactive CLI:

python main.py

System Workflow:

1. Fetch Context: On startup, the fetch_user_info node automatically retrieves passenger data.

2. Intent Routing: The Primary Assistant analyzes your request.

3. Task Delegation: Control is shifted to the specialized sub-agent (e.g., Flight Assistant).

4. Approval Loop: If you attempt to "Cancel a Ticket," the system will pause and ask:

   “Do you approve this operation? Input 'y' to continue.”

Error Handling

The system implements a create_tool_node_with_fallback mechanism. If a tool fails (API timeout or invalid parameters), the handle_tool_error function catches the exception and prompts the LLM to fix its query without crashing the workflow.

Workflow Graph

(Recommendation: Use LangGraph's get_graph().draw_mermaid_png() to generate a visual and place it here)

• Nodes: primary_assistant, update_flight, book_hotel, leave_skill, etc.
• Edges: Conditional routing based on dialog_state and tool calls.

License

This project is licensed under the MIT License - see the LICENSE file for details.

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Disclaimer: This project is a simulation for educational and developmental purposes and is not directly affiliated with Ctrip.