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Multi-agent travel planning assistant powered by LangGraph state machines, Google Gemini, and web scraping via BrightData MCP. Features intelligent flight and hotel search with automated email reporting.

LLM Google Gemini 2.0
Orchestration LangGraph
Backend FastAPI
Web Scraping BrightData MCP
Email SendGrid

Workflow 1: LangGraph Travel Agent State Machine

%%{init: {'theme': 'dark', 'themeVariables': { 'primaryColor': '#C17852', 'primaryTextColor': '#F0F6FC', 'primaryBorderColor': '#4A5E32', 'lineColor': '#E6C98F', 'secondaryColor': '#161B22', 'tertiaryColor': '#0D1117', 'background': '#0D1117', 'mainBkg': '#161B22', 'nodeBorder': '#4A5E32', 'clusterBkg': '#161B22', 'clusterBorder': '#4A5E32', 'titleColor': '#E6C98F', 'edgeLabelBackground': '#161B22'}}}%%
flowchart TB
    subgraph Input["📥 USER REQUEST"]
        REQ[/"🗺️ Travel Request
Origin, Destination, Dates"/]
    end

    subgraph StateGraph["🔄 LANGGRAPH STATE MACHINE"]
        direction TB
        
        STATE[("📊 TravelAgentState
Shared Memory")]
        
        subgraph Nodes["Graph Nodes"]
            N1["✈️ find_flights"]
            N2["🏨 find_hotels"]
            N3["📧 send_email"]
        end
        
        subgraph Edges["Conditional Edges"]
            E1{"flights_searched?"}
            E2{"hotels_searched?"}
        end
    end

    subgraph Checkpointing["💾 PERSISTENCE"]
        MEM["🧠 MemorySaver
Thread Checkpoints"]
    end

    subgraph Output["📤 RESULTS"]
        END1(("🏁 END"))
    end

    REQ --> STATE
    STATE --> N1
    N1 --> E1
    E1 -->|"Yes"| N2
    E1 -->|"No + Error"| N3
    N2 --> E2
    E2 -->|"Yes"| N3
    E2 -->|"Error"| END1
    N3 --> END1
    
    N1 -.-> MEM
    N2 -.-> MEM
    N3 -.-> MEM

State Management: LangGraph maintains TravelAgentState across nodes, enabling conditional routing based on search completion flags (flights_searched, hotels_searched). MemorySaver provides thread-safe checkpointing.

Workflow 2: Flight Search ReAct Agent

%%{init: {'theme': 'dark', 'themeVariables': { 'primaryColor': '#C17852', 'primaryTextColor': '#F0F6FC', 'primaryBorderColor': '#4A5E32', 'lineColor': '#E6C98F', 'secondaryColor': '#161B22', 'tertiaryColor': '#0D1117', 'background': '#0D1117', 'mainBkg': '#161B22', 'nodeBorder': '#4A5E32', 'clusterBkg': '#161B22', 'clusterBorder': '#4A5E32', 'titleColor': '#E6C98F', 'edgeLabelBackground': '#161B22'}}}%%
flowchart TB
    subgraph Input["📥 SEARCH PARAMS"]
        P1["🛫 Origin"]
        P2["🛬 Destination"]
        P3["📅 Dates"]
        P4["👥 Travelers"]
    end

    subgraph ParamExtraction["🔍 PARAM EXTRACTION"]
        LLM1["🧠 Gemini LLM
Natural Language → Structured"]
        EXTRACT["📋 Extract:
Airport Codes, Dates, Count"]
    end

    subgraph MCPClient["🌐 BRIGHTDATA MCP CLIENT"]
        CONFIG["⚙️ MCP Server Config
API Token, Zones"]
        ADAPTER["🔌 LangChain Adapter"]
        TOOLS["🛠️ Scraping Tools
search_engine, scrape_as_markdown"]
    end

    subgraph ReActAgent["🤖 REACT AGENT"]
        AGENT["🎯 create_react_agent()
Gemini + MCP Tools"]
        SEARCH["🔎 Search Sites:
Google Flights, Expedia, Kayak"]
        RAW["📄 Raw Results"]
    end

    subgraph Structuring["📊 RESULT STRUCTURING"]
        PROMPT["📝 Structure Prompt"]
        STRUCT_LLM["🧠 with_structured_output()"]
        FLIGHT_OBJ["✈️ FlightSearchResults
Pydantic Model"]
    end

    subgraph Output["📤 STATE UPDATE"]
        FLIGHTS[("✈️ flights: List[FlightResult]")]
        FLAG["🚩 flights_searched: True"]
    end

    P1 & P2 & P3 & P4 --> LLM1
    LLM1 --> EXTRACT
    EXTRACT --> CONFIG
    CONFIG --> ADAPTER
    ADAPTER --> TOOLS
    TOOLS --> AGENT
    AGENT --> SEARCH
    SEARCH --> RAW
    RAW --> PROMPT
    PROMPT --> STRUCT_LLM
    STRUCT_LLM --> FLIGHT_OBJ
    FLIGHT_OBJ --> FLIGHTS
    FLIGHT_OBJ --> FLAG

Workflow 3: Hotel Search ReAct Agent

%%{init: {'theme': 'dark', 'themeVariables': { 'primaryColor': '#C17852', 'primaryTextColor': '#F0F6FC', 'primaryBorderColor': '#4A5E32', 'lineColor': '#E6C98F', 'secondaryColor': '#161B22', 'tertiaryColor': '#0D1117', 'background': '#0D1117', 'mainBkg': '#161B22', 'nodeBorder': '#4A5E32', 'clusterBkg': '#161B22', 'clusterBorder': '#4A5E32', 'titleColor': '#E6C98F', 'edgeLabelBackground': '#161B22'}}}%%
flowchart LR
    subgraph State["📊 FROM STATE"]
        DEST["📍 Destination"]
        DATES["📅 Check-in/out"]
        STARS["⭐ Star Rating"]
        BUDGET["💰 Budget"]
    end

    subgraph Calculation["🧮 PREPARATION"]
        NIGHTS["🌙 Calculate Nights"]
        FILTER["🔧 Build Filters"]
    end

    subgraph Agent["🤖 HOTEL REACT AGENT"]
        direction TB
        MCP["🌐 BrightData MCP"]
        SCRAPE["🔍 Scrape Hotel Sites:
Booking.com, Hotels.com"]
        EXTRACT["📋 Extract Data"]
    end

    subgraph Structuring["📊 STRUCTURING"]
        STRUCT["🧠 HotelSearchResults
Pydantic Model"]
        VALIDATE["✅ Validate Fields"]
    end

    subgraph Output["📤 STATE UPDATE"]
        HOTELS[("🏨 hotels: List[HotelResult]")]
        FLAG["🚩 hotels_searched: True"]
    end

    DEST & DATES --> NIGHTS
    STARS & BUDGET --> FILTER
    NIGHTS --> MCP
    FILTER --> MCP
    MCP --> SCRAPE
    SCRAPE --> EXTRACT
    EXTRACT --> STRUCT
    STRUCT --> VALIDATE
    VALIDATE --> HOTELS
    VALIDATE --> FLAG

Workflow 4: AI-Powered Email Report Generation

%%{init: {'theme': 'dark', 'themeVariables': { 'primaryColor': '#C17852', 'primaryTextColor': '#F0F6FC', 'primaryBorderColor': '#4A5E32', 'lineColor': '#E6C98F', 'secondaryColor': '#161B22', 'tertiaryColor': '#0D1117', 'background': '#0D1117', 'mainBkg': '#161B22', 'nodeBorder': '#4A5E32', 'clusterBkg': '#161B22', 'clusterBorder': '#4A5E32', 'titleColor': '#E6C98F', 'edgeLabelBackground': '#161B22'}}}%%
flowchart TB
    subgraph State["📊 AGGREGATE FROM STATE"]
        FLIGHTS["✈️ Flight Results"]
        HOTELS["🏨 Hotel Results"]
        PARAMS["🗺️ Trip Parameters"]
    end

    subgraph ContentBuild["📝 CONTENT BUILDING"]
        BUILD["🔧 _build_email_content()"]
        FORMAT["📋 Format Flight & Hotel
Details as Text"]
    end

    subgraph LLMGeneration["🧠 LLM HTML GENERATION"]
        PROMPT["📝 Email System Prompt:
Convert to Beautiful HTML"]
        CHAIN["⛓️ ChatPromptTemplate | LLM"]
        HTML["📄 Generated HTML Email"]
    end

    subgraph SendGrid["📧 SENDGRID DELIVERY"]
        MAIL["📬 Mail Object:
from, to, subject, html"]
        API["🌐 SendGrid API"]
        SEND["📤 sg.send()"]
    end

    subgraph Output["📤 STATE UPDATE"]
        SUCCESS["✅ email_sent: True"]
        STATUS["📊 email_status"]
    end

    FLIGHTS --> BUILD
    HOTELS --> BUILD
    PARAMS --> BUILD
    BUILD --> FORMAT
    FORMAT --> PROMPT
    PROMPT --> CHAIN
    CHAIN --> HTML
    HTML --> MAIL
    MAIL --> API
    API --> SEND
    SEND --> SUCCESS
    SEND --> STATUS

Workflow 5: Complete System Architecture

%%{init: {'theme': 'dark', 'themeVariables': { 'primaryColor': '#C17852', 'primaryTextColor': '#F0F6FC', 'primaryBorderColor': '#4A5E32', 'lineColor': '#E6C98F', 'secondaryColor': '#161B22', 'tertiaryColor': '#0D1117', 'background': '#0D1117', 'mainBkg': '#161B22', 'nodeBorder': '#4A5E32', 'clusterBkg': '#161B22', 'clusterBorder': '#4A5E32', 'titleColor': '#E6C98F', 'edgeLabelBackground': '#161B22'}}}%%
flowchart TB
    subgraph Frontend["🖥️ REACT FRONTEND"]
        UI["💻 Trip Planner UI"]
        WS["🔌 WebSocket Client"]
    end

    subgraph Backend["⚙️ FASTAPI BACKEND"]
        REST["🌐 POST /travel"]
        WSEND["🔌 WS /ws/thread_id"]
        DOCS["📚 /docs (Swagger)"]
    end

    subgraph LangGraph["🔄 LANGGRAPH ENGINE"]
        GRAPH["📊 StateGraph"]
        NODES["🔲 Nodes: flights, hotels, email"]
        MEMORY["💾 MemorySaver"]
    end

    subgraph Agents["🤖 REACT AGENTS"]
        FLIGHT_AGENT["✈️ Flight Agent"]
        HOTEL_AGENT["🏨 Hotel Agent"]
    end

    subgraph External["🌐 EXTERNAL SERVICES"]
        GEMINI["🧠 Google Gemini API"]
        BRIGHT["🔍 BrightData MCP"]
        SEND["📧 SendGrid API"]
    end

    subgraph DataSources["🌍 TRAVEL DATA SOURCES"]
        GF["Google Flights"]
        EXP["Expedia"]
        BOOK["Booking.com"]
        KAYAK["Kayak"]
    end

    UI <-->|"HTTP/WS"| REST
    UI <-->|"Real-time"| WSEND
    REST --> GRAPH
    GRAPH --> NODES
    NODES --> MEMORY
    NODES --> FLIGHT_AGENT
    NODES --> HOTEL_AGENT
    FLIGHT_AGENT --> GEMINI
    HOTEL_AGENT --> GEMINI
    FLIGHT_AGENT --> BRIGHT
    HOTEL_AGENT --> BRIGHT
    BRIGHT --> GF & EXP & KAYAK
    BRIGHT --> BOOK
    NODES --> SEND