Build a Facebook Messenger customer service AI chatbot with Google Gemini

🤖 Build a customer service AI chatbot for Facebook Messenger with Google Gemini

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📌 Overview

A streamlined Facebook Messenger chatbot powered by AI with conversation memory. This is a simplified version designed for quick deployment, learning, and testing — not suitable for production environments.

Base workflows:

• Smart message batching AI-powered Facebook Messenger chatbot use Data Table
• Smart human takeover & auto pause AI-powered Facebook Messenger chatbot

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🎯 What This Workflow Does

✅ Core Features:

• Receives messages from Facebook Messenger via webhook
• Processes user messages with Google Gemini AI
• Maintains conversation context using Simple Memory node
• Automatically responds with AI-generated replies
• Handles webhook verification for Facebook setup
• Send image or video to customer through Facebook Messenger

🔹 Simplified Approach:

• Memory: Simple Memory node (10-message window)
• Format: Cleans text, strips markdown, truncates >1900 chars
• Response: Single message delivery

⚠️ Limitations & Trade-offs:

1. No Smart Batching → fragmented user messages cause spam-like replies
2. No Human Takeover Detection → bot continues even when admin joins
3. Basic Memory Management → no persistence, not reliable in production
4. Basic Text Formatting → strips markdown, truncates brutally, no smart splitting

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🚀 When to Upgrade

Upgrade to full workflows when you need:

• Production deployment with reliability & persistence
• Analytics & tracking (query history, reports)
• Professional formatting (bold, italic, lists, code blocks)
• Handling long messages (>2000 chars)
• Smart batching for fragmented inputs
• Human handoff detection
• Full conversation persistence

Key upgrades available:

• Smart message batching workflow
• Smart human takeover workflow

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⚙️ Setup Requirements

Facebook Setup

1. Create Facebook App at developers.facebook.com
2. Add Messenger product
3. Configure webhook:

• URL: https://your-domain.com/webhook/your-path
• Verify token: secure string
• Subscribe to: messages, messaging_postbacks

1. Generate Page Access Token
2. Copy token to "Set Context" node

n8n Setup

1. Import workflow
2. Edit "Set Context" node → update page_access_token
3. Configure "Gemini Flash" node credentials
4. Deploy workflow (must be publicly accessible)

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🔄 How It Works

User Message → Facebook Webhook → Validation
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Set Context (extract user_id, message, token)
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Mark Seen → Show Typing
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AI Agent (Gemini + 10-message memory)
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Format Output (remove markdown, truncate)
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Send Response via Facebook API

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🏗️ Architecture Overview

Section 1: Webhook & Initial Processing

• Facebook Webhook: handles GET (verification) & POST (messages)
• Confirm Webhook: returns challenge / acknowledges receipt
• Filters text messages only
• Blocks echo messages from bot itself

Section 2: AI Processing with Memory

• Set Context: extracts user_id, message, token
• Seen & Typing: user feedback
• Conversation Memory: 10-message window, per-user isolation
• Process Merged Message: AI Agent with Jenix persona
• Gemini Flash: Google’s AI model for response generation

Section 3: Format & Delivery

• Cuts replies >2000 chars, strips markdown
• Sends text via Facebook Graph API

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🎨 Customisation Guide

• Bot Personality: edit system prompt in "Process Merged Message" node
• Memory: adjust contextWindowLength (default 10), change sessionKey if needed
• AI Model: replace Gemini Flash with OpenAI, Anthropic Claude, or other LLMs

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📌 Important Notes

⚠️ Production Warning: testing only, memory lost on n8n restart in queue mode 📊 No Analytics: no history storage, no reporting 🔧 Format Limitations: responses ≤1800 chars, markdown stripped, no complex formatting

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🛠️ Troubleshooting

• Bot not responding → check token, webhook accessibility, event subscriptions
• Memory not working → verify session key, ensure not in queue mode, restart workflow
• Messages truncated → adjust system prompt for conciseness, reduce response length

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📜 License & Credits

Created by: Nguyễn Thiệu Toàn (Jay Nguyen)

• Email: [email protected]
• Website: nguyenthieutoan.com
• n8n Creator: n8n.io/creators/nguyenthieutoan
• Company: GenStaff