Route vendor invoice approvals with gpt-5.6-terra, Gmail, Google Sheets and Telegram

by Khairul Muhtadin ✓ · 5 views · created 2026-09-03 · Invoice Processing, AI RAG

What this workflow does

This AI workflow has 18 nodes and runs when an HTTP POST request hits its webhook URL. Along the way it connects OpenAI Chat Model, Google Sheets, Gmail and Telegram.

How it runs

Trigger: When an HTTP POST request hits its webhook URL.

1. Normalize Invoice (Edit Fields (Set)): sets 9 fields: invoice_id, vendor_name, vendor_email…
2. Validate Invoice Input (If): checks a condition and branches into true / false
3. AI Invoice Assistant (AI Agent): runs an AI agent, with model: AP Model; 2 tools (Vendor Master Tool, Approval Policy Tool)
4. Alert Invalid Invoice (Telegram): uses Telegram
5. Parse Invoice Decision (Code): runs custom JavaScript code
6. Email Invalid Notice (Gmail): uses Gmail
7. Route Approval Decision (Code): runs custom JavaScript code
8. Log Invoice to Sheet (Google Sheets): append
9. Reattach Invoice Decision (Edit Fields (Set)): sets 13 fields: invoice_id, vendor_name, vendor_email…
10. If: checks a condition and branches into true / false

…plus 4 more steps. See the full node list below.

Services it uses

OpenAI Chat ModelGoogle SheetsGmailTelegram

Before you upgrade to n8n 3.0

Nodes used (10)

• Webhookn8n-nodes-base.webhook
• Edit Fields (Set)n8n-nodes-base.set
• Ifn8n-nodes-base.if
• AI Agent@n8n/n8n-nodes-langchain.agent
• OpenAI Chat Model@n8n/n8n-nodes-langchain.lmChatOpenAi
• Google Sheets Tooln8n-nodes-base.googleSheetsTool
• Coden8n-nodes-base.code
• Google Sheetsn8n-nodes-base.googleSheets
• Gmailn8n-nodes-base.gmail
• Telegramn8n-nodes-base.telegram

From the author

Invoice approvals without the bottleneck. Vendor invoices arrive via webhook, AI checks them against your vendor and policy data, and each one is either auto-approved or routed to a human reviewer. Every decision logged to Sheets, everyone notified. Last…

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