Classify Purchase Requisitions with Gemini, Gmail & Slack | n8n

Automatically classify purchase requisitions with Gemini, then route for approval via Gmail & Slack

This n8n workflow receives new purchase requisitions through a webhook, uses Google Gemini to classify each PR into a procurement category with confidence and risk signals, and then either auto-approves or sends it for manual review—with full logging and stakeholder notifications via Google Sheets, Gmail, and Slack.

What this workflow does

• Receives PR submissions as a POST request to the webhook endpoint (example: /pr-submission).
• Validates required fields including PR ID, requester, description, and amount, then normalizes the payload into a consistent structure.
• Classifies with Google Gemini by sending requisition details plus the allowed category list, requesting a strict JSON response (category, confidence, risk, correction, reasoning).
• Decides approval vs. manual review based on confidence thresholds and misclassification risk.
• If eligible: marks the requisition as auto-approved and ready for ERP routing.
• If not eligible: marks it pending manual review and creates a review ticket flow via Gmail.
• Logs an audit record to Google Sheets and sends status updates through Gmail and a Slack channel.

Use cases

• Reduce procurement bottlenecks by auto-classifying PRs that meet confidence and risk thresholds.
• Flag ambiguous or high-risk requisitions for human review automatically.
• Maintain a clear audit trail for each categorized purchase requisition in Google Sheets.

Technical details (n8n)

• Webhook endpoint for incoming requisition data.
• Nodes: if, set, code, gmail, merge, slack.
• Google Gemini integration for strict JSON category classification.
• Gmail OAuth2 for email notifications/review tickets.