Fix Google Merchant Center disapprovals with GPT-4o-mini, Shopify, and Slack

Quick overview This workflow scans Google Merchant Center for disapproved Shopify products, uses OpenAI to draft minimal compliant fixes (title/description/GTIN actions), routes proposals to Slack for approval, applies approved changes back to Shopify, and tracks outcomes in Google Sheets with a daily verification report and Slack Q&A.

How it works Runs on a daily schedule (7 AM IST to detect disapproved items and 8 AM IST to verify applied fixes) or when an approval link webhook is opened from Slack. Fetches products from the Google Merchant API, keeps items with DISAPPROVED (or optionally DEMOTED) issues for the configured country, and extracts issue details plus a Shopify product/variant mapping from the offer ID. Loads fix history and a GTIN master from Google Sheets, skips recently handled items, checks GTIN candidates (including check-digit validation), and pulls the current product details from Shopify via the Admin GraphQL API. Sends the combined Merchant Center + Shopify context to OpenAI (gpt-4o-mini) to identify the root cause and generate the smallest safe fix, then validates the proposed text/GTIN against configured rules and confidence thresholds. Writes either a fix proposal or a human task into the Google Sheets “Fix History” tab, posts a daily Slack digest, and sends fix proposals to Slack with one-time Approve/Reject links. When someone approves, verifies the signed token and proposal status, updates the Shopify product (and variant barcode when needed), records the result back to Google Sheets, and posts a confirmation to Slack (or records a rejection). On the 8 AM run, re-fetches Merchant Center products, marks applied proposals as resolved or still disapproved in Google Sheets, and posts a verification report to Slack. Replies to Slack app mentions by using an OpenAI agent that queries Google Sheets tools to answer questions about proposal status and disapproval history in the thread.

Setup Create Shopify Admin API access (e.g., a custom app with read_products and write_products) and add it as HTTP Header Auth for the Shopify GraphQL requests, then set your Shopify domain in the workflow config. Add Google OAuth2 credentials for the Google Merchant API with scope https://www.googleapis.com/auth/content and update the Merchant Center account ID and country code in the workflow config. Create a Google Sheet with “Fix History” and “GTIN Master” tabs, connect Google Sheets credentials, and replace REPLACE_WITH_GOOGLE_SHEET_ID wherever it appears. Connect Slack credentials, set the target channel IDs for digest/proposals/status messages, and ensure your Slack app can receive app_mention events. Add OpenAI credentials for gpt-4o-mini and review/update the workflow config values (approval webhook domain, approval_secret, title/description limits, and regex rules) before activating. Set this workflow as its own error workflow in n8n settings and replace the Slack error-alert channel ID so failed runs are reported.