n8n Workflow: Reconcile CSV Imports in Google Sheets + Drive + Gmail

Reconcile CSV imports against your Google Sheets master—then draft reviewer-ready Gmail updates

This n8n workflow compares incoming CSV records with a Google Sheets “Master” before importing anything new. It validates each batch, captures reviewer decisions in Sheets, detects conflicts or changes, exports only approved new records to Google Drive, and prepares Gmail drafts so review outcomes are always ready to send.

What this workflow does

• Receives a batch request (manual demo trigger or an n8n form submission) with a batch ID and Google Drive file ID.
• Loads import context from Google Sheets by reading the “Imports” register and the “Master” sheet, then downloads the source CSV from Google Drive.
• Validates and classifies records by checking required columns and formats, rejecting duplicate record IDs in the CSV, and comparing each row to the Master to determine whether it’s new, unchanged, conflicting, or invalid.
• Writes a case/proposal back to “Imports”, including hashes and a detailed proposal summary.
• Creates Gmail drafts that instruct reviewers to approve, reject, or request changes—keeping review communications consistent and ready.
• Waits for a reviewer decision by polling the “Imports” sheet on an interval until a valid decision is recorded (including matching proposal hash and reviewer email) or the window times out.
• Re-checks Master for staleness after approval by re-reading Master and marking the case stale if it changed since the proposal snapshot.
• Exports approved new records as a CSV to a private Google Drive folder, reusing an existing export if available, then records the final status and output file ID in “Imports”.
• Creates the final Gmail update once the workflow completes.

Use cases

• Preventing duplicate or conflicting imports by reconciling CSV exports with a Sheets-based system of record.
• Formal review workflows for SaaS data updates, with reviewer decisions tracked in Google Sheets.
• Controlled, auditable exports to Google Drive only after approval and “Master” change checks.

Technical details

• Google Sheets: reads Imports and Master; writes reviewer cases, hashes, statuses, and output file IDs.
• Google Drive: downloads the source CSV and exports approved new-record CSVs to a private folder.
• Gmail: drafts review requests and final outcomes.
• n8n nodes used: if, set, code, no op, wait, gmail.