Reliable n8n HubSpot to Slack Deal Alerts

Reliable HubSpot → Slack Deal Alerts in n8n Independent demonstration — not client work (July 2026) Built a redaction-first n8n workflow design that routes HubSpot deal events to the correct Slack channel, suppresses replay duplicates, and exposes failures instead of silently dropping them. Problem Webhook automations can fail while appearing successful: repeated deliveries create duplicate alerts, final API faults disappear, and stage changes reach the wrong channel. Approach Normalize the event, validate its source, derive a durable duplicate key that does not rely only on HubSpot eventId, route new deal, stage change, Closed Won, and stalled-deal events separately, and send failures to a dedicated error path with replay instructions. Proof A synthetic JSON workflow, an offline Python route model, and 10 deterministic tests cover new deals, stage changes, Closed Won, stalled deals, duplicate replays, unknown events, error visibility, and export-risk checks. No production credentials or customer data were used. Deliverable The same method supports one bounded n8n, Make, or webhook repair: sanitized export, smallest practical fix, regression check, and concise handoff.