Durable Postgres Job Runner for n8n: Claude + WhatsApp

Durable Postgres Job Runner for n8n—Powered by Claude + WhatsApp Approvals

Turn long-running, multi-step automations in n8n into resilient “durable jobs” backed by Postgres—complete with automatic recovery, pause/resume/cancel controls, and approval gates sent via WhatsApp using Anthropic Claude.

What this workflow does

This n8n workflow exposes two webhooks to manage reliable execution of tasks across multiple steps:

• Receives and validates work: Accepts a POST request on /webhook/durable-job, validates the task and steps, creates an idempotent job record, and stores the initial job state in Postgres.
• Claims an atomic lease: Uses guarded/atomic logic in Postgres to claim a lease, then decides what to do next based on the latest saved state and any requested control action.
• Executes runnable steps with Claude: For runnable steps, it sends the current prompt to the Anthropic Messages API (optionally using web_search), and records output, token usage, and cost back into Postgres as a checkpoint.
• Handles approval-required steps: Marks the job as awaiting approval in Postgres, then sends approve/reject links via WhatsApp. It waits up to 24 hours for a webhook-based decision.
• Applies control actions: Accepts POST requests on /webhook/durable-job-control to pause, resume, cancel, retry, approve, or reject—using guarded SQL updates—then re-queues the job when appropriate.
• Auto-recovery loop: Runs every minute to find stale/interrupted jobs, re-claims them for recovery, and fails jobs that exceed the configured recovery limit.
• Terminal notifications: On completion or failure, updates final state in Postgres and sends a terminal notification via WhatsApp.

Use cases

• Run production-grade n8n pipelines that can survive crashes and expired leases.
• Require human approval for high-risk steps (e.g., outbound messages or irreversible actions) via WhatsApp links.
• Guarantee exactly-once-like behavior with idempotent job records and checkpointed Claude outputs.

Technical details

• n8n nodes: if, set, code, wait, switch, webhook
• Backends: Postgres for job state, leases, checkpoints, and guarded SQL updates
• AI integration: Anthropic Messages API (with optional web_search)
• Approvals + notifications: WhatsApp via webhook-driven approve/reject links