n8n workflow automation with retries, logging, and review queues

PURPOSE

Designs and outputs n8n workflow JSON with robust triggers, idempotency, error handling, logging, retries, and human-in-the-loop review queues.

WHEN TO USE

• TRIGGERS:
• Build an n8n workflow that runs every Monday and emails the compliance summary.
• Add error handling and retries to this workflow, plus a review queue for failures.
• Create a webhook workflow that logs every run and writes a status row to a tracker.
• Make this n8n flow idempotent so it does not duplicate records when it reruns.
• Instrument this workflow with audit logs and a human approval step.
• DO NOT USE WHEN…
• You need code-only automation without n8n (use a scripting/CI skill).
• You need to bypass security controls or hide audit trails.
• You need to purchase or recommend prohibited items/services.

INPUTS

• REQUIRED:
• Workflow intent: trigger type + schedule/timezone + success criteria.
• Targets: where to write results (email/Drive/Sheet/DB) and required fields.
• OPTIONAL:
• Existing n8n workflow JSON to modify.
• Sample payloads / example records.
• Definition of dedup keys (what makes a record unique).
• EXAMPLES:
• Cron: Monday 08:00 Europe/London; send summary email + Drive upload
• Webhook: receive JSON; route to folders

OUTPUTS

• Default (read-only): a workflow design spec (nodes, data contracts, failure modes).
• If explicitly requested: workflow.json (n8n importable JSON) + runbook.md (from template).

Success = workflow is idempotent, logs every run, retries safely, and routes failures to a review queue.

WORKFLOW

1. Clarify trigger:

• Cron/webhook/manual; schedule/timezone; concurrency expectations.

1. Define data contract:

• input schema, required fields, and validation rules.

1. Design idempotency:

• choose dedup key(s) and storage (DB/Sheet) to prevent duplicates on retries.

1. Add observability:

• generate run_id, log start/end, store status row and error details.

1. Implement error handling:

• per-node error branches, retry with backoff, and final failure notification.

1. Add human-in-the-loop (HITL) review queue:

• write failed items to a queue (Sheet/DB) and require approval to reprocess.

1. “No silent failure” gates:

• if counts/thresholds fail, stop workflow and alert.

1. Output:

• If asked for JSON: produce importable n8n workflow JSON + runbook.

1. STOP AND ASK THE USER if:

• destination systems are unknown,
• no dedup key exists,
• credential strategy (env vars) is not specified,
• the workflow needs privileged access not yet approved.

OUTPUT FORMAT

If outputting n8n workflow JSON, conform to:

json
{
  "name": "<workflow name>",
  "nodes": [ { "name": "Trigger", "type": "n8n-nodes-base.cron", "parameters": {}, "position": [0,0] } ],
  "connections": {},
  "settings": {},
  "active": false
}

Also output runbook.md using assets/runbook-template.md.

SAFETY & EDGE CASES

• Read-only by default; only emit workflow JSON when explicitly requested.
• Do not include secrets in JSON; reference env vars/credential names only.
• Include audit logging + failure notifications; avoid workflows that can silently drop data.
• Prefer least privilege: call only required APIs and minimize scopes.

EXAMPLES

• Input: “Cron every Monday, email compliance summary, retry failures.”

Output: Node map + workflow.json with Cron → Fetch → Aggregate → Email, plus error branches to review queue.

• Input: “Webhook that logs runs and writes status row.”

Output: Webhook → Validate → Process → Append status row; on error → log + notify + queue.