Explicit Link Keys Before Merge with Post-Merge Reference Recovery Audit

How it works

1. 1.Manual Trigger starts both branches.
2. 2.Branch A Code emits three rows and adds linkKey = A#index#fingerprint(orderId,amount).
3. 3.Branch B Code emits rows at indexes 0, 2, 3 (index 1 intentionally missing, one invalid row) with linkKey = B#index#fingerprint(orderId,status).
4. 4.Merge in append mode joins branch A to input 1 and branch B to input 2.
5. 5.Final Code counts items per branch, detects duplicate keys, computes index-level gaps, flags invalid rows, outputs enriched items plus one verification report item.
6. 6.Set with includeOtherFields:true appends workflowPattern to every item.

Use cases

• Guarantee per-item reference recovery after merging branches
• Detect a lost item by its index instead of only a count delta
• Produce stable reference expressions that survive Merge
• Audit link-key uniqueness before building downstream logic

Requirements

• n8n 2.45.7 or a compatible version
• No credentials and no network access
• Replace both rows arrays with real items of the same schema
• Update keyFields per branch with your real distinguishing fields

Setup and testing in n8n

1. Import the workflow JSON and open it.
2. Click Execute Workflow and inspect the Stamp Pattern Name output.
3. Verify the six linked items each carry a unique linkKey with linkKeyUnique=true.
4. Verify the report item shows indexGaps for branch B at index 1 and invalidItems for the empty orderId row.
5. Edge cases: duplicate a row in branch A so status becomes failed_duplicate_keys; empty both rows arrays to get the empty_input report.

Service Value

Ready-made workflow template for automation delivery and service execution.