Merge Drift Dual-Run Reverse Index Balance Auditor

How it works

1. 1.Run the manual trigger; a Code node emits the fictional source including one invalid record with no category
2. 2.Paths A and B each build the reverse index (category to count); B drops record id=4 to simulate drift
3. 3.Merge node in append mode collects both outputs from two independent inputs
4. 4.A Code node balances each category count in A and B against the source and computes deltas
5. 5.The If node checks full balance: deficit routes to the false output into NoOp blocking sorting; balance routes to the Set counts report

Use cases

• Proving merge result consistency between Desktop and Docker before adoption
• Detecting silently dropped rows between branches before sorting
• Auditing reverse indexes built from countable categories

Requirements

• n8n 2.45.4 with manualTrigger, code, set, if, merge, noOp and stickyNote nodes
• Each dual-run path wired to its own Merge input; never join both IF outputs to the same input
• No credentials; for real use replace the source array with a real input node of the same schema

Setup and testing in n8n

1. Import the JSON into n8n and run Run Merge Drift Audit manually
2. Normal/invalid case: the source includes a record without a category counted as __uncategorized
3. Expect one item from Mismatch Branch with balanced=false and a one-record shipping deficit
4. Remove the id!==4 filter in path B and rerun: flow reaches the Set report with auditStatus=index-balanced-ready-for-sort

Service Value

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