Merge Pairing Coverage Balance with Tagged Orphan Padding

How it works

1. 1.Manual Trigger starts the batch with no external setup.
2. 2.Code "Emit Tagged Merge Append Output" emits 8 tagged items (5 for branch A, 3 for branch B including one record with a missing id).
3. 3.Code "Classify Pairing Coverage" splits branches, sorts by seq and classifies each row as paired, orphan_branch_a or orphan_branch_b.
4. 4.IF "Is Row Paired?" routes paired rows to output 0 and orphan rows to output 1.
5. 5.NoOp passes paired rows through and keeps the path valid even when empty.
6. 6.Set adds padding_injected and missing_side_label to orphan rows with includeOtherFields:true.
7. 7.Merge in append mode joins both paths on separate inputs.
8. 8.Final Code node (runOnceForAllItems) emits exactly one coverage report item.

Use cases

• Detecting partial Merge results in multi-run batch flows
• Reconciling orders against payments with unequal branch lengths
• Documenting orphan rows before a seemingly complete report is forwarded
• Batch quality audit: missing identifiers and amount mismatches

Requirements

• n8n 2.45.7 or newer
• No credentials and no outbound calls required
• For real data: tag each item with branch, seq and record before the classifier node

Setup and testing in n8n

1. Import the JSON and click Execute Workflow.
2. Confirm the final report returns paired_count=3, orphan_branch_a_count=2 and coverage_percent=60.
3. Extend branch B to five rows in the sample node and confirm coverage_percent=100 with no orphan rows.
4. Empty both sample arrays and confirm coverage_status=EMPTY_BATCH.
5. Add an item with an unknown branch tag and confirm it is counted in ignored_untagged without errors.

Service Value

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