Keep provenance with each item
Carry a stable record ID or event ID through the workflow so later steps can be connected to the original input. When a step filters, maps, or combines data, retain enough context to explain which source records contributed.
Record transformation versions or rule names when business logic changes over time. This helps explain why two runs produced different outcomes and supports review when a downstream result is challenged.
Log for diagnosis without leaking data
Store concise status, counts, identifiers, and error details rather than copying full confidential payloads into logs. Apply access controls and retention limits to run history just as you would to the source data.
Test traceability with a sample that exercises normal, filtered, and failed paths. Confirm that you can reconstruct how a final value was derived and identify the responsible step while respecting privacy requirements.