Many DAGs look tidy in documentation and fuzzy at 02:14. The transform failed, the chat fills with “was this the API or our mapper?”, and minutes pass while people reconstruct ownership from commit history.
A one-page ownership chart
For each stage — extract, validate, transform, load, publish — name a primary and a backup human, plus the system of record for credentials. Hang it where operators already look (runbook wiki, printed near the war-room display).
Review it after every assessment
Service Rivercore includes ownership notes in reliability assessments because gaps here prolong incidents more often than missing indexes. When two teams both assume the other owns schema drift, the page has nowhere useful to land.
If your overnight chat archaeology feels familiar, bring that pain to a discovery call.