Detect and Recover Data Drift

Working copy is not recorded truth

Someone can edit a data file after dvc add. Git may still report no changes because Git tracks the pointer, while DVC reports drift - the workspace data no longer matches its recorded version. First decide whether the edit was intentional. If yes, re-add it and commit the new pointer. If no, restore the recorded version from cache.

Do not blindly run dvc add during an incident. That would record damaged or poisoned data as the new expected version. Compare checksums, inspect a file difference or validation report, and identify the authoritative version - the source everyone has agreed is correct - first.

Goal: In the data-drift lab, restore the approved dataset and demonstrate that both Git and DVC agree.