What data-quality checks do you put on a pipeline, and how do you catch bad data before it spreads?

Bad data silently poisons everything downstream (dashboards, models, decisions), and 'it ran without error' is not 'it's correct.' The signal is the categories of checks and failing loud at the boundary.

Updated Aug 2026 · Grounded in real Applied AI Engineer interview loops and written to a senior-engineer editorial bar.