Deployment Patterns
Ship It Like You Don't Trust It
9 min+100 XPStep 1/11
Offline metrics lie politely
Your challenger model beats the champion by three points on the held-out test set. Lovely — except the test set is a photograph of last quarter's world. Before the challenger touches a user, you want evidence from this quarter's world, gathered without betting the product on it.
That's what deployment patterns are: a graduated series — shadow mode → canary → full rollout — where each stage buys more evidence at slightly more risk, and rollback works at every single stage.
warning
The gap between 'won the offline eval' and 'wins in production' is where the bodies are buried. The test set can't see feature drift, feedback loops, or a user base that changed since February.