## Summary The `Key` model delegates to `user` but doesn't enforce user presence via Rails validations or database constraints. This creates ambiguity about whether `key.user` can be `nil`. ## Investigation Needed 1. Determine if `user_id: nil` is a valid state for keys 2. Check production data for keys with `NULL user_id` 3. Either add validation/constraints OR update code to handle nil users consistently ## Context During code review, it was discovered that while the Key model delegates to user (suggesting it should always be present), Rails and the database don't actually prevent `user_id` from being `nil`.