- Fix numerous ActiveSupport and ActiveModel bugs including Cache::NullStore local caching, Inflector.humanize(nil) errors, and improved error messages for EventedFileUpdateChecker and model errors
- Resolve multiple ActiveRecord issues: correct enum missing methods, include nils in in_order_of, fix new_record? for destroyed records, restore has_one behavior, and address query argument duplication with AR instances
- Update Action View caching behavior for collection rendering, prevent double-encoding of field ids, and adjust scaffold redirect responses to use 303 for XHR updates