This document discusses the challenges of offline work in mobile applications. It explains that users often lose connectivity due to issues like poor network coverage, elevators, or localized failures. When connectivity is lost, apps can crash or enter an invalid state. The document then discusses strategies for offline work, including downstream caching of data to allow working offline, and upstream caching of user actions to sync later. It notes the tradeoff between consistency and availability and considers which types of tasks are suitable for offline support. Overall, the document provides an overview of the technical challenges of enabling offline functionality in mobile apps.