State Management and Data Flow Questions

Comprehensive coverage of strategies and patterns for managing application state and the flow of data in user interfaces and across system boundaries. Topics include local component state, derived state, and decisions about lifting state versus keeping it local; unidirectional data flow and event based updates; context providers and dependency injection for sharing state; and external state containers and libraries. Candidates should be able to explain criteria for selecting a solution based on application complexity, rendering performance, network characteristics, scalability, and team familiarity, and describe trade offs introduced by different libraries and architectures. Core engineering techniques include predictable state updates through immutability and pure update functions, minimizing duplicated and derived state, normalizing state shape, and designing for testability and debuggability. Synchronization concerns cover caching strategies and staleness models, when to refetch versus rely on cached data, optimistic and pessimistic update patterns and reconciliation, conflict resolution, and consistency across distributed front ends and server side systems. Also include considerations for rendering performance, concurrency, server side rendering, instrumentation, and debugging patterns used to reason about state in production.