This document outlines the modules, libraries, and components that make up an Android application for creating collages. It describes the purpose and responsibilities of each module, including lib-image-loader for loading images, lib-util for shared utilities, lib-component for common components, lib-widget for widgets, lib-reactive for reactive programming, lib-history for undo/redo, and lib-collage-editor for editing collages. It also addresses some questions about where certain components should be located and future plans to add additional modules.