Search engine

Methods, systems, and apparatus, including computer programs encoded on a computer-storage medium, for using a search engine implemented on a user device to identify topics or tasks associated with native application content. The method may include actions of receiving a set of data that is generated by the native application and that includes (i) native application content, and (ii) context information associated with the native application content, generating a cluster feature-vector representation based on the set of data, storing the cluster feature-vector representations in a search engine index on the user device, identifying a set of cluster feature-vector representations that are associated with a particular feature-vector representation, identifying one or more tasks that are associated with the set of cluster feature-vector representations, and providing, for output, a user interface including a selectable control that identifies one or more of the tasks.