12. The method according to claim 9 , wherein the state associated with the pre-defined function is selected from a warm-up, initial, in-progress, confirmation, disambiguate, or final state.
9. A method, implemented by a computing device comprising a microphone, the method comprising: receiving, by a voice-controlled digital personal assistant, a digital voice input generated by a user, wherein the digital voice input is received via the microphone; performing natural language processing using the digital voice input to determine a user voice command, wherein the user voice command comprises a request to perform a pre-defined function of a third-party voice-enabled application, and wherein the pre-defined function is identified using a data structure that defines functions supported by available third-party voice-enabled applications using voice input, the third-party voice-enabled applications comprising pre-defined functions that are capable of being executed using user interfaces of the third-party voice-enabled applications and pre-defined functions that are capable of being headlessly executed without using the user interfaces of the third-party voice-enabled applications, and the data structure defining how the pre-defined function is capable of being executed by the digital personal assistant; in response to determining the user voice command comprising the request to perform the pre-defined function of the third-party application, using the data structure to select between headlessly executing the pre-defined function of the third-party voice-enabled application and executing the pre-defined function using the user interface of the third-party voice-enabled application; causing the third-party voice-enabled application to execute the pre-defined function as a background process without a user interface of the third-party voice-enabled application appearing on a display of the computing device; receiving a response from the third-party voice-enabled application indicating a state associated with the pre-defined function; and providing, by a user interface of the voice-controlled digital personal assistant, a response to the user based on the received state associated with the pre-defined function so that the response comes from within a context of the user interface of the voice-controlled digital personal assistant without surfacing the user interface of the third-party voice-enabled application.