The idea that I want to capture here is what must a bright smart phone user know in order to gain the advantages of confinement. Crude idea: There is some ritual that the user learns that may not be programmed and that the user must take to move a secret beyond some established protection boundary.
Just now I want to imagine a notion of perimeter, not of screen space, or physical space, or campus space, but of social space. If I understood better how the brain worked regarding social maters this might go better. I strive to harness instincts, cultural or innate. I presume that we divide our world into a few compartments. When we think “I should tell my friends about that.” it is generally in the context of some particular compartment of friends. The marvelous movie “Westside story” dwelt on on these issues and succeeded well because audiences were well attuned to these subtleties.
This suggests software that is compartment savvy but without sense of categories of human social compartments. Such compartments would also serve the professional who contracts with different customers. In such cases the user would be in charge of controlling this software. Some computer usage might warrant control by an outside agent as when an employer provides a personal computer (or smart phone) while allowing some privacy to the user for personal business. The latter case would presume a device including software foundation built by a mutually trusted supplier.
The descriptions of factory logic on this site are directed to the programmer and not suitable to the general user. I can imagine a small but prominent signal on the screen that signals the user the current compartment. Compartment software is factory savvy and factories within the compartment will be suitable for secrets therein. User actions to transfer information beyond the compartment will require visible steps to which the user will have been introduced.