More typing of generics, better commenting of properties

Editor assessment

The subject gestures at improved generic typing and property comments but never says which subsystem is affected or what becomes possible for consumers, so the practical impact stays unknown until the diff is opened. The feat type is defensible for type-level capability work, though refactor fits equally; the rubric tolerates straddling choices. No scope identifies the area, and no body explains the motivation or gives an example of the new generics, which is where the teaching value would live. Style itself is clean. Understandable only vaguely; acceptable rather than good.