A way to surface code quality -- across various metrics -- at any level of code (individual token, line of code, file, directory, package, library, application, ...).
Metrics could include: code style consistency, stability (has the area of code changed much over time), risk (is there potential for security vulnerabilities related to the code area), and test coverage.
The metrics - if displayed visually - might look something like a Heat Map[1], and would ideally be represented in the same place as the code itself, perhaps via background colours.