Find Untested Sources

Purpose

Coverage tools answer "which lines were executed?" — they require a green build and a passing test run, which is minutes-to-tens-of-minutes on a real repo. The question this skill answers is different and much cheaper:

Which source files have no test file referencing any of their declared types/symbols?

That's the question an agent asks before writing a new test — and it can be answered statically in a few seconds by parsing source files, with no build, no dependency resolution, and no compilation. The output is a deterministic test-pairing map that lets the agent pick the next file to test without reading the entire codebase first.

Two engines — pick one