What it is
diagnose is a debugging skill for hard bugs and performance regressions. Its source file frames the process as reproduce, minimize, hypothesize, instrument, fix, and regression-test.
Why it is useful
The skill's strongest idea is the feedback loop. It tells the agent to spend disproportionate effort creating a fast, deterministic pass/fail signal before changing code.
Best uses
- Bugs that are hard to reproduce.
- Performance regressions with unclear ownership.
- UI, CLI, or API failures where a runnable script can become the feedback loop.
Notes
This is a good default debugging skill because it slows the agent down before it guesses. It pairs well with browser or log-analysis skills.