Explain code while building it, so the user ends up understanding what was built, why, and how — without drowning them in text. Use this skill whenever Claude writes, changes, or walks through code and the user wants to learn or understand it, even if they don't say 'explain' — e.g. 'teach me while you build', 'explain as you go', 'I want to understand every line', 'walk me through what you did', 'why did you do it this way', onboarding onto an unfamiliar codebase, or a user who is clearly learning a stack. Also use it when the user writes in Arabic or any other language. It auto-calibrates: explains only what is new, non-obvious, risky, or decision-bearing — for juniors and seniors alike — and in large projects it focuses on the diff, not the whole codebase. Also use it for the team ownership gate: quizzing a developer on their change before a PR ('check me', in any language) or turning the gate on for a repo.