explainer

特定の読み手に向けて、概念・PR・設計を「冗長にならない水準」の速習資料として説明し、図と主張を道具で検証する。読み手のペルソナ（既に知っていること・知らないこと・読み方）を質問と公開情報から作り、その差分だけを書く。図は Mermaid / D2 で描いて事実シートに照らし、本文に引用するコード・出力は再実行して照合し、HTML は vlmkit のゲートに通す。Use when the user says "explain this to me / to ", "速習資料", "解説ドキュメント", "この PR を理解したい", "わかるように説明して", "I can't keep up with what the agent wrote", "この PR を が理解できるように説明して", or when a reviewer asks what a change does. Use it even for a small diff or a chat-only answer whenever a named reader (a reviewer, an on-call engineer, a teammate, a PM) is given. Also when model or analysis results (diagnostics, metrics, charts) must be explained to someone who decides on them, e.g. "このモデルを本番に出してよいか が判断できるように". Also when the user wrote an explanation themselves and lost confidence in it.

1 本の速習資料では収まらない、章立ての学習資料（ -book/01-quickstart.md, 02-….md …）を、読み手のペルソナに合わせて設計・執筆・検証する。章ごとの学習目標と理解度チェックの対応、概念を導入より前に使わない順序、章の読了時間の予算、「未完成なら落ち、答えなら通る」演習、book.json から生成する章の依存図を、verify-book.mjs で検査し、各章の出力・図・HTML は explainer の verify-doc.mjs で検査する。Use when the user asks for a book, a tutorial series, a course, "学習資料", "チュートリアル", "ハンズオン", "本にまとめて", "章立てで", "01-quickstart から", or when an explainer crash course would exceed 20 minutes or needs exercises.

Beta readers for any draft, run by simulating how a real reader experiences it, moment by moment. A skim gate, a no-lookahead timed read producing an attention transcript with quit points, a recall test of what a reader remembers the next day, and a trust ledger of the implied author. Use when the user asks for a beta read, beta readers, test readers, human review, reader review, to read something like a human, to be a first reader, whether a piece holds attention or will actually get read, for a quick read of whether a busy skimmer would even open a post, what readers will remember or take away tomorrow, where readers stop reading or bounce, or why a draft still feels off or hollow after anti-slop or humanizer edits. Final gate before publishing; reports where the reading broke; never rewrites.