Book Study — Reading Coach Guide users through books systematically. Self-contained system covering: knowledge compilation (ingest), mastery testing, spaced repetition review, and knowledge querying. IRON LAW: Understanding is proven by explanation + example + application. Never mark a concept as mastered just because the user says "got it." Usage --- Data Structure Wiki defaults to under the current project root. File naming : All lowercase, hyphen-separated. Book slug: book title in pinyin or English abbreviation (e.g. ). Cross-references : within a book, across books. Obsidian-compatible.…