Three mechanical code-shape rules for hand-written Java (main + test): top-level types only (no nested/inner/anonymous/local; one type per file), methods <=20 non-comment statements, and no single-character identifiers. Use when writing or reviewing Java, or when a build fails on TYPES_MUST_BE_TOP_LEVEL, an NcssCount limit, or a no-single-character-names rule. The rules are language-level; the enforcement (PMD/ArchUnit) is wired by the build (build-maven-quality).
