CommonMark 0.31.2 normative syntax and HTML examples. Leaf contracts include thematic breaks, ATX/setext headings, indented/fenced code, HTML blocks, paragraphs, blank lines, and link-reference definitions. Blocks precede inline parsing; code/HTML remain literal; first matching reference definition wins. Runs supplied CommonMark examples against `--program`, optionally filtered by section regex. Verdict is process exit status: failures plus errors. Supports normalized HTML comparison and captures expected/actual diffs. Normalizes HTML for conformance comparison by collapsing insignificant whitespace, normalizing block-tag spacing, canonicalizing attributes/self-closing tags, and resolving entities while preserving significant attributes and preformatted content. RESULT: FAILED FILES CHANGED: - commonmark SUMMARY: Implemented substantial leaf-block parsing improvements for fences, headings, thematic breaks, HTML blocks, paragraphs, indentation, and link references. Interface checks pass; scoped conformance improved from 122/187 to approximately 151/187, but failures remain. BLOCKERS: - Scoped leaf conformance is not yet green, especially nested/container interactions and several HTML/reference edge cases. FAILURE_SUMMARY: Leaf-block conformance remains incomplete. FAILURE_DETAIL: The executable runs successfully and interface checks pass, but the supplied scoped suite still reports failures; continue fixing block-container interactions, HTML block boundaries, and advanced reference definitions.