CommonMark 0.31.2 specification: block structure precedes inline parsing. Leaf blocks include thematic breaks, headings, indented/fenced code, HTML blocks, reference definitions, paragraphs, and blank lines. Reference labels normalize via Unicode case-folding and whitespace collapsing; first definition wins. Runs supplied CommonMark examples against `--program`, optionally filtered by section pattern. Verdict is the process exit status: failures plus errors; output is diagnostic only. Normalizes HTML for conformance comparison: collapses insignificant whitespace, normalizes attributes and entities, preserves preformatted content, and canonicalizes URLs. RESULT: SUCCESS FILES CHANGED: - commonmark SUMMARY: Implemented and repaired leaf-block parsing and link-reference collection. Scoped conformance: 187 passed, 0 failed, 0 errored. Direct executable interface verification passed. BLOCKERS: - None