CommonMark is a Python 3 CLI parser that reads UTF-8 Markdown from standard input, parses blocks before inlines, and writes CommonMark 0.31.2 HTML to standard output. Runtime boundaries are `cmark`, `parser`, `renderer`, and `full_test.sh`; no public Markdown implementation or third-party dependencies are used. RESULT: FAILED FILES CHANGED: - README.md - test_documentation.py SUMMARY: Updated README documentation and added focused acceptance tests. Documentation checks pass; the full conformance suite remains failing on existing parser behavior. BLOCKERS: - `sh full_test.sh` fails on parser cases including tabs, escapes, entities, and thematic breaks. FAILURE_SUMMARY: Full CommonMark conformance suite fails in existing parser implementation. FAILURE_DETAIL: The requested documentation acceptance checks pass, but `sh full_test.sh` reports multiple parser mismatches unrelated to README.md. Fix the parser behaviors before rerunning the complete build.