CommonMark 0.31.2 normative Markdown-to-HTML behavior. Parse block structure before inline structure; support block quotes with nesting, lazy continuation, blank-line separation, and contained blocks. Conformance examples are embedded under section headings. Conformance harness accepts `--spec`, `--program`, and optional `--pattern`; invokes the program with Markdown on stdin, compares normalized HTML, and exits nonzero for failures or errors. Full-suite verdict is determined solely by process exit status. RESULT: FAILED FILES CHANGED: - parser/blocks.py - test_block_quotes.py SUMMARY: Implemented nested block quotes, lazy continuation handling, blank-separated quote boundaries, and quoted code/fence termination. Block quote conformance passes: 25/25. Focused tests pass: 14/14. BLOCKERS: - The required full suite still fails in pre-existing areas outside this build block: 414 passed, 241 failed. FAILURE_SUMMARY: Full CommonMark suite has 241 failures outside block-quote scope. FAILURE_DETAIL: Block-quote acceptance passes, but `sh full_test.sh` exits 241 because leaf blocks, lists, inlines, links, images, and HTML behavior remain incomplete. Subsequent build blocks must address those failures.