nx_build_doc.nx

nx_build_doc.nx -- render a single .md document into final HTML. The atomic build unit for nx_build_site (the bits-up replacement for nishi-pages/build/build.py). Composes: nx_frontmatter -- split "---YAML---body" nx_yaml_subset -- parse the frontmatter YAML metadata nx_md_render -- markdown body -> HTML nx_http_template -- {{ var }} + {{ var | raw }} substitution Pipeline for one .md doc: 1. Read source bytes 2. Split frontmatter -> (yaml_bytes, body_bytes) 3. Parse yaml metadata into NxYamlDoc (title, date, layout, etc.) 4. Render markdown body -> body_html 5. Apply inner template (post.html or page.html) substituting page.title, page.date, page.author, body (raw) 6. Apply outer layout (layout.html) substituting site.*, page.*, content (raw) where content = inner template output 7. Caller writes the final HTML wherever it wants nx_safety_envelope: intended_use: render one md doc end-to-end for nx_build_site sil_target: SIL2 evidence: bench/nx_build_doc_smoke.nx round-trips a known fixture and asserts the output bytes contain the expected substituted values verdict: NOT_YET_EVALUATED -- pending smoke