fix(markdown): resolve issue #245 formatting parser boundaries

[ThisIs-Developer]

What changed

• replace document-wide footnote and dollar rewrites with grammar-aware Marked extensions
• keep inline/display TeX atomic and scope legacy \color{name}{content} for MathJax 3
• de-duplicate heading IDs per render, including segmented worker blocks
• preserve Unicode letters and combining marks in heading anchors with stable fallback IDs
• make footnote labels case-insensitive, leave undefined calls literal, generate collision-safe IDs, and link every repeated reference back from the note
• support multi-term Markdown Extra definition lists without preempting GFM/CommonMark lists, Setext headings, thematic breaks, indented code, reference definitions, tables, fenced code, headings, or HTML
• route structurally sensitive large documents through full parsing so loose lists, indented code, and multiline HTML comments are not split across worker blocks
• preserve literal dollars and footnote syntax inside fenced and inline code
• keep DOMPurify sanitization intact and mirror every renderer change in the packaged desktop app
• add regression coverage for all 11 reports plus the additional audit findings

Why

Issue #245 exposed a shared architectural cause: document-wide regex preprocessing and naive large-document segmentation could run before Marked established code, math, and block boundaries. The broader audit also found raw ASCII-only slugging and incomplete footnote state management.

Mixed - and * list markers already produced separate GFM lists and required regression coverage rather than a parser change. Definition lists remain the existing Markdown Extra extension; this PR does not add a new Markdown flavor or dependency.

How it was tested

• npm run check:static — passed
• final Chromium formatting suite — 12/12 passed
• affected Firefox/WebKit definition-list checks — 4/4 passed
• cross-browser formatting audit — every case passed across Chromium, Firefox, and WebKit (one WebKit startup timeout passed immediately in isolation)
• npm run test:e2e:cross-browser — 12/12 passed
• complete Chromium run — 153/157 passed initially; three unrelated resource/timing failures passed serially, while the pre-existing tab-close persistence race remains unrelated to renderer files and reproducible in isolation
• exact 5,796-character shared snapshot tested in Edit, Split, and Preview modes
• exact Issue 10 expression verified with real MathJax: only the intended terms are colored; operators and delimiters remain uncolored
• verified unique and Unicode heading targets, repeated footnote back-links, zero MathJax errors, no critical fresh-load console errors, DOMPurify sanitization, syntax checks, and web/desktop renderer parity

Documentation

No user documentation changes are required. The changes restore the reported syntax while preserving GFM, the existing Markdown Extra definition-list extension, standard MathJax 3 behavior, code isolation, and sanitization.

Closes #245

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
markdown-viwer	Ready	Preview	Aug 24, 2026 5:38pm

[cloudflare-workers-and-pages]

Deploying markdownviewer with    Cloudflare Pages

Latest commit:	fc54b97
Status:	✅  Deploy successful!
Preview URL:	https://412b92e4.markdownviewer.pages.dev
Branch Preview URL:	https://fix-issue-245-formatting-pip.markdownviewer.pages.dev

View logs