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Markdown → HTML — Domain Orchestrator

Markdown to HTML markdown-html-orchestrator Source

Install: claude /plugin install markdown-html-skills

Thariq Shihipar's argument (Claude Code HTML output essay, Medium 2026): markdown collapses past 100 lines for agent-generated artifacts. Long specs, code reviews, and architecture explainers lose density, hierarchy, and lightweight interaction the moment they exceed a screen of text. HTML restores all three — single-file, browser-native, shareable.

This orchestrator forks context, classifies the input markdown deterministically, routes to the right converter sub-skill, and returns a digest with the output path. Heavy intake (full markdown bodies, diffs, slide decks) stays in the forked context.

Domain status (complete): all five skills are live — orchestrator + design-system (onboarding + shared brand tokens) + the three converter sub-skills (md-document, md-review, md-slides). Always route conversions to the shipped converter's scripts; never hand-render HTML inline.

When to invoke

Symptom Sub-skill
"Convert this RFC / spec / report / explainer to HTML" — long-form doc md-document
"Turn this PR writeup / code review into HTML" — markdown with diff blocks md-review
"Make a slide deck from this markdown" — --- boundaries or H1 cadence md-slides

Pre-flight gates (hard refusals)

  1. Below the 100-line threshold. Markdown wins below 100 lines (Shihipar). The classifier prints below_min_lines: true and route_explainer.py refuses. Tell the user to keep their input as markdown.
  2. Design-system not onboarded. If ~/.config/markdown-html/design-system.json doesn't exist (or its setup_completed_at is null), refuse. Point the user at python3 markdown-html/skills/design-system/scripts/onboard.py (or --defaults for a zero-touch run).
  3. Unwritable save location. output_path_resolver.py refuses if the configured default_output_dir (or --out override) isn't writable.

Routing logic (deterministic)

Two-signal threshold pattern lifted from research-ops/skills/research-ops-skills/SKILL.md. Filename hint = 2 points; each content signal = 1 point. Silent-route allowed when winner ≥ 3 AND (runner-up = 0 OR winner ≥ 2× runner-up). Below threshold → one clarifying question with a recommended answer.

Signal table

Signal class Filename hints Content signals Sub-skill
DOCUMENT report.md, *-doc.md, spec.md, rfc-*.md, *-analysis.md, *-explainer.md ## Table of Contents (2), ^#, ^##, markdown table rows, > [!NOTE]/[!TIP]/[!IMPORTANT] callouts md-document
REVIEW review.md, *-pr-*.md, *.diff.md, code-review*.md ```diff (2), ^[-+]{3} (2), ^@@ (2), > [!BLOCKER]/[!MAJOR]/[!MINOR]/[!NIT] (2), LGTM/nit:/blocker: md-review
SLIDES deck.md, slides.md, *-talk.md, presentation*.md ^---$ ≥ 3 (2 + per-boundary), <!-- notes: (2), H1 count ≥ 5 with median gap ≤ 12 lines (2) md-slides

The pipeline:

python3 markdown-html/skills/markdown-html-orchestrator/scripts/doctype_classifier.py \
    --input <path>.md --output json \
  | python3 markdown-html/skills/markdown-html-orchestrator/scripts/route_explainer.py

route_explainer.py checks the design-system status, applies the < 100-line refusal, and prints one of: ROUTE_SILENTLY -> md-<type>, ASK_USER one question: ..., or REFUSE — fix the issues above.

Workflow

Step 1 — Confirm onboarding

If the user has never run onboarding, surface the one-time setup:

python3 markdown-html/skills/design-system/scripts/onboard.py

Ten questions, 1-2 minutes. Captures brand primary + accent + heading/body Google Fonts + design style (editorial/technical/minimal/playful) + default output dir + syntax theme + TOC behavior + optional logo/company. Stored at ~/.config/markdown-html/design-system.json. Re-runnable with --scope project for per-repo overrides.

Step 2 — Classify the input

Run doctype_classifier.py on the markdown. Inspect the verdict.

Step 3 — Route or ask

Pipe the classification into route_explainer.py. If it says ROUTE_SILENTLY, forward the original markdown + the design-system config into the named sub-skill's renderer in the forked context. If it says ASK_USER, ask ONE question with the recommended answer.

Step 4 — Resolve the output path

python3 markdown-html/skills/markdown-html-orchestrator/scripts/output_path_resolver.py \
    --input <path>.md --doctype <document|review|slides>

Collision handling defaults to -2 / -3 / ... suffix; --on-collision timestamp for stamped names.

Step 5 — Hand off to the sub-skill

The routed converter sub-skill's renderer (md-document/scripts/, md-review/scripts/, or md-slides/scripts/) takes the input markdown, the design-system config, and the resolved output path, and writes a single self-contained HTML file. The orchestrator returns a ≤ 100-word digest: input lines, output path, design style applied, top 3 features used (TOC, search, code-copy, etc.), and one forcing question for the user. Never render HTML by hand — the converter scripts own the rendering.

Forcing-question library (Matt Pocock grill-with-docs pattern)

Walk these one at a time, with a recommended answer per question, citing the canon. Lift this list into /cs:grill-markdown-html for plan-stage interrogation.

  1. What decision does this HTML drive — is the reader skimming, deciding, or presenting? Recommended: name it first; density follows from purpose. Canon: Shihipar — "match output format to consumption context"; Tufte — Visual Display of Quantitative Information, ch. 1.
  2. Is the input markdown ≥ 100 lines? Recommended: yes — below that, keep it as markdown. Canon: Shihipar — markdown still wins under 100 lines.
  3. Is the design-system onboarded? Recommended: yes, globally (~/.config/markdown-html/design-system.json). Canon: research-ops onboarding pattern (research-ops/CLAUDE.md §8); WCAG 2.2 §1.4.3 (text contrast 4.5:1).
  4. Where does the output save, and will it overwrite anything? Recommended: the configured default_output_dir with --on-collision suffix. Canon: Matt Pocock handoff skill — never silently overwrite a working artifact.
  5. Document type confidence — silent-route or one question? Recommended: silent-route only when the classifier's verdict is one of document/review/slides AND silent_route_allowed: true. Otherwise ask. Canon: research-ops two-signal threshold (research-ops/skills/research-ops-skills/SKILL.md §"Routing logic").

Never run a sub-skill before the lane is locked.

Assumptions

  1. User has a markdown file ≥ 100 lines they want to convert.
  2. User has run onboarding once (~/.config/markdown-html/design-system.json exists with setup_completed_at populated).
  3. Single-file HTML output is acceptable (no multi-file site, no embedded server, no build step).
  4. Externals limited to Google Fonts CSS + Prism.js CDN (jsdelivr / cdnjs).

Non-goals

  • Not a landing-page generator (use marketing/landing/).
  • Not an interactive prompt-tuning playground (use Anthropic's official playground plugin).
  • Not a static-site generator (no multi-file output, no site index).
  • Not a PDF generator (slides use @media print; user prints from browser).
  • Not a watch / live-reload pipeline (conversion is one-shot).

Distinct from

  • Anthropic Playground plugin (/playground) — builds interactive controls (sliders, knobs, drag-drop) for prompt tuning, with a copy-prompt-back loop. This plugin converts existing markdown documents to HTML. Different tools for different jobs.
  • marketing/landing/ — generates landing pages from scratch (Phase-0 intake → 3 sections → branded TSX/HTML). This plugin converts an existing markdown file you already have.
  • engineering/handoff/ + productivity/handoff/ — preserve session continuity between Claude conversations. Different artifact type (handoff brief vs. document conversion).

Output artifacts

Sub-skill Artifact Status
md-document doc-<slug>.html (single file, sticky TOC, collapsibles, search, code-copy, scrollspy) ✓ live
md-review review-<slug>.html (2-col diff + severity margin notes + jump-nav) ✓ live
md-slides deck-<slug>.html (arrow-key nav + presenter mode + print-to-PDF) ✓ live

Anti-patterns (do not)

  • ❌ Convert markdown < 100 lines — markdown still wins. Refuse and tell the user.
  • ❌ Run the orchestrator before the design-system is onboarded. The output looks broken without tokens.
  • ❌ Silently chain two sub-skills (e.g., "convert doc AND make slides from it"). Pick one, finish, ask before chaining.
  • ❌ Use external JS frameworks (React/Vue/Svelte). Vanilla JS + IntersectionObserver only. Prism.js CDN is the single exception.
  • ❌ Multi-file output (extracted CSS, asset directories). Single file or nothing — that's the whole point.
  • ❌ Overwrite an existing output file by default. The path resolver suffixes -2, -3, …; --on-collision overwrite is opt-in only.

References

  • Spec: Thariq Shihipar — "Claude Code HTML output" (Medium, 2026)
  • Forking pattern: research-ops/skills/research-ops-skills/SKILL.md (context: fork, two-signal routing)
  • Customization pattern: research-ops/skills/clinical-research/scripts/ (onboard.py, config_loader.py)
  • Brand palette math: marketing/landing/skills/landing/scripts/brand_palette_validator.py (WCAG + HSL derive)
  • Information-density canon: Tufte; Shihipar's thariqs.github.io/html-effectiveness/ gallery; Wattenberger interactive essays; Maggie Appleton digital gardens