Planpage

planpage — interactive HTML plans for skills

Like mcp-ui, but for terminal skills. This skill is a thin consumer of the open-source planpage package (on npm — npm i planpage, or zero-install with npx planpage). The components, the render engine, the auto-captured gallery, and the post-back server all live there as the single source of truth. Don't hand-roll HTML here; author with the package.

What the package gives you

• Components — SectionCard, PickBlock, DiffBlock, TreePanel, Flow, CodeBlock, CodeExplorer (IDE-style file tree + editor pane, per-file before/after), plus plan-native pieces: Callout, RiskList, Steps, Timeline, OptionCompare, PlanSummary, Accordion, AnnotatedCode. Browse them live: npx planpage library --open.
• Templates — plan-brief (a whole agent plan on one page), before-after, code-style-plan (its canonical takes either a single code snippet or a multi-file files list → the CodeExplorer), library.
• render() / renderHighlighted() — render(<Template {...data} />) → a self-contained HTML string (Tailwind + Mermaid from CDN, light/dark theme). await renderHighlighted(…) also bakes in real VSCode syntax colour (Shiki, TS/JS-first) at render time — no CDN, no client JS to read colour. npx planpage render … highlights for you.
• serve — a never-hang post-back server (OS-assigned ephemeral port 49152+, idle timeout, file:// + clipboard fallback) that collects one Decision.

Quick start (how a skill uses it)

1. Assemble the page from the package's components (or a whole template):

   import { render, PlanBrief } from "planpage";
   const html = render(<PlanBrief title="…" steps={/* … */} risks={/* … */} />);
   

   or straight from the CLI: npx planpage render plan-brief --data plan.json.
2. Write it to the OS temp dir ($TMPDIR/<name>-<timestamp>.html) — nothing lands in the repo.
3. Serve + collect the decision on a safe ephemeral port:

   npx planpage serve <html-path> <decision-out.json> --timeout 600
   

   It prints the local URL, opens the browser, and blocks until the user clicks Approve / Adjust (or the idle timeout fires), then writes the decision JSON and exits 0.
4. Read <decision-out.json> and act on it.

Fallback — never hang. Headless / no Node / port blocked → open the file directly (file://); the page's Copy decision button puts the same JSON (base64) on the clipboard to paste back. A non-TTY caller always has a decision path.

The decision contract

The page posts one JSON object; the server writes it verbatim to the out-path:

{ "approved": true, "flips": ["rule.function-form"], "revisit": ["rule.error-shape"], "notes": "keep classes only in the DB layer" }

• approved — Approve (true) vs Adjust (false).
• flips — data-ids of PickBlocks the user flipped (chosen ↔ rejected). Re-open the grill on these.
• revisit — data-ids marked "revisit" without a firm decision.
• notes — free text from the notes box.

Every interactive component carries a stable data-id; that id is what appears in flips / revisit. Name ids meaningfully (rule.error-shape, move.orders-dir) so a bare id tells you what to re-open.

Rules

• The package owns the HTML; the skill owns the content. Reference planpage and plug in content — don't re-derive the shell. When a report needs a new widget, add it to the package (with a gallery entry) so every skill inherits it.
• Self-contained. No repo assets, no build step at render time; Tailwind + Mermaid from CDN, and syntax colour baked into the HTML by Shiki (no CDN, no client JS).
• Never block a script. serve carries an idle timeout; the fallback is copy-paste. A headless / non-TTY caller must still reach a decision.
• Installing the package adds no skills. npx planpage init scaffolds one ready render-plan skill (wired to npx planpage) into .claude/skills/ — ship that to end users; the package itself is just the engine.