# WP-39 — Showcase: linked code snippets + teaching animations

Status: todo
Phase: 8 — platform/DX/showcase
Priority: P1

## Why

The `/concepts` showcase shows live components, but its code snippets are hand-authored
`innerHTML` strings with manual highlighting — they drift from the real code. And the animation
toolkit (`withViewTransitions`, native `animate.enter/leave`, reduced-motion-safe keyframes in
`styles.scss`) is proven in dashboard/upload but unused for teaching motion.

## Decisions

- **Anti-drift snippets:** load _real_ source excerpts via Vite `?raw` imports with `// #region name`
  markers + a tiny pure extractor; render with lightweight highlighting. No more `innerHTML` literals.
- On the Storybook/MDX side, use `<Source>`/Canvas "show code" consistently (extend beyond the
  current 4 of 14 pages).
- **Reuse** the existing motion toolkit (no new animation lib): `animate.enter/leave` on the
  fold/union demos + a "step through `reduce`" animation for the TEA loop; keep reduced-motion-safe.

## Files

- `src/app/showcase/concepts.page.ts` — replace `innerHTML` snippets with `?raw`+region excerpts;
  apply animations.
- New tiny extractor util (pure) + spec (region slicing).
- `src/docs/machines.mdx`, `fp-in-ui.mdx`, `remote-data.mdx` — reference the live linked snippets.

## Acceptance criteria

- [ ] Every showcase snippet is sourced from a real file (edit the source → snippet updates); none
      hand-copied.
- [ ] The TEA/fold demos animate (reduced-motion respected); no new animation dependency.
- [ ] Storybook a11y stays green; `npm run ci` green.