Kintsugi

My prompt: "Kintsugi. - make it ultimate zen japanese magic! 😃"

Process: Claude (Opus 5.5 in Claude Code) first wrote the master prompt below, then built it and tested it in the same session (headless Chrome: 60 fps, real drag and tap input, light and dark, phone, a 0x0 iframe). One follow-up from me: "make the end of the scroll hanging on the wall a lighter more rendered wood… also change the wood beam to be rendered as wood".

--- Master prompt ---

Build "Kintsugi": break a Japanese tea bowl, then mend it with gold. Make it the calmest, most magical three.js toy on the web, so zen that people play it slowly on purpose.

Write it as a Japanese potter, a lacquer master and a top creative technologist. Every fact must be correct, and say on screen what is simplified. There is ONE object, a tea bowl, and three gestures: lift and let go, tap a piece home, touch a crack. Polish beats features.

## Technical rules

- ONE self-contained HTML file. Load three.js through a pinned import map: `https://cdn.jsdelivr.net/npm/three@0.170.0/build/three.module.js`, with `three/addons/` mapped to the same version's `examples/jsm/`.
- Fonts come from Google Fonts: Inter, plus Shippori Mincho for the Japanese. Make no other network calls, and use no image, HDR or audio files.
- It runs in a sandboxed iframe that can be 0×0 at load. Use a ResizeObserver, never throw on a zero size, and use no alert(). Wrap localStorage in try/catch.
- It works from a 360px phone up to desktop, with mouse, touch and keyboard.
- Run at 60 fps with devicePixelRatio capped at 2. Pause when the tab is hidden and respect reduced motion.
- Seed all randomness. No TODOs and no console errors.

## The room

- A quiet tatami room. The bowl sits on a low black lacquer stand.
- Behind it hangs a blank paper scroll on a plaster wall.
- Afternoon sun comes through a lattice window, casting soft bars of light, with maple leaves swaying in the shadow. Dust drifts in the beam.
- Light mode is a pale paper room. Dark mode is night, with moonlight and a warm lantern glow.
- Like a gallery, it is black and white, and gold is the only colour, apart from one small red seal at the end.

## The bowls

There are four real chawan forms at real sizes. Shape each one as a lathe profile with a foot ring, given a handmade wobble.

- **Black Raku** (Kyoto, 1580s). Tall, with knife-cut facets and an uneven "mountain path" rim. Semi-matte black glaze with an orange-peel surface.
- **Shino** (Mino, late 1500s). Wide, with a squarish mouth. Thick milky white glaze with pinholes, an orange fire blush where it runs thin, and a few iron-brush reeds.
- **Tenmoku** (Jian, Song dynasty). A cone with a small foot and a groove under the rim. Glossy black glaze with silvery oil spots, a rust-brown rim, and the glaze stopping in a thick roll above a dark foot.
- **Celadon** (Longquan, Song dynasty). Deep and jade green, with fine crackle lines and a reddish iron foot.

Render the glazes procedurally in the shader, so they stay crisp at any zoom. Each needs an unglazed foot, an inside where the glaze pools, and a clay body that shows on every break.

## 1. Lift and let go

- Drag the bowl up. It follows your finger and tips forward as you lift it. A small readout shows the height and about how many pieces it will make.
- Let go and it falls. The higher the drop, the more pieces (4 to 14).
- On impact, time stops:
  1. White-hot cracks race across the glaze from the point that hit.
  2. The pieces drift apart in slow motion and hang in the air, turning gently.
  3. Clay dust freezes around them, and the dust in the sunbeam stops too.
- Breaks must look real. Use a seeded Voronoi on the bowl surface with a warped metric, denser near the impact. Every piece is a solid shell with rough break faces in the clay body colour, with a thin line of glaze along each edge.

## 2. Bring the pieces home

- Tap a piece and it glides home along a slow arc. It seats with a soft click and a koto note.
- The notes climb a Japanese pentatonic scale, piece by piece.
- A hairline crack appears only where two home pieces meet.
- "Gather all" brings the rest home one at a time.

## 3. Pour the gold

- Touch any crack and liquid gold flows out from that point along the crack network, at a calm 3 cm/s:
  - It branches at every junction.
  - It flows over the rim and down the inside.
  - It glows white-hot at the front, then settles into raised, burnished lacquer seams that vary in width like real kintsugi.
- Every touch starts another flow. You can also choose silver, or red urushi lacquer.
- When every seam is full:
  1. The bowl floats back down to its stand.
  2. An ensō paints itself on the scroll, as one dry-brush stroke with a red seal.
  3. The bowl is given a poetic name, set in vertical Japanese with romaji and English. Pick it from real Japanese words such as 稲妻 Inazuma "Lightning" or 雨上がり Ameagari "After the Rain".

## Sound

Make it soft, ASMR-calm and all synthesised:

- **Room.** A faint room tone. Water drops ring like a suikinkutsu (a buried water jar) in a long reverb.
- **Break.** A gentle ceramic tink with scattered micro-clinks, then a held breath of a pad while time stands still.
- **Mending.** A Karplus-Strong koto pluck for each piece.
- **Gold.** Wind-chime grains while the gold flows, and a singing-bowl (rin) strike when it is done.
- Nothing harsh, and nothing mechanical.

## Facts panel

- Kintsugi (金継ぎ, "golden joinery") joins the pieces with urushi lacquer, then dusts the seams with powdered gold. The real thing takes weeks or months to cure, and it is simplified here.
- The Bakōhan legend: a shogun's celadon bowl came back from a repair in China held with metal staples.
- The break is part of the bowl's history, not something to hide.
- Add one line on each bowl's origin.