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Matrix digital rain · muse-wonder

Output generated Cost / run $0.3813 Runtime 121.2s

Prompt for this run

Build an animated Matrix-style digital rain effect on a full-screen black canvas. Use HTML, CSS, and JavaScript as needed. Write it to `index.html` in the current working directory using your file tools. Inline your own CSS and JavaScript. Do not use external assets, CDNs, or network requests. No third-party libraries are provided. Required behavior: - Draw multiple independently moving columns of green katakana glyphs, each with a brighter leading character and a fading trail. - Vary column speed and start position. Recycle columns after they leave the bottom so the effect continues without accumulating off-screen state. - Provide Pause/Resume and Restart. Pause freezes the animation; Restart resets the columns and clears previous trails. - Resize the canvas and column layout to fit the viewport without stretching an old screenshot or leaving an uncovered strip. - Use locally available fonts and procedural drawing; no external fonts or images. Choose glyphs, brightness, and timing freely. Verify: Sample the animation at several moments to inspect independently moving columns, brighter leading glyphs, and fading trails. Pause and resume to check that the image freezes and continues, then use Restart and check that old trails are cleared.

⛨ sandboxed Open in new tab ↗

TAKE IT TO CODE

A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.

RUN

modelmuse-wonder
vendorMeta
harnesspi 0.87.1 · browser iteration
generated2026-10-15

METRICS

runtime121.2s
tokens in271k
tokens out6.3k
cached219k
cost / run$0.3813
Transcript · 31 messages
system

user

Build an animated Matrix-style digital rain effect on a full-screen black canvas. Use HTML, CSS, and JavaScript as needed. Write it to `index.html` in the current working directory using your file tools. Inline your own CSS and JavaScript. Do not use external assets, CDNs, or network requests. No third-party libraries are provided. Required behavior: - Draw multiple independently moving columns of green katakana glyphs, each with a brighter leading character and a fading trail. - Vary column speed and start position. Recycle columns after they leave the bottom so the effect continues without accumulating off-screen state. - Provide Pause/Resume and Restart. Pause freezes the animation; Restart resets the columns and clears previous trails. - Resize the canvas and column layout to fit the viewport without stretching an old screenshot or leaving an uncovered strip. - Use locally available fonts and procedural drawing; no external fonts or images. Choose glyphs, brightness, and timing freely. Verify: Sample the animation at several moments to inspect independently moving columns, brighter leading glyphs, and fading trails. Pause and resume to check that the image freezes and continues, then use Restart and check that old trails are cleared.

assistant
thinking
Implementing a full-screen canvas Matrix rain with katakana, variable speed, fading trail, and accessible Pause/Resume and Restart controls with resize handling.Choosing per-column trail buffers with fractional head stepping and glow for performance.
→ write index.html (10417 bytes)
toolResult

Successfully wrote to index.html

assistant
thinking
→ browser {"action":"inspect"}
toolResult
 
Frame 1, +1ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n⏸ Pause\n↻ Restart\n60 columns · 60 streams\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ browser {"action":"motion"}
toolResult
 
Frame 1, +0ms
[Browser image supplied to model]
Frame 2, +565ms
[Browser image supplied to model]
Frame 3, +1129ms
[Browser image supplied to model]
Frame 4, +1694ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n⏸ Pause\n↻ Restart\n60 columns · 60 streams\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ browser {"action":"click","x":251,"y":44}
toolResult
 
Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n▶ Resume\n↻ Restart\n60 columns · 60 streams\nPAUSED\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ browser {"action":"screenshot"}
toolResult
 
Frame 1, +1ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n▶ Resume\n↻ Restart\n60 columns · 60 streams\nPAUSED\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ browser {"action":"click","x":367,"y":44}
toolResult
 
Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing.","error: Failed to execute 'setTransform' on 'CanvasRenderingContext2D': The provided value is not of type 'DOMMatrixInit'."],"dom":"MATRIX // RAIN\n▶ Resume\n↻ Restart\n60 columns · 60 streams\nPAUSED\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ read {"path":"index.html"}
toolResult
 
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Matrix Digital Rain</title>
<style>
  * { margin:0; padding:0; box-sizing:border-box; }
  html, body { width:100%; height:100%; overflow:hidden; background:#000; }
  body { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace; }
  #rain {
    position:fixed; inset:0; display:block; width:100vw; height:100vh; background:#000;
  }
  .hud {
    position:fixed; top:16px; left:16px; z-index:10;
    display:flex; align-items:center; gap:10px; flex-wrap:wrap;
    padding:10px 12px; border:1px solid rgba(0,255,70,.35); border-radius:10px;
    background:rgba(0,12,3,.72); backdrop-filter: blur(4px);
    box-shadow:0 0 22px rgba(0,255,65,.14), inset 0 0 18px rgba(0,255,65,.05);
    color:#9dffb0; user-select:none;
  }
  .title {
    font-size:13px; letter-spacing:.28em; font-weight:700; color:#d8ffe0;
    text-shadow:0 0 8px #00ff41, 0 0 20px rgba(0,255,65,.6); white-space:nowrap;
  }
  .title span { color:#00ff41; }
  button {
    appearance:none; cursor:pointer; font:inherit; font-size:13px; font-weight:700;
    letter-spacing:.06em; color:#041505; background:#2dff5e; border:1px solid #7dff96;
    padding:8px 14px; border-radius:7px; box-shadow:0 0 12px rgba(0,255,65,.35);
    min-width:104px;
  }
  button:hover { background:#69ff88; }
  button:active { transform:translateY(1px); }
  button:focus-visible { outline:2px solid #eaffea; outline-offset:3px; }
  button.secondary { background:transparent; color:#8dff9f; box-shadow:none; }
  button.secondary:hover { background:rgba(0,255,65,.14); color:#d8ffe0; }
  .meta { font-size:11px; letter-spacing:.08em; color:rgba(157,255,176,.75); white-space:nowrap; }
  .hint {
    position:fixed; right:16px; bottom:14px; z-index:10; font-size:11px; letter-spacing:.08em;
    color:rgba(140,255,165,.55); text-shadow:0 0 6px rgba(0,255,65,.5); user-select:none;
    background:rgba(0,0,0,.45); padding:6px 8px; border-radius:6px;
  }
  .paused-badge {
    position:fixed; left:50%; top:74px; transform:translateX(-50%); z-index:10;
    display:none; padding:7px 14px; border:1px solid rgba(0,255,70,.5); border-radius:999px;
    background:rgba(0,10,2,.78); color:#d8ffe0; font-size:12px; letter-spacing:.35em; text-indent:.35em;
    text-shadow:0 0 8px #00ff41;
  }
  body.is-paused .paused-badge { display:block; }
  @media (max-width:560px){
    .title{font-size:11px; letter-spacing:.18em}
    .meta{display:none}
    .hint{display:none}
    button{min-width:92px; padding:8px 10px}
    .hud{left:10px; top:10px; right:10px}
  }
</style>
</head>
<body>
<canvas id="rain" aria-label="Animated Matrix-style digital rain of green katakana characters"></canvas>

<div class="hud" role="group" aria-label="Animation controls">
  <div class="title">MATRIX <span>//</span> RAIN</div>
  <button id="pauseBtn" type="button" aria-pressed="false">⏸ Pause</button>
  <button id="restartBtn" type="button" class="secondary">↻ Restart</button>
  <div class="meta" id="meta" aria-live="off">— columns</div>
</div>
<div class="paused-badge" aria-hidden="true">PAUSED</div>
<div class="hint">SPACE — pause / resume &nbsp;·&nbsp; R — restart</div>

<script>
(() => {
  'use strict';

  const canvas = document.getElementById('rain');
  const ctx = canvas.getContext('2d');
  const pauseBtn = document.getElementById('pauseBtn');
  const restartBtn = document.getElementById('restartBtn');
  const meta = document.getElementById('meta');

  // Half-width + full katakana, digits and a few latin glyphs — all procedural text, no assets.
  const GLYPHS = 'アィウェオカキクケコサシスセソタチツテトナニヌネノ0123456789Z=:・."=*+-<>¦｜╌ﾊﾐﾋｰｳｼﾅﾓﾆｻﾜﾂｵﾘｱﾎﾃﾏｹﾒｴｶｷﾑﾕﾗｾﾈｽﾀﾇﾎﾍﾌﾔﾖﾙﾚﾛﾝ';
  const rand = (min, max) => min + Math.random() * (max - min);
  const pick = () => GLYPHS[(Math.random() * GLYPHS.length) | 0];

  const FONT_SIZE = 17;          // px (CSS pixels) per glyph cell height
  const COL_W = 20;              // px between columns
  let W = 0, H = 0, DPR = 1, rows = 0, columns = [];

  function makeColumn(x, startAnywhere) {
    const len = Math.floor(rand(10, 30));
    const chars = Array.from({ length: len }, pick);
    return {
      x,
      // Head position in row units (float for smooth, varied speed).
      // Start staggered above / within the screen so columns don't begin in a line.
      head: startAnywhere ? rand(-6, rows + len) : rand(-rows * 0.9, -2),
      speed: rand(4.5, 19),       // rows per second — independently varied
      len,
      chars,
      lastRow: null,
      flicker: rand(0.02, 0.12)   // chance per step to mutate a trail glyph
    };
  }

  function initColumns(startAnywhere) {
    const count = Math.max(1, Math.ceil(W / COL_W));
    columns = Array.from({ length: count }, (_, i) => makeColumn(i * COL_W, !!startAnywhere));
    meta.textContent = count + ' columns · ' + columns.length + ' streams';
  }

  function resize() {
    DPR = Math.min(window.devicePixelRatio || 1, 2);
    W = window.innerWidth;
    H = window.innerHeight;
    rows = Math.max(1, Math.ceil(H / FONT_SIZE));
    // Setting width/height resets the bitmap — we then repaint solid black,
    // so no stretched old frame and no uncovered strip can remain.
    canvas.width = Math.round(W * DPR);
    canvas.height = Math.round(H * DPR);
    canvas.style.width = W + 'px';
    canvas.style.height = H + 'px';
    ctx.setTransform(DPR, 0, 0, DPR, 0, 0);
    ctx.fillStyle = '#000';
    ctx.fillRect(0, 0, W, H);
    initColumns(true); // rebuild layout for the new viewport
    if (paused) draw(0); // keep a frozen, correctly-sized frame while paused
  }

  function stepColumn(col, dt) {
    col.head += col.speed * dt;
    const headRow = Math.floor(col.head);

    if (col.lastRow === null) col.lastRow = headRow;
    // Advance the glyph stream once per row crossed.
    while (col.lastRow < headRow) {
      col.chars.unshift(pick());
      if (col.chars.length > col.len) col.chars.pop();
      // Occasional flicker inside the trail.
      if (Math.random() < col.flicker && col.chars.length > 2) {
        col.chars[1 + ((Math.random() * (col.chars.length - 1)) | 0)] = pick();
      }
      col.lastRow++;
    }

    // Recycle once the whole trail has left the bottom: reset above the
    // screen with fresh speed/length. No state accumulates off-screen.
    if ((col.head - col.len) * FONT_SIZE > H) {
      const fresh = makeColumn(col.x, false);
      fresh.head = rand(-14, -1);
      Object.assign(col, fresh);
    }
  }

  function draw(dt) {
    // Full opaque repaint each frame: trails are drawn with explicit
    // per-glyph alpha, so brightness genuinely fades with distance.
    ctx.fillStyle = '#000';
    ctx.fillRect(0, 0, W, H);
    ctx.font = '700 ' + FONT_SIZE + 'px ui-monospace, Menlo, Consolas, monospace';
    ctx.textBaseline = 'top';

    for (const col of columns) {
      const headRow = Math.floor(col.head);
      for (let i = 0; i < col.chars.length; i++) {
        const row = headRow - i;
        if (row < -1 || row > rows + 1) continue;
        const y = row * FONT_SIZE;
        const t = i / col.chars.length; // 0 = head, 1 = tail

        if (i === 0) {
          // Bright leading glyph: near-white core with a green glow.
          ctx.shadowColor = '#00ff41';
          ctx.shadowBlur = 14;
          ctx.fillStyle = '#eaffea';
        } else if (i === 1) {
          ctx.shadowColor = '#00ff41';
          ctx.shadowBlur = 8;
          ctx.fillStyle = 'rgba(120,255,150,' + (0.95 - t * 0.35).toFixed(3) + ')';
        } else {
          ctx.shadowBlur = 0;
          // Classic matrix green, fading exponentially toward the tail.
          const alpha = Math.max(0, Math.pow(1 - t, 1.6) * 0.9);
          if (alpha < 0.02) continue;
          const g = Math.floor(255 - t * 110);
          ctx.fillStyle = 'rgba(0,' + g + ',45,' + alpha.toFixed(3) + ')';
        }
        ctx.fillText(col.chars[i], col.x + 2, y);
      }
    }
    ctx.shadowBlur = 0;
  }

  let rafId = null;
  let lastTime = 0;
  let paused = false;

  function frame(now) {
    if (paused) return;
    const dt = Math.min(0.05, lastTime ? (now - lastTime) / 1000 : 0.016);
    lastTime = now;
    for (const col of columns) stepColumn(col, dt);
    draw(dt);
    rafId = requestAnimationFrame(frame);
  }

  function setPaused(value) {
    paused = value;
    document.body.classList.toggle('is-paused', paused);
    pauseBtn.textContent = paused ? '▶ Resume' : '⏸ Pause';
    pauseBtn.setAttribute('aria-pressed', String(paused));
    if (paused) {
      if (rafId !== null) cancelAnimationFrame(rafId);
      rafId = null;
      // Canvas is intentionally left untouched: the last frame freezes.
    } else {
      lastTime = 0; // avoid a time jump on resume
      if (rafId === null) rafId = requestAnimationFrame(frame);
    }
  }

  function restart() {
    // Clear every trace of previous trails, rebuild all columns, run again.
    ctx.save();
    ctx.setTransform(1, 0, 0, 1);
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.restore();
    ctx.fillStyle = '#000';
    ctx.fillRect(0, 0, W, H);
    initColumns(false);
    // Draw one fresh frame immediately (heads mostly above the screen),
    // then ensure the loop is running.
    draw(0);
    if (paused) setPaused(false);
    else { lastTime = 0; if (rafId === null) rafId = requestAnimationFrame(frame); }
  }

  pauseBtn.addEventListener('click', () => setPaused(!paused));
  restartBtn.addEventListener('click', restart);
  window.addEventListener('keydown', (e) => {
    if (e.code === 'Space' && !/BUTTON/.test(document.activeElement.tagName)) {
      e.preventDefault(); setPaused(!paused);
    } else if (e.key === 'r' || e.key === 'R') {
      restart();
    }
  });

  let resizeTimer = null;
  window.addEventListener('resize', () => {
    clearTimeout(resizeTimer);
    resizeTimer = setTimeout(resize, 60);
  });

  // Exposed for inspection / automated verification.
  window.matrixRain = {
    get paused() { return paused; },
    get columnCount() { return columns.length; },
    get columns() { return columns.map(c => ({ x: c.x, head: c.head, speed: c.speed, len: c.len })); },
    pause: () => setPaused(true),
    resume: () => setPaused(false),
    restart
  };

  resize();
  initColumns(true);
  draw(0);
  rafId = requestAnimationFrame(frame);
})();
</script>
</body>
</html>

assistant
 
thinking
Debugging a canvas setTransform error by checking variable scope, call order, and function signature.
→ edit {"edits":[{"oldText":"  function restart() {\n    // Clear every trace of previous trails, rebuild all columns, run again.\n    ctx.save();\
toolResult
 
Successfully replaced 1 block(s) in index.html.
assistant
 
thinking
→ browser {"action":"reload"}
toolResult
 
Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n⏸ Pause\n↻ Restart\n60 columns · 60 streams\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ browser {"action":"click","x":367,"y":44}
toolResult
 
Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n⏸ Pause\n↻ Restart\n60 columns · 60 streams\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ browser {"action":"screenshot"}
toolResult
 
Frame 1, +1ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n⏸ Pause\n↻ Restart\n60 columns · 60 streams\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ browser {"action":"click","x":251,"y":44}
toolResult
 
Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n▶ Resume\n↻ Restart\n60 columns · 60 streams\nPAUSED\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
→ browser {"action":"click","x":251,"y":44}
toolResult
 
Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"MATRIX // RAIN\n⏸ Pause\n↻ Restart\n60 columns · 60 streams\nSPACE — pause / resume  ·  R — restart","images":"attached"}
assistant
 
thinking
→ bash {"command":"ls -l index.html && grep -nEi 'https?://|<link|<img|url\\(|@import|src=' index.html || echo 'no external references found'"}
toolResult
 
-rw-r--r-- 1 node node 10521 Oct 15 04:09 index.html
no external references found

assistant
 
thinking
Created `index.html` — a self-contained Matrix digital rain with no external assets:

- Full-screen black canvas with 60 independently moving katakana columns at varied speeds/start positions, bright near-white glowing heads, and green trails fading per-glyph
- Columns recycle above the screen after their trails exit the bottom
- **Pause/Resume** (button or Space) and **Restart** (button or R); resize rebuilds canvas/columns and repaints black (no stretched frame or uncovered strip)

Verified in browser:
- Motion sampling across multiple frames showed columns moving at different rates with brighter leading glyphs and fading trails
- Pause froze the frame identically across successive screenshots and showed Resume/PAUSED state; Resume continued from the frozen position
- Caught and fixed a real bug during testing: Restart threw a `setTransform` error (4-arg call) and did nothing — fixed, re-tested: Restart now clears the screen to black, then fresh columns re-enter, with no console errors
- Confirmed no external references (`http`, `<link>`, `<img>`, etc.) in the file

Not verified: actual viewport resizing (the browser tool uses a fixed 1200×800 viewport), though the resize handler was implemented to reset the bitmap and rebuild the column layout.