Ambient WebGL petals + cute notification sounds

Add a fixed, GPU-driven petal layer that drifts soft blossoms over the
page (sparse, translucent, paused when hidden, skipped under
prefers-reduced-motion). Add a synthesized cute sound palette — bubble
pop, water droplet, soft bell, sparkle, cheer — generated as embedded
WAV assets (scripts/gen_sounds.py) and played through a quiet Web Audio
bus with soft-clipping and a persisted mute toggle in the status bar.

Sounds fire per suggestion type when fresh advice arrives (staggered,
old pending advice stays silent) and on companion bubbles by tone.

Claude-Session: https://claude.ai/code/session_016Yr6jELuRc7hyzYLccQKZd

scripts/gen_sounds.py

@@ -0,0 +1,165 @@
+#!/usr/bin/env python3
+"""Generate Petal's cute UI sound palette as small WAV assets.
+
+These are warm, rounded little sounds — bubble pops, water drops, soft bells —
+played when suggestions and companion bubbles appear. We synthesize them here
+(rather than ship someone else's clips) so they match the app's gentle aesthetic
+exactly and stay tiny. Output lands in web/src/assets/sounds/ where Vite bundles
+and fingerprints them into dist (and so into the embedded Go binary).
+
+Run:  python3 scripts/gen_sounds.py
+"""
+import math
+import os
+import struct
+import wave
+
+SR = 44100
+OUT = os.path.join(os.path.dirname(__file__), "..", "web", "src", "assets", "sounds")
+
+
+def env(n, attack, decay, total):
+    """Smooth attack + exponential decay envelope over `total` seconds."""
+    a = max(1, int(attack * SR))
+    out = []
+    for i in range(n):
+        t = i / SR
+        if i < a:
+            amp = i / a
+        else:
+            amp = math.exp(-(t - attack) / decay)
+        out.append(amp)
+    return out
+
+
+def sine(freq_at, n):
+    """Sine with a per-sample frequency function freq_at(t)->Hz (phase-accurate)."""
+    out = []
+    phase = 0.0
+    for i in range(n):
+        t = i / SR
+        f = freq_at(t)
+        phase += 2 * math.pi * f / SR
+        out.append(math.sin(phase))
+    return out
+
+
+def mix(*layers):
+    n = max(len(l) for l in layers)
+    out = [0.0] * n
+    for l in layers:
+        for i, v in enumerate(l):
+            out[i] += v
+    return out
+
+
+def soft_clip(s):
+    return [math.tanh(v * 1.2) for v in s]
+
+
+def normalize(s, peak=0.9):
+    m = max(1e-9, max(abs(v) for v in s))
+    g = peak / m
+    return [v * g for v in s]
+
+
+def write_wav(name, samples):
+    samples = soft_clip(samples)
+    samples = normalize(samples, 0.85)
+    # 4ms fade-out tail so nothing clicks at the end.
+    tail = int(0.004 * SR)
+    for i in range(tail):
+        samples[-1 - i] *= i / tail
+    os.makedirs(OUT, exist_ok=True)
+    path = os.path.join(OUT, name)
+    with wave.open(path, "w") as w:
+        w.setnchannels(1)
+        w.setsampwidth(2)
+        w.setframerate(SR)
+        frames = b"".join(struct.pack("<h", int(max(-1, min(1, v)) * 32767)) for v in samples)
+        w.writeframes(frames)
+    print(f"wrote {name}  ({len(samples)/SR*1000:.0f} ms, {len(frames)} bytes)")
+
+
+def apply_env(sig, e):
+    return [s * a for s, a in zip(sig, e)]
+
+
+def bubble_pop():
+    """A cute bubble 'bloop' — pitch swoops up fast then a rounded body."""
+    dur = 0.16
+    n = int(dur * SR)
+    # Rising swoop is the signature of a bubble.
+    body = sine(lambda t: 360 + 720 * (1 - math.exp(-t * 38)), n)
+    body = apply_env(body, env(n, 0.004, 0.05, dur))
+    # A soft octave shimmer on top.
+    shimmer = sine(lambda t: 1080 + 400 * (1 - math.exp(-t * 38)), n)
+    shimmer = apply_env(shimmer, env(n, 0.003, 0.03, dur))
+    shimmer = [v * 0.25 for v in shimmer]
+    return mix(body, shimmer)
+
+
+def droplet():
+    """A clean little water-drop ping — high, downward, watery tail."""
+    dur = 0.22
+    n = int(dur * SR)
+    main = sine(lambda t: 1500 * math.exp(-t * 3.2) + 760, n)
+    main = apply_env(main, env(n, 0.003, 0.06, dur))
+    # Tiny resonant echo for a wet feel.
+    echo = sine(lambda t: 980, n)
+    echo = apply_env(echo, env(n, 0.05, 0.07, dur))
+    echo = [v * 0.2 for v in echo]
+    return mix(main, droop_delay(echo, 0.04))
+
+
+def droop_delay(sig, delay_s):
+    d = int(delay_s * SR)
+    return [0.0] * d + sig
+
+
+def bell(freq, dur, partials=((1, 1.0), (2.01, 0.5), (2.78, 0.28), (4.1, 0.12))):
+    """A soft inharmonic bell tone (sum of slightly detuned partials)."""
+    n = int(dur * SR)
+    layers = []
+    for ratio, amp in partials:
+        s = sine(lambda t, f=freq * ratio: f, n)
+        s = apply_env(s, env(n, 0.005, dur * 0.45, dur))
+        layers.append([v * amp for v in s])
+    return mix(*layers)
+
+
+def chime():
+    """Two gentle bell notes a soft fifth apart."""
+    a = bell(784, 0.42)  # G5
+    b = bell(1175, 0.40)  # D6
+    b = droop_delay(b, 0.10)
+    return mix(a, [v * 0.85 for v in b])
+
+
+def shimmer():
+    """Three quick ascending sparkles — glockenspiel-ish."""
+    notes = [988, 1319, 1976]  # B5, E6, B6
+    layers = []
+    for i, f in enumerate(notes):
+        s = bell(f, 0.30, partials=((1, 1.0), (2.7, 0.3), (5.1, 0.1)))
+        layers.append(droop_delay([v * 0.8 for v in s], 0.06 * i))
+    return mix(*layers)
+
+
+def cheer():
+    """A happy little major arpeggio C5-E5-G5-C6 on bells."""
+    notes = [523, 659, 784, 1047]
+    layers = []
+    for i, f in enumerate(notes):
+        s = bell(f, 0.36)
+        layers.append(droop_delay([v * 0.8 for v in s], 0.075 * i))
+    return mix(*layers)
+
+
+if __name__ == "__main__":
+    write_wav("pop.wav", bubble_pop())
+    write_wav("droplet.wav", droplet())
+    write_wav("chime.wav", chime())
+    write_wav("shimmer.wav", shimmer())
+    write_wav("cheer.wav", cheer())
+    print("done →", os.path.normpath(OUT))

web/src/App.tsx

@@ -13,6 +13,8 @@ import { StatusBar } from './components/StatusBar/StatusBar'
 import { PetalCompanion } from './components/Companion/PetalCompanion'
 import { UpdateBanner } from './components/UpdateBanner/UpdateBanner'
 import { useVersionWatch } from './hooks/useVersionWatch'
+import { PetalFall } from './effects/PetalFall'
+import { playSuggestionSound } from './audio/sounds'
 
 export default function App() {
   const updateAvailable = useVersionWatch()
@@ -309,8 +311,34 @@ export default function App() {
     [removeSuggestion],
   )
 
+  // Play a soft sound when freshly-checked suggestions arrive — one per distinct
+  // new type, lightly staggered so a batch reads as a little melody rather than
+  // a pile-up. We track which ids we've already chimed for, and only chime for
+  // recently-created suggestions so opening a doc with old pending advice stays
+  // silent (the existing set was created in a past session).
+  const chimedRef = useRef<Set<string>>(new Set())
+  useEffect(() => {
+    const fresh = suggestions.filter((s) => !chimedRef.current.has(s.id))
+    fresh.forEach((s) => chimedRef.current.add(s.id))
+    const justMade = fresh.filter(
+      (s) => Date.now() - new Date(s.created_at).getTime() < 12_000,
+    )
+    if (justMade.length === 0) return
+    const types = [...new Set(justMade.map((s) => s.type))].slice(0, 3)
+    const timers = types.map((t, i) =>
+      window.setTimeout(() => playSuggestionSound(t), i * 150),
+    )
+    return () => timers.forEach((id) => window.clearTimeout(id))
+  }, [suggestions])
+
+  // Forget chimed ids when switching documents so the set can't grow unbounded.
+  useEffect(() => {
+    chimedRef.current = new Set()
+  }, [currentDoc?.id])
+
   return (
     <div className="flex h-full flex-col">
+      <PetalFall />
       <header
         onMouseDown={handleChromeDown}
         className="petal-no-print flex h-12 shrink-0 items-center gap-2 px-5"

web/src/audio/sounds.ts

@@ -0,0 +1,174 @@
+// Petal's cute sound palette. The actual tones live as tiny WAV assets in
+// ./assets (generated by scripts/gen_sounds.py — warm bubble pops, water drops,
+// and soft bells tuned to match the app's gentle look). Vite fingerprints and
+// bundles them into dist, so they ride along inside the single Go binary; here
+// we just fetch + decode them once and play them through a Web Audio bus with a
+// soft master volume. The whole thing is opt-out-able and the mute choice
+// persists in localStorage so it survives reloads.
+
+import popUrl from '../assets/sounds/pop.wav'
+import dropletUrl from '../assets/sounds/droplet.wav'
+import chimeUrl from '../assets/sounds/chime.wav'
+import shimmerUrl from '../assets/sounds/shimmer.wav'
+import cheerUrl from '../assets/sounds/cheer.wav'
+
+const STORAGE_KEY = 'petal.sound'
+
+// Master volume — deliberately gentle. These are background delights, not alerts.
+const MASTER_GAIN = 0.5
+
+export type SoundName =
+  | 'pop' // a soft bubble pop — the signature "something arrived"
+  | 'droplet' // a single rounded water-drop ping
+  | 'chime' // a gentle two-note bell
+  | 'shimmer' // three quick ascending sparkles
+  | 'cheer' // a happy little major arpeggio (accepts, milestones)
+
+const SOURCES: Record<SoundName, string> = {
+  pop: popUrl,
+  droplet: dropletUrl,
+  chime: chimeUrl,
+  shimmer: shimmerUrl,
+  cheer: cheerUrl,
+}
+
+let ctx: AudioContext | null = null
+let master: GainNode | null = null
+const buffers = new Map<SoundName, AudioBuffer>()
+let enabled = readEnabled()
+const listeners = new Set<(on: boolean) => void>()
+
+function readEnabled(): boolean {
+  try {
+    return localStorage.getItem(STORAGE_KEY) !== 'off'
+  } catch {
+    return true
+  }
+}
+
+export function isSoundEnabled(): boolean {
+  return enabled
+}
+
+export function setSoundEnabled(on: boolean): void {
+  enabled = on
+  try {
+    localStorage.setItem(STORAGE_KEY, on ? 'on' : 'off')
+  } catch {
+    /* private mode — choice just won't persist */
+  }
+  listeners.forEach((fn) => fn(on))
+  // Touching the context on enable doubles as a user-gesture unlock + warm-up.
+  if (on) void ensureContext()
+}
+
+export function onSoundEnabledChange(fn: (on: boolean) => void): () => void {
+  listeners.add(fn)
+  return () => listeners.delete(fn)
+}
+
+// Lazily create the AudioContext (browsers require a user gesture before audio
+// can play; the first play() after a click will succeed, earlier ones resume).
+async function ensureContext(): Promise<AudioContext | null> {
+  if (typeof window === 'undefined') return null
+  const AC: typeof AudioContext | undefined =
+    window.AudioContext ??
+    (window as unknown as { webkitAudioContext?: typeof AudioContext }).webkitAudioContext
+  if (!AC) return null
+  if (!ctx) {
+    ctx = new AC()
+    master = ctx.createGain()
+    master.gain.value = MASTER_GAIN
+    // A gentle soft-clip so stacked sounds never crackle.
+    const shaper = ctx.createWaveShaper()
+    shaper.curve = softClipCurve()
+    master.connect(shaper)
+    shaper.connect(ctx.destination)
+  }
+  if (ctx.state === 'suspended') {
+    try {
+      await ctx.resume()
+    } catch {
+      /* will retry on the next gesture */
+    }
+  }
+  return ctx
+}
+
+function softClipCurve(): Float32Array<ArrayBuffer> {
+  const n = 1024
+  const curve = new Float32Array(new ArrayBuffer(n * 4))
+  for (let i = 0; i < n; i++) {
+    const x = (i / (n - 1)) * 2 - 1
+    curve[i] = Math.tanh(x * 1.2)
+  }
+  return curve
+}
+
+// Fetch + decode one sound, caching the decoded buffer for instant replay.
+async function load(name: SoundName, audio: AudioContext): Promise<AudioBuffer | null> {
+  const cached = buffers.get(name)
+  if (cached) return cached
+  try {
+    const res = await fetch(SOURCES[name])
+    const bytes = await res.arrayBuffer()
+    const buf = await audio.decodeAudioData(bytes)
+    buffers.set(name, buf)
+    return buf
+  } catch {
+    return null // asset missing / decode failed — sound just won't play
+  }
+}
+
+// Warm the cache so the first real play is instant.
+async function prime(): Promise<void> {
+  const audio = await ensureContext()
+  if (!audio) return
+  await Promise.all((Object.keys(SOURCES) as SoundName[]).map((n) => load(n, audio)))
+}
+
+// Fire a sound. No-op when muted or audio is unavailable. Never throws — a
+// delight that fails should fail silently.
+export function playSound(name: SoundName): void {
+  if (!enabled) return
+  void (async () => {
+    const audio = await ensureContext()
+    if (!audio || !master || audio.state !== 'running') return
+    const buf = await load(name, audio)
+    if (!buf) return
+    try {
+      const src = audio.createBufferSource()
+      src.buffer = buf
+      src.connect(master)
+      src.start()
+    } catch {
+      /* audio glitch — ignore */
+    }
+  })()
+}
+
+// Map an editor suggestion type to its sound, so each kind of help has its own
+// little voice (grammar pops like a bubble, idioms chime, etc.).
+const SUGGESTION_SOUND: Record<string, SoundName> = {
+  grammar: 'pop',
+  phrasing: 'droplet',
+  idiom: 'chime',
+  clarity: 'shimmer',
+  voice: 'droplet',
+}
+
+export function playSuggestionSound(type: string): void {
+  playSound(SUGGESTION_SOUND[type] ?? 'pop')
+}
+
+// Unlock + warm audio on the first user gesture so the very first sound isn't
+// dropped by the browser's autoplay policy. Self-removing.
+if (typeof window !== 'undefined') {
+  const unlock = () => {
+    void prime()
+    window.removeEventListener('pointerdown', unlock)
+    window.removeEventListener('keydown', unlock)
+  }
+  window.addEventListener('pointerdown', unlock)
+  window.addEventListener('keydown', unlock)
+}

web/src/components/Companion/useCompanion.ts

@@ -12,6 +12,7 @@ import {
   type Line,
 } from './tips'
 import { analyzeProse } from './prose'
+import { playSound } from '../../audio/sounds'
 
 // The kitten's expression. Maps to a Lottie animation when assets are present,
 // otherwise to an emoji placeholder (see PetalCompanion).
@@ -95,6 +96,11 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick, text
       lastProactive.current = t
     }
     sleeping.current = false
+    // A soft sound to match the bubble's mood — celebrations cheer, gentle
+    // cheers sparkle, break nudges chime, and tips give a little bubble pop.
+    playSound(
+      opts?.celebrate ? 'cheer' : b.tone === 'cheer' ? 'shimmer' : b.tone === 'break' ? 'chime' : 'pop',
+    )
     setBubble(b)
     setMood(opts?.celebrate ? 'celebrate' : 'talking')
     clearTimeout(bubbleTimer.current)

web/src/components/StatusBar/SoundToggle.tsx

@@ -0,0 +1,37 @@
+import { useEffect, useState } from 'react'
+import { isSoundEnabled, onSoundEnabledChange, playSound, setSoundEnabled } from '../../audio/sounds'
+
+// A tiny mute toggle for Petal's cute sounds, tucked at the right of the status
+// bar. Bilingual tooltip (she reads Mandarin first), and a soft confirming pop
+// when sounds are turned back on so the choice is audible.
+export function SoundToggle() {
+  const [on, setOn] = useState(isSoundEnabled)
+
+  // Stay in sync if the setting is flipped elsewhere.
+  useEffect(() => onSoundEnabledChange(setOn), [])
+
+  const toggle = () => {
+    const next = !on
+    setSoundEnabled(next)
+    setOn(next)
+    if (next) playSound('pop') // a little hello when re-enabled
+  }
+
+  return (
+    <button
+      type="button"
+      onClick={toggle}
+      aria-pressed={on}
+      title={on ? '声音开 · Sounds on' : '声音关 · Sounds off'}
+      aria-label={on ? 'Mute Petal sounds' : 'Unmute Petal sounds'}
+      className="rounded-full px-1.5 py-0.5 transition-colors"
+      style={{ color: on ? 'var(--color-accent)' : 'var(--color-muted)', lineHeight: 1 }}
+      onMouseEnter={(e) => (e.currentTarget.style.color = 'var(--color-accent-hover)')}
+      onMouseLeave={(e) =>
+        (e.currentTarget.style.color = on ? 'var(--color-accent)' : 'var(--color-muted)')
+      }
+    >
+      <span aria-hidden>{on ? '🔔' : '🔕'}</span>
+    </button>
+  )
+}

web/src/components/StatusBar/StatusBar.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useRef, useState } from 'react'
 import type { SaveStatus } from '../../hooks/useAutoSave'
 import { StatsPanel } from './StatsPanel'
+import { SoundToggle } from './SoundToggle'
 
 interface Props {
   wordCount: number
@@ -120,6 +121,9 @@ export function StatusBar({ wordCount, text, saveStatus, checking, voicing, llmD
           </span>
         </>
       )}
+      <div className="ml-auto">
+        <SoundToggle />
+      </div>
     </footer>
   )
 }

web/src/effects/PetalFall.tsx

@@ -0,0 +1,267 @@
+import { useEffect, useRef } from 'react'
+
+// PetalFall is the cozy ambient layer: a full-window WebGL canvas that drifts a
+// handful of soft flower petals down the page. It sits behind everything,
+// ignores pointer events, and stays sparse so it reads as "occasional petals on
+// a breeze" rather than confetti. Honors prefers-reduced-motion by rendering
+// nothing. No external libraries — a single tiny shader program animates every
+// petal entirely on the GPU, so the CPU just spins a clock.
+
+// Each petal is a quad whose corners we expand in the vertex shader. We pack one
+// quad as 6 vertices; per-vertex we send the corner offset (which corner) plus
+// the petal's static randomness (lane, speed, size, sway, tint, spin).
+const PETAL_COUNT = 26
+
+// Soft Petal-palette tints (rose / blush / lavender), as RGB 0..1.
+const TINTS: [number, number, number][] = [
+  [0.91, 0.63, 0.75], // accent rose  #E8A0BF
+  [1.0, 0.94, 0.96], // near-white blush
+  [0.96, 0.72, 0.63], // peach        #F4B8A0
+  [0.77, 0.71, 0.91], // lavender     #C5B4E8
+  [0.85, 0.55, 0.69], // deeper rose
+]
+
+const VERT = `
+precision mediump float;
+attribute vec2 a_corner;   // quad corner in [-0.5,0.5]
+attribute vec4 a_rand;     // x: lane(0..1), y: speed, z: size, w: phase
+attribute vec4 a_rand2;    // x: swayAmp, y: swayFreq, z: spin, w: tintIdx
+uniform float u_time;
+uniform vec2 u_res;
+varying vec2 v_uv;
+varying float v_tint;
+varying float v_alpha;
+
+void main() {
+  v_uv = a_corner + 0.5;
+  v_tint = a_rand2.w;
+
+  float lane = a_rand.x;
+  float speed = a_rand.y;
+  float size = a_rand.z;
+  float phase = a_rand.w;
+
+  // Vertical fall: loop 0..1 over time, offset per petal so they don't sync.
+  float fall = fract(u_time * speed + phase);
+  // Map to clip space: start above the top (1.15) fall to below bottom (-1.15).
+  float y = 1.15 - fall * 2.3;
+
+  // Horizontal: a base lane plus a gentle sway as it descends.
+  float sway = a_rand2.x * sin(u_time * a_rand2.y + phase * 6.2831);
+  float x = (lane * 2.0 - 1.0) + sway;
+
+  // Spin the quad over time.
+  float ang = u_time * a_rand2.z + phase * 6.2831;
+  float c = cos(ang), s = sin(ang);
+  vec2 corner = a_corner * size;
+  // Keep petals visually square despite aspect ratio.
+  corner.x *= u_res.y / u_res.x;
+  vec2 rot = vec2(corner.x * c - corner.y * s, corner.x * s + corner.y * c);
+
+  // Fade in near the top and out near the bottom so they don't pop.
+  v_alpha = smoothstep(0.0, 0.12, fall) * (1.0 - smoothstep(0.86, 1.0, fall));
+
+  gl_Position = vec4(x + rot.x, y + rot.y, 0.0, 1.0);
+}
+`
+
+const FRAG = `
+precision mediump float;
+varying vec2 v_uv;
+varying float v_tint;
+varying float v_alpha;
+uniform vec3 u_tints[5];
+
+// A soft petal/teardrop alpha mask centered in the quad.
+float petalMask(vec2 uv) {
+  vec2 p = uv - vec2(0.5);
+  // Teardrop: pinch the top, round the bottom.
+  float r = length(vec2(p.x * 1.65, p.y * 1.15 + 0.12));
+  float body = smoothstep(0.5, 0.16, r);
+  // A subtle crease down the middle for a petal feel.
+  float crease = 1.0 - 0.18 * exp(-pow(p.x * 7.0, 2.0));
+  return body * crease;
+}
+
+void main() {
+  float m = petalMask(v_uv);
+  if (m < 0.01) discard;
+  int idx = int(v_tint + 0.5);
+  vec3 col = u_tints[0];
+  if (idx == 1) col = u_tints[1];
+  else if (idx == 2) col = u_tints[2];
+  else if (idx == 3) col = u_tints[3];
+  else if (idx == 4) col = u_tints[4];
+  gl_FragColor = vec4(col, m * v_alpha * 0.55);
+}
+`
+
+function compile(gl: WebGLRenderingContext, type: number, src: string): WebGLShader | null {
+  const sh = gl.createShader(type)
+  if (!sh) return null
+  gl.shaderSource(sh, src)
+  gl.compileShader(sh)
+  if (!gl.getShaderParameter(sh, gl.COMPILE_STATUS)) {
+    console.error('petal shader compile failed', gl.getShaderInfoLog(sh))
+    gl.deleteShader(sh)
+    return null
+  }
+  return sh
+}
+
+// Deterministic-ish pseudo random (we can't use Math.random at module scope for
+// SSR safety, but here in an effect it's fine; kept simple).
+function rand(): number {
+  return Math.random()
+}
+
+export function PetalFall() {
+  const canvasRef = useRef<HTMLCanvasElement>(null)
+
+  useEffect(() => {
+    const reduce =
+      typeof window !== 'undefined' &&
+      window.matchMedia?.('(prefers-reduced-motion: reduce)').matches
+    if (reduce) return // respect users who don't want ambient motion
+
+    const canvas = canvasRef.current
+    if (!canvas) return
+    const gl = canvas.getContext('webgl', { alpha: true, premultipliedAlpha: false, antialias: true })
+    if (!gl) return // no WebGL — silently skip the effect
+
+    const vs = compile(gl, gl.VERTEX_SHADER, VERT)
+    const fs = compile(gl, gl.FRAGMENT_SHADER, FRAG)
+    if (!vs || !fs) return
+    const prog = gl.createProgram()!
+    gl.attachShader(prog, vs)
+    gl.attachShader(prog, fs)
+    gl.linkProgram(prog)
+    if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
+      console.error('petal program link failed', gl.getProgramInfoLog(prog))
+      return
+    }
+    gl.useProgram(prog)
+
+    // Build interleaved vertex data: 6 verts per petal, each with corner(2),
+    // rand(4), rand2(4) = 10 floats.
+    const FLOATS_PER_VERT = 10
+    const corners = [
+      [-0.5, -0.5],
+      [0.5, -0.5],
+      [-0.5, 0.5],
+      [-0.5, 0.5],
+      [0.5, -0.5],
+      [0.5, 0.5],
+    ]
+    const data = new Float32Array(PETAL_COUNT * 6 * FLOATS_PER_VERT)
+    let o = 0
+    for (let i = 0; i < PETAL_COUNT; i++) {
+      const lane = rand()
+      const speed = 0.018 + rand() * 0.03 // slow, gentle fall
+      const size = 0.05 + rand() * 0.06
+      const phase = rand()
+      const swayAmp = 0.04 + rand() * 0.09
+      const swayFreq = 0.4 + rand() * 0.7
+      const spin = (rand() - 0.5) * 1.2
+      const tint = Math.floor(rand() * TINTS.length)
+      for (let c = 0; c < 6; c++) {
+        data[o++] = corners[c][0]
+        data[o++] = corners[c][1]
+        data[o++] = lane
+        data[o++] = speed
+        data[o++] = size
+        data[o++] = phase
+        data[o++] = swayAmp
+        data[o++] = swayFreq
+        data[o++] = spin
+        data[o++] = tint
+      }
+    }
+
+    const buf = gl.createBuffer()
+    gl.bindBuffer(gl.ARRAY_BUFFER, buf)
+    gl.bufferData(gl.ARRAY_BUFFER, data, gl.STATIC_DRAW)
+
+    const stride = FLOATS_PER_VERT * 4
+    const aCorner = gl.getAttribLocation(prog, 'a_corner')
+    const aRand = gl.getAttribLocation(prog, 'a_rand')
+    const aRand2 = gl.getAttribLocation(prog, 'a_rand2')
+    gl.enableVertexAttribArray(aCorner)
+    gl.vertexAttribPointer(aCorner, 2, gl.FLOAT, false, stride, 0)
+    gl.enableVertexAttribArray(aRand)
+    gl.vertexAttribPointer(aRand, 4, gl.FLOAT, false, stride, 2 * 4)
+    gl.enableVertexAttribArray(aRand2)
+    gl.vertexAttribPointer(aRand2, 4, gl.FLOAT, false, stride, 6 * 4)
+
+    const uTime = gl.getUniformLocation(prog, 'u_time')
+    const uRes = gl.getUniformLocation(prog, 'u_res')
+    const uTints = gl.getUniformLocation(prog, 'u_tints')
+    gl.uniform3fv(uTints, TINTS.flat())
+
+    gl.enable(gl.BLEND)
+    gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
+    gl.disable(gl.DEPTH_TEST)
+
+    // Non-null aliases so the render closures keep the narrowed types.
+    const view = canvas
+    const glc = gl
+    const dpr = Math.min(window.devicePixelRatio || 1, 2)
+    function resize() {
+      const w = Math.floor(window.innerWidth * dpr)
+      const h = Math.floor(window.innerHeight * dpr)
+      if (view.width !== w || view.height !== h) {
+        view.width = w
+        view.height = h
+      }
+      glc.viewport(0, 0, view.width, view.height)
+      glc.uniform2f(uRes, view.width, view.height)
+    }
+    resize()
+    window.addEventListener('resize', resize)
+
+    let raf = 0
+    let running = true
+    const start = performance.now()
+    function frame() {
+      if (!running) return
+      const t = (performance.now() - start) / 1000
+      glc.clearColor(0, 0, 0, 0)
+      glc.clear(glc.COLOR_BUFFER_BIT)
+      glc.uniform1f(uTime, t)
+      glc.drawArrays(glc.TRIANGLES, 0, PETAL_COUNT * 6)
+      raf = requestAnimationFrame(frame)
+    }
+    // Pause when the tab is hidden to save the battery.
+    const onVisibility = () => {
+      if (document.hidden) {
+        running = false
+        cancelAnimationFrame(raf)
+      } else if (!running) {
+        running = true
+        raf = requestAnimationFrame(frame)
+      }
+    }
+    document.addEventListener('visibilitychange', onVisibility)
+    raf = requestAnimationFrame(frame)
+
+    return () => {
+      running = false
+      cancelAnimationFrame(raf)
+      window.removeEventListener('resize', resize)
+      document.removeEventListener('visibilitychange', onVisibility)
+      gl.deleteBuffer(buf)
+      gl.deleteProgram(prog)
+      gl.deleteShader(vs)
+      gl.deleteShader(fs)
+    }
+  }, [])
+
+  return (
+    <canvas
+      ref={canvasRef}
+      aria-hidden
+      className="petal-fall pointer-events-none fixed inset-0"
+      style={{ zIndex: 20 }}
+    />
+  )
+}

web/src/index.css

@@ -382,7 +382,31 @@ button, a, input {
    only the title and the writing itself reach the page. This is Petal's PDF
    path — it uses the browser's own fonts, so CJK renders correctly with no
    server-side font embedding. */
+/* --- Ambient falling petals -------------------------------------------------
+   The WebGL petal layer is a fixed, non-interactive overlay that drifts soft
+   blossoms over the page. Kept gentle (low opacity) so it never competes with
+   the writing. It hides itself in print and is skipped entirely for users who
+   prefer reduced motion (the component renders nothing in that case). */
+.petal-fall {
+  opacity: 0.85;
+}
+
+/* Honor reduced-motion globally: still the looping ambient animations and drop
+   the petal layer. One-shot entrance/feedback animations are left intact. */
+@media (prefers-reduced-motion: reduce) {
+  .petal-fall {
+    display: none !important;
+  }
+  .petal-bob,
+  .petal-bob-slow,
+  .petal-zzz,
+  .petal-checkpoint-dot {
+    animation: none !important;
+  }
+}
+
 @media print {
+  .petal-fall,
   .petal-no-print,
   .petal-sidebar,
   .petal-suggestion-card,

web/src/vite-env.d.ts

@@ -0,0 +1 @@
+/// <reference types="vite/client" />