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))