feat(seasonal): redesign all 11 seasonal themes as modular per-theme overlays

Split the 808-line SeasonalEffect monolith into one self-contained module per theme under seasonal/themes/ (<Theme>.tsx + <Theme>.css.ts), and gave every theme a premium, research-backed redesign (one Opus agent per theme against a shared brief). SeasonalEffect now just imports the 11 overlays and dispatches; the orphaned shared Seasonal.css.ts is removed (each theme owns its keyframes). Each overlay: layered oklch palettes, GPU-only animation (transform/opacity), `contain: layout paint style` to kill repaint flicker, ≤~40-element perf budget, particles seeded once via useMemo (no per-frame state), a gorgeous STATIC prefers-reduced-motion form (the settings preview thumbnail), WCAG-AA-preserving low opacities, and no new deps / no external assets (inline SVG data-URIs, Tauri/CSP-safe). Themes: Halloween, Christmas, New Year, Autumn, April Fools, Lunar New Year, Valentines, St. Patrick's, Earth Day, Deep Space, Arcade. Gates: tsc clean, ESLint clean, Prettier clean, build OK, 551 tests pass. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-30 19:41:58 -04:00
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+import React, { useMemo } from 'react';
+import { SeasonalOverlayProps } from '../types';
+import {
+  animLeafFall,
+  animLeafSway,
+  animLeafFlutter,
+  animSunShaft,
+  animMoteDrift,
+  animMoteTwinkle,
+  animEmberPulse,
+} from './Autumn.css';
+
+/**
+ * AutumnOverlay — warm falling leaves.
+ *
+ * A full-screen, pointer-events:none ambient decoration. The parent supplies a
+ * fixed inset:0 overflow:hidden pointer-events:none container at the correct
+ * z-index, so this component only returns absolutely-positioned aria-hidden
+ * children and never sets position:fixed / z-index / pointer-events.
+ *
+ * Composition (back to front):
+ *   1. amber -> rust ambient gradient wash (cozy low-sun atmosphere)
+ *   2. soft angled sun shafts breathing high across the scene
+ *   3. drifting pollen / dust motes catching the light
+ *   4. maple & oak leaf silhouettes tumbling and rotating as they fall
+ *   5. a warm low-saturation vignette that frames + protects text contrast
+ *
+ * All motion is transform/opacity only (compositor-friendly). When `reduced`
+ * is true we render a static-but-gorgeous scene: a handful of leaves at rest,
+ * still sun shafts, and the warm vignette — no `animation` anywhere. The
+ * settings preview always passes reduced=true, so the still form stands alone.
+ */
+
+// Warm autumn palette in oklch. Kept low-saturation enough to never fight the
+// chat text underneath. Each leaf picks a tone for variety.
+const LEAF_TONES = [
+  'oklch(0.75 0.15 70)', // amber
+  'oklch(0.55 0.16 40)', // rust
+  'oklch(0.82 0.13 85)', // warm gold
+  'oklch(0.62 0.16 55)', // burnt orange
+  'oklch(0.5 0.14 35)', // deep ember
+];
+
+// Two leaf silhouettes as inline SVG path data (no external assets, CSP-safe).
+// `maple` = classic five-lobed maple; `oak` = rounded-lobe oak blade.
+const MAPLE_PATH =
+  'M50 4 L57 30 L78 18 L66 40 L92 40 L70 52 L84 74 L58 62 L56 92 L50 70 ' +
+  'L44 92 L42 62 L16 74 L30 52 L8 40 L34 40 L22 18 L43 30 Z';
+const OAK_PATH =
+  'M50 4 C58 14 56 22 64 24 C74 22 74 32 68 36 C78 38 76 48 68 50 ' +
+  'C78 54 74 64 66 64 C70 74 60 78 54 72 C54 84 50 96 50 96 ' +
+  'C50 96 46 84 46 72 C40 78 30 74 34 64 C26 64 22 54 32 50 ' +
+  'C24 48 22 38 32 36 C26 32 26 22 36 24 C44 22 42 14 50 4 Z';
+
+/** Build a CSS-ready data-URI of a single tinted leaf silhouette. */
+function leafDataUri(kind: 'maple' | 'oak', fill: string): string {
+  const path = kind === 'maple' ? MAPLE_PATH : OAK_PATH;
+  // A faint vein line gives the blade depth without extra DOM nodes.
+  const svg =
+    `<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'>` +
+    `<path d='${path}' fill='${fill}' fill-opacity='0.92'/>` +
+    `<path d='M50 96 L50 24' stroke='oklch(0.42 0.12 38)' stroke-opacity='0.35' ` +
+    `stroke-width='2.5' fill='none' stroke-linecap='round'/>` +
+    `</svg>`;
+  return `url("data:image/svg+xml,${encodeURIComponent(svg)}")`;
+}
+
+type Leaf = {
+  kind: 'maple' | 'oak';
+  uri: string;
+  left: number; // vw column
+  size: number; // px
+  duration: number; // s — fall time
+  delay: number; // s
+  swayDuration: number; // s — wrapper sway
+  flutterDuration: number; // s — inner flutter
+  tilt: number; // deg — resting rotation (used for static scene)
+  opacity: number;
+};
+
+type Mote = {
+  left: number;
+  bottom: number;
+  size: number;
+  duration: number;
+  delay: number;
+  twinkle: number;
+  opacity: number;
+};
+
+// A few hand-placed leaves at rest for the reduced/static scene — arranged so
+// they read as "settled" near edges and corners, never over the busy center.
+const RESTING_LEAVES: ReadonlyArray<{
+  kind: 'maple' | 'oak';
+  left: number;
+  top: number;
+  size: number;
+  tilt: number;
+  tone: number;
+  opacity: number;
+}> = [
+  { kind: 'maple', left: 6, top: 14, size: 46, tilt: -22, tone: 0, opacity: 0.4 },
+  { kind: 'oak', left: 88, top: 22, size: 38, tilt: 28, tone: 1, opacity: 0.34 },
+  { kind: 'maple', left: 16, top: 78, size: 54, tilt: 16, tone: 3, opacity: 0.42 },
+  { kind: 'oak', left: 80, top: 82, size: 44, tilt: -34, tone: 4, opacity: 0.36 },
+  { kind: 'maple', left: 50, top: 90, size: 40, tilt: 8, tone: 2, opacity: 0.32 },
+  { kind: 'oak', left: 70, top: 8, size: 32, tilt: -12, tone: 2, opacity: 0.3 },
+];
+
+export function AutumnOverlay({ reduced }: SeasonalOverlayProps) {
+  // Deterministic pseudo-random field, computed ONCE. No per-frame state.
+  const { leaves, motes } = useMemo(() => {
+    const LEAF_COUNT = 16;
+    const MOTE_COUNT = 12;
+
+    const builtLeaves: Leaf[] = Array.from({ length: LEAF_COUNT }, (_, i) => {
+      const kind: 'maple' | 'oak' = i % 3 === 0 ? 'oak' : 'maple';
+      const tone = LEAF_TONES[i % LEAF_TONES.length];
+      const sizeBucket = i % 4; // 0..3 → depth bucket for parallax
+      const size = 22 + sizeBucket * 9; // 22..49 px
+      return {
+        kind,
+        uri: leafDataUri(kind, tone),
+        left: (i * 6.13 + 4) % 100,
+        size,
+        // Larger (nearer) leaves fall a touch faster; all slow + cozy.
+        duration: 16 - sizeBucket * 1.6 + (i % 3) * 1.3,
+        delay: -((i * 1.37) % 16), // negative → staggered, already mid-fall
+        swayDuration: 5 + (i % 5) * 0.8,
+        flutterDuration: 1.6 + (i % 4) * 0.45,
+        tilt: ((i * 53) % 70) - 35,
+        opacity: 0.34 + sizeBucket * 0.08, // nearer → slightly bolder
+      };
+    });
+
+    const builtMotes: Mote[] = Array.from({ length: MOTE_COUNT }, (_, i) => ({
+      left: (i * 8.7 + 5) % 100,
+      bottom: (i * 4.3) % 30, // start in lower third, drift up
+      size: 2 + (i % 3),
+      duration: 16 + (i % 6) * 2.4,
+      delay: -((i * 2.1) % 16),
+      twinkle: 2.2 + (i % 4) * 0.6,
+      opacity: 0.4 + (i % 3) * 0.12,
+    }));
+
+    return { leaves: builtLeaves, motes: builtMotes };
+  }, []);
+
+  return (
+    <>
+      {/* 1. Ambient amber → rust atmospheric wash. Layered oklch gradients give
+            depth: a warm low-sun glow from the upper-left, a rust pool at the
+            base, and a faint gold core. Kept very low opacity. */}
+      <div
+        aria-hidden="true"
+        style={{
+          position: 'absolute',
+          inset: 0,
+          backgroundImage: [
+            'radial-gradient(120% 90% at 18% 8%, oklch(0.82 0.13 85 / 0.16) 0%, transparent 55%)',
+            'radial-gradient(130% 100% at 50% 118%, oklch(0.55 0.16 40 / 0.18) 0%, transparent 60%)',
+            'linear-gradient(180deg, oklch(0.75 0.15 70 / 0.07) 0%, transparent 40%, oklch(0.5 0.14 35 / 0.08) 100%)',
+          ].join(','),
+          contain: 'layout paint style',
+        }}
+      />
+
+      {/* 2. Soft angled low-sun light shafts. Two long beams skewed to suggest
+            late-afternoon light raking across the room. */}
+      {[
+        { left: -8, rotate: 18, w: 38, opacity: 0.5, dur: 17, delay: 0 },
+        { left: 46, rotate: 14, w: 30, opacity: 0.38, dur: 22, delay: -6 },
+        { left: 78, rotate: 22, w: 26, opacity: 0.32, dur: 19, delay: -11 },
+      ].map((shaft, i) => (
+        <div
+          key={`shaft-${i}`}
+          aria-hidden="true"
+          style={{
+            position: 'absolute',
+            top: '-30%',
+            left: `${shaft.left}%`,
+            width: `${shaft.w}vw`,
+            height: '160%',
+            transformOrigin: 'top center',
+            transform: `rotate(${shaft.rotate}deg)`,
+            backgroundImage:
+              'linear-gradient(90deg, transparent 0%, oklch(0.85 0.12 82 / 0.5) 50%, transparent 100%)',
+            filter: 'blur(14px)',
+            mixBlendMode: 'screen',
+            opacity: reduced ? shaft.opacity * 0.85 : undefined,
+            willChange: reduced ? undefined : 'transform, opacity',
+            contain: 'layout paint style',
+            animation: reduced
+              ? 'none'
+              : `${animSunShaft} ${shaft.dur}s ease-in-out ${shaft.delay}s infinite`,
+          }}
+        />
+      ))}
+
+      {/* 3. Drifting pollen / dust motes catching the light. Static scene omits
+            them — stillness reads cleaner at rest. */}
+      {!reduced &&
+        motes.map((m, i) => (
+          <div
+            key={`mote-${i}`}
+            aria-hidden="true"
+            style={{
+              position: 'absolute',
+              left: `${m.left}%`,
+              bottom: `${m.bottom}%`,
+              width: `${m.size}px`,
+              height: `${m.size}px`,
+              willChange: 'transform, opacity',
+              animation: `${animMoteDrift} ${m.duration}s linear ${m.delay}s infinite`,
+            }}
+          >
+            <div
+              style={{
+                width: '100%',
+                height: '100%',
+                borderRadius: '50%',
+                background:
+                  'radial-gradient(circle, oklch(0.88 0.1 85 / 0.95) 0%, oklch(0.78 0.12 70 / 0.4) 60%, transparent 100%)',
+                opacity: m.opacity,
+                animation: `${animMoteTwinkle} ${m.twinkle}s ease-in-out infinite`,
+              }}
+            />
+          </div>
+        ))}
+
+      {/* 4. Falling / resting maple & oak leaves. */}
+      {reduced
+        ? RESTING_LEAVES.map((leaf, i) => (
+            <div
+              key={`rest-${i}`}
+              aria-hidden="true"
+              style={{
+                position: 'absolute',
+                left: `${leaf.left}%`,
+                top: `${leaf.top}%`,
+                width: `${leaf.size}px`,
+                height: `${leaf.size}px`,
+                backgroundImage: leafDataUri(leaf.kind, LEAF_TONES[leaf.tone]),
+                backgroundSize: 'contain',
+                backgroundRepeat: 'no-repeat',
+                transform: `translate(-50%, -50%) rotate(${leaf.tilt}deg)`,
+                opacity: leaf.opacity,
+                filter: 'drop-shadow(0 2px 3px oklch(0.3 0.08 40 / 0.35))',
+              }}
+            />
+          ))
+        : leaves.map((leaf, i) => (
+            // Sway wrapper: horizontal wind motion, decoupled from the fall.
+            <div
+              key={`leaf-${i}`}
+              aria-hidden="true"
+              style={{
+                position: 'absolute',
+                top: 0,
+                left: `${leaf.left}%`,
+                width: `${leaf.size}px`,
+                height: `${leaf.size}px`,
+                willChange: 'transform',
+                contain: 'layout paint style',
+                animation: `${animLeafSway} ${leaf.swayDuration}s ease-in-out ${leaf.delay}s infinite`,
+              }}
+            >
+              {/* Fall wrapper: vertical descent + tumble rotation. */}
+              <div
+                style={{
+                  width: '100%',
+                  height: '100%',
+                  willChange: 'transform, opacity',
+                  animation: `${animLeafFall} ${leaf.duration}s linear ${leaf.delay}s infinite`,
+                }}
+              >
+                {/* Inner blade: the actual silhouette + flutter wobble. */}
+                <div
+                  style={{
+                    width: '100%',
+                    height: '100%',
+                    backgroundImage: leaf.uri,
+                    backgroundSize: 'contain',
+                    backgroundRepeat: 'no-repeat',
+                    opacity: leaf.opacity,
+                    filter: 'drop-shadow(0 1px 2px oklch(0.3 0.08 40 / 0.3))',
+                    animation: `${animLeafFlutter} ${leaf.flutterDuration}s ease-in-out infinite`,
+                  }}
+                />
+              </div>
+            </div>
+          ))}
+
+      {/* 5. Warm low-saturation vignette. Frames the scene and gently darkens
+            edges — protecting central chat text contrast. Breathes faintly. */}
+      <div
+        aria-hidden="true"
+        style={{
+          position: 'absolute',
+          inset: 0,
+          backgroundImage:
+            'radial-gradient(120% 110% at 50% 45%, transparent 52%, oklch(0.38 0.07 45 / 0.14) 82%, oklch(0.3 0.06 40 / 0.22) 100%)',
+          contain: 'layout paint style',
+          opacity: reduced ? 1 : undefined,
+          animation: reduced ? 'none' : `${animEmberPulse} 9s ease-in-out infinite`,
+        }}
+      />
+    </>
+  );
+}