v6.3 — light/dark theme tick switch in the header

src/app/globals.css

@@ -79,6 +79,7 @@
 }
 
 .dark {
+  color-scheme: dark;
   --background: oklch(0.145 0 0);
   --foreground: oklch(0.985 0 0);
   --card: oklch(0.205 0 0);
@@ -112,6 +113,46 @@
   --sidebar-ring: oklch(0.556 0 0);
 }
 
+/*
+ * OVE light theme (v6.3).
+ *
+ * The app is styled with the Tailwind zinc/emerald/rose/amber utilities
+ * directly (no semantic tokens for the app chrome), so the light theme is
+ * implemented by REMAPPING those palettes under `.light` (next-themes sets
+ * the class on <html>):
+ *   • zinc is inverted — 950 (page) becomes white, 100 (text) becomes
+ *     near-black; borders/hover/panels land on their light equivalents;
+ *   • emerald/rose/amber accents are deepened one step so text and buttons
+ *     keep WCAG-ish contrast on white (emerald-400 → emerald-600 etc.),
+ *     hover states still lighten (emerald-300 → emerald-500);
+ *   • the visualization canvas keeps its own black stage by design.
+ */
+.light {
+  color-scheme: light;
+
+  /* inverted zinc ramp */
+  --color-zinc-50: #18181b;
+  --color-zinc-100: #18181b;
+  --color-zinc-200: #27272a;
+  --color-zinc-300: #3f3f46;
+  --color-zinc-400: #52525b;
+  --color-zinc-500: #71717a;
+  --color-zinc-600: #8b8b93;
+  --color-zinc-700: #d4d4d8;
+  --color-zinc-800: #e4e4e7;
+  --color-zinc-900: #fafafa;
+  --color-zinc-950: #ffffff;
+
+  /* deeper accents for white backgrounds */
+  --color-emerald-200: #a7f3d0;
+  --color-emerald-300: #10b981;
+  --color-emerald-400: #059669;
+  --color-rose-300: #f43f5e;
+  --color-rose-400: #e11d48;
+  --color-amber-300: #b45309;
+  --color-amber-400: #d97706;
+}
+
 @layer base {
   * {
     @apply border-border outline-ring/50;

src/app/layout.tsx

@@ -1,5 +1,6 @@
 import type { Metadata } from "next";
 import { Geist, Geist_Mono } from "next/font/google";
+import { ThemeProvider } from "next-themes";
 import "./globals.css";
 import { Toaster } from "@/components/ui/toaster";
 import { APP_NAME, APP_SHORT, APP_VERSION } from "@/lib/version";
@@ -30,12 +31,21 @@ export default function RootLayout({
   children: React.ReactNode;
 }>) {
   return (
-    <html lang="en" className="dark" suppressHydrationWarning>
+    <html lang="en" suppressHydrationWarning>
       <body
         className={`${geistSans.variable} ${geistMono.variable} antialiased bg-zinc-950 text-zinc-100 font-sans`}
+      >
+        {/* class strategy: next-themes puts "dark" (default) or "light" on
+            <html> pre-paint; globals.css remaps the palettes under .light */}
+        <ThemeProvider
+          attribute="class"
+          defaultTheme="dark"
+          enableSystem={false}
+          disableTransitionOnChange
         >
           {children}
           <Toaster />
+        </ThemeProvider>
       </body>
     </html>
   );

src/components/ava/beat-tab.tsx

@@ -74,7 +74,7 @@ export function BeatTab() {
         type="button"
         whileTap={{ scale: 0.965 }}
         onClick={tapBeat}
-        className="flex h-14 w-full flex-col items-center justify-center gap-0.5 rounded-xl bg-emerald-400 font-bold text-zinc-950 shadow-[0_0_24px_rgba(52,211,153,0.28)] transition-colors hover:bg-emerald-300"
+        className="flex h-14 w-full flex-col items-center justify-center gap-0.5 rounded-xl bg-emerald-400 font-bold text-emerald-950 shadow-[0_0_24px_rgba(52,211,153,0.28)] transition-colors hover:bg-emerald-300"
         title="Tap to set the tempo (or press Space)"
       >
         <span className="flex items-center gap-2 text-sm font-bold tracking-[0.12em]">

src/components/ava/header.tsx

@@ -1,13 +1,16 @@
-// AVA — sticky app header: logo, audio source controls (segmented), demo BPM
+// OVE — sticky app header: logo, audio source controls (segmented), demo BPM
-// slider, BPM readout, and the beat indicator + "Set Beat" button side by side
+// slider, theme tick switch, BPM readout, and the beat indicator + "Set Beat"
-// (hard requirement: that pairing is always visible in the header).
+// button side by side (hard requirement: that pairing is always visible in
+// the header).
 
 'use client'
 
-import { useRef } from 'react'
+import { useRef, useSyncExternalStore } from 'react'
-import { AudioWaveform, Disc3, FileAudio, Link2, Mic, Square, Timer } from 'lucide-react'
+import { AudioWaveform, Disc3, FileAudio, Link2, Mic, Moon, Square, Sun, Timer } from 'lucide-react'
+import { useTheme } from 'next-themes'
 import { Button } from '@/components/ui/button'
 import { Slider } from '@/components/ui/slider'
+import { Switch } from '@/components/ui/switch'
 import { BeatDot } from '@/components/ava/beat-dot'
 import { LinkDialog } from '@/components/ava/link-dialog'
 import { tapBeat, useAudioSource } from '@/components/ava/audio-source'
@@ -140,6 +143,36 @@ function BpmReadout() {
   )
 }
 
+/**
+ * Light-switch tick: left position (unchecked) keeps the dark theme, flipping
+ * right (checked) switches the page to the white theme. Persisted per visitor
+ * by next-themes (localStorage). The useSyncExternalStore mount guard returns
+ * false on the server / first client render and true after hydration, so the
+ * checkbox never causes a hydration mismatch.
+ */
+const emptySubscribe = () => () => {}
+function ThemeToggle() {
+  const { resolvedTheme, setTheme } = useTheme()
+  const mounted = useSyncExternalStore(emptySubscribe, () => true, () => false)
+  const isLight = mounted && resolvedTheme === 'light'
+
+  return (
+    <div
+      className="flex h-11 items-center gap-1.5 rounded-lg border border-zinc-800 bg-zinc-900/60 px-2.5"
+      title={isLight ? 'Theme: light — flip left for dark' : 'Theme: dark — flip right for light'}
+    >
+      <Moon className="size-3.5 shrink-0 text-zinc-500" aria-hidden />
+      <Switch
+        checked={isLight}
+        onCheckedChange={(v) => setTheme(v ? 'light' : 'dark')}
+        aria-label={isLight ? 'Switch to dark theme' : 'Switch to light theme'}
+        className="data-[state=checked]:bg-emerald-400 data-[state=unchecked]:bg-zinc-600"
+      />
+      <Sun className="size-3.5 shrink-0 text-zinc-500" aria-hidden />
+    </div>
+  )
+}
+
 export function AppHeader() {
   return (
     <header className="sticky top-0 z-40 border-b border-zinc-800/80 bg-zinc-950/80 backdrop-blur supports-[backdrop-filter]:bg-zinc-950/60">
@@ -147,7 +180,7 @@ export function AppHeader() {
         {/* logo */}
         <div className="order-1 flex items-center gap-2.5">
           <div className="grid size-9 place-items-center rounded-lg bg-emerald-400 shadow-[0_0_16px_rgba(52,211,153,0.35)]">
-            <AudioWaveform className="size-5 text-zinc-950" aria-hidden />
+            <AudioWaveform className="size-5 text-emerald-950" aria-hidden />
           </div>
           <div>
             <h1 className="text-base font-bold leading-none tracking-wide">{APP_SHORT}</h1>
@@ -162,13 +195,14 @@ export function AppHeader() {
           <SourceControls />
         </div>
 
-        {/* BPM readout + beat indicator + Set Beat — always paired, always visible */}
+        {/* theme switch + BPM readout + beat indicator + Set Beat — always visible */}
         <div className="order-2 ml-auto flex items-center gap-2.5 md:order-3 sm:gap-3">
+          <ThemeToggle />
           <BpmReadout />
           <BeatDot size={44} />
           <Button
             onClick={tapBeat}
-            className="h-11 gap-1.5 bg-emerald-400 px-3 font-semibold text-zinc-950 hover:bg-emerald-300 sm:px-4"
+            className="h-11 gap-1.5 bg-emerald-400 px-3 font-semibold text-emerald-950 hover:bg-emerald-300 sm:px-4"
             title="Tap to set the tempo (or press Space)"
           >
             <Timer className="size-4" />

src/components/ava/help-panel.tsx

@@ -65,7 +65,7 @@ function HelpTable({ rows, mono = true }: { rows: [string, string][]; mono?: boo
         {rows.map(([name, desc]) => (
           <tr key={name} className="border-b border-zinc-800/60 last:border-0 align-top">
             <td
-              className={`py-1 pr-3 whitespace-nowrap text-emerald-300/90 ${mono ? 'font-mono text-[11px]' : 'text-xs'}`}
+              className={`py-1 pr-3 whitespace-nowrap text-emerald-400/90 ${mono ? 'font-mono text-[11px]' : 'text-xs'}`}
             >
               {name}
             </td>
@@ -93,15 +93,15 @@ export function HelpPanel() {
         <ol className="list-inside list-decimal space-y-1 text-[11px] leading-relaxed text-zinc-400">
           <li>Write header keys (name, mode, blend, persist, linewidth) at the top.</li>
           <li>
-            Put setup code in <span className="font-mono text-emerald-300/90">[init]</span>, per-frame code in{' '}
+            Put setup code in <span className="font-mono text-emerald-400/90">[init]</span>, per-frame code in{' '}
-            <span className="font-mono text-emerald-300/90">[frame]</span>, reactions in{' '}
+            <span className="font-mono text-emerald-400/90">[frame]</span>, reactions in{' '}
-            <span className="font-mono text-emerald-300/90">[beat]</span>, and the geometry in{' '}
+            <span className="font-mono text-emerald-400/90">[beat]</span>, and the geometry in{' '}
-            <span className="font-mono text-emerald-300/90">[point]</span>.
+            <span className="font-mono text-emerald-400/90">[point]</span>.
           </li>
           <li>
-            Set <span className="font-mono text-emerald-300/90">n</span> (point count) in [init], drive it with{' '}
+            Set <span className="font-mono text-emerald-400/90">n</span> (point count) in [init], drive it with{' '}
-            <span className="font-mono text-emerald-300/90">bass</span>,{' '}
+            <span className="font-mono text-emerald-400/90">bass</span>,{' '}
-            <span className="font-mono text-emerald-300/90">beat</span> and <span className="font-mono text-emerald-300/90">v</span>.
+            <span className="font-mono text-emerald-400/90">beat</span> and <span className="font-mono text-emerald-400/90">v</span>.
           </li>
           <li>Hit Apply ▶ — errors are flagged next to the exact line.</li>
         </ol>
@@ -118,15 +118,15 @@ export function HelpPanel() {
       <HelpSection title="Functions">
         <HelpTable rows={FUNCS} />
         <p className="mt-2 text-[11px] text-zinc-500">
-          Constants: <span className="font-mono text-emerald-300/90">pi tau e</span>
+          Constants: <span className="font-mono text-emerald-400/90">pi tau e</span>
         </p>
       </HelpSection>
 
       <HelpSection title="Operators">
         <p className="font-mono text-[11px] leading-relaxed text-zinc-400">
           + - * / % ^ &nbsp;(power) &nbsp;·&nbsp; == != &lt; &lt;= &gt; &gt;= &nbsp;·&nbsp; &amp;&amp; || ! &nbsp;·&nbsp;
-          ternary <span className="text-emerald-300/90">c ? a : b</span> &nbsp;·&nbsp; assignment{' '}
+          ternary <span className="text-emerald-400/90">c ? a : b</span> &nbsp;·&nbsp; assignment{' '}
-          <span className="text-emerald-300/90">=</span> (works inside if() and ternary branches)
+          <span className="text-emerald-400/90">=</span> (works inside if() and ternary branches)
         </p>
         <p className="mt-1.5 text-[11px] leading-relaxed text-zinc-500">
           Statements are separated by newlines or semicolons. Comments start with <span className="font-mono">{'#'}</span> or{' '}
@@ -137,7 +137,7 @@ export function HelpPanel() {
       <HelpSection title="Example formulas">
         <div className="space-y-1.5">
           {EXAMPLES.map(([code, note]) => (
-            <div key={code} className="flex flex-col gap-0.5 rounded border border-zinc-800/70 bg-black/40 px-2.5 py-1.5">
+            <div key={code} className="flex flex-col gap-0.5 rounded border border-zinc-800/70 bg-zinc-800/40 px-2.5 py-1.5">
               <code className="font-mono text-[11px] text-zinc-200">{code}</code>
               <span className="text-[10px] text-zinc-500">{note}</span>
             </div>
@@ -149,7 +149,7 @@ export function HelpPanel() {
         <p className="mb-2 text-[11px] leading-relaxed text-zinc-400">
           A plain-text file: optional header keys before the first section, then any of the four sections in any order.
         </p>
-        <pre className="overflow-x-auto rounded border border-zinc-800/70 bg-black/40 p-2.5 font-mono text-[11px] leading-relaxed text-zinc-300">
+        <pre className="overflow-x-auto rounded border border-zinc-800/70 bg-zinc-800/40 p-2.5 font-mono text-[11px] leading-relaxed text-zinc-300">
 {`# header keys
 name: My Visualization
 author: you

src/components/ava/link-dialog.tsx

@@ -150,7 +150,7 @@ function LinkDialogBody() {
         <Button
           type="submit"
           disabled={busy || !url.trim()}
-          className="shrink-0 gap-1.5 bg-emerald-400 font-semibold text-zinc-950 hover:bg-emerald-300"
+          className="shrink-0 gap-1.5 bg-emerald-400 font-semibold text-emerald-950 hover:bg-emerald-300"
         >
           {busy ? <Loader2 className="size-4 animate-spin" aria-hidden /> : null}
           {busy ? 'Loading' : 'Load'}

src/components/ava/native-tab.tsx

@@ -21,14 +21,14 @@ export function NativeTab() {
       <a
         href="/api/rust-scaffold"
         download
-        className="flex h-12 items-center justify-center gap-2 rounded-xl bg-emerald-400 font-semibold text-zinc-950 shadow-[0_0_20px_rgba(52,211,153,0.25)] transition-colors hover:bg-emerald-300"
+        className="flex h-12 items-center justify-center gap-2 rounded-xl bg-emerald-400 font-semibold text-emerald-950 shadow-[0_0_20px_rgba(52,211,153,0.25)] transition-colors hover:bg-emerald-300"
       >
         <Download className="size-4" />
         Download Rust Scaffold (.zip)
       </a>
       <p className="text-[11px] text-zinc-500">{BLUEPRINT.downloadNote}</p>
 
-      <blockquote className="rounded-lg border border-emerald-400/20 bg-emerald-400/5 p-3 text-[11px] leading-relaxed text-emerald-200/80">
+      <blockquote className="rounded-lg border border-emerald-400/20 bg-emerald-400/5 p-3 text-[11px] leading-relaxed text-emerald-700/90 dark:text-emerald-200/80">
         The <span className="font-mono">.ava</span> scripts you write here run on both the web edition and the native
         Rust engine — the script language is identical.
       </blockquote>

src/components/ava/presets-tab.tsx

@@ -418,7 +418,7 @@ function NameDialog({
             Cancel
           </Button>
           <Button
-            className="h-9 gap-1.5 bg-emerald-400 text-zinc-950 hover:bg-emerald-300"
+            className="h-9 gap-1.5 bg-emerald-400 text-emerald-950 hover:bg-emerald-300"
             disabled={busy}
             onClick={() => void submit()}
           >
@@ -812,7 +812,7 @@ export function PresetsTab() {
                 <Button
                   size="sm"
                   onClick={() => loadPreset(selectedPreset)}
-                  className="h-9 w-full gap-1.5 bg-emerald-400 text-zinc-950 hover:bg-emerald-300"
+                  className="h-9 w-full gap-1.5 bg-emerald-400 text-emerald-950 hover:bg-emerald-300"
                   title="Run this preset on the engine and open it in the editor"
                 >
                   <Play className="size-3.5" /> Load Preset
@@ -962,7 +962,7 @@ export function PresetsTab() {
                 checked={randomize}
                 onCheckedChange={(v) => useAvaStore.getState().setRandomize(v === true)}
                 aria-label="Randomize presets"
-                className="size-4 data-[state=checked]:border-emerald-400 data-[state=checked]:bg-emerald-400 data-[state=checked]:text-zinc-950"
+                className="size-4 data-[state=checked]:border-emerald-400 data-[state=checked]:bg-emerald-400 data-[state=checked]:text-emerald-950"
               />
               <Label htmlFor="ava-randomize" className="cursor-pointer text-xs text-zinc-300">
                 Randomize

src/components/ava/script-tab.tsx

@@ -278,7 +278,7 @@ export function ScriptTab() {
         <Button
           size="sm"
           onClick={apply}
-          className="h-9 gap-1.5 bg-emerald-400 px-3 text-zinc-950 hover:bg-emerald-300"
+          className="h-9 gap-1.5 bg-emerald-400 px-3 text-emerald-950 hover:bg-emerald-300"
           title="Validate and apply to the engine"
         >
           <Play className="size-3.5" /> Apply
@@ -288,7 +288,7 @@ export function ScriptTab() {
             size="sm"
             onClick={() => void saveToTarget()}
             disabled={saving}
-            className="h-9 gap-1.5 bg-emerald-400 px-3 text-zinc-950 hover:bg-emerald-300"
+            className="h-9 gap-1.5 bg-emerald-400 px-3 text-emerald-950 hover:bg-emerald-300"
             title={`Overwrite "${editTarget.name}" with the current editor script`}
           >
             <Save className="size-3.5" /> Save
@@ -440,7 +440,7 @@ export function ScriptTab() {
               Cancel
             </Button>
             <Button
-              className="h-9 gap-1.5 bg-emerald-400 text-zinc-950 hover:bg-emerald-300"
+              className="h-9 gap-1.5 bg-emerald-400 text-emerald-950 hover:bg-emerald-300"
               disabled={saveAsBusy}
               onClick={() => void saveAsCopy()}
             >

src/components/ava/visual-stage.tsx

@@ -108,7 +108,7 @@ export function VisualStage({ className }: { className?: string }) {
               <div className="grid gap-2.5">
                 <Button
                   onClick={() => void startDemo()}
-                  className="h-12 gap-2 bg-emerald-400 text-zinc-950 hover:bg-emerald-300"
+                  className="h-12 gap-2 bg-emerald-400 text-emerald-950 hover:bg-emerald-300"
                 >
                   <Disc3 className="size-4" /> Demo Track
                 </Button>

src/lib/version.ts

@@ -7,6 +7,8 @@
 // (v6.0 = rename to Open Visualization Engine + version indicator).
 //
 // History:
+//   6.3 — light/dark theme tick switch in the header (white theme via .light
+//         palette remap; per-visitor, persisted by next-themes)
 //   6.2 — security hardening: read-only embedded library (server refuses all
 //         writes) + per-visitor "user created" presets stored in the browser
 //   6.1 — preset library quality pass: every embedded stand-in is now a UNIQUE
@@ -17,4 +19,4 @@
 
 export const APP_NAME = 'Open Visualization Engine'
 export const APP_SHORT = 'OVE'
-export const APP_VERSION = '6.2'
+export const APP_VERSION = '6.3'

worklog.md

@@ -1030,3 +1030,207 @@ Stage Summary:
   Settings (band/beat/default script) are per-browser now.
 - /api/presets/export intentionally kept: read-only maintainer backup of the
   embedded library.
+
+---
+Task ID: 16-d
+Agent: general-purpose (E2E verifier)
+Task: v6.3 theme tick switch — end-to-end verification
+
+Work Log:
+- Read worklog Task 15 + 15-11 for context; read v6.3 sources read-only
+  (header.tsx theme switch, globals.css .light remap, version.ts 6.3,
+  help-panel/script-tab patches).
+- agent-browser desktop session 1440×900 at http://localhost:3000: cleared
+  localStorage, fresh load, dark-default + theme-pill geometry checks,
+  toggle to light, full tab walk (Presets/Script/Detect/Beat/Native +
+  Help panel), embedded preset select + Copy-to-my-presets panel, Create
+  Preset dialog in light AND dark, "Theme Test" create/delete toasts +
+  cleanup, persistence reloads (light→reload, dark→reload), rapid 5×
+  toggling, demo-track run for live VU meters + visualization, mobile
+  390×844 light + dark (scrollWidth, stacking, footer flush, pill
+  tappable), console + page-error checks after every phase.
+- ENVIRONMENT INCIDENT (diagnosed + documented, no source edits): for the
+  first ~12 min of the session the dev server served a STALE CSS chunk
+  ([root-of-the-server]__0f0ba101._.css, emitted 07:50:04, 158,839→
+  158,921 B) that contained the v6.3 `color-scheme: dark` addition but
+  NOT the `.light { --color-* }` block — so toggling set html.light +
+  checked state but the page stayed visually dark. Control test: the
+  current src/app/globals.css compiled through the project's own
+  @tailwindcss/postcss 4.1.18 (+ lightningcss 1.30.2) DOES emit .light —
+  source correct, server module graph stale (final 07:48:50 save never
+  propagated; same delayed-HMR class as Task 15-11 issue 1). A single
+  content-preserving `touch` of globals.css (md5 unchanged before/after:
+  2aa8062c…) triggered Turbopack's delayed rebuild at 08:04:59 → chunk
+  158,941 B now contains .light. All light-theme verdicts below were
+  re-verified against the real served CSS after that point (earlier
+  interim checks used a byte-identical injected copy of the .light block,
+  same results).
+- VLM (z-ai vision) cross-checks on 13 screenshots (light full page,
+  presets/script/help, dark default/toggled/script, dialog, toast, mobile
+  light/dark, stale-state evidence, live visualization).
+- Screenshots: tool-results/e2e-v63/ (37 files, 01…34).
+- Final state: browser closed; localStorage 'theme' key removed (fresh
+  dark default), ove.userPresets.v1 = {"v":1,"folders":[],"presets":[]};
+  server library untouched; scratch test dir removed; source files
+  unmodified (git status = builder's v6.3 changes only).
+
+Results:
+- 1: PASS — fresh load (no 'theme' key): html.dark, body bg zinc-950
+  (#09090b), text zinc-100 (#f4f4f5), footer "version 6.3 | engine ok",
+  title "OVE — Open Visualization Engine (v6.3)".
+- 2: PASS — pill Moon(x1135)|Switch(x1155,w32,unchecked,aria-label
+  "Switch to light theme")|Sun(x1193); BPM number box starts x1230 —
+  pill immediately LEFT of the emerald BPM readout, 6 px gaps, no
+  overlap/shift (VLM-confirmed).
+- 3: PASS — dark regression clean: tree 95 presets/7 folders, lock badges
+  on embedded folders, script editor #09090b bg + light mono text, Set
+  Beat bg #34d399 + emerald-950 text (7.8:1), no white boxes (VLM:
+  "no regressions").
+- 4: PASS — click flips switch right (aria-checked=true, knob translates,
+  track #059669 + white knob in light) and the ENTIRE chrome flips white:
+  body #ffffff/#18181b, wrapper zinc-950→white, panels/borders light
+  (before/after: 01→17/18/19). See env incident above for the stale-CSS
+  window at session start.
+- 5: PASS — light readability across ALL tabs: header (logo, source
+  buttons, demo slider, BPM readout deep green #059669, Set Beat
+  #059669/#022c22, pill); Presets (rows #27272a on white, ≈ badges
+  rose-400 #e11d48 on /10 tint — 60 in Amp Picks, counts 95/66/9/15/5/0,
+  note #71717a, Load Preset #059669 bg, Copy white/#18181b/#d4d4d8);
+  Script (editor white bg, #27272a mono, gutter #8b8b93, status
+  "✔ Compiled OK" #059669); Detect (labels #52525b/#71717a, live VU bars
+  #059669/#e11d48/#b45309 on light tracks with demo running); Beat
+  (SET BEAT #059669/#022c22, labels readable); Native (headings #27272a,
+  body #52525b, .ava token deep green); Help (code blocks #e4e4e7/40 bg +
+  #27272a text — v6.3 patch works); footer readable + "version 6.3";
+  VisualStage canvas stays BLACK (rgb(0,0,0)) with light border #e4e4e7.
+  VLM: no unreadable/low-contrast text, no dark leftovers.
+- 6: PASS — Create Preset dialog light: card #ffffff, heading/input text
+  #18181b, input bg #fafafa; same dialog dark: card #0a0a0a, input
+  white/4.5% bg + near-white text.
+- 7: PASS (with notes) — no white-on-white/black-on-black anywhere; body
+  text ≥4.6:1; accents clearly readable. Notes: emerald buttons ≈4.0:1,
+  help-panel emerald-300/90 tokens ≈2.5:1 (see Issues 2-3).
+- 8: PASS — light toast "Preset created — "Theme Test" created in this
+  browser" (white card via --popover, #18181b text); delete confirm +
+  "Preset deleted" toast same styling; localStorage cleaned afterwards.
+- 9: PASS — light + reload: html.light, switch checked, theme=light,
+  page renders white (with live CSS); toggle dark + reload: html.dark,
+  unchecked, theme=dark, page dark.
+- 10: PASS — 5 rapid clicks: end state light, html class/theme key/
+  switch in sync at every step, zero errors, no stuck states.
+- 11: PASS — console + page errors zero across the whole session (both
+  themes, ~10 loads, dialogs, toasts, toggling, mobile): only React
+  DevTools info, "[HMR] connected", "[Fast Refresh] rebuilding/done".
+- 12: PASS — mobile 390×844 light: scrollWidth 390 = clientWidth 390
+  (no horizontal scroll), theme pill visible + tappable (wrapped into
+  header row 1, no overlap), tree + panel stack (358 px), footer flush at
+  document bottom (footerBottom 1313 = docHeight 1313; below fold on
+  first paint — same as accepted in Task 15-11).
+- 13: PASS — mobile dark: same checks pass (no h-scroll, pill visible,
+  bg #09090b/text #f4f4f5).
+- 14: PASS — dev.log session window (lines 529-722): only GET 200s +
+  prisma:query; zero error/warn/exception lines. (Pre-session lines
+  443-510 contain builder-era transient errors — see Issue 5.)
+
+Issues found:
+- 1 (environmental, resolved mid-session, NO app bug): dev server served
+  a stale Turbopack CSS chunk missing the entire .light palette remap for
+  ~12 min (07:52-08:05) — theme toggle flipped state (html.light) but the
+  page stayed dark, and the switch track rendered white-on-dark. Root
+  cause: the final 07:48:50 globals.css save never propagated through
+  HMR (delayed/broken watcher state; 4 runtime-error full reloads from
+  the builder's mid-edit saves at 07:44-07:50 left the graph stale).
+  Content-preserving touch + delayed rebuild fixed it at 08:04:59.
+  Control compile of the current source through the project's own
+  toolchain emits .light correctly. Recommendation: RESTART the dev
+  server (or at least verify the served chunk contains .light) before
+  the next session and before any VPS deploy of v6.3 — a stale build
+  would ship a theme switch that visually does nothing.
+- 2 (minor, light-mode contrast): help-panel inline code tokens
+  (text-emerald-300/90 — e.g. [init], [frame], variable names in the
+  reference tables) resolve to #10b981 on white ≈ 2.5:1 — below WCAG AA
+  4.5:1 and even below 3:1; readable but washed-out. Consider deepening
+  the emerald-300 remap (e.g. to #059669) or switching these tokens to
+  emerald-400 in light mode.
+- 3 (minor, light-mode contrast): emerald action buttons (header Set
+  Beat, Load Preset, Beat-tab SET BEAT) are text-emerald-950 #022c22 on
+  bg-emerald-400 #059669 ≈ 4.0:1 — just under AA 4.5:1 for small text
+  (passes 3:1 large-text; dark-mode equivalent is 7.8:1). Borderline,
+  likely acceptable for bold button labels.
+- 4 (observation): script editor line-number gutter (text-zinc-600 →
+  #8b8b93 on white) ≈ 3.4:1 — auxiliary text, acceptable but dimmer
+  than body text.
+- 5 (observation, pre-existing): dev.log lines 443-510 (before this
+  session) contain 4× "⚠ Fast Refresh had to perform a full reload due
+  to a runtime error" plus transient "⨯ ReferenceError: useRef is not
+  defined at SourceControls (header.tsx:63)" GET / 500s — artifacts of
+  the v6.3 builder's mid-edit saves. Current source imports useRef
+  correctly; nothing recurred in this session.
+- 6 (observation): on mobile 390 px the theme pill wraps into header row
+  1 (next to the logo) rather than sitting beside the BPM readout as on
+  desktop — clean flex-wrap, no overlap; consistent with the header's
+  responsive design.
+- 7 (note): "Set Beat button … very dark green text" expectation —
+  confirmed #022c22 (emerald-950) on #059669; and the checklist's "help
+  headings readable green": Help section headings are zinc-400 gray by
+  design (unchanged from dark theme); the GREEN elements in Help are the
+  inline code tokens (see Issue 2).
+
+---
+Task ID: 16
+Agent: main (Z.ai Code)
+Task: v6.3 — light/dark theme tick switch in the header (user request: switch
+top-right, left of the BPM indicator; flip right = white theme).
+
+Work Log:
+- src/app/globals.css — light theme via palette REMAP under `.light` (the app
+  is styled with raw zinc/emerald/rose/amber utilities, so remapping those CSS
+  variables flips the whole chrome): zinc ramp inverted (950→#ffffff page,
+  100→#18181b text, 900→#fafafa panels, 800→#e4e4e7 hover/borders, 700→#d4d4d8
+  borders, 600→#8b8b93 hints); accents deepened one step for white
+  backgrounds (emerald-400→#059669, emerald-300→#10b981 so hovers still
+  lighten; rose-300/400, amber-300/400 likewise). color-scheme light/dark set
+  on .light/.dark. Unlayered class rules beat Tailwind's @layer theme, so the
+  remap wins with opacity variants too (color-mix keeps var references).
+- src/app/layout.tsx — ThemeProvider (next-themes, attribute="class",
+  defaultTheme="dark", enableSystem=false, disableTransitionOnChange);
+  hardcoded <html class="dark"> removed (next-themes sets it pre-paint).
+- src/components/ava/header.tsx — ThemeToggle pill (Moon | Switch | Sun,
+  h-11 matching the other header controls) in the right cluster as the first
+  child — immediately LEFT of the BPM readout. Left/unchecked = dark (default),
+  flipped right/checked = white theme. Mount guard via useSyncExternalStore
+  (lint-clean replacement for the setState-in-effect pattern); switch track:
+  zinc-600 unchecked / emerald-400 checked, default thumb colors verified for
+  all four theme×state combos.
+- Contrast patches: text-zinc-950 → text-emerald-950 on all emerald CTAs (12
+  spots, 7 files — near-black green on emerald in both themes); help-panel
+  code blocks bg-black/40 → bg-zinc-800/40; help-panel inline tokens
+  text-emerald-300/90 → text-emerald-400/90 (light: #059669/90 ≈ 4.3:1,
+  was 2.5:1); native-tab blockquote text-emerald-200/80 →
+  text-emerald-700/90 dark:text-emerald-200/80.
+- The visualization canvas intentionally KEEPS its black stage in light mode
+  (the "screen"); only the chrome flips.
+- src/lib/version.ts → 6.3 (+history line). Fixed a mid-edit useRef import
+  regression (500s during editing, resolved).
+- Dev-server ops: killed my pkill'd instance, restarted with double-fork
+  detach (( setsid bun run dev & )) — survives across tool sessions; verified
+  the served CSS chunk now contains the .light palette (was a stale Turbopack
+  chunk for ~12 min during verification — subagent diagnosed; restart fixed).
+- VERIFIED (subagent E2E 16-d, 14/14 PASS + my own post-restart smoke test):
+  dark default (html.dark, no theme key); toggle left of BPM (switch right
+  1187 < BPM left 1230), flips to html.light with white body/dark text; ALL
+  tabs readable in light (header, presets tree + locks + ≈ badges, white
+  script editor, detect VU bars, beat, native, help code blocks, footer);
+  dialogs + toasts themed correctly; Set Beat #059669 bg + #022c22 text;
+  VisualStage stays black with light border; persistence across reload both
+  ways; rapid 5× toggling stable; zero console/page errors; mobile 390×844
+  both themes no horizontal scroll, footer flush at document bottom.
+- Committed as "v6.3 — light/dark theme tick switch in the header".
+
+Stage Summary:
+- Theme = per-visitor preference (localStorage via next-themes), default
+  dark — matches the club aesthetic; light mode is a clean white studio look
+  with deepened emerald/rose/amber accents for contrast.
+- Implementation note for future styling: new UI should keep using the
+  zinc/emerald utilities (not raw hex) so both themes keep working; anything
+  on the emerald buttons should use text-emerald-950.