Introduce a light/dark MODE axis orthogonal to the existing accent
themes. Neutral surface tokens now live in html[data-mode="light|dark"]
blocks; accent tokens (--primary*, --ring, --chart-1, --sidebar-primary*)
stay in html[data-theme] blocks, so any accent works in either mode.
- globals.css: split neutrals (mode) from accent (theme); add light
palette; dark values unchanged (dark stays the default).
- lib/themes.ts: Mode type, DEFAULT_MODE=dark, MODE_STORAGE_KEY, isMode.
- use-theme.tsx: provider owns mode/setMode/toggleMode + cross-tab sync.
- layout.tsx: boot script applies persisted mode before first paint
(no flash); colorScheme "dark light".
- mode-toggle.tsx (header sun/moon) + themed-toaster.tsx (mode-aware).
- appearance-panel.tsx: light/dark control + updated copy.
- Tokenize hardcoded neutral colors (slate/white/gray) -> semantic
tokens across the app so every surface flips with mode. Flow canvas
and message-bubble timestamps made mode-aware too.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>