feat: optimize web ui

packages/web/src/lib/theme.tsx

@@ -0,0 +1,64 @@
+import { createContext, useContext, useState, useEffect, type ReactNode } from 'react';
+
+type Theme = 'light' | 'dark' | 'system';
+
+type ThemeContextType = {
+  theme: Theme;
+  resolved: 'light' | 'dark';
+  setTheme: (t: Theme) => void;
+};
+
+const ThemeContext = createContext<ThemeContextType | null>(null);
+
+function getSystemTheme(): 'light' | 'dark' {
+  return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
+}
+
+function applyTheme(theme: Theme) {
+  const resolved = theme === 'system' ? getSystemTheme() : theme;
+  if (theme === 'system') {
+    document.documentElement.removeAttribute('data-theme');
+  } else {
+    document.documentElement.setAttribute('data-theme', theme);
+  }
+  return resolved;
+}
+
+export function ThemeProvider({ children }: { children: ReactNode }) {
+  const [theme, setThemeState] = useState<Theme>(() => {
+    return (localStorage.getItem('agent-fox-theme') as Theme) || 'system';
+  });
+  const [resolved, setResolved] = useState<'light' | 'dark'>(() => applyTheme(
+    (localStorage.getItem('agent-fox-theme') as Theme) || 'system'
+  ));
+
+  const setTheme = (t: Theme) => {
+    localStorage.setItem('agent-fox-theme', t);
+    setThemeState(t);
+    setResolved(applyTheme(t));
+  };
+
+  useEffect(() => {
+    setResolved(applyTheme(theme));
+  }, [theme]);
+
+  useEffect(() => {
+    if (theme !== 'system') return;
+    const mq = window.matchMedia('(prefers-color-scheme: dark)');
+    const handler = () => setResolved(applyTheme('system'));
+    mq.addEventListener('change', handler);
+    return () => mq.removeEventListener('change', handler);
+  }, [theme]);
+
+  return (
+    <ThemeContext.Provider value={{ theme, resolved, setTheme }}>
+      {children}
+    </ThemeContext.Provider>
+  );
+}
+
+export function useTheme() {
+  const ctx = useContext(ThemeContext);
+  if (!ctx) throw new Error('useTheme must be used within ThemeProvider');
+  return ctx;
+}