WIP jordan

app/composables/useAppTheme.ts

@@ -0,0 +1,46 @@
+import type { AppThemeId } from '~/types/app-theme'
+import { APP_THEME_OPTIONS } from '~/types/app-theme'
+
+const STORAGE_KEY = 'policy-ui.theme.v1'
+
+const VALID: AppThemeId[] = ['light', 'purple', 'dark', 'dark-purple']
+
+function isThemeId(x: string): x is AppThemeId {
+  return (VALID as string[]).includes(x)
+}
+
+export function useAppTheme() {
+  const themeId = ref<AppThemeId>('light')
+
+  function applyTheme(id: AppThemeId) {
+    themeId.value = id
+    if (import.meta.client) {
+      document.documentElement.setAttribute('data-theme', id)
+      try {
+        localStorage.setItem(STORAGE_KEY, id)
+      } catch {
+        /* ignore */
+      }
+    }
+  }
+
+  onMounted(() => {
+    if (!import.meta.client) return
+    try {
+      const raw = localStorage.getItem(STORAGE_KEY)
+      if (raw && isThemeId(raw)) {
+        applyTheme(raw)
+        return
+      }
+    } catch {
+      /* ignore */
+    }
+    applyTheme('light')
+  })
+
+  return {
+    themeId,
+    themeOptions: APP_THEME_OPTIONS,
+    applyTheme
+  }
+}