diff --git a/admin/src/components/shell/PluginRail.vue b/admin/src/components/shell/PluginRail.vue
index 8cb36fc..d859f7d 100644
--- a/admin/src/components/shell/PluginRail.vue
+++ b/admin/src/components/shell/PluginRail.vue
@@ -26,10 +26,14 @@ const { collapsed, narrow, setCollapsed } = useSidebar()
 
 // The top button cycles the theme (system, light, dark) and names the
 // current choice; the icon shows it.
-const themeIcon = computed(() => ({ system: SunMoon, light: Sun, dark: Moon })[themeChoice.value])
-const themeLabel = computed(() =>
-  t('backend::lang.nav.theme', { mode: t(`backend::lang.nav.theme_${themeChoice.value}`) }),
-)
+// Full key literals, so the phrasebook SPA-key check sees every key.
+const themeModes = {
+  system: { icon: SunMoon, key: 'backend::lang.nav.theme_system' },
+  light: { icon: Sun, key: 'backend::lang.nav.theme_light' },
+  dark: { icon: Moon, key: 'backend::lang.nav.theme_dark' },
+} as const
+const themeIcon = computed(() => themeModes[themeChoice.value].icon)
+const themeLabel = computed(() => t('backend::lang.nav.theme', { mode: t(themeModes[themeChoice.value].key) }))
 
 const active = computed(() => activeEntry(String(route.params.vendor ?? ''), String(route.params.plugin ?? '')))