diff --git a/packages/opencode/src/cli/cmd/tui/app.tsx b/packages/opencode/src/cli/cmd/tui/app.tsx
index dc052c4d2e..549c7c34a7 100644
--- a/packages/opencode/src/cli/cmd/tui/app.tsx
+++ b/packages/opencode/src/cli/cmd/tui/app.tsx
@@ -212,7 +212,7 @@ function App() {
   const command = useCommandDialog()
   const sdk = useSDK()
   const toast = useToast()
-  const { theme, mode, setMode } = useTheme()
+  const { theme, mode, setMode, locked, lock, unlock } = useTheme()
   const sync = useSync()
   const exit = useExit()
   const promptRef = usePromptRef()
@@ -557,7 +557,7 @@ function App() {
       category: "System",
     },
     {
-      title: "Toggle appearance",
+      title: "Toggle Theme Mode",
       value: "theme.switch_mode",
       onSelect: (dialog) => {
         setMode(mode() === "dark" ? "light" : "dark")
@@ -565,6 +565,16 @@ function App() {
       },
       category: "System",
     },
+    {
+      title: locked() ? "Unlock Theme Mode" : "Lock Theme Mode",
+      value: "theme.mode.lock",
+      onSelect: (dialog) => {
+        if (locked()) unlock()
+        else lock()
+        dialog.clear()
+      },
+      category: "System",
+    },
     {
       title: "Help",
       value: "help.show",
diff --git a/packages/opencode/src/cli/cmd/tui/context/theme.tsx b/packages/opencode/src/cli/cmd/tui/context/theme.tsx
index d786e0b491..a3d268afd3 100644
--- a/packages/opencode/src/cli/cmd/tui/context/theme.tsx
+++ b/packages/opencode/src/cli/cmd/tui/context/theme.tsx
@@ -283,9 +283,15 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
     const renderer = useRenderer()
     const config = useTuiConfig()
     const kv = useKV()
+    const pick = (value: unknown) => {
+      if (value === "dark" || value === "light") return value
+      return
+    }
+    const lock = pick(kv.get("theme_mode_lock"))
     const [store, setStore] = createStore({
       themes: DEFAULT_THEMES,
-      mode: kv.get("theme_mode", props.mode),
+      mode: lock ?? pick(kv.get("theme_mode", props.mode)) ?? props.mode,
+      lock,
       active: (config.theme ?? kv.get("theme", "opencode")) as string,
       ready: false,
     })
@@ -345,16 +351,30 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
         })
     }
 
-    function update(mode: "dark" | "light") {
+    function apply(mode: "dark" | "light") {
+      kv.set("theme_mode", mode)
       if (store.mode === mode) return
       setStore("mode", mode)
-      kv.set("theme_mode", mode)
       renderer.clearPaletteCache()
       resolveSystemTheme(mode)
     }
 
+    function pin(mode: "dark" | "light" = store.mode) {
+      setStore("lock", mode)
+      kv.set("theme_mode_lock", mode)
+      apply(mode)
+    }
+
+    function free() {
+      setStore("lock", undefined)
+      kv.set("theme_mode_lock", undefined)
+      const mode = renderer.themeMode
+      if (mode) apply(mode)
+    }
+
     const handle = (mode: "dark" | "light") => {
-      update(mode)
+      if (store.lock) return
+      apply(mode)
     }
     renderer.on(CliRenderEvents.THEME_MODE, handle)
     onCleanup(() => {
@@ -390,8 +410,17 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
       mode() {
         return store.mode
       },
+      locked() {
+        return store.lock !== undefined
+      },
+      lock() {
+        pin(store.mode)
+      },
+      unlock() {
+        free()
+      },
       setMode(mode: "dark" | "light") {
-        update(mode)
+        pin(mode)
       },
       set(theme: string) {
         setStore("active", theme)