diff --git a/packages/opencode/src/cli/cmd/tui/context/theme.tsx b/packages/opencode/src/cli/cmd/tui/context/theme.tsx
index 2320c08ccc6..9288efc720f 100644
--- a/packages/opencode/src/cli/cmd/tui/context/theme.tsx
+++ b/packages/opencode/src/cli/cmd/tui/context/theme.tsx
@@ -282,9 +282,16 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
   init: (props: { mode: "dark" | "light" }) => {
     const config = useTuiConfig()
     const kv = useKV()
+
+    function configMode(): "dark" | "light" | undefined {
+      const override = config.theme_mode
+      if (override === "light" || override === "dark") return override
+      return undefined
+    }
+
     const [store, setStore] = createStore({
       themes: DEFAULT_THEMES,
-      mode: kv.get("theme_mode", props.mode),
+      mode: configMode() ?? kv.get("theme_mode", props.mode),
       active: (config.theme ?? kv.get("theme", "opencode")) as string,
       ready: false,
     })
@@ -294,6 +301,11 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
       if (theme) setStore("active", theme)
     })
 
+    createEffect(() => {
+      const override = configMode()
+      if (override) setStore("mode", override)
+    })
+
     function init() {
       resolveSystemTheme()
       getCustomThemes()
diff --git a/packages/opencode/src/config/tui-schema.ts b/packages/opencode/src/config/tui-schema.ts
index f9068e3f01d..cf9b4fa4cc7 100644
--- a/packages/opencode/src/config/tui-schema.ts
+++ b/packages/opencode/src/config/tui-schema.ts
@@ -28,6 +28,12 @@ export const TuiInfo = z
   .object({
     $schema: z.string().optional(),
     theme: z.string().optional(),
+    theme_mode: z
+      .enum(["light", "dark", "system"])
+      .optional()
+      .describe(
+        "Override the detected terminal color scheme. Set to 'light' or 'dark' to force a mode, or 'system' to auto-detect from terminal.",
+      ),
     keybinds: KeybindOverride.optional(),
   })
   .extend(TuiOptions.shape)