diff --git a/packages/opencode/src/cli/cmd/tui/plugin/internal.ts b/packages/opencode/src/cli/cmd/tui/plugin/internal.ts
index 2ba8e745b5..7fe348ad08 100644
--- a/packages/opencode/src/cli/cmd/tui/plugin/internal.ts
+++ b/packages/opencode/src/cli/cmd/tui/plugin/internal.ts
@@ -21,7 +21,7 @@ export type InternalTuiPlugin = Omit<TuiPluginModule, "id"> & {
 }
 
 export function internalTuiPlugins(
-  flags: Pick<RuntimeFlags.Info, "diffViewer" | "experimentalEventSystem">,
+  flags: Pick<RuntimeFlags.Info, "experimentalEventSystem">,
 ): InternalTuiPlugin[] {
   return [
     HomeFooter,
@@ -35,7 +35,7 @@ export function internalTuiPlugins(
     Notifications,
     PluginManager,
     WhichKey,
-    ...(flags.diffViewer ? [DiffViewer] : []),
+    DiffViewer,
     ...(flags.experimentalEventSystem ? [SessionV2Debug] : []),
   ]
 }
diff --git a/packages/opencode/src/effect/runtime-flags.ts b/packages/opencode/src/effect/runtime-flags.ts
index 55b453c011..8d9d1fd97a 100644
--- a/packages/opencode/src/effect/runtime-flags.ts
+++ b/packages/opencode/src/effect/runtime-flags.ts
@@ -15,7 +15,6 @@ export class Service extends ConfigService.Service<Service>()("@opencode/Runtime
   autoShare: bool("OPENCODE_AUTO_SHARE"),
   pure: bool("OPENCODE_PURE"),
   disableDefaultPlugins: bool("OPENCODE_DISABLE_DEFAULT_PLUGINS"),
-  diffViewer: bool("OPENCODE_DIFF_VIEWER"),
   disableChannelDb: bool("OPENCODE_DISABLE_CHANNEL_DB"),
   disableEmbeddedWebUi: bool("OPENCODE_DISABLE_EMBEDDED_WEB_UI"),
   disableExternalSkills: bool("OPENCODE_DISABLE_EXTERNAL_SKILLS"),