feat(tui): initial impl of diff viewer (#28476)

packages/opencode/src/cli/cmd/tui/plugin/internal.ts

@@ -10,6 +10,7 @@ import PluginManager from "../feature-plugins/system/plugins"
 import Notifications from "../feature-plugins/system/notifications"
 import SessionV2Debug from "../feature-plugins/system/session-v2"
 import WhichKey from "../feature-plugins/system/which-key"
+import DiffViewer from "../feature-plugins/system/diff-viewer"
 import type { TuiPlugin, TuiPluginModule } from "@opencode-ai/plugin/tui"
 import type { RuntimeFlags } from "@/effect/runtime-flags"
 
@@ -19,7 +20,7 @@ export type InternalTuiPlugin = Omit<TuiPluginModule, "id"> & {
   enabled?: boolean
 }
 
-export function internalTuiPlugins(flags: Pick<RuntimeFlags.Info, "experimentalEventSystem">): InternalTuiPlugin[] {
+export function internalTuiPlugins(flags: Pick<RuntimeFlags.Info, "diffViewer" | "experimentalEventSystem">): InternalTuiPlugin[] {
   return [
     HomeFooter,
     HomeTips,
@@ -32,6 +33,7 @@ export function internalTuiPlugins(flags: Pick<RuntimeFlags.Info, "experimentalE
     Notifications,
     PluginManager,
     WhichKey,
+    ...(flags.diffViewer ? [DiffViewer] : []),
     ...(flags.experimentalEventSystem ? [SessionV2Debug] : []),
   ]
 }