[dev-tools] add feature flag for new panel ui

Author: devjiwonchoi

packages/next/src/build/define-env.ts

@@ -289,6 +289,8 @@ export function getDefineEnv({
       : {}),
     'process.env.__NEXT_DEVTOOL_SEGMENT_EXPLORER':
       config.experimental.devtoolSegmentExplorer ?? false,
+    'process.env.__NEXT_DEVTOOL_NEW_PANEL_UI':
+      config.experimental.devtoolNewPanelUI ?? false,
     'process.env.__NEXT_TURBOPACK_PERSISTENT_CACHE':
       config.experimental.turbopackPersistentCaching ?? false,
   }

packages/next/src/server/config-schema.ts

@@ -500,6 +500,7 @@ export const configSchema: zod.ZodType<NextConfig> = z.lazy(() =>
           .optional(),
         globalNotFound: z.boolean().optional(),
         devtoolSegmentExplorer: z.boolean().optional(),
+        devtoolNewPanelUI: z.boolean().optional(),
       })
       .optional(),
     exportPathMap: z

packages/next/src/server/config-shared.ts

@@ -699,6 +699,11 @@ export interface ExperimentalConfig {
    * Enable segment viewer for the app directory in dev tool.
    */
   devtoolSegmentExplorer?: boolean
+
+  /**
+   * Enable new panel UI for the dev tool.
+   */
+  devtoolNewPanelUI?: boolean
 }
 
 export type ExportPathMap = {