add an experimental feature to enable a whole app module graph

Author: lukesandberg

crates/next-api/src/project.rs

@@ -785,7 +785,12 @@ impl Project {
 
     #[turbo_tasks::function]
     pub(super) async fn per_page_module_graph(&self) -> Result<Vc<bool>> {
-        Ok(Vc::cell(*self.mode.await? == NextMode::Development))
+        Ok(Vc::cell(
+            !*self
+                .next_config
+                .turbo_use_whole_app_module_graph(*self.mode)
+                .await?,
+        ))
     }
 
     #[turbo_tasks::function]

crates/next-core/src/next_config.rs

@@ -877,6 +877,7 @@ pub struct ExperimentalConfig {
     turbopack_tree_shaking: Option<bool>,
     turbopack_scope_hoisting: Option<bool>,
     turbopack_use_system_tls_certs: Option<bool>,
+    turbopack_use_whole_app_module_graph_in_dev: Option<bool>,
     /// Disable automatic configuration of the sass loader.
     #[serde(default)]
     turbopack_use_builtin_sass: Option<bool>,
@@ -1839,6 +1840,16 @@ impl NextConfig {
         }))
     }
 
+    #[turbo_tasks::function]
+    pub async fn turbo_use_whole_app_module_graph(&self, mode: Vc<NextMode>) -> Result<Vc<bool>> {
+        Ok(Vc::cell(match *mode.await? {
+            NextMode::Development => self
+                .experimental
+                .turbopack_use_whole_app_module_graph_in_dev
+                .unwrap_or(false),
+            NextMode::Build => true,
+        }))
+    }
     #[turbo_tasks::function]
     pub async fn client_source_maps(&self, mode: Vc<NextMode>) -> Result<Vc<bool>> {
         let source_maps = self.experimental.turbopack_source_maps;

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

@@ -476,6 +476,7 @@ export const configSchema: zod.ZodType<NextConfig> = z.lazy(() =>
         turbopackUseSystemTlsCerts: z.boolean().optional(),
         turbopackUseBuiltinBabel: z.boolean().optional(),
         turbopackUseBuiltinSass: z.boolean().optional(),
+        turbopackUseWholeAppModuleGraphInDev: z.boolean().optional(),
         optimizePackageImports: z.array(z.string()).optional(),
         optimizeServerReact: z.boolean().optional(),
         clientTraceMetadata: z.array(z.string()).optional(),

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

@@ -660,6 +660,11 @@ export interface ExperimentalConfig {
    */
   turbopackUseBuiltinSass?: boolean
 
+  /**
+   * Whether to use the whole app module graph in development mode.  This makes development mode chunking more like production but may come with an HMR performance regression.
+   */
+  turbopackUseWholeAppModuleGraphInDev?: boolean
+
   /**
    * For use with `@next/mdx`. Compile MDX files using the new Rust compiler.
    * @see https://nextjs.org/docs/app/api-reference/next-config-js/mdxRs