From 0096c7d226b575f8c6997ca622fcbacfc415bebd Mon Sep 17 00:00:00 2001
From: Luke Sandberg <lukeisandberg@gmail.com>
Date: Sun, 12 Oct 2025 22:42:50 -0700
Subject: [PATCH] introduce an option to use the whole app module graph in
 development

---
 crates/next-api/src/project.rs                       | 10 ++++++++--
 crates/next-core/src/next_config.rs                  | 12 ++++++++++++
 packages/next/src/server/config-schema.ts            |  1 +
 packages/next/src/server/config-shared.ts            |  6 ++++++
 .../turbopack-core/src/chunk/chunking_context.rs     |  1 +
 5 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/crates/next-api/src/project.rs b/crates/next-api/src/project.rs
index 67250477318fc..cc0f2990be0cf 100644
--- a/crates/next-api/src/project.rs
+++ b/crates/next-api/src/project.rs
@@ -792,7 +792,12 @@ 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]
@@ -996,7 +1001,8 @@ impl Project {
             };
 
             // At this point all modules have been computed and we can get rid of the node.js
-            // process pools
+            // process pools, in watch mode we don't completely turn it down since we do expect
+            // invalidations
             if *self.is_watch_enabled().await? {
                 turbopack_node::evaluate::scale_down();
             } else {
diff --git a/crates/next-core/src/next_config.rs b/crates/next-core/src/next_config.rs
index 3c41b2b02388c..b7342242dc941 100644
--- a/crates/next-core/src/next_config.rs
+++ b/crates/next-core/src/next_config.rs
@@ -877,6 +877,7 @@ pub struct ExperimentalConfig {
     turbopack_scope_hoisting: Option<bool>,
     turbopack_import_type_bytes: 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>,
@@ -1840,6 +1841,17 @@ 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(true),
+            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;
diff --git a/packages/next/src/server/config-schema.ts b/packages/next/src/server/config-schema.ts
index 712af8e4f4675..c40811927990e 100644
--- a/packages/next/src/server/config-schema.ts
+++ b/packages/next/src/server/config-schema.ts
@@ -309,6 +309,7 @@ export const experimentalSchema = {
   turbopackUseBuiltinBabel: z.boolean().optional(),
   turbopackUseBuiltinSass: z.boolean().optional(),
   turbopackModuleIds: z.enum(['named', 'deterministic']).optional(),
+  turbopackUseWholeAppModuleGraphInDev: z.boolean().optional(),
   optimizePackageImports: z.array(z.string()).optional(),
   optimizeServerReact: z.boolean().optional(),
   clientTraceMetadata: z.array(z.string()).optional(),
diff --git a/packages/next/src/server/config-shared.ts b/packages/next/src/server/config-shared.ts
index 1a4a4737e55d9..a43c319a7efab 100644
--- a/packages/next/src/server/config-shared.ts
+++ b/packages/next/src/server/config-shared.ts
@@ -491,6 +491,12 @@ export interface ExperimentalConfig {
    */
   turbopackModuleIds?: 'named' | 'deterministic'
 
+  /**
+   * Whether to compute the whole app module graph in development mode. This may reduce memory usage
+   * by enabling more sharing of chunking decisions across routes.
+   */
+  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
diff --git a/turbopack/crates/turbopack-core/src/chunk/chunking_context.rs b/turbopack/crates/turbopack-core/src/chunk/chunking_context.rs
index 519b1cb1bb66f..96dab6b46d756 100644
--- a/turbopack/crates/turbopack-core/src/chunk/chunking_context.rs
+++ b/turbopack/crates/turbopack-core/src/chunk/chunking_context.rs
@@ -138,6 +138,7 @@ pub struct ChunkingConfigs(FxHashMap<ResolvedVc<Box<dyn ChunkType>>, ChunkingCon
 pub trait ChunkingContext {
     #[turbo_tasks::function]
     fn name(self: Vc<Self>) -> Vc<RcStr>;
+    /// Whether to use file URIs in source maps.
     #[turbo_tasks::function]
     fn should_use_file_source_map_uris(self: Vc<Self>) -> Vc<bool>;
     /// The root path of the project