From bfd6b33952872117bfa1456ebc1384ff35b8af56 Mon Sep 17 00:00:00 2001
From: Elecmonkey <elecmonkey@hotmail.com>
Date: Fri, 12 Jun 2026 14:12:38 +0800
Subject: [PATCH 1/2] fix(react-start): dedupe rsbuild dependencies

---
 .changeset/tiny-phones-dedup.md            |  5 +++++
 packages/react-start/src/plugin/rsbuild.ts | 18 ++++++++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 .changeset/tiny-phones-dedup.md

diff --git a/.changeset/tiny-phones-dedup.md b/.changeset/tiny-phones-dedup.md
new file mode 100644
index 0000000000..80ab56cb5f
--- /dev/null
+++ b/.changeset/tiny-phones-dedup.md
@@ -0,0 +1,5 @@
+---
+'@tanstack/react-start': patch
+---
+
+Deduplicate React and TanStack packages in the React Start Rsbuild plugin.
diff --git a/packages/react-start/src/plugin/rsbuild.ts b/packages/react-start/src/plugin/rsbuild.ts
index 7e0fcbb6c2..885fae9e20 100644
--- a/packages/react-start/src/plugin/rsbuild.ts
+++ b/packages/react-start/src/plugin/rsbuild.ts
@@ -10,6 +10,21 @@ import type {
 } from '@tanstack/start-plugin-core/rsbuild'
 import type { RsbuildPlugin } from '@rsbuild/core'
 
+const reactStartRsbuildEnvironmentOverrides = {
+  all: {
+    resolve: {
+      dedupe: [
+        'react',
+        'react-dom',
+        '@tanstack/react-start',
+        '@tanstack/react-router',
+      ],
+    },
+  },
+} satisfies NonNullable<
+  TanStackStartRsbuildPluginCoreOptions['rsbuild']
+>['environments']
+
 export function tanstackStart(
   options?: TanStackStartRsbuildInputConfig & { rsc?: { enabled?: boolean } },
 ): RsbuildPlugin {
@@ -20,6 +35,9 @@ export function tanstackStart(
     defaultEntryPaths: reactStartDefaultEntryPaths,
     providerEnvironmentName: RSBUILD_ENVIRONMENT_NAMES.server,
     ssrIsProvider: true,
+    rsbuild: {
+      environments: reactStartRsbuildEnvironmentOverrides,
+    },
   }
 
   if (rscEnabled) {

From 5cc2eeac5cfcce2cdbabdedc5f643e82351909f0 Mon Sep 17 00:00:00 2001
From: Elecmonkey <elecmonkey@hotmail.com>
Date: Wed, 17 Jun 2026 02:13:10 +0800
Subject: [PATCH 2/2] fix(react-start): only dedupe react packages in rsbuild
 plugin

---
 .changeset/tiny-phones-dedup.md            | 2 +-
 packages/react-start/src/plugin/rsbuild.ts | 7 +------
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/.changeset/tiny-phones-dedup.md b/.changeset/tiny-phones-dedup.md
index 80ab56cb5f..c55a797b8b 100644
--- a/.changeset/tiny-phones-dedup.md
+++ b/.changeset/tiny-phones-dedup.md
@@ -2,4 +2,4 @@
 '@tanstack/react-start': patch
 ---
 
-Deduplicate React and TanStack packages in the React Start Rsbuild plugin.
+Deduplicate React packages in the React Start Rsbuild plugin.
diff --git a/packages/react-start/src/plugin/rsbuild.ts b/packages/react-start/src/plugin/rsbuild.ts
index 885fae9e20..bd159690f1 100644
--- a/packages/react-start/src/plugin/rsbuild.ts
+++ b/packages/react-start/src/plugin/rsbuild.ts
@@ -13,12 +13,7 @@ import type { RsbuildPlugin } from '@rsbuild/core'
 const reactStartRsbuildEnvironmentOverrides = {
   all: {
     resolve: {
-      dedupe: [
-        'react',
-        'react-dom',
-        '@tanstack/react-start',
-        '@tanstack/react-router',
-      ],
+      dedupe: ['react', 'react-dom'],
     },
   },
 } satisfies NonNullable<