Fix/rsbuild static chunk availability

.changeset/rsbuild-static-chunk-availability.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/start-plugin-core': patch
+---
+
+Resolve Rsbuild static chunk imports in each chunk's own loading context. A shared chunk no longer links one route's CSS and preloads into its sibling routes, and each route still links the split chunks the shared chunk uses in that route.

e2e/react-start/deferred-hydration/src/routes/__root.tsx

@@ -7,6 +7,9 @@ import {
   Scripts,
   createRootRoute,
 } from '@tanstack/react-router'
+import { Hydrate } from '@tanstack/react-start'
+import { never } from '@tanstack/react-start/hydration'
+import rootDeferredStyles from '../shared/root-deferred.module.css'
 
 export const Route = createRootRoute({
   head: () => ({
@@ -173,6 +176,14 @@ function RootDocument({ children }: { children: React.ReactNode }) {
           <Link to="/scroll-restoration">Scroll</Link>
         </nav>
         {children}
+        <Hydrate when={never()}>
+          <div
+            data-testid="css-root-never"
+            className={rootDeferredStyles.panel}
+          >
+            Root deferred CSS
+          </div>
+        </Hydrate>
         <Scripts />
       </body>
     </html>

e2e/react-start/deferred-hydration/src/shared/root-deferred.module.css

@@ -0,0 +1,3 @@
+.panel {
+  color: rgb(21, 43, 65);
+}

e2e/react-start/deferred-hydration/tests/hydration.spec.ts

@@ -845,7 +845,7 @@ test.describe('Hydrate CSS delivery', () => {
     'production hydration coverage runs against the preview server',
   )
 
-  test('ships CSS for deferred, never, shared, and nested boundaries without JavaScript', async ({
+  test('ships CSS for root, deferred, never, shared, and nested boundaries without JavaScript', async ({
     browser,
     request,
   }) => {
@@ -857,6 +857,7 @@ test.describe('Hydrate CSS delivery', () => {
     htmlContainsText(html, 'Deferred CSS')
     htmlContainsText(html, 'Never CSS')
     htmlContainsText(html, 'Nested CSS')
+    htmlContainsText(html, 'Root deferred CSS')
 
     const context = await browser.newContext({ javaScriptEnabled: false })
     const page = await context.newPage()
@@ -871,6 +872,12 @@ test.describe('Hydrate CSS delivery', () => {
       await expect(page.getByTestId('css-never')).toHaveText('Never CSS')
       await expect(page.getByTestId('css-nested')).toHaveText('Nested CSS')
 
+      await expectCssProperty(
+        page,
+        'css-root-never',
+        'color',
+        'rgb(21, 43, 65)',
+      )
       await expectCssProperty(page, 'css-outer', 'color', 'rgb(12, 34, 56)')
       await expectCssProperty(
         page,