fix(router-core): enhance basePath handling

e2e/react-router/basepath-file-based/src/routeTree.gen.ts

@@ -9,9 +9,15 @@
 // Additionally, you should also exclude this file from your linter and/or formatter to prevent it from being checked or modified.
 
 import { Route as rootRouteImport } from './routes/__root'
+import { Route as RedirectRouteImport } from './routes/redirect'
 import { Route as AboutRouteImport } from './routes/about'
 import { Route as IndexRouteImport } from './routes/index'
 
+const RedirectRoute = RedirectRouteImport.update({
+  id: '/redirect',
+  path: '/redirect',
+  getParentRoute: () => rootRouteImport,
+} as any)
 const AboutRoute = AboutRouteImport.update({
   id: '/about',
   path: '/about',
@@ -26,31 +32,42 @@ const IndexRoute = IndexRouteImport.update({
 export interface FileRoutesByFullPath {
   '/': typeof IndexRoute
   '/about': typeof AboutRoute
+  '/redirect': typeof RedirectRoute
 }
 export interface FileRoutesByTo {
   '/': typeof IndexRoute
   '/about': typeof AboutRoute
+  '/redirect': typeof RedirectRoute
 }
 export interface FileRoutesById {
   __root__: typeof rootRouteImport
   '/': typeof IndexRoute
   '/about': typeof AboutRoute
+  '/redirect': typeof RedirectRoute
 }
 export interface FileRouteTypes {
   fileRoutesByFullPath: FileRoutesByFullPath
-  fullPaths: '/' | '/about'
+  fullPaths: '/' | '/about' | '/redirect'
   fileRoutesByTo: FileRoutesByTo
-  to: '/' | '/about'
-  id: '__root__' | '/' | '/about'
+  to: '/' | '/about' | '/redirect'
+  id: '__root__' | '/' | '/about' | '/redirect'
   fileRoutesById: FileRoutesById
 }
 export interface RootRouteChildren {
   IndexRoute: typeof IndexRoute
   AboutRoute: typeof AboutRoute
+  RedirectRoute: typeof RedirectRoute
 }
 
 declare module '@tanstack/react-router' {
   interface FileRoutesByPath {
+    '/redirect': {
+      id: '/redirect'
+      path: '/redirect'
+      fullPath: '/redirect'
+      preLoaderRoute: typeof RedirectRouteImport
+      parentRoute: typeof rootRouteImport
+    }
     '/about': {
       id: '/about'
       path: '/about'
@@ -71,6 +88,7 @@ declare module '@tanstack/react-router' {
 const rootRouteChildren: RootRouteChildren = {
   IndexRoute: IndexRoute,
   AboutRoute: AboutRoute,
+  RedirectRoute: RedirectRoute,
 }
 export const routeTree = rootRouteImport
   ._addFileChildren(rootRouteChildren)

e2e/react-router/basepath-file-based/src/routes/index.tsx

@@ -20,6 +20,16 @@ function App() {
       >
         Navigate to /about with document reload
       </button>
+      <button
+        data-testid="to-redirect-btn"
+        onClick={() =>
+          navigate({
+            to: '/redirect',
+          })
+        }
+      >
+        Navigate to /redirect
+      </button>
     </div>
   )
 }

e2e/react-router/basepath-file-based/src/routes/redirect.tsx

@@ -0,0 +1,12 @@
+import { createFileRoute, redirect } from '@tanstack/react-router'
+
+export const Route = createFileRoute('/redirect')({
+  beforeLoad: async () => {
+    throw redirect({ to: '/about' })
+  },
+  component: RouteComponent,
+})
+
+function RouteComponent() {
+  return <div>Hello "/redirect"!</div>
+}

e2e/react-router/basepath-file-based/tests/reload-document.test.ts

@@ -16,3 +16,13 @@ test('navigate() respects basepath for when reloadDocument=true', async ({
   await page.waitForURL('/app/')
   await expect(page.getByTestId(`home-component`)).toBeInViewport()
 })
+
+test('redirect respects basepath', async ({ page }) => {
+  await page.goto(`/app/`)
+  await expect(page.getByTestId(`home-component`)).toBeInViewport()
+
+  const redirectBtn = page.getByTestId(`to-redirect-btn`)
+  await redirectBtn.click()
+  await page.waitForURL('/app/about')
+  await expect(page.getByTestId(`about-component`)).toBeInViewport()
+})

e2e/react-start/custom-basepath/tests/navigation.spec.ts

@@ -47,9 +47,8 @@ test('Server function URLs correctly include app basepath', async ({
 test('client-side redirect', async ({ page, baseURL }) => {
   await page.goto('/redirect')
   await page.getByTestId('link-to-throw-it').click()
-  await page.waitForLoadState('networkidle')
-
-  expect(await page.getByTestId('post-view').isVisible()).toBe(true)
+  await page.waitForURL(`${baseURL}/posts/1`)
+  await expect(page.getByTestId('post-view')).toBeInViewport()
   expect(page.url()).toBe(`${baseURL}/posts/1`)
 })
 

packages/router-core/src/rewrite.ts

@@ -36,23 +36,37 @@ export function rewriteBasepath(opts: {
     ? normalizedBasepathWithSlash
     : normalizedBasepathWithSlash.toLowerCase()
 
+  const removeBasePath = (pathname: string) => {
+    const normalizedPath = opts.caseSensitive
+      ? pathname
+      : pathname.toLowerCase()
+
+    // Handle exact basepath match (e.g., /my-app -> /)
+    if (normalizedPath === checkBasepath) {
+      return '/'
+    }
+
+    if (normalizedPath.startsWith(checkBasepathWithSlash)) {
+      // Handle basepath with trailing content (e.g., /my-app/users -> /users)
+      return pathname.slice(normalizedBasepath.length)
+    }
+
+    return pathname
+  }
+
   return {
     input: ({ url }) => {
-      const pathname = opts.caseSensitive
-        ? url.pathname
-        : url.pathname.toLowerCase()
+      url.pathname = removeBasePath(url.pathname)
 
-      // Handle exact basepath match (e.g., /my-app -> /)
-      if (pathname === checkBasepath) {
-        url.pathname = '/'
-      } else if (pathname.startsWith(checkBasepathWithSlash)) {
-        // Handle basepath with trailing content (e.g., /my-app/users -> /users)
-        url.pathname = url.pathname.slice(normalizedBasepath.length)
-      }
       return url
     },
     output: ({ url }) => {
-      url.pathname = joinPaths(['/', trimmedBasepath, url.pathname])
+      url.pathname = joinPaths([
+        '/',
+        trimmedBasepath,
+        removeBasePath(url.pathname),
+      ])
+
       return url
     },
   } satisfies LocationRewrite

packages/router-core/src/router.ts

@@ -1758,11 +1758,11 @@ export class RouterCore<
 
       // If a rewrite function is provided, use it to rewrite the URL
       const rewrittenUrl = executeRewriteOutput(this.rewrite, url)
+      const rewrittenFullPath = `${rewrittenUrl.pathname}${rewrittenUrl.search}${rewrittenUrl.hash}`
 
       return {
-        publicHref:
-          rewrittenUrl.pathname + rewrittenUrl.search + rewrittenUrl.hash,
-        href: fullPath,
+        publicHref: rewrittenFullPath,
+        href: rewrittenFullPath,
         url: rewrittenUrl,
         pathname: nextPathname,
         search: nextSearch,