Add basename support to RSC Framework Mode (#14264)

Author: markdalgleish

.changeset/flat-shoes-own.md

@@ -0,0 +1,5 @@
+---
+"react-router": patch
+---
+
+In RSC Data Mode when using a custom basename, fix hydration errors for routes that only have client loaders

integration/helpers/rsc-vite-framework/package.json

@@ -21,7 +21,7 @@
     "@vanilla-extract/css": "^1.17.4",
     "@vanilla-extract/vite-plugin": "^5.1.1",
     "@vitejs/plugin-react": "^4.5.2",
-    "@vitejs/plugin-rsc": "0.4.25",
+    "@vitejs/plugin-rsc": "0.4.26",
     "cross-env": "^7.0.3",
     "typescript": "^5.1.6",
     "vite": "^6.2.0",

integration/helpers/rsc-vite-framework/start.js

@@ -4,7 +4,7 @@ import reactRouterRequestHandler from "./build/server/index.js";
 
 const app = express();
 
-app.use(express.static("build/client"));
+app.use(process.env.VITE_BASE || "/", express.static("build/client"));
 
 app.get("/.well-known/appspecific/com.chrome.devtools.json", (_, res) => {
   res.status(404);

integration/helpers/rsc-vite/package.json

@@ -10,7 +10,7 @@
     "typecheck": "tsc"
   },
   "devDependencies": {
-    "@vitejs/plugin-rsc": "0.4.25",
+    "@vitejs/plugin-rsc": "0.4.26",
     "@types/express": "^5.0.0",
     "@types/node": "^22.13.1",
     "@types/react": "^19.1.8",

integration/helpers/vite.ts

@@ -337,17 +337,23 @@ export const reactRouterServe = async ({
 export const runStartScript = async ({
   cwd,
   port,
+  viteBase,
   basename,
 }: {
   cwd: string;
   port: number;
+  viteBase?: string;
   basename?: string;
 }) => {
   let nodeBin = process.argv[0];
   let proc = spawn(nodeBin, ["start.js"], {
     cwd,
     stdio: "pipe",
-    env: { NODE_ENV: "production", PORT: port.toFixed(0) },
+    env: {
+      NODE_ENV: "production",
+      PORT: port.toFixed(0),
+      VITE_BASE: viteBase,
+    },
   });
   await waitForServer(proc, { port, basename });
   return () => proc.kill();