Add basename support to RSC Framework Mode

.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();