nitrojs · pi0 · Mar 23, 2026 · Mar 13, 2026 · Mar 14, 2026 · Mar 14, 2026
@@ -11,6 +11,7 @@ import { watch as chokidarWatch } from "chokidar";
 import { watch as fsWatch } from "node:fs";
 import { join } from "pathe";
 import { debounce } from "perfect-debounce";
+import { withBase } from "ufo";
 import { scanHandlers } from "../../scan.ts";
 import { getEnvRunner } from "./env.ts";
 
@@ -198,6 +199,12 @@ export async function configureViteDevServer(ctx: NitroPluginContext, server: Vi
       return next();
     }
     nodeReq._nitroHandled = true;
+
+    const baseURL = nitro.options.baseURL || "/";
+    const originalURL = nodeReq.url;
+    if (baseURL !== "/") {
+      nodeReq.url = withBase(nodeReq.url, baseURL);
+    }
     try {
       // Create web API compat request
       const req = new NodeRequest({ req: nodeReq, res: nodeRes });
@@ -219,19 +226,30 @@ export async function configureViteDevServer(ctx: NitroPluginContext, server: Vi
       return await sendNodeResponse(nodeRes, envRes);
     } catch (error) {
       return next(error);
+    } finally {
+      if (baseURL !== "/") {
+        nodeReq.url = originalURL;
+      }
     }
   };
 
   // Handle server routes first to avoid conflicts with static assets served by Vite from the root
   // https://github.com/vitejs/vite/pull/20866
   server.middlewares.use(function nitroDevMiddlewarePre(req, res, next) {
     const fetchDest = req.headers["sec-fetch-dest"];
+    const ext = req.url!.match(/\.([a-z0-9]+)(?:[?#]|$)/i)?.[1];
+    const isNitroRoute = ext
+      ? !!nitro.routing.routes.match(
+          req.method || "",
+          new URL(withBase(req.url!, nitro.options.baseURL), "http://localhost").pathname
+        )
+      : false;
     res.setHeader("vary", "sec-fetch-dest");
     if (
       // Originating from browser tab or no fetch dest (curl, fetch, etc) and (not script, style, image, etc)
       (!fetchDest || /^(document|iframe|frame|empty)$/.test(fetchDest)) &&
-      // No file extension (not /src/index.ts)
-      !req.url!.match(/\.([a-z0-9]+)(?:[?#]|$)/i)?.[1] &&
+      // No file extension (not /src/index.ts) unless it is an explicit Nitro route
+      (!ext || isNitroRoute) &&
       // Special prefixes (/__vue-router/auto-routes, /@vite-plugin-layouts/, etc)
       !/^\/(?:__|@)/.test(req.url!)
     ) {

@@ -0,0 +1 @@
+export default (event: any) => event.context.params!.param;
@@ -0,0 +1,11 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Nitro Base URL Dotted Param Fixture</title>
+  </head>
+  <body>
+    <div id="app">fixture</div>
+  </body>
+</html>
@@ -0,0 +1,3 @@
+{
+  "extends": "nitro/tsconfig"
+}
@@ -0,0 +1,13 @@
+import { defineConfig } from "vite";
+import { nitro } from "nitro/vite";
+
+export default defineConfig({
+  base: "/subdir/",
+  plugins: [
+    nitro({
+      baseURL: "/subdir/",
+      serverDir: "./",
+      serveStatic: false,
+    }),
+  ],
+});
@@ -0,0 +1,49 @@
+import { fileURLToPath } from "node:url";
+import type { ViteDevServer } from "vite";
+import { beforeAll, afterAll, describe, expect, test } from "vitest";
+
+const { createServer } = (await import(
+  process.env.NITRO_VITE_PKG || "vite"
+)) as typeof import("vite");
+
+describe("vite:baseURL dotted params", { sequential: true }, () => {
+  let server: ViteDevServer;
+  let serverURL: string;
+
+  const rootDir = fileURLToPath(new URL("./baseurl-dotted-param-fixture", import.meta.url));
+
+  beforeAll(async () => {
+    process.chdir(rootDir);
+    server = await createServer({ root: rootDir });
+    await server.listen("0" as unknown as number);
+    const addr = server.httpServer?.address() as {
+      port: number;
+      address: string;
+      family: string;
+    };
+    serverURL = `http://${addr.family === "IPv6" ? `[${addr.address}]` : addr.address}:${addr.port}`;
+  }, 30_000);
+
+  afterAll(async () => {
+    await server?.close();
+  });
+
+  test("serves Nitro API routes with dotted params under baseURL without redirecting", async () => {
+    for (const fetchDest of ["empty", "document", undefined]) {
+      const headers: Record<string, string> = {};
+      if (fetchDest) {
+        headers["sec-fetch-dest"] = fetchDest;
+      }
+      const response = await fetch(`${serverURL}/subdir/api/proxy/todos/Package.todos.Entity.3`, {
+        headers,
+        redirect: "manual",
+      });
+
+      expect(response.status, `sec-fetch-dest: ${fetchDest}`).toBe(200);
+      expect(response.headers.get("location"), `sec-fetch-dest: ${fetchDest}`).toBeNull();
+      expect(await response.text(), `sec-fetch-dest: ${fetchDest}`).toBe(
+        "todos/Package.todos.Entity.3"
+      );
+    }
+  });
+});
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		export default (event: any) => event.context.params!.param;