fix(tanstack-start): Fix event handler return type mismatch (#5051)

.changeset/great-peaches-yell.md

@@ -0,0 +1,5 @@
+---
+"@clerk/tanstack-start": patch
+---
+
+Fix type mismatch between TanStack Start and Clerk event handlers

packages/tanstack-start/package.json

@@ -69,7 +69,8 @@
   "devDependencies": {
     "@tanstack/react-router": "^1.97.25",
     "@tanstack/start": "^1.97.25",
-    "esbuild-plugin-file-path-extensions": "^2.1.2"
+    "esbuild-plugin-file-path-extensions": "^2.1.2",
+    "h3": "^1.13.0"
   },
   "peerDependencies": {
     "@tanstack/react-router": ">=1.85.9",

packages/tanstack-start/src/server/middlewareHandler.ts

@@ -1,5 +1,5 @@
 import type { AnyRouter } from '@tanstack/react-router';
-import type { EventHandler } from 'vinxi/http';
+import type { eventHandler } from 'h3';
 
 import { authenticateRequest } from './authenticateRequest';
 import { loadOptions } from './loadOptions';
@@ -11,13 +11,16 @@ export type HandlerCallback<TRouter extends AnyRouter> = (ctx: {
   router: TRouter;
   responseHeaders: Headers;
 }) => Response | Promise<Response>;
-export type CustomizeStartHandler<TRouter extends AnyRouter> = (cb: HandlerCallback<TRouter>) => EventHandler;
+
+export type CustomizeStartHandler<TRouter extends AnyRouter> = (
+  cb: HandlerCallback<TRouter>,
+) => ReturnType<typeof eventHandler>;
 
 export function createClerkHandler<TRouter extends AnyRouter>(
   eventHandler: CustomizeStartHandler<TRouter>,
   clerkOptions: LoaderOptions = {},
 ) {
-  return (cb: HandlerCallback<TRouter>): EventHandler => {
+  return (cb: HandlerCallback<TRouter>) => {
     return eventHandler(async ({ request, router, responseHeaders }) => {
       try {
         const loadedOptions = loadOptions(request, clerkOptions);