diff --git a/apps/web/vite.config.ts b/apps/web/vite.config.ts
index 31968b3bb7ebd..cd4f48a64fcff 100644
--- a/apps/web/vite.config.ts
+++ b/apps/web/vite.config.ts
@@ -7,6 +7,7 @@ import { playwright } from "vite-plus/test/browser-playwright";
 import { defineProject, type TestProjectInlineConfiguration } from "vite-plus/test/config";
 import "vite-plus/test/config";
 import { defineConfig, type Connect, type Plugin } from "vite-plus";
+import * as Hash from "effect/Hash";
 import pkg from "./package.json" with { type: "json" };
 
 import {
@@ -80,6 +81,12 @@ const unitTestProject = {
 
 // Anything that renders React or touches the DOM is named *.browser.test.{ts,tsx} and runs
 // in headless Chromium through the same plugins as the app, so it exercises compiled code.
+// Vitest's fixed browser API port (63315) collides when two checkouts run
+// browser tests at once, and `server.strictPort` above is inherited, so the
+// second run fails instead of moving on. Hash the checkout path like
+// scripts/dev-runner.ts does, into 61000-64999 (above Linux's ephemeral range).
+const browserTestApiPort = 61_000 + ((Hash.string(import.meta.dirname) >>> 0) % 4_000);
+
 const browserTestProject = {
   extends: true,
   // Pre-bundled so the first test importing userEvent does not trigger a mid-run reload.
@@ -89,6 +96,7 @@ const browserTestProject = {
     include: ["src/**/*.browser.test.{ts,tsx}"],
     hookTimeout: 15_000,
     testTimeout: 15_000,
+    api: { port: browserTestApiPort, strictPort: false },
     browser: {
       enabled: true,
       headless: true,