diff --git a/src/routes/application-starter.index.tsx b/src/routes/application-starter.index.tsx
index a5eb6619f..63d6ee7e2 100644
--- a/src/routes/application-starter.index.tsx
+++ b/src/routes/application-starter.index.tsx
@@ -1,6 +1,6 @@
 import * as React from 'react'
 import { ClientOnly, createFileRoute } from '@tanstack/react-router'
-import { z } from 'zod'
+import * as v from 'valibot'
 import { seo } from '~/utils/seo'
 
 const LazyApplicationStarterPage = React.lazy(() =>
@@ -12,21 +12,26 @@ const LazyApplicationStarterPage = React.lazy(() =>
 )
 
 // Search params schema for shareable URLs
-const applicationStarterSearchSchema = z
-  .object({
-    name: z.string().optional(),
-    framework: z.string().optional(),
-    features: z.string().optional(), // comma-separated feature IDs
-    pm: z.enum(['pnpm', 'npm', 'yarn', 'bun']).optional(),
-    tailwind: z.enum(['false']).optional(),
-    tab: z.enum(['summary', 'code', 'preview']).optional(),
-    file: z.string().optional(), // selected file in files tab
-    addon: z.string().optional(), // selected addon in addons tab
-    addonFile: z.string().optional(), // selected file in addon view
-    template: z.string().optional(),
+const applicationStarterSearchSchema = v.pipe(
+  v.unknown(),
+  v.check(
+    (input) => !Array.isArray(input),
+    'Expected a search parameters object',
+  ),
+  v.looseObject({
+    name: v.optional(v.string()),
+    framework: v.optional(v.string()),
+    features: v.optional(v.string()), // comma-separated feature IDs
+    pm: v.optional(v.picklist(['pnpm', 'npm', 'yarn', 'bun'])),
+    tailwind: v.optional(v.literal('false')),
+    tab: v.optional(v.picklist(['summary', 'code', 'preview'])),
+    file: v.optional(v.string()), // selected file in files tab
+    addon: v.optional(v.string()), // selected addon in addons tab
+    addonFile: v.optional(v.string()), // selected file in addon view
+    template: v.optional(v.string()),
     // Feature options as key.value params handled dynamically
-  })
-  .passthrough()
+  }),
+)
 
 export const Route = createFileRoute('/application-starter/')({
   ssr: false,
diff --git a/tests/application-starter-search.test.ts b/tests/application-starter-search.test.ts
new file mode 100644
index 000000000..2b293fbe4
--- /dev/null
+++ b/tests/application-starter-search.test.ts
@@ -0,0 +1,63 @@
+/// <reference types="node" />
+
+import assert from 'node:assert/strict'
+import test from 'node:test'
+import { Route } from '../src/routes/application-starter.index'
+
+const schema = Route.options.validateSearch
+assert.ok(schema && typeof schema === 'object' && '~standard' in schema)
+const standardSchema = schema['~standard']
+
+test('application starter preserves optional fields and custom feature options', async () => {
+  for (const input of [
+    {},
+    { name: undefined },
+    {
+      name: '',
+      framework: 'react',
+      features: 'router,query',
+      pm: 'pnpm',
+      tailwind: 'false',
+      tab: 'preview',
+      file: 'src/main.tsx',
+      addon: 'query',
+      addonFile: 'package.json',
+      template: 'custom',
+      'query.mode': 'offline',
+      custom: { nested: [1, false, null] },
+    },
+    ...['pnpm', 'npm', 'yarn', 'bun'].map((pm) => ({ pm })),
+    ...['summary', 'code', 'preview'].map((tab) => ({ tab })),
+  ]) {
+    const result = await standardSchema.validate(input)
+    assert.equal(result.issues, undefined)
+    assert.deepEqual(result.value, input)
+  }
+})
+
+test('application starter rejects invalid known fields instead of coercing them', async () => {
+  for (const input of [
+    null,
+    [],
+    'name=app',
+    { pm: 'deno' },
+    { tailwind: true },
+    { tailwind: 'true' },
+    { tab: 'unknown' },
+    ...[
+      'name',
+      'framework',
+      'features',
+      'pm',
+      'tailwind',
+      'tab',
+      'file',
+      'addon',
+      'addonFile',
+      'template',
+    ].flatMap((key) => [null, 0, false, []].map((value) => ({ [key]: value }))),
+  ]) {
+    const result = await standardSchema.validate(input)
+    assert.ok(result.issues?.length, JSON.stringify(input))
+  }
+})