diff --git a/packages/worker/client/ensure-crypto-random-uuid.node.test.ts b/packages/worker/client/ensure-crypto-random-uuid.node.test.ts
new file mode 100644
index 0000000000..da0882c1bd
--- /dev/null
+++ b/packages/worker/client/ensure-crypto-random-uuid.node.test.ts
@@ -0,0 +1,40 @@
+import { expect, test } from 'vitest'
+import { ensureCryptoRandomUUID } from './ensure-crypto-random-uuid.ts'
+
+const uuidPattern =
+	/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i
+
+test('ensureCryptoRandomUUID polyfills missing randomUUID from getRandomValues and leaves an existing implementation alone', () => {
+	const bytes = new Uint8Array(16).fill(0xab)
+	const getRandomValues = (target: Uint8Array) => {
+		target.set(bytes.subarray(0, target.length))
+		return target
+	}
+	const cryptoWithoutUuid = {
+		getRandomValues,
+	} as Crypto
+
+	ensureCryptoRandomUUID(cryptoWithoutUuid)
+
+	expect(typeof cryptoWithoutUuid.randomUUID).toBe('function')
+	const first = cryptoWithoutUuid.randomUUID()
+	expect(first).toMatch(uuidPattern)
+	expect(first[14]).toBe('4')
+	expect(['8', '9', 'a', 'b']).toContain(first[19]!.toLowerCase())
+
+	const existing = () => 'already-present-uuid'
+	const cryptoWithUuid = {
+		getRandomValues,
+		randomUUID: existing,
+	} as Crypto
+
+	ensureCryptoRandomUUID(cryptoWithUuid)
+	expect(cryptoWithUuid.randomUUID).toBe(existing)
+	expect(cryptoWithUuid.randomUUID()).toBe('already-present-uuid')
+
+	const empty = {} as Crypto
+	ensureCryptoRandomUUID(empty)
+	expect(empty.randomUUID).toBeUndefined()
+
+	ensureCryptoRandomUUID(undefined)
+})
diff --git a/packages/worker/client/ensure-crypto-random-uuid.ts b/packages/worker/client/ensure-crypto-random-uuid.ts
new file mode 100644
index 0000000000..42079d290f
--- /dev/null
+++ b/packages/worker/client/ensure-crypto-random-uuid.ts
@@ -0,0 +1,42 @@
+/**
+ * Remix's reconcile runtime calls `crypto.randomUUID()` for frame ids.
+ * Some in-app browsers (e.g. Twitter/X on iOS) expose `crypto` /
+ * `getRandomValues` but not `randomUUID`, which aborts client hydration.
+ * Install a RFC 4122 v4 polyfill before `run()` when needed.
+ */
+export function ensureCryptoRandomUUID(
+	cryptoApi: Crypto | undefined = globalThis.crypto,
+): void {
+	if (!cryptoApi) return
+	if (typeof cryptoApi.randomUUID === 'function') return
+	if (typeof cryptoApi.getRandomValues !== 'function') return
+
+	const polyfill = function randomUUID(
+		this: Crypto,
+	): `${string}-${string}-${string}-${string}-${string}` {
+		const bytes = new Uint8Array(16)
+		this.getRandomValues(bytes)
+		// Version 4 + RFC 4122 variant bits.
+		bytes[6] = (bytes[6]! & 0x0f) | 0x40
+		bytes[8] = (bytes[8]! & 0x3f) | 0x80
+		const hex = Array.from(bytes, (byte) =>
+			byte.toString(16).padStart(2, '0'),
+		).join('')
+		return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20)}` as `${string}-${string}-${string}-${string}-${string}`
+	}
+
+	try {
+		Object.defineProperty(cryptoApi, 'randomUUID', {
+			configurable: true,
+			enumerable: false,
+			writable: true,
+			value: polyfill,
+		})
+	} catch {
+		try {
+			cryptoApi.randomUUID = polyfill
+		} catch {
+			// Leave crypto unchanged; Remix will still throw if it calls randomUUID.
+		}
+	}
+}
diff --git a/packages/worker/client/entry.tsx b/packages/worker/client/entry.tsx
index 67a44aa161..c37c26c47b 100644
--- a/packages/worker/client/entry.tsx
+++ b/packages/worker/client/entry.tsx
@@ -7,7 +7,10 @@ import {
 	initSentryClient,
 } from '#client/sentry-client.ts'
 import { AppRoot, APP_ROOT_ENTRY_ID } from './app-root.tsx'
+import { ensureCryptoRandomUUID } from './ensure-crypto-random-uuid.ts'
 
+// Remix frame ids call crypto.randomUUID(); some in-app browsers omit it.
+ensureCryptoRandomUUID()
 initSentryClient(document)
 
 const clientRegistry: Record<string, typeof AppRoot> = {