diff --git a/packages/util/__tests__/runtime.test.ts b/packages/util/__tests__/runtime.test.ts
new file mode 100644
index 000000000..7c168ae34
--- /dev/null
+++ b/packages/util/__tests__/runtime.test.ts
@@ -0,0 +1,47 @@
+import { afterEach, describe, expect, test, vi } from 'vitest';
+import { shouldUseGlobalFetchAndWebSocket } from '../src/index.js';
+
+describe('shouldUseGlobalFetchAndWebSocket', () => {
+	afterEach(() => {
+		vi.unstubAllGlobals();
+	});
+
+	test('GIVEN browser env with fetch and WebSocket THEN returns true', () => {
+		vi.stubGlobal('process', undefined);
+		vi.stubGlobal('fetch', () => void 0);
+		vi.stubGlobal('WebSocket', class {});
+		expect(shouldUseGlobalFetchAndWebSocket()).toBe(true);
+	});
+
+	test('GIVEN browser env without fetch or WebSocket THEN returns false', () => {
+		vi.stubGlobal('process', undefined);
+		vi.stubGlobal('fetch', globalThis.fetch);
+		vi.stubGlobal('WebSocket', globalThis.WebSocket);
+		// @ts-expect-error Testing missing globals
+		delete globalThis.fetch;
+		// @ts-expect-error Testing missing globals
+		delete globalThis.WebSocket;
+		expect(shouldUseGlobalFetchAndWebSocket()).toBe(false);
+	});
+
+	test('GIVEN Cloudflare Workers with nodejs_compat THEN returns true', () => {
+		vi.stubGlobal('process', { versions: { node: '22.19.0' } });
+		vi.stubGlobal('WebSocketPair', class {});
+		expect(shouldUseGlobalFetchAndWebSocket()).toBe(true);
+	});
+
+	test('GIVEN Node.js THEN returns false', () => {
+		vi.stubGlobal('process', { versions: { node: '22.19.0' } });
+		expect(shouldUseGlobalFetchAndWebSocket()).toBe(false);
+	});
+
+	test('GIVEN Deno THEN returns true', () => {
+		vi.stubGlobal('process', { versions: { deno: '1.0.0' } });
+		expect(shouldUseGlobalFetchAndWebSocket()).toBe(true);
+	});
+
+	test('GIVEN Bun THEN returns true', () => {
+		vi.stubGlobal('process', { versions: { bun: '1.0.0' } });
+		expect(shouldUseGlobalFetchAndWebSocket()).toBe(true);
+	});
+});
diff --git a/packages/util/src/functions/runtime.ts b/packages/util/src/functions/runtime.ts
index a84014397..d06f16c9b 100644
--- a/packages/util/src/functions/runtime.ts
+++ b/packages/util/src/functions/runtime.ts
@@ -6,6 +6,14 @@ export function shouldUseGlobalFetchAndWebSocket() {
 		return 'fetch' in globalThis && 'WebSocket' in globalThis;
 	}
 
+	// Cloudflare Workers with nodejs_compat polyfills process (including
+	// process.versions.node), but natively supports the Web WebSocket API.
+	// WebSocketPair is a Workers-only global; no other runtime exposes it.
+	// @ts-expect-error WebSocketPair is not in the globalThis type
+	if (typeof globalThis.WebSocketPair !== 'undefined') {
+		return true;
+	}
+
 	if ('versions' in globalThis.process) {
 		return 'deno' in globalThis.process.versions || 'bun' in globalThis.process.versions;
 	}