diff --git a/src/polyfills.ts b/src/polyfills.ts
index c9c8fde..f5aa7d9 100644
--- a/src/polyfills.ts
+++ b/src/polyfills.ts
@@ -1,7 +1,7 @@
 /**
  * Polyfills that must run before any other app code (including LangChain/LangGraph).
  * This file is imported as the very first line in App.tsx so that ReadableStream
- * exists before @langchain/core or @langchain/langgraph are loaded.
+ * and crypto.getRandomValues exist before @langchain/core / uuid are loaded.
  */
 import 'web-streams-polyfill';
 
@@ -13,3 +13,33 @@ if (typeof (g as any).ReadableStream === 'undefined') {
   (g as any).WritableStream = ponyfill.WritableStream;
   (g as any).TransformStream = ponyfill.TransformStream;
 }
+
+// Polyfill crypto.getRandomValues for React Native/Expo (required by uuid, LangChain, etc.)
+if (typeof g !== 'undefined') {
+  const cryptoObj = (g as any).crypto;
+  if (!cryptoObj || typeof (cryptoObj.getRandomValues) !== 'function') {
+    try {
+      const ExpoCrypto = require('expo-crypto');
+      const getRandomValues = (array: ArrayBufferView): ArrayBufferView => {
+        ExpoCrypto.getRandomValues(array);
+        return array;
+      };
+      if (!(g as any).crypto) (g as any).crypto = {};
+      (g as any).crypto.getRandomValues = getRandomValues;
+    } catch (e) {
+      console.warn('[polyfills] crypto.getRandomValues polyfill failed:', e);
+    }
+  }
+}
+
+// Polyfill AbortSignal.prototype.throwIfAborted (required by fetch/LangChain in RN; not present in older runtimes)
+const AbortSignalGlobal = (g as any).AbortSignal;
+if (typeof AbortSignalGlobal === 'function' && AbortSignalGlobal.prototype && typeof AbortSignalGlobal.prototype.throwIfAborted !== 'function') {
+  AbortSignalGlobal.prototype.throwIfAborted = function (this: AbortSignal) {
+    if (this.aborted) {
+      const e = new Error('Aborted');
+      e.name = 'AbortError';
+      throw e;
+    }
+  };
+}