diff --git a/packages/cli/src/ui/hooks/useHistoryManager.ts b/packages/cli/src/ui/hooks/useHistoryManager.ts
index c6ceabb920..4035264484 100644
--- a/packages/cli/src/ui/hooks/useHistoryManager.ts
+++ b/packages/cli/src/ui/hooks/useHistoryManager.ts
@@ -83,7 +83,12 @@ export function useHistory({
             return prevHistory; // Don't add the duplicate
           }
         }
-        return [...prevHistory, newItem];
+        const newHistory = [...prevHistory, newItem];
+        // Enforce a hard limit of 1000 items to prevent unbounded memory growth
+        if (newHistory.length > 1000) {
+          return newHistory.slice(newHistory.length - 1000);
+        }
+        return newHistory;
       });
 
       // Record UI-specific messages, but don't do it if we're actually loading
diff --git a/packages/core/src/services/chatRecordingService.ts b/packages/core/src/services/chatRecordingService.ts
index c71519f858..c2afc8867a 100644
--- a/packages/core/src/services/chatRecordingService.ts
+++ b/packages/core/src/services/chatRecordingService.ts
@@ -577,6 +577,12 @@ export class ChatRecordingService {
   ) {
     const conversation = this.readConversation();
     updateFn(conversation);
+    // Enforce a hard limit of 1000 items to prevent unbounded memory and file growth
+    if (conversation.messages.length > 1000) {
+      conversation.messages = conversation.messages.slice(
+        conversation.messages.length - 1000,
+      );
+    }
     this.writeConversation(conversation);
   }