2 files changed, 9 insertions, 7 deletions
diff --git a/packages/core/src/core/client.ts b/packages/core/src/core/client.ts
index 94c598bf..9cc8f328 100644
--- a/packages/core/src/core/client.ts
+++ b/packages/core/src/core/client.ts
@@ -475,9 +475,11 @@ export class GeminiClient {
       await cg.countTokens({ model: this.model, contents: newHistory })
     ).totalTokens;
 
-    return {
-      originalTokenCount,
-      newTokenCount,
-    };
+    return originalTokenCount && newTokenCount
+      ? {
+          originalTokenCount,
+          newTokenCount,
+        }
+      : null;
   }
 }
diff --git a/packages/core/src/core/turn.ts b/packages/core/src/core/turn.ts
index 4c0a297e..5a8b57e0 100644
--- a/packages/core/src/core/turn.ts
+++ b/packages/core/src/core/turn.ts
@@ -110,13 +110,13 @@ export type ServerGeminiErrorEvent = {
 };
 
 export interface ChatCompressionInfo {
-  originalTokenCount: number | undefined;
-  newTokenCount: number | undefined;
+  originalTokenCount: number;
+  newTokenCount: number;
 }
 
 export type ServerGeminiChatCompressedEvent = {
   type: GeminiEventType.ChatCompressed;
-  value: ChatCompressionInfo;
+  value: ChatCompressionInfo | null;
 };
 
 export type ServerGeminiUsageMetadataEvent = {