fix(core): preserve dynamic tool descriptions on session resume (#18835)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/core/src/core/geminiChat.ts

@@ -1007,6 +1007,8 @@ export class GeminiChat {
         status: call.status,
         timestamp: new Date().toISOString(),
         resultDisplay,
+        description:
+          'invocation' in call ? call.invocation?.getDescription() : undefined,
       };
     });
 

packages/core/src/services/chatRecordingService.test.ts

@@ -370,6 +370,36 @@ describe('ChatRecordingService', () => {
       expect(geminiMsg.toolCalls![0].name).toBe('testTool');
     });
 
+    it('should preserve dynamic description and NOT overwrite with generic one', () => {
+      chatRecordingService.recordMessage({
+        type: 'gemini',
+        content: '',
+        model: 'gemini-pro',
+      });
+
+      const dynamicDescription = 'DYNAMIC DESCRIPTION (e.g. Read file foo.txt)';
+      const toolCall: ToolCallRecord = {
+        id: 'tool-1',
+        name: 'testTool',
+        args: {},
+        status: CoreToolCallStatus.Success,
+        timestamp: new Date().toISOString(),
+        description: dynamicDescription,
+      };
+
+      chatRecordingService.recordToolCalls('gemini-pro', [toolCall]);
+
+      const sessionFile = chatRecordingService.getConversationFilePath()!;
+      const conversation = JSON.parse(
+        fs.readFileSync(sessionFile, 'utf8'),
+      ) as ConversationRecord;
+      const geminiMsg = conversation.messages[0] as MessageRecord & {
+        type: 'gemini';
+      };
+
+      expect(geminiMsg.toolCalls![0].description).toBe(dynamicDescription);
+    });
+
     it('should create a new message if the last message is not from gemini', () => {
       chatRecordingService.recordMessage({
         type: 'user',

packages/core/src/services/chatRecordingService.ts

@@ -347,7 +347,8 @@ export class ChatRecordingService {
       return {
         ...toolCall,
         displayName: toolInstance?.displayName || toolCall.name,
-        description: toolInstance?.description || '',
+        description:
+          toolCall.description?.trim() || toolInstance?.description || '',
         renderOutputAsMarkdown: toolInstance?.isOutputMarkdown || false,
       };
     });