Refactor(chat): Introduce custom Chat class for future modifications

- Copied the `Chat` class from `@google/genai` into `packages/server/src/core/geminiChat.ts`.
- This change is in preparation for future modifications to the chat handling logic.
- Updated relevant files to use the new `GeminiChat` class.

Part of https://github.com/google-gemini/gemini-cli/issues/551

1 files changed, 3 insertions, 2 deletions

diff --git a/packages/server/src/core/turn.test.ts b/packages/server/src/core/turn.test.ts
index 90d3407f..44bb983f 100644
--- a/packages/server/src/core/turn.test.ts
+++ b/packages/server/src/core/turn.test.ts
@@ -11,8 +11,9 @@ import {
   ServerGeminiToolCallRequestEvent,
   ServerGeminiErrorEvent,
 } from './turn.js';
-import { Chat, GenerateContentResponse, Part, Content } from '@google/genai';
+import { GenerateContentResponse, Part, Content } from '@google/genai';
 import { reportError } from '../utils/errorReporting.js';
+import { GeminiChat } from './geminiChat.js';
 
 const mockSendMessageStream = vi.fn();
 const mockGetHistory = vi.fn();
@@ -54,7 +55,7 @@ describe('Turn', () => {
       sendMessageStream: mockSendMessageStream,
       getHistory: mockGetHistory,
     };
-    turn = new Turn(mockChatInstance as unknown as Chat);
+    turn = new Turn(mockChatInstance as unknown as GeminiChat);
     mockGetHistory.mockReturnValue([]);
     mockSendMessageStream.mockResolvedValue((async function* () {})());
   });