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, 2 insertions, 2 deletions

diff --git a/packages/server/src/core/turn.ts b/packages/server/src/core/turn.ts
index a02b5eb6..d5c7eb58 100644
--- a/packages/server/src/core/turn.ts
+++ b/packages/server/src/core/turn.ts
@@ -6,7 +6,6 @@
 
 import {
   Part,
-  Chat,
   PartListUnion,
   GenerateContentResponse,
   FunctionCall,
@@ -20,6 +19,7 @@ import {
 import { getResponseText } from '../utils/generateContentResponseUtilities.js';
 import { reportError } from '../utils/errorReporting.js';
 import { getErrorMessage } from '../utils/errors.js';
+import { GeminiChat } from './geminiChat.js';
 
 // Define a structure for tools passed to the server
 export interface ServerTool {
@@ -113,7 +113,7 @@ export class Turn {
   }>;
   private debugResponses: GenerateContentResponse[];
 
-  constructor(private readonly chat: Chat) {
+  constructor(private readonly chat: GeminiChat) {
     this.pendingToolCalls = [];
     this.debugResponses = [];
   }