Refactor: Centralize GeminiClient in Config (#693)

Co-authored-by: N. Taylor Mullen <ntaylormullen@google.com>

packages/core/src/tools/web-fetch.ts

@@ -4,13 +4,12 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { GoogleGenAI, GroundingMetadata } from '@google/genai';
+import { GroundingMetadata } from '@google/genai';
 import { SchemaValidator } from '../utils/schemaValidator.js';
 import { BaseTool, ToolResult } from './tools.js';
 import { getErrorMessage } from '../utils/errors.js';
 import { Config } from '../config/config.js';
 import { getResponseText } from '../utils/generateContentResponseUtilities.js';
-import { retryWithBackoff } from '../utils/retry.js';
 
 // Interfaces for grounding metadata (similar to web-search.ts)
 interface GroundingChunkWeb {
@@ -49,9 +48,6 @@ export interface WebFetchToolParams {
 export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
   static readonly Name: string = 'web_fetch';
 
-  private ai: GoogleGenAI;
-  private modelName: string;
-
   constructor(private readonly config: Config) {
     super(
       WebFetchTool.Name,
@@ -69,12 +65,6 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
         type: 'object',
       },
     );
-
-    const apiKeyFromConfig = this.config.getApiKey();
-    this.ai = new GoogleGenAI({
-      apiKey: apiKeyFromConfig === '' ? undefined : apiKeyFromConfig,
-    });
-    this.modelName = this.config.getModel();
   }
 
   validateParams(params: WebFetchToolParams): string | null {
@@ -109,7 +99,7 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
 
   async execute(
     params: WebFetchToolParams,
-    _signal: AbortSignal,
+    signal: AbortSignal,
   ): Promise<ToolResult> {
     const validationError = this.validateParams(params);
     if (validationError) {
@@ -120,23 +110,14 @@ export class WebFetchTool extends BaseTool<WebFetchToolParams, ToolResult> {
     }
 
     const userPrompt = params.prompt;
+    const geminiClient = this.config.getGeminiClient();
 
     try {
-      const apiCall = () =>
-        this.ai.models.generateContent({
-          model: this.modelName,
-          contents: [
-            {
-              role: 'user',
-              parts: [{ text: userPrompt }],
-            },
-          ],
-          config: {
-            tools: [{ urlContext: {} }],
-          },
-        });
-
-      const response = await retryWithBackoff(apiCall);
+      const response = await geminiClient.generateContent(
+        [{ role: 'user', parts: [{ text: userPrompt }] }],
+        { tools: [{ urlContext: {} }] },
+        signal, // Pass signal
+      );
 
       console.debug(
         `[WebFetchTool] Full response for prompt "${userPrompt.substring(0, 50)}...":`,