feat: Support thinking settings for Gemini models (#19591)

packages/@n8n/nodes-langchain/nodes/llms/LmChatGoogleVertex/LmChatGoogleVertex.node.ts

@@ -1,6 +1,6 @@
-import type { SafetySetting } from '@google/generative-ai';
 import { ProjectsClient } from '@google-cloud/resource-manager';
-import { ChatVertexAI } from '@langchain/google-vertexai';
+import type { GoogleAISafetySetting } from '@langchain/google-common';
+import { ChatVertexAI, type ChatVertexAIInput } from '@langchain/google-vertexai';
 import { formatPrivateKey } from 'n8n-nodes-base/dist/utils/utilities';
 import {
 	NodeConnectionTypes,
@@ -11,12 +11,13 @@ import {
 	type ILoadOptionsFunctions,
 	type JsonObject,
 	NodeOperationError,
+	validateNodeParameters,
 } from 'n8n-workflow';
 
 import { getConnectionHintNoticeField } from '@utils/sharedFields';
 
 import { makeErrorFromStatus } from './error-handling';
-import { additionalOptions } from '../gemini-common/additional-options';
+import { getAdditionalOptions } from '../gemini-common/additional-options';
 import { makeN8nLlmFailedAttemptHandler } from '../n8nLlmFailedAttemptHandler';
 import { N8nLlmTracing } from '../N8nLlmTracing';
 
@@ -90,7 +91,7 @@ export class LmChatGoogleVertex implements INodeType {
 					'The model which will generate the completion. <a href="https://cloud.google.com/vertex-ai/generative-ai/docs/learn/models">Learn more</a>.',
 				default: 'gemini-2.5-flash',
 			},
-			additionalOptions,
+			getAdditionalOptions({ supportsThinkingBudget: true }),
 		],
 	};
 
@@ -143,21 +144,29 @@ export class LmChatGoogleVertex implements INodeType {
 			temperature: 0.4,
 			topK: 40,
 			topP: 0.9,
-		}) as {
-			maxOutputTokens: number;
-			temperature: number;
-			topK: number;
-			topP: number;
-		};
+		});
+
+		// Validate options parameter
+		validateNodeParameters(
+			options,
+			{
+				maxOutputTokens: { type: 'number', required: false },
+				temperature: { type: 'number', required: false },
+				topK: { type: 'number', required: false },
+				topP: { type: 'number', required: false },
+				thinkingBudget: { type: 'number', required: false },
+			},
+			this.getNode(),
+		);
 
 		const safetySettings = this.getNodeParameter(
 			'options.safetySettings.values',
 			itemIndex,
 			null,
-		) as SafetySetting[];
+		) as GoogleAISafetySetting[];
 
 		try {
-			const model = new ChatVertexAI({
+			const modelConfig: ChatVertexAIInput = {
 				authOptions: {
 					projectId,
 					credentials: {
@@ -186,7 +195,14 @@ export class LmChatGoogleVertex implements INodeType {
 
 					throw error;
 				}),
-			});
+			};
+
+			// Add thinkingBudget if specified
+			if (options.thinkingBudget !== undefined) {
+				modelConfig.thinkingBudget = options.thinkingBudget;
+			}
+
+			const model = new ChatVertexAI(modelConfig);
 
 			return {
 				response: model,