feat: Use Sonnet 4.5 for AI Workflow Builder (no-changelog) (#20351)

packages/@n8n/ai-workflow-builder.ee/evaluations/core/environment.ts

@@ -4,7 +4,7 @@ import { MemorySaver } from '@langchain/langgraph';
 import { Client } from 'langsmith/client';
 import type { INodeTypeDescription } from 'n8n-workflow';
 
-import { anthropicClaudeSonnet4 } from '../../src/llm-config.js';
+import { anthropicClaudeSonnet45 } from '../../src/llm-config.js';
 import { WorkflowBuilderAgent } from '../../src/workflow-builder-agent.js';
 import { loadNodesFromFile } from '../load-nodes.js';
 
@@ -25,7 +25,7 @@ export async function setupLLM(): Promise<BaseChatModel> {
 	if (!apiKey) {
 		throw new Error('N8N_AI_ANTHROPIC_KEY environment variable is required');
 	}
-	return await anthropicClaudeSonnet4({ apiKey });
+	return await anthropicClaudeSonnet45({ apiKey });
 }
 
 /**

packages/@n8n/ai-workflow-builder.ee/evaluations/utils/evaluation-helpers.ts

@@ -7,7 +7,7 @@ import type { INodeTypeDescription } from 'n8n-workflow';
 import { join } from 'path';
 import pc from 'picocolors';
 
-import { anthropicClaudeSonnet4 } from '../../src/llm-config';
+import { anthropicClaudeSonnet45 } from '../../src/llm-config';
 import type { ChatPayload } from '../../src/workflow-builder-agent';
 import { WorkflowBuilderAgent } from '../../src/workflow-builder-agent';
 import type { Violation } from '../types/evaluation';
@@ -23,7 +23,7 @@ export async function setupLLM(): Promise<BaseChatModel> {
 	if (!apiKey) {
 		throw new Error('N8N_AI_ANTHROPIC_KEY environment variable is required');
 	}
-	return await anthropicClaudeSonnet4({ apiKey });
+	return await anthropicClaudeSonnet45({ apiKey });
 }
 
 /**

packages/@n8n/ai-workflow-builder.ee/src/ai-workflow-builder-agent.service.ts

@@ -9,7 +9,7 @@ import { INodeTypes } from 'n8n-workflow';
 import type { IUser, INodeTypeDescription } from 'n8n-workflow';
 
 import { LLMServiceError } from '@/errors';
-import { anthropicClaudeSonnet4 } from '@/llm-config';
+import { anthropicClaudeSonnet45 } from '@/llm-config';
 import { SessionManagerService } from '@/session-manager.service';
 import { WorkflowBuilderAgent, type ChatPayload } from '@/workflow-builder-agent';
 
@@ -41,7 +41,7 @@ export class AiWorkflowBuilderService {
 		authHeaders?: Record<string, string>;
 		apiKey?: string;
 	} = {}): Promise<ChatAnthropic> {
-		return await anthropicClaudeSonnet4({
+		return await anthropicClaudeSonnet45({
 			baseUrl,
 			apiKey,
 			headers: {

packages/@n8n/ai-workflow-builder.ee/src/llm-config.ts

@@ -47,10 +47,10 @@ export const gpt41 = async (config: LLMProviderConfig) => {
 	});
 };
 
-export const anthropicClaudeSonnet4 = async (config: LLMProviderConfig) => {
+export const anthropicClaudeSonnet45 = async (config: LLMProviderConfig) => {
 	const { ChatAnthropic } = await import('@langchain/anthropic');
-	return new ChatAnthropic({
-		model: 'claude-sonnet-4-20250514',
+	const model = new ChatAnthropic({
+		model: 'claude-sonnet-4-5',
 		apiKey: config.apiKey,
 		temperature: 0,
 		maxTokens: MAX_OUTPUT_TOKENS,
@@ -59,4 +59,9 @@ export const anthropicClaudeSonnet4 = async (config: LLMProviderConfig) => {
 			defaultHeaders: config.headers,
 		},
 	});
+
+	// Remove Langchain default topP parameter since Sonnet 4.5 doesn't allow setting both temperature and topP
+	delete model.topP;
+
+	return model;
 };

packages/@n8n/ai-workflow-builder.ee/src/test/ai-workflow-builder-agent.service.test.ts

@@ -8,7 +8,7 @@ import type { IUser, INodeTypes, INodeTypeDescription } from 'n8n-workflow';
 
 import { AiWorkflowBuilderService } from '@/ai-workflow-builder-agent.service';
 import { LLMServiceError } from '@/errors';
-import { anthropicClaudeSonnet4 } from '@/llm-config';
+import { anthropicClaudeSonnet45 } from '@/llm-config';
 import { SessionManagerService } from '@/session-manager.service';
 import { formatMessages } from '@/utils/stream-processor';
 import { WorkflowBuilderAgent, type ChatPayload } from '@/workflow-builder-agent';
@@ -20,7 +20,7 @@ jest.mock('langsmith');
 jest.mock('@/workflow-builder-agent');
 jest.mock('@/session-manager.service');
 jest.mock('@/llm-config', () => ({
-	anthropicClaudeSonnet4: jest.fn(),
+	anthropicClaudeSonnet45: jest.fn(),
 }));
 jest.mock('@/utils/stream-processor', () => ({
 	formatMessages: jest.fn(),
@@ -36,8 +36,8 @@ const MockedSessionManagerService = SessionManagerService as jest.MockedClass<
 	typeof SessionManagerService
 >;
 
-const anthropicClaudeSonnet4Mock = anthropicClaudeSonnet4 as jest.MockedFunction<
-	typeof anthropicClaudeSonnet4
+const anthropicClaudeSonnet45Mock = anthropicClaudeSonnet45 as jest.MockedFunction<
+	typeof anthropicClaudeSonnet45
 >;
 const formatMessagesMock = formatMessages as jest.MockedFunction<typeof formatMessages>;
 
@@ -157,7 +157,7 @@ describe('AiWorkflowBuilderService', () => {
 			return mockAgent;
 		});
 
-		anthropicClaudeSonnet4Mock.mockResolvedValue(mockChatAnthropic);
+		anthropicClaudeSonnet45Mock.mockResolvedValue(mockChatAnthropic);
 
 		// Mock onCreditsUpdated callback
 		mockOnCreditsUpdated = jest.fn();
@@ -441,7 +441,7 @@ describe('AiWorkflowBuilderService', () => {
 
 		it('should throw LLMServiceError when model setup fails', async () => {
 			const testError = new Error('Model setup failed');
-			anthropicClaudeSonnet4Mock.mockRejectedValue(testError);
+			anthropicClaudeSonnet45Mock.mockRejectedValue(testError);
 
 			const generator = service.chat(mockPayload, mockUser);
 
@@ -450,7 +450,7 @@ describe('AiWorkflowBuilderService', () => {
 
 		it('should include error details in LLMServiceError', async () => {
 			const testError = new Error('Specific error message');
-			anthropicClaudeSonnet4Mock.mockRejectedValue(testError);
+			anthropicClaudeSonnet45Mock.mockRejectedValue(testError);
 
 			const generator = service.chat(mockPayload, mockUser);
 
@@ -473,7 +473,7 @@ describe('AiWorkflowBuilderService', () => {
 			const generator = serviceWithoutClient.chat(mockPayload, mockUser);
 			await generator.next();
 
-			expect(anthropicClaudeSonnet4Mock).toHaveBeenCalledWith({
+			expect(anthropicClaudeSonnet45Mock).toHaveBeenCalledWith({
 				baseUrl: undefined,
 				apiKey: 'test-env-key',
 				headers: {