From 2fff38827ae0e61bad951bfe36a5c40ca9e86aac Mon Sep 17 00:00:00 2001
From: yehorkardash <yehor.kardash@n8n.io>
Date: Wed, 22 Oct 2025 16:39:08 +0300
Subject: [PATCH] fix(OpenAI Node): Don't include function calls when
 conversation id is used (#21047)

---
 .../actions/text/response.operation.test.ts   | 102 ++++++++++++++++++
 .../v2/actions/text/response.operation.ts     |  16 ++-
 2 files changed, 108 insertions(+), 10 deletions(-)

diff --git a/packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/test/v2/actions/text/response.operation.test.ts b/packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/test/v2/actions/text/response.operation.test.ts
index d64921187dc..7fa02f5093c 100644
--- a/packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/test/v2/actions/text/response.operation.test.ts
+++ b/packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/test/v2/actions/text/response.operation.test.ts
@@ -522,6 +522,108 @@ describe('OpenAI Response Operation', () => {
 
 			expect(mockTool.invoke).toHaveBeenCalledWith('test input');
 			expect(mockApiRequest).toHaveBeenCalledTimes(2);
+			expect(mockApiRequest).toHaveBeenNthCalledWith(2, 'POST', '/responses', {
+				body: {
+					model: 'gpt-4o',
+					input: [
+						{
+							type: 'reasoning',
+							content: 'I need to use the test tool to get information',
+						},
+						{
+							type: 'function_call',
+							call_id: 'call_123',
+							name: 'test_tool',
+							arguments: JSON.stringify({ input: 'test input' }),
+						},
+						{
+							call_id: 'call_123',
+							output: 'Tool response',
+							type: 'function_call_output',
+						},
+					],
+					tools: [{ name: 'test_tool', type: 'function', parameters: {}, strict: false }],
+				},
+			});
+			expect(result).toEqual([
+				{
+					json: finalResponse,
+					pairedItem: { item: 0 },
+				},
+			]);
+		});
+
+		it('should not include function_call or reasoning items in the request if there is a conversation', async () => {
+			const mockTool = {
+				name: 'test_tool',
+				invoke: jest.fn().mockResolvedValue('Tool response'),
+				schema: {
+					typeName: 'ZodObject',
+					_def: { typeName: 'ZodObject', shape: () => ({}) },
+					parse: jest.fn(),
+					safeParse: jest.fn(),
+				},
+				call: jest.fn(),
+				description: 'Test tool',
+				returnDirect: false,
+			} as any;
+
+			const initialResponse = {
+				id: 'resp_123',
+				status: 'completed',
+				output: [
+					{
+						type: 'reasoning',
+						content: 'I need to use the test tool to get information',
+					},
+					{
+						type: 'function_call',
+						call_id: 'call_123',
+						name: 'test_tool',
+						arguments: JSON.stringify({ input: 'test input' }),
+					},
+				],
+			};
+
+			const finalResponse = {
+				id: 'resp_123',
+				status: 'completed',
+				output: [
+					{
+						type: 'message',
+						role: 'assistant',
+						content: [{ type: 'output_text', text: 'Final response' }],
+					},
+				],
+			};
+
+			mockGetConnectedTools.mockResolvedValue([mockTool]);
+			mockCreateRequest.mockResolvedValue({
+				model: 'gpt-4o',
+				input: [],
+				tools: [{ name: 'test_tool', type: 'function', parameters: {}, strict: false }],
+				conversation: 'conv_123',
+			});
+			mockApiRequest.mockResolvedValueOnce(initialResponse).mockResolvedValueOnce(finalResponse);
+
+			const result = await execute.call(mockExecuteFunctions, 0);
+
+			expect(mockTool.invoke).toHaveBeenCalledWith('test input');
+			expect(mockApiRequest).toHaveBeenCalledTimes(2);
+			expect(mockApiRequest).toHaveBeenNthCalledWith(2, 'POST', '/responses', {
+				body: {
+					model: 'gpt-4o',
+					input: [
+						{
+							call_id: 'call_123',
+							output: 'Tool response',
+							type: 'function_call_output',
+						},
+					],
+					tools: [{ name: 'test_tool', type: 'function', parameters: {}, strict: false }],
+					conversation: 'conv_123',
+				},
+			});
 			expect(result).toEqual([
 				{
 					json: finalResponse,
diff --git a/packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/v2/actions/text/response.operation.ts b/packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/v2/actions/text/response.operation.ts
index ad4c4478700..8bfb1039169 100644
--- a/packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/v2/actions/text/response.operation.ts
+++ b/packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/v2/actions/text/response.operation.ts
@@ -706,7 +706,6 @@ export async function execute(this: IExecuteFunctions, i: number): Promise<INode
 
 	const hasFunctionCall = () => toolCalls.some((item) => item.type === 'function_call');
 
-	const answeredToolCalls = new Set<string>();
 	let currentIteration = 1;
 	// make sure there's actually a function call to answer
 	while (toolCalls.length && hasFunctionCall()) {
@@ -714,14 +713,13 @@ export async function execute(this: IExecuteFunctions, i: number): Promise<INode
 			break;
 		}
 
+		// if there's conversation, we don't need to include function_call or reasoning items in the request
+		// if we include them, OpenAI will throw "Duplicate item with id" error
+		if (!body.conversation) {
+			body.input.push.apply(body.input, toolCalls);
+		}
+
 		for (const item of toolCalls) {
-			if (item.type === 'function_call' && answeredToolCalls.has(item.call_id)) {
-				continue;
-			}
-
-			// include function_call or reasoning items in the request
-			body.input.push(item);
-
 			if (item.type === 'function_call') {
 				const functionName = item.name;
 				const functionArgs = item.arguments;
@@ -745,8 +743,6 @@ export async function execute(this: IExecuteFunctions, i: number): Promise<INode
 					call_id: callId,
 					output: functionResponse,
 				});
-
-				answeredToolCalls.add(callId);
 			}
 		}