fix(Reranker Cohere Node): Add 'Top N' parameter to control document return count (#17921)

packages/@n8n/nodes-langchain/nodes/rerankers/RerankerCohere/RerankerCohere.node.ts

@@ -70,16 +70,26 @@ export class RerankerCohere implements INodeType {
 					},
 				],
 			},
+			{
+				displayName: 'Top N',
+				name: 'topN',
+				type: 'number',
+				description: 'The maximum number of documents to return after reranking',
+				default: 3,
+			},
 		],
 	};
 
 	async supplyData(this: ISupplyDataFunctions, itemIndex: number): Promise<SupplyData> {
 		this.logger.debug('Supply data for reranking Cohere');
 		const modelName = this.getNodeParameter('modelName', itemIndex, 'rerank-v3.5') as string;
+		const topN = this.getNodeParameter('topN', itemIndex, 3) as number;
 		const credentials = await this.getCredentials<{ apiKey: string }>('cohereApi');
+
 		const reranker = new CohereRerank({
 			apiKey: credentials.apiKey,
 			model: modelName,
+			topN,
 		});
 
 		return {

packages/@n8n/nodes-langchain/nodes/rerankers/RerankerCohere/test/RerankerCohere.node.test.ts

@@ -55,7 +55,9 @@ describe('RerankerCohere', () => {
 	it('should create CohereRerank with default model and return wrapped instance', async () => {
 		// Setup mocks
 		const mockCredentials = { apiKey: 'test-api-key' };
-		(mockSupplyDataFunctions.getNodeParameter as jest.Mock).mockReturnValue('rerank-v3.5');
+		(mockSupplyDataFunctions.getNodeParameter as jest.Mock)
+			.mockReturnValueOnce('rerank-v3.5') // modelName
+			.mockReturnValueOnce(3); // topN (default)
 		(mockSupplyDataFunctions.getCredentials as jest.Mock).mockResolvedValue(mockCredentials);
 
 		// Execute
@@ -66,10 +68,12 @@ describe('RerankerCohere', () => {
 			0,
 			'rerank-v3.5',
 		);
+		expect(mockSupplyDataFunctions.getNodeParameter).toHaveBeenCalledWith('topN', 0, 3);
 		expect(mockSupplyDataFunctions.getCredentials).toHaveBeenCalledWith('cohereApi');
 		expect(CohereRerank).toHaveBeenCalledWith({
 			apiKey: 'test-api-key',
 			model: 'rerank-v3.5',
+			topN: 3,
 		});
 		expect(logWrapper).toHaveBeenCalledWith(mockCohereRerank, mockSupplyDataFunctions);
 		expect(result.response).toEqual({ logWrapped: mockCohereRerank });
@@ -78,9 +82,9 @@ describe('RerankerCohere', () => {
 	it('should create CohereRerank with custom model', async () => {
 		// Setup mocks
 		const mockCredentials = { apiKey: 'custom-api-key' };
-		(mockSupplyDataFunctions.getNodeParameter as jest.Mock).mockReturnValue(
+		(mockSupplyDataFunctions.getNodeParameter as jest.Mock)
-			'rerank-multilingual-v3.0',
+			.mockReturnValueOnce('rerank-multilingual-v3.0') // modelName
-		);
+			.mockReturnValueOnce(3); // topN (default)
 		(mockSupplyDataFunctions.getCredentials as jest.Mock).mockResolvedValue(mockCredentials);
 
 		// Execute
@@ -90,13 +94,16 @@ describe('RerankerCohere', () => {
 		expect(CohereRerank).toHaveBeenCalledWith({
 			apiKey: 'custom-api-key',
 			model: 'rerank-multilingual-v3.0',
+			topN: 3,
 		});
 	});
 
 	it('should handle different item indices', async () => {
 		// Setup mocks
 		const mockCredentials = { apiKey: 'test-api-key' };
-		(mockSupplyDataFunctions.getNodeParameter as jest.Mock).mockReturnValue('rerank-english-v3.0');
+		(mockSupplyDataFunctions.getNodeParameter as jest.Mock)
+			.mockReturnValueOnce('rerank-english-v3.0') // modelName
+			.mockReturnValueOnce(3); // topN (default)
 		(mockSupplyDataFunctions.getCredentials as jest.Mock).mockResolvedValue(mockCredentials);
 
 		// Execute with different item index
@@ -108,11 +115,14 @@ describe('RerankerCohere', () => {
 			2,
 			'rerank-v3.5',
 		);
+		expect(mockSupplyDataFunctions.getNodeParameter).toHaveBeenCalledWith('topN', 2, 3);
 	});
 
 	it('should throw error when credentials are missing', async () => {
 		// Setup mocks
-		(mockSupplyDataFunctions.getNodeParameter as jest.Mock).mockReturnValue('rerank-v3.5');
+		(mockSupplyDataFunctions.getNodeParameter as jest.Mock)
+			.mockReturnValueOnce('rerank-v3.5') // modelName
+			.mockReturnValueOnce(3); // topN (default)
 		(mockSupplyDataFunctions.getCredentials as jest.Mock).mockRejectedValue(
 			new Error('Missing credentials'),
 		);
@@ -126,7 +136,9 @@ describe('RerankerCohere', () => {
 	it('should use fallback model when parameter is not provided', async () => {
 		// Setup mocks - getNodeParameter returns the fallback value
 		const mockCredentials = { apiKey: 'test-api-key' };
-		(mockSupplyDataFunctions.getNodeParameter as jest.Mock).mockReturnValue('rerank-v3.5'); // fallback value
+		(mockSupplyDataFunctions.getNodeParameter as jest.Mock)
+			.mockReturnValueOnce('rerank-v3.5') // modelName (fallback value)
+			.mockReturnValueOnce(3); // topN (fallback value)
 		(mockSupplyDataFunctions.getCredentials as jest.Mock).mockResolvedValue(mockCredentials);
 
 		// Execute
@@ -136,6 +148,65 @@ describe('RerankerCohere', () => {
 		expect(CohereRerank).toHaveBeenCalledWith({
 			apiKey: 'test-api-key',
 			model: 'rerank-v3.5',
+			topN: 3,
+		});
+	});
+
+	it('should create CohereRerank with custom topN value', async () => {
+		// Setup mocks
+		const mockCredentials = { apiKey: 'test-api-key' };
+		(mockSupplyDataFunctions.getNodeParameter as jest.Mock)
+			.mockReturnValueOnce('rerank-v3.5') // modelName
+			.mockReturnValueOnce(10); // topN (custom value)
+		(mockSupplyDataFunctions.getCredentials as jest.Mock).mockResolvedValue(mockCredentials);
+
+		// Execute
+		await rerankerCohere.supplyData.call(mockSupplyDataFunctions, 0);
+
+		// Verify custom topN is used
+		expect(CohereRerank).toHaveBeenCalledWith({
+			apiKey: 'test-api-key',
+			model: 'rerank-v3.5',
+			topN: 10,
+		});
+		expect(mockSupplyDataFunctions.getNodeParameter).toHaveBeenCalledWith('topN', 0, 3);
+	});
+
+	it('should create CohereRerank with topN value of 1', async () => {
+		// Setup mocks
+		const mockCredentials = { apiKey: 'test-api-key' };
+		(mockSupplyDataFunctions.getNodeParameter as jest.Mock)
+			.mockReturnValueOnce('rerank-english-v3.0') // modelName
+			.mockReturnValueOnce(1); // topN (edge case value)
+		(mockSupplyDataFunctions.getCredentials as jest.Mock).mockResolvedValue(mockCredentials);
+
+		// Execute
+		await rerankerCohere.supplyData.call(mockSupplyDataFunctions, 0);
+
+		// Verify edge case topN is used
+		expect(CohereRerank).toHaveBeenCalledWith({
+			apiKey: 'test-api-key',
+			model: 'rerank-english-v3.0',
+			topN: 1,
+		});
+	});
+
+	it('should create CohereRerank with large topN value', async () => {
+		// Setup mocks
+		const mockCredentials = { apiKey: 'test-api-key' };
+		(mockSupplyDataFunctions.getNodeParameter as jest.Mock)
+			.mockReturnValueOnce('rerank-multilingual-v3.0') // modelName
+			.mockReturnValueOnce(100); // topN (large value)
+		(mockSupplyDataFunctions.getCredentials as jest.Mock).mockResolvedValue(mockCredentials);
+
+		// Execute
+		await rerankerCohere.supplyData.call(mockSupplyDataFunctions, 0);
+
+		// Verify large topN is used
+		expect(CohereRerank).toHaveBeenCalledWith({
+			apiKey: 'test-api-key',
+			model: 'rerank-multilingual-v3.0',
+			topN: 100,
 		});
 	});
 });