feat(core): Implement partial execution of tool nodes (no-changelog) (#14939)

packages/cli/src/manual-execution.service.ts

@@ -6,6 +6,8 @@ import {
 	recreateNodeExecutionStack,
 	WorkflowExecute,
 	Logger,
+	isTool,
+	rewireGraph,
 } from 'n8n-core';
 import type {
 	IPinData,
@@ -107,6 +109,21 @@ export class ManualExecutionService {
 
 			const startNode = this.getExecutionStartNode(data, workflow);
 
+			if (data.destinationNode) {
+				const destinationNode = workflow.getNode(data.destinationNode);
+				a.ok(
+					destinationNode,
+					`Could not find a node named "${data.destinationNode}" in the workflow.`,
+				);
+
+				// Rewire graph to be able to execute the destination tool node
+				if (isTool(destinationNode, workflow.nodeTypes)) {
+					workflow = rewireGraph(destinationNode, DirectedGraph.fromWorkflow(workflow)).toWorkflow({
+						...workflow,
+					});
+				}
+			}
+
 			// Can execute without webhook so go on
 			const workflowExecute = new WorkflowExecute(additionalData, data.executionMode);
 

packages/core/src/execution-engine/__tests__/workflow-execute.test.ts

@@ -631,6 +631,64 @@ describe('WorkflowExecute', () => {
 				new DirectedGraph().addNode(orphan).toWorkflow({ ...workflow }),
 			);
 		});
+
+		//  ┌───────┐     ┌───────────┐
+		//  │trigger├────►│agentNode  │
+		//  └───────┘     └───────────┘
+		//                       │ ┌──────┐
+		//                       └─│ Tool │
+		//                         └──────┘
+		it('rewires graph for partial execution of tools', async () => {
+			// ARRANGE
+			const waitPromise = createDeferredPromise<IRun>();
+			const additionalData = Helpers.WorkflowExecuteAdditionalData(waitPromise);
+			const workflowExecute = new WorkflowExecute(additionalData, 'manual');
+			const nodeTypes = Helpers.NodeTypes();
+
+			const trigger = createNodeData({ name: 'trigger', type: 'n8n-nodes-base.manualTrigger' });
+			const tool = createNodeData({ name: 'tool', type: 'n8n-nodes-base.toolTest' });
+			const agentNode = createNodeData({ name: 'agent' });
+
+			const workflow = new DirectedGraph()
+				.addNodes(trigger, tool, agentNode)
+				.addConnections(
+					{ from: trigger, to: agentNode },
+					{ from: tool, to: agentNode, type: NodeConnectionTypes.AiTool },
+				)
+				.toWorkflow({ name: '', active: false, nodeTypes });
+			const pinData: IPinData = {};
+			const runData: IRunData = {
+				[trigger.name]: [toITaskData([{ data: { value: 1 } }])],
+			};
+			const dirtyNodeNames: string[] = [];
+
+			const processRunExecutionDataSpy = jest
+				.spyOn(workflowExecute, 'processRunExecutionData')
+				.mockImplementationOnce(jest.fn());
+
+			const expectedTool = {
+				...tool,
+				rewireOutputLogTo: NodeConnectionTypes.AiTool,
+			};
+
+			const expectedGraph = new DirectedGraph()
+				.addNodes(trigger, expectedTool)
+				.addConnections({ from: trigger, to: expectedTool })
+				.toWorkflow({ ...workflow });
+
+			// ACT
+			await workflowExecute.runPartialWorkflow2(
+				workflow,
+				runData,
+				pinData,
+				dirtyNodeNames,
+				tool.name,
+			);
+
+			// ASSERT
+			expect(processRunExecutionDataSpy).toHaveBeenCalledTimes(1);
+			expect(processRunExecutionDataSpy).toHaveBeenCalledWith(expectedGraph);
+		});
 	});
 
 	describe('checkReadyForExecution', () => {

packages/core/src/execution-engine/partial-execution-utils/__tests__/is-tool.test.ts

@@ -0,0 +1,51 @@
+import { mock } from 'jest-mock-extended';
+import { type INode, type INodeTypes, NodeConnectionTypes } from 'n8n-workflow';
+
+import { isTool } from '../is-tool';
+
+const mockNode = mock<INode>({ id: '1', type: 'n8n-nodes-base.openAi', typeVersion: 1 });
+const mockNodeTypes = mock<INodeTypes>();
+
+describe('isTool', () => {
+	it('should return true for a node with AiTool output', () => {
+		mockNodeTypes.getByNameAndVersion.mockReturnValue({
+			description: {
+				outputs: [NodeConnectionTypes.AiTool],
+				version: 0,
+				defaults: {
+					name: '',
+					color: '',
+				},
+				inputs: [NodeConnectionTypes.Main],
+				properties: [],
+				displayName: '',
+				name: '',
+				group: [],
+				description: '',
+			},
+		});
+		const result = isTool(mockNode, mockNodeTypes);
+		expect(result).toBe(true);
+	});
+
+	it('returns false for node with no AiTool output', () => {
+		mockNodeTypes.getByNameAndVersion.mockReturnValue({
+			description: {
+				outputs: [NodeConnectionTypes.Main],
+				version: 0,
+				defaults: {
+					name: '',
+					color: '',
+				},
+				inputs: [NodeConnectionTypes.Main],
+				properties: [],
+				displayName: '',
+				name: '',
+				group: [],
+				description: '',
+			},
+		});
+		const result = isTool(mockNode, mockNodeTypes);
+		expect(result).toBe(false);
+	});
+});

packages/core/src/execution-engine/partial-execution-utils/__tests__/rewire-graph.test.ts

@@ -0,0 +1,118 @@
+import { NodeConnectionTypes } from 'n8n-workflow';
+
+import { createNodeData } from './helpers';
+import { DirectedGraph } from '../directed-graph';
+import { rewireGraph } from '../rewire-graph';
+
+describe('rewireGraph()', () => {
+	it('rewires a simple graph with a tool node', () => {
+		const tool = createNodeData({ name: 'tool', type: 'n8n-nodes-base.ai-tool' });
+		const root = createNodeData({ name: 'root' });
+		const trigger = createNodeData({ name: 'trigger' });
+
+		const graph = new DirectedGraph();
+		graph.addNodes(trigger, root, tool);
+		graph.addConnections(
+			{ from: trigger, to: root, type: NodeConnectionTypes.Main },
+			{ from: tool, to: root, type: NodeConnectionTypes.AiTool },
+		);
+
+		const rewiredGraph = rewireGraph(tool, graph);
+
+		const toolConnections = rewiredGraph.getDirectParentConnections(tool);
+		expect(toolConnections).toHaveLength(1);
+		expect(toolConnections[0].from.name).toBe('trigger');
+		expect(toolConnections[0].type).toBe(NodeConnectionTypes.Main);
+
+		expect(rewiredGraph.hasNode(root.name)).toBe(false);
+	});
+
+	it('rewires all incoming connections of the root node to the tool', () => {
+		const tool = createNodeData({ name: 'tool', type: 'n8n-nodes-base.ai-tool' });
+		const root = createNodeData({ name: 'root' });
+		const trigger = createNodeData({ name: 'trigger' });
+		const secondNode = createNodeData({ name: 'secondNode' });
+		const thirdNode = createNodeData({ name: 'thirdNode' });
+
+		const graph = new DirectedGraph();
+		graph.addNodes(trigger, root, tool, secondNode, thirdNode);
+		graph.addConnections(
+			{ from: trigger, to: secondNode, type: NodeConnectionTypes.Main },
+			{ from: trigger, to: thirdNode, type: NodeConnectionTypes.Main },
+			{ from: tool, to: root, type: NodeConnectionTypes.AiTool },
+			{ from: secondNode, to: root, type: NodeConnectionTypes.Main },
+			{ from: thirdNode, to: root, type: NodeConnectionTypes.Main },
+		);
+
+		const rewiredGraph = rewireGraph(tool, graph);
+
+		const toolConnections = rewiredGraph.getDirectParentConnections(tool);
+		expect(toolConnections).toHaveLength(2);
+		expect(toolConnections.map((cn) => cn.from.name).sort()).toEqual(
+			['secondNode', 'thirdNode'].sort(),
+		);
+	});
+
+	it('ignores non-main connections when rewiring', () => {
+		const tool = createNodeData({ name: 'tool', type: 'n8n-nodes-base.ai-tool' });
+		const root = createNodeData({ name: 'root' });
+		const parent = createNodeData({ name: 'parent' });
+		const trigger = createNodeData({ name: 'trigger' });
+		const child = createNodeData({ name: 'child' });
+
+		const graph = new DirectedGraph();
+		graph.addNodes(trigger, root, tool, parent, child);
+		graph.addConnections(
+			{ from: trigger, to: root, type: NodeConnectionTypes.Main },
+			{ from: parent, to: root, type: NodeConnectionTypes.AiLanguageModel },
+			{ from: child, to: root, type: NodeConnectionTypes.AiTool },
+			{ from: tool, to: root, type: NodeConnectionTypes.AiTool },
+		);
+
+		const rewiredGraph = rewireGraph(tool, graph);
+
+		const toolConnections = rewiredGraph.getDirectParentConnections(tool);
+		expect(toolConnections).toHaveLength(1);
+		expect(toolConnections[0].type).toBe(NodeConnectionTypes.Main);
+	});
+
+	it('sets rewireOutputLogTo to AiTool on the tool node', () => {
+		const tool = createNodeData({ name: 'tool', type: 'n8n-nodes-base.ai-tool' });
+		const trigger = createNodeData({ name: 'trigger' });
+		const root = createNodeData({ name: 'root' });
+
+		const graph = new DirectedGraph();
+		graph.addNodes(trigger, root, tool);
+		graph.addConnections(
+			{ from: trigger, to: root, type: NodeConnectionTypes.Main },
+			{ from: tool, to: root, type: NodeConnectionTypes.AiTool },
+		);
+
+		rewireGraph(tool, graph);
+
+		expect(tool.rewireOutputLogTo).toBe(NodeConnectionTypes.AiTool);
+	});
+
+	it('fails when the tool has no incoming connections', () => {
+		const tool = createNodeData({ name: 'tool', type: 'n8n-nodes-base.ai-tool' });
+		const root = createNodeData({ name: 'root' });
+
+		const graph = new DirectedGraph();
+		graph.addNodes(root, tool);
+
+		expect(() => rewireGraph(tool, graph)).toThrow();
+	});
+
+	it('removes the root node from the graph', () => {
+		const tool = createNodeData({ name: 'tool', type: 'n8n-nodes-base.ai-tool' });
+		const root = createNodeData({ name: 'root' });
+
+		const graph = new DirectedGraph();
+		graph.addNodes(root, tool);
+		graph.addConnections({ from: tool, to: root, type: NodeConnectionTypes.AiTool });
+
+		const rewiredGraph = rewireGraph(tool, graph);
+
+		expect(rewiredGraph.hasNode(root.name)).toBe(false);
+	});
+});

packages/core/src/execution-engine/partial-execution-utils/index.ts

@@ -6,3 +6,5 @@ export { recreateNodeExecutionStack } from './recreate-node-execution-stack';
 export { cleanRunData } from './clean-run-data';
 export { handleCycles } from './handle-cycles';
 export { filterDisabledNodes } from './filter-disabled-nodes';
+export { isTool } from './is-tool';
+export { rewireGraph } from './rewire-graph';

packages/core/src/execution-engine/partial-execution-utils/is-tool.ts

@@ -0,0 +1,6 @@
+import { type INode, type INodeTypes, NodeConnectionTypes } from 'n8n-workflow';
+
+export function isTool(node: INode, nodeTypes: INodeTypes) {
+	const type = nodeTypes.getByNameAndVersion(node.type, node.typeVersion);
+	return type.description.outputs.includes(NodeConnectionTypes.AiTool);
+}

packages/core/src/execution-engine/partial-execution-utils/rewire-graph.ts

@@ -0,0 +1,29 @@
+import * as a from 'assert/strict';
+import { type INode, NodeConnectionTypes } from 'n8n-workflow';
+
+import { type DirectedGraph } from './directed-graph';
+
+export function rewireGraph(tool: INode, graph: DirectedGraph): DirectedGraph {
+	graph = graph.clone();
+	const children = graph.getChildren(tool);
+
+	a.ok(children.size > 0, 'Tool must be connected to a root node');
+
+	const rootNode = [...children][0];
+
+	a.ok(rootNode);
+
+	const allIncomingConnection = graph
+		.getDirectParentConnections(rootNode)
+		.filter((cn) => cn.type === NodeConnectionTypes.Main);
+
+	tool.rewireOutputLogTo = NodeConnectionTypes.AiTool;
+
+	for (const cn of allIncomingConnection) {
+		graph.addConnection({ from: cn.from, to: tool });
+	}
+
+	graph.removeNode(rootNode);
+
+	return graph;
+}

packages/core/src/execution-engine/workflow-execute.ts

@@ -68,6 +68,8 @@ import {
 	recreateNodeExecutionStack,
 	handleCycles,
 	filterDisabledNodes,
+	rewireGraph,
+	isTool,
 } from './partial-execution-utils';
 import { RoutingNode } from './routing-node';
 import { TriggersAndPollers } from './triggers-and-pollers';
@@ -356,6 +358,11 @@ export class WorkflowExecute {
 
 		let graph = DirectedGraph.fromWorkflow(workflow);
 
+		// Partial execution of nodes as tools
+		if (isTool(destination, workflow.nodeTypes)) {
+			graph = rewireGraph(destination, graph);
+			workflow = graph.toWorkflow({ ...workflow });
+		} else {
 			// Edge Case 1:
 			// Support executing a single node that is not connected to a trigger
 			const destinationHasNoParents = graph.getDirectParentConnections(destination).length === 0;
@@ -392,6 +399,7 @@ export class WorkflowExecute {
 
 				return this.processRunExecutionData(graph.toWorkflow({ ...workflow }));
 			}
+		}
 
 		// 1. Find the Trigger
 		const trigger = findTriggerForPartialExecution(workflow, destinationNodeName, runData);
@@ -1704,6 +1712,13 @@ export class WorkflowExecute {
 						main: nodeSuccessData,
 					} as ITaskDataConnections;
 
+					// Rewire output data log to the given connectionType
+					if (executionNode.rewireOutputLogTo) {
+						taskData.data = {
+							[executionNode.rewireOutputLogTo]: nodeSuccessData,
+						} as ITaskDataConnections;
+					}
+
 					this.runExecutionData.resultData.runData[executionNode.name].push(taskData);
 
 					if (this.runExecutionData.waitTill) {

packages/core/test/helpers/constants.ts

@@ -43,6 +43,25 @@ export const predefinedNodesTypes: INodeTypeData = {
 		type: new SplitInBatches(),
 		sourcePath: '',
 	},
+	'n8n-nodes-base.toolTest': {
+		sourcePath: '',
+		type: {
+			description: {
+				displayName: 'Test tool',
+				name: 'toolTest',
+				group: ['transform'],
+				version: 1,
+				description: 'Test tool',
+				inputs: [],
+				defaults: {
+					name: 'Test Tool',
+					color: '#0000FF',
+				},
+				outputs: [NodeConnectionTypes.AiTool],
+				properties: [],
+			},
+		},
+	},
 	'n8n-nodes-base.versionTest': {
 		sourcePath: '',
 		type: {

packages/workflow/src/Interfaces.ts

@@ -1135,6 +1135,7 @@ export interface INode {
 	credentials?: INodeCredentials;
 	webhookId?: string;
 	extendsCredential?: string;
+	rewireOutputLogTo?: NodeConnectionType;
 }
 
 export interface IPinData {