Merge pull request #403 from czlonkowski/feat/workflow-activation-operations

CHANGELOG.md

@@ -7,6 +7,111 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.22.11] - 2025-01-06
+
+### ✨ New Features
+
+**Issue #399: Workflow Activation via Diff Operations**
+
+Added workflow activation and deactivation as diff operations in `n8n_update_partial_workflow`, using n8n's dedicated API endpoints.
+
+#### Problem
+
+The n8n API provides dedicated `POST /workflows/{id}/activate` and `POST /workflows/{id}/deactivate` endpoints, but these were not accessible through n8n-mcp. Users could not programmatically control workflow activation status, forcing manual activation through the n8n UI.
+
+#### Solution
+
+Implemented activation/deactivation as diff operations, following the established pattern of metadata operations like `updateSettings` and `updateName`. This keeps the tool count manageable (40 tools, not 42) and provides a consistent interface.
+
+#### Changes
+
+**API Client** (`src/services/n8n-api-client.ts`):
+- Added `activateWorkflow(id: string): Promise<Workflow>` method
+- Added `deactivateWorkflow(id: string): Promise<Workflow>` method
+- Both use POST requests to dedicated n8n API endpoints
+
+**Diff Engine Types** (`src/types/workflow-diff.ts`):
+- Added `ActivateWorkflowOperation` interface
+- Added `DeactivateWorkflowOperation` interface
+- Added `shouldActivate` and `shouldDeactivate` flags to `WorkflowDiffResult`
+- Increased supported operations from 15 to 17
+
+**Diff Engine** (`src/services/workflow-diff-engine.ts`):
+- Added validation for activation (requires activatable triggers)
+- Added operation application logic
+- Transfers activation intent from workflow object to result
+- Validates workflow has activatable triggers (webhook, schedule, etc.)
+- Rejects workflows with only `executeWorkflowTrigger` (cannot activate)
+
+**Handler** (`src/mcp/handlers-workflow-diff.ts`):
+- Checks `shouldActivate` and `shouldDeactivate` flags after workflow update
+- Calls appropriate API methods
+- Includes activation status in response message and details
+- Handles activation/deactivation errors gracefully
+
+**Documentation** (`src/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.ts`):
+- Updated operation count from 15 to 17
+- Added "Workflow Activation Operations" section
+- Added activation tip to essentials
+
+**Tool Registration** (`src/mcp/handlers-n8n-manager.ts`):
+- Removed "Cannot activate/deactivate workflows via API" from limitations
+
+#### Usage
+
+```javascript
+// Activate workflow
+n8n_update_partial_workflow({
+  id: "workflow_id",
+  operations: [{
+    type: "activateWorkflow"
+  }]
+})
+
+// Deactivate workflow
+n8n_update_partial_workflow({
+  id: "workflow_id",
+  operations: [{
+    type: "deactivateWorkflow"
+  }]
+})
+
+// Combine with other operations
+n8n_update_partial_workflow({
+  id: "workflow_id",
+  operations: [
+    {type: "updateNode", nodeId: "abc", updates: {name: "Updated"}},
+    {type: "activateWorkflow"}
+  ]
+})
+```
+
+#### Validation
+
+- **Activation**: Requires at least one enabled activatable trigger node
+- **Deactivation**: Always valid
+- **Error Handling**: Clear messages when activation fails due to missing triggers
+- **Trigger Detection**: Uses `isActivatableTrigger()` utility (Issue #351 compliance)
+
+#### Benefits
+
+- ✅ Consistent with existing architecture (metadata operations pattern)
+- ✅ Keeps tool count at 40 (not 42)
+- ✅ Atomic operations - activation happens after workflow update
+- ✅ Proper validation - prevents activation without triggers
+- ✅ Clear error messages - guides users on trigger requirements
+- ✅ Works with other operations - can update and activate in one call
+
+#### Credits
+
+- **@ArtemisAI** - Original investigation and API endpoint discovery
+- **@cmj-hub** - Implementation attempt and PR contribution
+- Architectural guidance from project maintainer
+
+Resolves #399
+
+Conceived by Romuald Członkowski - [www.aiadvisors.pl/en](https://www.aiadvisors.pl/en)
+
 ## [2.22.10] - 2025-11-04
 
 ### 🐛 Bug Fixes

package.json

@@ -1,6 +1,6 @@
 {
   "name": "n8n-mcp",
-  "version": "2.22.10",
+  "version": "2.22.11",
   "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",

package.runtime.json

@@ -1,6 +1,6 @@
 {
   "name": "n8n-mcp-runtime",
-  "version": "2.22.10",
+  "version": "2.22.11",
   "description": "n8n MCP Server Runtime Dependencies Only",
   "private": true,
   "dependencies": {

src/mcp/handlers-n8n-manager.ts

@@ -1561,7 +1561,6 @@ export async function handleListAvailableTools(context?: InstanceContext): Promi
         maxRetries: config.maxRetries
       } : null,
       limitations: [
-        'Cannot activate/deactivate workflows via API',
         'Cannot execute workflows directly (must use webhooks)',
         'Cannot stop running executions',
         'Tags and credentials have limited API support'

src/mcp/handlers-workflow-diff.ts

@@ -245,15 +245,52 @@ export async function handleUpdatePartialWorkflow(
     // Update workflow via API
     try {
       const updatedWorkflow = await client.updateWorkflow(input.id, diffResult.workflow!);
-      
+
+      // Handle activation/deactivation if requested
+      let finalWorkflow = updatedWorkflow;
+      let activationMessage = '';
+
+      if (diffResult.shouldActivate) {
+        try {
+          finalWorkflow = await client.activateWorkflow(input.id);
+          activationMessage = ' Workflow activated.';
+        } catch (activationError) {
+          logger.error('Failed to activate workflow after update', activationError);
+          return {
+            success: false,
+            error: 'Workflow updated successfully but activation failed',
+            details: {
+              workflowUpdated: true,
+              activationError: activationError instanceof Error ? activationError.message : 'Unknown error'
+            }
+          };
+        }
+      } else if (diffResult.shouldDeactivate) {
+        try {
+          finalWorkflow = await client.deactivateWorkflow(input.id);
+          activationMessage = ' Workflow deactivated.';
+        } catch (deactivationError) {
+          logger.error('Failed to deactivate workflow after update', deactivationError);
+          return {
+            success: false,
+            error: 'Workflow updated successfully but deactivation failed',
+            details: {
+              workflowUpdated: true,
+              deactivationError: deactivationError instanceof Error ? deactivationError.message : 'Unknown error'
+            }
+          };
+        }
+      }
+
       return {
         success: true,
-        data: updatedWorkflow,
-        message: `Workflow "${updatedWorkflow.name}" updated successfully. Applied ${diffResult.operationsApplied} operations.`,
+        data: finalWorkflow,
+        message: `Workflow "${finalWorkflow.name}" updated successfully. Applied ${diffResult.operationsApplied} operations.${activationMessage}`,
         details: {
           operationsApplied: diffResult.operationsApplied,
-          workflowId: updatedWorkflow.id,
-          workflowName: updatedWorkflow.name,
+          workflowId: finalWorkflow.id,
+          workflowName: finalWorkflow.name,
+          active: finalWorkflow.active,
           applied: diffResult.applied,
           failed: diffResult.failed,
           errors: diffResult.errors,

src/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.ts

@@ -4,7 +4,7 @@ export const n8nUpdatePartialWorkflowDoc: ToolDocumentation = {
   name: 'n8n_update_partial_workflow',
   category: 'workflow_management',
   essentials: {
-    description: 'Update workflow incrementally with diff operations. Types: addNode, removeNode, updateNode, moveNode, enable/disableNode, addConnection, removeConnection, rewireConnection, cleanStaleConnections, replaceConnections, updateSettings, updateName, add/removeTag. Supports smart parameters (branch, case) for multi-output nodes. Full support for AI connections (ai_languageModel, ai_tool, ai_memory, ai_embedding, ai_vectorStore, ai_document, ai_textSplitter, ai_outputParser).',
+    description: 'Update workflow incrementally with diff operations. Types: addNode, removeNode, updateNode, moveNode, enable/disableNode, addConnection, removeConnection, rewireConnection, cleanStaleConnections, replaceConnections, updateSettings, updateName, add/removeTag, activateWorkflow, deactivateWorkflow. Supports smart parameters (branch, case) for multi-output nodes. Full support for AI connections (ai_languageModel, ai_tool, ai_memory, ai_embedding, ai_vectorStore, ai_document, ai_textSplitter, ai_outputParser).',
     keyParameters: ['id', 'operations', 'continueOnError'],
     example: 'n8n_update_partial_workflow({id: "wf_123", operations: [{type: "rewireConnection", source: "IF", from: "Old", to: "New", branch: "true"}]})',
     performance: 'Fast (50-200ms)',
@@ -19,11 +19,12 @@ export const n8nUpdatePartialWorkflowDoc: ToolDocumentation = {
       'For AI connections, specify sourceOutput type (ai_languageModel, ai_tool, etc.)',
       'Batch AI component connections for atomic updates',
       'Auto-sanitization: ALL nodes auto-fixed during updates (operator structures, missing metadata)',
-      'Node renames automatically update all connection references - no manual connection operations needed'
+      'Node renames automatically update all connection references - no manual connection operations needed',
+      'Activate/deactivate workflows: Use activateWorkflow/deactivateWorkflow operations (requires activatable triggers like webhook/schedule)'
     ]
   },
   full: {
-    description: `Updates workflows using surgical diff operations instead of full replacement. Supports 15 operation types for precise modifications. Operations are validated and applied atomically by default - all succeed or none are applied.
+    description: `Updates workflows using surgical diff operations instead of full replacement. Supports 17 operation types for precise modifications. Operations are validated and applied atomically by default - all succeed or none are applied.
 
 ## Available Operations:
 
@@ -48,6 +49,10 @@ export const n8nUpdatePartialWorkflowDoc: ToolDocumentation = {
 - **addTag**: Add a workflow tag
 - **removeTag**: Remove a workflow tag
 
+### Workflow Activation Operations (2 types):
+- **activateWorkflow**: Activate the workflow to enable automatic execution via triggers
+- **deactivateWorkflow**: Deactivate the workflow to prevent automatic execution
+
 ## Smart Parameters for Multi-Output Nodes
 
 For **IF nodes**, use semantic 'branch' parameter instead of technical sourceIndex:

src/services/n8n-api-client.ts

@@ -170,6 +170,24 @@ export class N8nApiClient {
     }
   }
 
+  async activateWorkflow(id: string): Promise<Workflow> {
+    try {
+      const response = await this.client.post(`/workflows/${id}/activate`);
+      return response.data;
+    } catch (error) {
+      throw handleN8nApiError(error);
+    }
+  }
+
+  async deactivateWorkflow(id: string): Promise<Workflow> {
+    try {
+      const response = await this.client.post(`/workflows/${id}/deactivate`);
+      return response.data;
+    } catch (error) {
+      throw handleN8nApiError(error);
+    }
+  }
+
   /**
    * Lists workflows from n8n instance.
    *

src/services/workflow-diff-engine.ts

@@ -25,6 +25,8 @@ import {
   UpdateNameOperation,
   AddTagOperation,
   RemoveTagOperation,
+  ActivateWorkflowOperation,
+  DeactivateWorkflowOperation,
   CleanStaleConnectionsOperation,
   ReplaceConnectionsOperation
 } from '../types/workflow-diff';
@@ -32,6 +34,7 @@ import { Workflow, WorkflowNode, WorkflowConnection } from '../types/n8n-api';
 import { Logger } from '../utils/logger';
 import { validateWorkflowNode, validateWorkflowConnections } from './n8n-validation';
 import { sanitizeNode, sanitizeWorkflowNodes } from './node-sanitizer';
+import { isActivatableTrigger } from '../utils/node-type-utils';
 
 const logger = new Logger({ prefix: '[WorkflowDiffEngine]' });
 
@@ -214,12 +217,23 @@ export class WorkflowDiffEngine {
         }
 
         const operationsApplied = request.operations.length;
+
+        // Extract activation flags from workflow object
+        const shouldActivate = (workflowCopy as any)._shouldActivate === true;
+        const shouldDeactivate = (workflowCopy as any)._shouldDeactivate === true;
+
+        // Clean up temporary flags
+        delete (workflowCopy as any)._shouldActivate;
+        delete (workflowCopy as any)._shouldDeactivate;
+
         return {
           success: true,
           workflow: workflowCopy,
           operationsApplied,
           message: `Successfully applied ${operationsApplied} operations (${nodeOperations.length} node ops, ${otherOperations.length} other ops)`,
-          warnings: this.warnings.length > 0 ? this.warnings : undefined
+          warnings: this.warnings.length > 0 ? this.warnings : undefined,
+          shouldActivate: shouldActivate || undefined,
+          shouldDeactivate: shouldDeactivate || undefined
         };
       }
     } catch (error) {
@@ -262,6 +276,10 @@ export class WorkflowDiffEngine {
       case 'addTag':
       case 'removeTag':
         return null; // These are always valid
+      case 'activateWorkflow':
+        return this.validateActivateWorkflow(workflow, operation);
+      case 'deactivateWorkflow':
+        return this.validateDeactivateWorkflow(workflow, operation);
       case 'cleanStaleConnections':
         return this.validateCleanStaleConnections(workflow, operation);
       case 'replaceConnections':
@@ -315,6 +333,12 @@ export class WorkflowDiffEngine {
       case 'removeTag':
         this.applyRemoveTag(workflow, operation);
         break;
+      case 'activateWorkflow':
+        this.applyActivateWorkflow(workflow, operation);
+        break;
+      case 'deactivateWorkflow':
+        this.applyDeactivateWorkflow(workflow, operation);
+        break;
       case 'cleanStaleConnections':
         this.applyCleanStaleConnections(workflow, operation);
         break;
@@ -847,13 +871,46 @@ export class WorkflowDiffEngine {
 
   private applyRemoveTag(workflow: Workflow, operation: RemoveTagOperation): void {
     if (!workflow.tags) return;
-    
+
     const index = workflow.tags.indexOf(operation.tag);
     if (index !== -1) {
       workflow.tags.splice(index, 1);
     }
   }
 
+  // Workflow activation operation validators
+  private validateActivateWorkflow(workflow: Workflow, operation: ActivateWorkflowOperation): string | null {
+    // Check if workflow has at least one activatable trigger
+    // Issue #351: executeWorkflowTrigger cannot activate workflows
+    const activatableTriggers = workflow.nodes.filter(
+      node => !node.disabled && isActivatableTrigger(node.type)
+    );
+
+    if (activatableTriggers.length === 0) {
+      return 'Cannot activate workflow: No activatable trigger nodes found. Workflows must have at least one enabled trigger node (webhook, schedule, email, etc.). Note: executeWorkflowTrigger cannot activate workflows as they can only be invoked by other workflows.';
+    }
+
+    return null;
+  }
+
+  private validateDeactivateWorkflow(workflow: Workflow, operation: DeactivateWorkflowOperation): string | null {
+    // Deactivation is always valid - any workflow can be deactivated
+    return null;
+  }
+
+  // Workflow activation operation appliers
+  private applyActivateWorkflow(workflow: Workflow, operation: ActivateWorkflowOperation): void {
+    // Set flag in workflow object to indicate activation intent
+    // The handler will call the API method after workflow update
+    (workflow as any)._shouldActivate = true;
+  }
+
+  private applyDeactivateWorkflow(workflow: Workflow, operation: DeactivateWorkflowOperation): void {
+    // Set flag in workflow object to indicate deactivation intent
+    // The handler will call the API method after workflow update
+    (workflow as any)._shouldDeactivate = true;
+  }
+
   // Connection cleanup operation validators
   private validateCleanStaleConnections(workflow: Workflow, operation: CleanStaleConnectionsOperation): string | null {
     // This operation is always valid - it just cleans up what it finds

src/types/workflow-diff.ts

@@ -114,6 +114,16 @@ export interface RemoveTagOperation extends DiffOperation {
   tag: string;
 }
 
+export interface ActivateWorkflowOperation extends DiffOperation {
+  type: 'activateWorkflow';
+  // No additional properties needed - just activates the workflow
+}
+
+export interface DeactivateWorkflowOperation extends DiffOperation {
+  type: 'deactivateWorkflow';
+  // No additional properties needed - just deactivates the workflow
+}
+
 // Connection Cleanup Operations
 export interface CleanStaleConnectionsOperation extends DiffOperation {
   type: 'cleanStaleConnections';
@@ -148,6 +158,8 @@ export type WorkflowDiffOperation =
   | UpdateNameOperation
   | AddTagOperation
   | RemoveTagOperation
+  | ActivateWorkflowOperation
+  | DeactivateWorkflowOperation
   | CleanStaleConnectionsOperation
   | ReplaceConnectionsOperation;
 
@@ -176,6 +188,8 @@ export interface WorkflowDiffResult {
   applied?: number[]; // Indices of successfully applied operations (when continueOnError is true)
   failed?: number[]; // Indices of failed operations (when continueOnError is true)
   staleConnectionsRemoved?: Array<{ from: string; to: string }>; // For cleanStaleConnections operation
+  shouldActivate?: boolean; // Flag to activate workflow after update (for activateWorkflow operation)
+  shouldDeactivate?: boolean; // Flag to deactivate workflow after update (for deactivateWorkflow operation)
 }
 
 // Helper type for node reference (supports both ID and name)

tests/integration/n8n-api/system/list-tools.test.ts

@@ -101,7 +101,6 @@ describe('Integration: handleListAvailableTools', () => {
 
       // Common known limitations
       const limitationsText = data.limitations.join(' ');
-      expect(limitationsText).toContain('Cannot activate');
       expect(limitationsText).toContain('Cannot execute workflows directly');
     });
   });

tests/unit/mcp/handlers-workflow-diff.test.ts

@@ -156,9 +156,11 @@ describe('handlers-workflow-diff', () => {
           operationsApplied: 1,
           workflowId: 'test-workflow-id',
           workflowName: 'Test Workflow',
+          active: true,
           applied: [0],
           failed: [],
           errors: [],
+          warnings: undefined,
         },
       });
 
@@ -633,5 +635,211 @@ describe('handlers-workflow-diff', () => {
         },
       });
     });
+
+    describe('Workflow Activation/Deactivation', () => {
+      it('should activate workflow after successful update', async () => {
+        const testWorkflow = createTestWorkflow({ active: false });
+        const updatedWorkflow = { ...testWorkflow, active: false };
+        const activatedWorkflow = { ...testWorkflow, active: true };
+
+        mockApiClient.getWorkflow.mockResolvedValue(testWorkflow);
+        mockDiffEngine.applyDiff.mockResolvedValue({
+          success: true,
+          workflow: updatedWorkflow,
+          operationsApplied: 1,
+          message: 'Success',
+          errors: [],
+          shouldActivate: true,
+        });
+        mockApiClient.updateWorkflow.mockResolvedValue(updatedWorkflow);
+        mockApiClient.activateWorkflow = vi.fn().mockResolvedValue(activatedWorkflow);
+
+        const result = await handleUpdatePartialWorkflow({
+          id: 'test-workflow-id',
+          operations: [{ type: 'activateWorkflow' }],
+        }, mockRepository);
+
+        expect(result.success).toBe(true);
+        expect(result.data).toEqual(activatedWorkflow);
+        expect(result.message).toContain('Workflow activated');
+        expect(result.details?.active).toBe(true);
+        expect(mockApiClient.activateWorkflow).toHaveBeenCalledWith('test-workflow-id');
+      });
+
+      it('should deactivate workflow after successful update', async () => {
+        const testWorkflow = createTestWorkflow({ active: true });
+        const updatedWorkflow = { ...testWorkflow, active: true };
+        const deactivatedWorkflow = { ...testWorkflow, active: false };
+
+        mockApiClient.getWorkflow.mockResolvedValue(testWorkflow);
+        mockDiffEngine.applyDiff.mockResolvedValue({
+          success: true,
+          workflow: updatedWorkflow,
+          operationsApplied: 1,
+          message: 'Success',
+          errors: [],
+          shouldDeactivate: true,
+        });
+        mockApiClient.updateWorkflow.mockResolvedValue(updatedWorkflow);
+        mockApiClient.deactivateWorkflow = vi.fn().mockResolvedValue(deactivatedWorkflow);
+
+        const result = await handleUpdatePartialWorkflow({
+          id: 'test-workflow-id',
+          operations: [{ type: 'deactivateWorkflow' }],
+        }, mockRepository);
+
+        expect(result.success).toBe(true);
+        expect(result.data).toEqual(deactivatedWorkflow);
+        expect(result.message).toContain('Workflow deactivated');
+        expect(result.details?.active).toBe(false);
+        expect(mockApiClient.deactivateWorkflow).toHaveBeenCalledWith('test-workflow-id');
+      });
+
+      it('should handle activation failure after successful update', async () => {
+        const testWorkflow = createTestWorkflow({ active: false });
+        const updatedWorkflow = { ...testWorkflow, active: false };
+
+        mockApiClient.getWorkflow.mockResolvedValue(testWorkflow);
+        mockDiffEngine.applyDiff.mockResolvedValue({
+          success: true,
+          workflow: updatedWorkflow,
+          operationsApplied: 1,
+          message: 'Success',
+          errors: [],
+          shouldActivate: true,
+        });
+        mockApiClient.updateWorkflow.mockResolvedValue(updatedWorkflow);
+        mockApiClient.activateWorkflow = vi.fn().mockRejectedValue(new Error('Activation failed: No trigger nodes'));
+
+        const result = await handleUpdatePartialWorkflow({
+          id: 'test-workflow-id',
+          operations: [{ type: 'activateWorkflow' }],
+        }, mockRepository);
+
+        expect(result.success).toBe(false);
+        expect(result.error).toBe('Workflow updated successfully but activation failed');
+        expect(result.details).toEqual({
+          workflowUpdated: true,
+          activationError: 'Activation failed: No trigger nodes',
+        });
+      });
+
+      it('should handle deactivation failure after successful update', async () => {
+        const testWorkflow = createTestWorkflow({ active: true });
+        const updatedWorkflow = { ...testWorkflow, active: true };
+
+        mockApiClient.getWorkflow.mockResolvedValue(testWorkflow);
+        mockDiffEngine.applyDiff.mockResolvedValue({
+          success: true,
+          workflow: updatedWorkflow,
+          operationsApplied: 1,
+          message: 'Success',
+          errors: [],
+          shouldDeactivate: true,
+        });
+        mockApiClient.updateWorkflow.mockResolvedValue(updatedWorkflow);
+        mockApiClient.deactivateWorkflow = vi.fn().mockRejectedValue(new Error('Deactivation failed'));
+
+        const result = await handleUpdatePartialWorkflow({
+          id: 'test-workflow-id',
+          operations: [{ type: 'deactivateWorkflow' }],
+        }, mockRepository);
+
+        expect(result.success).toBe(false);
+        expect(result.error).toBe('Workflow updated successfully but deactivation failed');
+        expect(result.details).toEqual({
+          workflowUpdated: true,
+          deactivationError: 'Deactivation failed',
+        });
+      });
+
+      it('should update workflow without activation when shouldActivate is false', async () => {
+        const testWorkflow = createTestWorkflow({ active: false });
+        const updatedWorkflow = { ...testWorkflow, active: false };
+
+        mockApiClient.getWorkflow.mockResolvedValue(testWorkflow);
+        mockDiffEngine.applyDiff.mockResolvedValue({
+          success: true,
+          workflow: updatedWorkflow,
+          operationsApplied: 1,
+          message: 'Success',
+          errors: [],
+          shouldActivate: false,
+          shouldDeactivate: false,
+        });
+        mockApiClient.updateWorkflow.mockResolvedValue(updatedWorkflow);
+        mockApiClient.activateWorkflow = vi.fn();
+        mockApiClient.deactivateWorkflow = vi.fn();
+
+        const result = await handleUpdatePartialWorkflow({
+          id: 'test-workflow-id',
+          operations: [{ type: 'updateName', name: 'Updated' }],
+        }, mockRepository);
+
+        expect(result.success).toBe(true);
+        expect(result.message).not.toContain('activated');
+        expect(result.message).not.toContain('deactivated');
+        expect(mockApiClient.activateWorkflow).not.toHaveBeenCalled();
+        expect(mockApiClient.deactivateWorkflow).not.toHaveBeenCalled();
+      });
+
+      it('should handle non-Error activation failures', async () => {
+        const testWorkflow = createTestWorkflow({ active: false });
+        const updatedWorkflow = { ...testWorkflow, active: false };
+
+        mockApiClient.getWorkflow.mockResolvedValue(testWorkflow);
+        mockDiffEngine.applyDiff.mockResolvedValue({
+          success: true,
+          workflow: updatedWorkflow,
+          operationsApplied: 1,
+          message: 'Success',
+          errors: [],
+          shouldActivate: true,
+        });
+        mockApiClient.updateWorkflow.mockResolvedValue(updatedWorkflow);
+        mockApiClient.activateWorkflow = vi.fn().mockRejectedValue('String error');
+
+        const result = await handleUpdatePartialWorkflow({
+          id: 'test-workflow-id',
+          operations: [{ type: 'activateWorkflow' }],
+        }, mockRepository);
+
+        expect(result.success).toBe(false);
+        expect(result.error).toBe('Workflow updated successfully but activation failed');
+        expect(result.details).toEqual({
+          workflowUpdated: true,
+          activationError: 'Unknown error',
+        });
+      });
+
+      it('should handle non-Error deactivation failures', async () => {
+        const testWorkflow = createTestWorkflow({ active: true });
+        const updatedWorkflow = { ...testWorkflow, active: true };
+
+        mockApiClient.getWorkflow.mockResolvedValue(testWorkflow);
+        mockDiffEngine.applyDiff.mockResolvedValue({
+          success: true,
+          workflow: updatedWorkflow,
+          operationsApplied: 1,
+          message: 'Success',
+          errors: [],
+          shouldDeactivate: true,
+        });
+        mockApiClient.updateWorkflow.mockResolvedValue(updatedWorkflow);
+        mockApiClient.deactivateWorkflow = vi.fn().mockRejectedValue({ code: 'UNKNOWN' });
+
+        const result = await handleUpdatePartialWorkflow({
+          id: 'test-workflow-id',
+          operations: [{ type: 'deactivateWorkflow' }],
+        }, mockRepository);
+
+        expect(result.success).toBe(false);
+        expect(result.error).toBe('Workflow updated successfully but deactivation failed');
+        expect(result.details).toEqual({
+          workflowUpdated: true,
+          deactivationError: 'Unknown error',
+        });
+      });
+    });
   });
 });

tests/unit/services/n8n-api-client.test.ts

@@ -362,19 +362,19 @@ describe('N8nApiClient', () => {
 
     it('should delete workflow successfully', async () => {
       mockAxiosInstance.delete.mockResolvedValue({ data: {} });
-      
+
       await client.deleteWorkflow('123');
-      
+
       expect(mockAxiosInstance.delete).toHaveBeenCalledWith('/workflows/123');
     });
 
     it('should handle deletion error', async () => {
-      const error = { 
+      const error = {
         message: 'Request failed',
-        response: { status: 404, data: { message: 'Not found' } } 
+        response: { status: 404, data: { message: 'Not found' } }
       };
       await mockAxiosInstance.simulateError('delete', error);
-      
+
       try {
         await client.deleteWorkflow('123');
         expect.fail('Should have thrown an error');
@@ -386,6 +386,178 @@ describe('N8nApiClient', () => {
     });
   });
 
+  describe('activateWorkflow', () => {
+    beforeEach(() => {
+      client = new N8nApiClient(defaultConfig);
+    });
+
+    it('should activate workflow successfully', async () => {
+      const workflow = { id: '123', name: 'Test', active: false, nodes: [], connections: {} };
+      const activatedWorkflow = { ...workflow, active: true };
+      mockAxiosInstance.post.mockResolvedValue({ data: activatedWorkflow });
+
+      const result = await client.activateWorkflow('123');
+
+      expect(mockAxiosInstance.post).toHaveBeenCalledWith('/workflows/123/activate');
+      expect(result).toEqual(activatedWorkflow);
+      expect(result.active).toBe(true);
+    });
+
+    it('should handle activation error - no trigger nodes', async () => {
+      const error = {
+        message: 'Request failed',
+        response: { status: 400, data: { message: 'Workflow must have at least one trigger node' } }
+      };
+      await mockAxiosInstance.simulateError('post', error);
+
+      try {
+        await client.activateWorkflow('123');
+        expect.fail('Should have thrown an error');
+      } catch (err) {
+        expect(err).toBeInstanceOf(N8nValidationError);
+        expect((err as N8nValidationError).message).toContain('trigger node');
+        expect((err as N8nValidationError).statusCode).toBe(400);
+      }
+    });
+
+    it('should handle activation error - workflow not found', async () => {
+      const error = {
+        message: 'Request failed',
+        response: { status: 404, data: { message: 'Workflow not found' } }
+      };
+      await mockAxiosInstance.simulateError('post', error);
+
+      try {
+        await client.activateWorkflow('non-existent');
+        expect.fail('Should have thrown an error');
+      } catch (err) {
+        expect(err).toBeInstanceOf(N8nNotFoundError);
+        expect((err as N8nNotFoundError).message).toContain('not found');
+        expect((err as N8nNotFoundError).statusCode).toBe(404);
+      }
+    });
+
+    it('should handle activation error - workflow already active', async () => {
+      const error = {
+        message: 'Request failed',
+        response: { status: 400, data: { message: 'Workflow is already active' } }
+      };
+      await mockAxiosInstance.simulateError('post', error);
+
+      try {
+        await client.activateWorkflow('123');
+        expect.fail('Should have thrown an error');
+      } catch (err) {
+        expect(err).toBeInstanceOf(N8nValidationError);
+        expect((err as N8nValidationError).message).toContain('already active');
+        expect((err as N8nValidationError).statusCode).toBe(400);
+      }
+    });
+
+    it('should handle server error during activation', async () => {
+      const error = {
+        message: 'Request failed',
+        response: { status: 500, data: { message: 'Internal server error' } }
+      };
+      await mockAxiosInstance.simulateError('post', error);
+
+      try {
+        await client.activateWorkflow('123');
+        expect.fail('Should have thrown an error');
+      } catch (err) {
+        expect(err).toBeInstanceOf(N8nServerError);
+        expect((err as N8nServerError).message).toBe('Internal server error');
+        expect((err as N8nServerError).statusCode).toBe(500);
+      }
+    });
+  });
+
+  describe('deactivateWorkflow', () => {
+    beforeEach(() => {
+      client = new N8nApiClient(defaultConfig);
+    });
+
+    it('should deactivate workflow successfully', async () => {
+      const workflow = { id: '123', name: 'Test', active: true, nodes: [], connections: {} };
+      const deactivatedWorkflow = { ...workflow, active: false };
+      mockAxiosInstance.post.mockResolvedValue({ data: deactivatedWorkflow });
+
+      const result = await client.deactivateWorkflow('123');
+
+      expect(mockAxiosInstance.post).toHaveBeenCalledWith('/workflows/123/deactivate');
+      expect(result).toEqual(deactivatedWorkflow);
+      expect(result.active).toBe(false);
+    });
+
+    it('should handle deactivation error - workflow not found', async () => {
+      const error = {
+        message: 'Request failed',
+        response: { status: 404, data: { message: 'Workflow not found' } }
+      };
+      await mockAxiosInstance.simulateError('post', error);
+
+      try {
+        await client.deactivateWorkflow('non-existent');
+        expect.fail('Should have thrown an error');
+      } catch (err) {
+        expect(err).toBeInstanceOf(N8nNotFoundError);
+        expect((err as N8nNotFoundError).message).toContain('not found');
+        expect((err as N8nNotFoundError).statusCode).toBe(404);
+      }
+    });
+
+    it('should handle deactivation error - workflow already inactive', async () => {
+      const error = {
+        message: 'Request failed',
+        response: { status: 400, data: { message: 'Workflow is already inactive' } }
+      };
+      await mockAxiosInstance.simulateError('post', error);
+
+      try {
+        await client.deactivateWorkflow('123');
+        expect.fail('Should have thrown an error');
+      } catch (err) {
+        expect(err).toBeInstanceOf(N8nValidationError);
+        expect((err as N8nValidationError).message).toContain('already inactive');
+        expect((err as N8nValidationError).statusCode).toBe(400);
+      }
+    });
+
+    it('should handle server error during deactivation', async () => {
+      const error = {
+        message: 'Request failed',
+        response: { status: 500, data: { message: 'Internal server error' } }
+      };
+      await mockAxiosInstance.simulateError('post', error);
+
+      try {
+        await client.deactivateWorkflow('123');
+        expect.fail('Should have thrown an error');
+      } catch (err) {
+        expect(err).toBeInstanceOf(N8nServerError);
+        expect((err as N8nServerError).message).toBe('Internal server error');
+        expect((err as N8nServerError).statusCode).toBe(500);
+      }
+    });
+
+    it('should handle authentication error during deactivation', async () => {
+      const error = {
+        message: 'Request failed',
+        response: { status: 401, data: { message: 'Invalid API key' } }
+      };
+      await mockAxiosInstance.simulateError('post', error);
+
+      try {
+        await client.deactivateWorkflow('123');
+        expect.fail('Should have thrown an error');
+      } catch (err) {
+        expect(err).toBeInstanceOf(N8nAuthenticationError);
+        expect((err as N8nAuthenticationError).message).toBe('Invalid API key');
+        expect((err as N8nAuthenticationError).statusCode).toBe(401);
+      }
+    });
+  });
+
   describe('listWorkflows', () => {
     beforeEach(() => {
       client = new N8nApiClient(defaultConfig);

tests/unit/services/workflow-diff-engine.test.ts

@@ -4269,4 +4269,358 @@ describe('WorkflowDiffEngine', () => {
       expect(result.workflow.connections["When clicking 'Execute workflow'"]).toBeDefined();
     });
   });
+
+  describe('Workflow Activation/Deactivation Operations', () => {
+    it('should activate workflow with activatable trigger nodes', async () => {
+      // Create workflow with webhook trigger (activatable)
+      const workflowWithTrigger = createWorkflow('Test Workflow')
+        .addWebhookNode({ id: 'webhook-1', name: 'Webhook Trigger' })
+        .addHttpRequestNode({ id: 'http-1', name: 'HTTP Request' })
+        .connect('webhook-1', 'http-1')
+        .build() as Workflow;
+
+      // Fix connections to use node names
+      const newConnections: any = {};
+      for (const [nodeId, outputs] of Object.entries(workflowWithTrigger.connections)) {
+        const node = workflowWithTrigger.nodes.find((n: any) => n.id === nodeId);
+        if (node) {
+          newConnections[node.name] = {};
+          for (const [outputName, connections] of Object.entries(outputs)) {
+            newConnections[node.name][outputName] = (connections as any[]).map((conns: any) =>
+              conns.map((conn: any) => {
+                const targetNode = workflowWithTrigger.nodes.find((n: any) => n.id === conn.node);
+                return { ...conn, node: targetNode ? targetNode.name : conn.node };
+              })
+            );
+          }
+        }
+      }
+      workflowWithTrigger.connections = newConnections;
+
+      const operation: any = {
+        type: 'activateWorkflow'
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(workflowWithTrigger, request);
+
+      expect(result.success).toBe(true);
+      expect(result.shouldActivate).toBe(true);
+      expect((result.workflow as any)._shouldActivate).toBeUndefined(); // Flag should be cleaned up
+    });
+
+    it('should reject activation if no activatable trigger nodes', async () => {
+      // Create workflow with no trigger nodes at all
+      const workflowWithoutActivatableTrigger = createWorkflow('Test Workflow')
+        .addNode({
+          id: 'set-1',
+          name: 'Set Node',
+          type: 'n8n-nodes-base.set',
+          typeVersion: 1,
+          position: [100, 100],
+          parameters: {}
+        })
+        .addHttpRequestNode({ id: 'http-1', name: 'HTTP Request' })
+        .connect('set-1', 'http-1')
+        .build() as Workflow;
+
+      // Fix connections to use node names
+      const newConnections: any = {};
+      for (const [nodeId, outputs] of Object.entries(workflowWithoutActivatableTrigger.connections)) {
+        const node = workflowWithoutActivatableTrigger.nodes.find((n: any) => n.id === nodeId);
+        if (node) {
+          newConnections[node.name] = {};
+          for (const [outputName, connections] of Object.entries(outputs)) {
+            newConnections[node.name][outputName] = (connections as any[]).map((conns: any) =>
+              conns.map((conn: any) => {
+                const targetNode = workflowWithoutActivatableTrigger.nodes.find((n: any) => n.id === conn.node);
+                return { ...conn, node: targetNode ? targetNode.name : conn.node };
+              })
+            );
+          }
+        }
+      }
+      workflowWithoutActivatableTrigger.connections = newConnections;
+
+      const operation: any = {
+        type: 'activateWorkflow'
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(workflowWithoutActivatableTrigger, request);
+
+      expect(result.success).toBe(false);
+      expect(result.errors).toBeDefined();
+      expect(result.errors![0].message).toContain('No activatable trigger nodes found');
+      expect(result.errors![0].message).toContain('executeWorkflowTrigger cannot activate workflows');
+    });
+
+    it('should reject activation if all trigger nodes are disabled', async () => {
+      // Create workflow with disabled webhook trigger
+      const workflowWithDisabledTrigger = createWorkflow('Test Workflow')
+        .addWebhookNode({ id: 'webhook-1', name: 'Webhook Trigger', disabled: true })
+        .addHttpRequestNode({ id: 'http-1', name: 'HTTP Request' })
+        .connect('webhook-1', 'http-1')
+        .build() as Workflow;
+
+      // Fix connections to use node names
+      const newConnections: any = {};
+      for (const [nodeId, outputs] of Object.entries(workflowWithDisabledTrigger.connections)) {
+        const node = workflowWithDisabledTrigger.nodes.find((n: any) => n.id === nodeId);
+        if (node) {
+          newConnections[node.name] = {};
+          for (const [outputName, connections] of Object.entries(outputs)) {
+            newConnections[node.name][outputName] = (connections as any[]).map((conns: any) =>
+              conns.map((conn: any) => {
+                const targetNode = workflowWithDisabledTrigger.nodes.find((n: any) => n.id === conn.node);
+                return { ...conn, node: targetNode ? targetNode.name : conn.node };
+              })
+            );
+          }
+        }
+      }
+      workflowWithDisabledTrigger.connections = newConnections;
+
+      const operation: any = {
+        type: 'activateWorkflow'
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(workflowWithDisabledTrigger, request);
+
+      expect(result.success).toBe(false);
+      expect(result.errors).toBeDefined();
+      expect(result.errors![0].message).toContain('No activatable trigger nodes found');
+    });
+
+    it('should activate workflow with schedule trigger', async () => {
+      // Create workflow with schedule trigger (activatable)
+      const workflowWithSchedule = createWorkflow('Test Workflow')
+        .addNode({
+          id: 'schedule-1',
+          name: 'Schedule',
+          type: 'n8n-nodes-base.scheduleTrigger',
+          typeVersion: 1,
+          position: [100, 100],
+          parameters: { rule: { interval: [{ field: 'hours', hoursInterval: 1 }] } }
+        })
+        .addHttpRequestNode({ id: 'http-1', name: 'HTTP Request' })
+        .connect('schedule-1', 'http-1')
+        .build() as Workflow;
+
+      // Fix connections
+      const newConnections: any = {};
+      for (const [nodeId, outputs] of Object.entries(workflowWithSchedule.connections)) {
+        const node = workflowWithSchedule.nodes.find((n: any) => n.id === nodeId);
+        if (node) {
+          newConnections[node.name] = {};
+          for (const [outputName, connections] of Object.entries(outputs)) {
+            newConnections[node.name][outputName] = (connections as any[]).map((conns: any) =>
+              conns.map((conn: any) => {
+                const targetNode = workflowWithSchedule.nodes.find((n: any) => n.id === conn.node);
+                return { ...conn, node: targetNode ? targetNode.name : conn.node };
+              })
+            );
+          }
+        }
+      }
+      workflowWithSchedule.connections = newConnections;
+
+      const operation: any = {
+        type: 'activateWorkflow'
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(workflowWithSchedule, request);
+
+      expect(result.success).toBe(true);
+      expect(result.shouldActivate).toBe(true);
+    });
+
+    it('should deactivate workflow successfully', async () => {
+      // Any workflow can be deactivated
+      const operation: any = {
+        type: 'deactivateWorkflow'
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(baseWorkflow, request);
+
+      expect(result.success).toBe(true);
+      expect(result.shouldDeactivate).toBe(true);
+      expect((result.workflow as any)._shouldDeactivate).toBeUndefined(); // Flag should be cleaned up
+    });
+
+    it('should deactivate workflow without trigger nodes', async () => {
+      // Create workflow without any trigger nodes
+      const workflowWithoutTrigger = createWorkflow('Test Workflow')
+        .addHttpRequestNode({ id: 'http-1', name: 'HTTP Request' })
+        .addNode({
+          id: 'set-1',
+          name: 'Set',
+          type: 'n8n-nodes-base.set',
+          typeVersion: 1,
+          position: [300, 100],
+          parameters: {}
+        })
+        .connect('http-1', 'set-1')
+        .build() as Workflow;
+
+      // Fix connections
+      const newConnections: any = {};
+      for (const [nodeId, outputs] of Object.entries(workflowWithoutTrigger.connections)) {
+        const node = workflowWithoutTrigger.nodes.find((n: any) => n.id === nodeId);
+        if (node) {
+          newConnections[node.name] = {};
+          for (const [outputName, connections] of Object.entries(outputs)) {
+            newConnections[node.name][outputName] = (connections as any[]).map((conns: any) =>
+              conns.map((conn: any) => {
+                const targetNode = workflowWithoutTrigger.nodes.find((n: any) => n.id === conn.node);
+                return { ...conn, node: targetNode ? targetNode.name : conn.node };
+              })
+            );
+          }
+        }
+      }
+      workflowWithoutTrigger.connections = newConnections;
+
+      const operation: any = {
+        type: 'deactivateWorkflow'
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(workflowWithoutTrigger, request);
+
+      expect(result.success).toBe(true);
+      expect(result.shouldDeactivate).toBe(true);
+    });
+
+    it('should combine activation with other operations', async () => {
+      // Create workflow with webhook trigger
+      const workflowWithTrigger = createWorkflow('Test Workflow')
+        .addWebhookNode({ id: 'webhook-1', name: 'Webhook Trigger' })
+        .addHttpRequestNode({ id: 'http-1', name: 'HTTP Request' })
+        .connect('webhook-1', 'http-1')
+        .build() as Workflow;
+
+      // Fix connections
+      const newConnections: any = {};
+      for (const [nodeId, outputs] of Object.entries(workflowWithTrigger.connections)) {
+        const node = workflowWithTrigger.nodes.find((n: any) => n.id === nodeId);
+        if (node) {
+          newConnections[node.name] = {};
+          for (const [outputName, connections] of Object.entries(outputs)) {
+            newConnections[node.name][outputName] = (connections as any[]).map((conns: any) =>
+              conns.map((conn: any) => {
+                const targetNode = workflowWithTrigger.nodes.find((n: any) => n.id === conn.node);
+                return { ...conn, node: targetNode ? targetNode.name : conn.node };
+              })
+            );
+          }
+        }
+      }
+      workflowWithTrigger.connections = newConnections;
+
+      const operations: any[] = [
+        {
+          type: 'updateName',
+          name: 'Updated Workflow Name'
+        },
+        {
+          type: 'addTag',
+          tag: 'production'
+        },
+        {
+          type: 'activateWorkflow'
+        }
+      ];
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations
+      };
+
+      const result = await diffEngine.applyDiff(workflowWithTrigger, request);
+
+      expect(result.success).toBe(true);
+      expect(result.operationsApplied).toBe(3);
+      expect(result.workflow!.name).toBe('Updated Workflow Name');
+      expect(result.workflow!.tags).toContain('production');
+      expect(result.shouldActivate).toBe(true);
+    });
+
+    it('should reject activation if workflow has executeWorkflowTrigger only', async () => {
+      // Create workflow with executeWorkflowTrigger (not activatable - Issue #351)
+      const workflowWithExecuteTrigger = createWorkflow('Test Workflow')
+        .addNode({
+          id: 'execute-1',
+          name: 'Execute Workflow Trigger',
+          type: 'n8n-nodes-base.executeWorkflowTrigger',
+          typeVersion: 1,
+          position: [100, 100],
+          parameters: {}
+        })
+        .addHttpRequestNode({ id: 'http-1', name: 'HTTP Request' })
+        .connect('execute-1', 'http-1')
+        .build() as Workflow;
+
+      // Fix connections
+      const newConnections: any = {};
+      for (const [nodeId, outputs] of Object.entries(workflowWithExecuteTrigger.connections)) {
+        const node = workflowWithExecuteTrigger.nodes.find((n: any) => n.id === nodeId);
+        if (node) {
+          newConnections[node.name] = {};
+          for (const [outputName, connections] of Object.entries(outputs)) {
+            newConnections[node.name][outputName] = (connections as any[]).map((conns: any) =>
+              conns.map((conn: any) => {
+                const targetNode = workflowWithExecuteTrigger.nodes.find((n: any) => n.id === conn.node);
+                return { ...conn, node: targetNode ? targetNode.name : conn.node };
+              })
+            );
+          }
+        }
+      }
+      workflowWithExecuteTrigger.connections = newConnections;
+
+      const operation: any = {
+        type: 'activateWorkflow'
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(workflowWithExecuteTrigger, request);
+
+      expect(result.success).toBe(false);
+      expect(result.errors).toBeDefined();
+      expect(result.errors![0].message).toContain('No activatable trigger nodes found');
+      expect(result.errors![0].message).toContain('executeWorkflowTrigger cannot activate workflows');
+    });
+  });
 });