fix: recognize all trigger node types including executeWorkflowTrigger (#351) (#352)

This fix addresses issue #351 where Execute Workflow Trigger and other
trigger nodes were incorrectly treated as regular nodes, causing
"disconnected node" errors during partial workflow updates.

## Changes

**1. Created Shared Trigger Detection Utilities**
- src/utils/node-type-utils.ts:
  - isTriggerNode(): Recognizes ALL trigger types using flexible pattern matching
  - isActivatableTrigger(): Returns false for executeWorkflowTrigger (not activatable)
  - getTriggerTypeDescription(): Human-readable trigger descriptions

**2. Updated Workflow Validation**
- src/services/n8n-validation.ts:
  - Replaced hardcoded webhookTypes Set with isTriggerNode() function
  - Added validation preventing activation of workflows with only executeWorkflowTrigger
  - Now recognizes 200+ trigger types across n8n packages

**3. Updated Workflow Validator**
- src/services/workflow-validator.ts:
  - Replaced inline trigger detection with shared isTriggerNode() function
  - Ensures consistency across all validation code paths

**4. Comprehensive Tests**
- tests/unit/utils/node-type-utils.test.ts:
  - Added 30+ tests for trigger detection functions
  - Validates all trigger types are recognized correctly
  - Confirms executeWorkflowTrigger is trigger but not activatable

## Impact

Before:
- Execute Workflow Trigger flagged as disconnected node
- Schedule/email/polling triggers also rejected
- Users forced to keep unnecessary webhook triggers

After:
- ALL trigger types recognized (executeWorkflowTrigger, scheduleTrigger, etc.)
- No disconnected node errors for triggers
- Clear error when activating workflow with only executeWorkflowTrigger
- Future-proof (new triggers automatically supported)

## Testing

- Build: ✅ Passes
- Typecheck: ✅ Passes
- Unit tests: ✅ All pass
- Validation test: ✅ Trigger detection working correctly

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

src/utils/node-classification.ts

@@ -9,6 +9,8 @@
  * notes being incorrectly flagged as disconnected nodes.
  */
 
+import { isTriggerNode as isTriggerNodeImpl } from './node-type-utils';
+
 /**
  * Check if a node type is a sticky note (documentation-only node)
  *
@@ -38,29 +40,27 @@ export function isStickyNote(nodeType: string): boolean {
 /**
  * Check if a node type is a trigger node
  *
+ * This function delegates to the comprehensive trigger detection implementation
+ * in node-type-utils.ts which supports 200+ trigger types using flexible
+ * pattern matching instead of a hardcoded list.
+ *
  * Trigger nodes:
  * - Start workflow execution
  * - Only need outgoing connections (no incoming connections required)
- * - Include webhooks, manual triggers, schedule triggers, etc.
+ * - Include webhooks, manual triggers, schedule triggers, email triggers, etc.
  * - Are the entry points for workflow execution
  *
  * Examples:
  * - Webhooks: Listen for HTTP requests
  * - Manual triggers: Started manually by user
  * - Schedule/Cron triggers: Run on a schedule
+ * - Execute Workflow Trigger: Invoked by other workflows
  *
  * @param nodeType - The node type to check
  * @returns true if the node is a trigger, false otherwise
  */
 export function isTriggerNode(nodeType: string): boolean {
-  const triggerTypes = [
-    'n8n-nodes-base.webhook',
-    'n8n-nodes-base.webhookTrigger',
-    'n8n-nodes-base.manualTrigger',
-    'n8n-nodes-base.cronTrigger',
-    'n8n-nodes-base.scheduleTrigger'
-  ];
-  return triggerTypes.includes(nodeType);
+  return isTriggerNodeImpl(nodeType);
 }
 
 /**

src/utils/node-type-utils.ts

@@ -140,4 +140,116 @@ export function getNodeTypeVariations(type: string): string[] {
 
   // Remove duplicates while preserving order
   return [...new Set(variations)];
+}
+
+/**
+ * Check if a node is ANY type of trigger (including executeWorkflowTrigger)
+ *
+ * This function determines if a node can start a workflow execution.
+ * Returns true for:
+ * - Webhook triggers (webhook, webhookTrigger)
+ * - Time-based triggers (schedule, cron)
+ * - Poll-based triggers (emailTrigger, slackTrigger, etc.)
+ * - Manual triggers (manualTrigger, start, formTrigger)
+ * - Sub-workflow triggers (executeWorkflowTrigger)
+ *
+ * Used for: Disconnection validation (triggers don't need incoming connections)
+ *
+ * @param nodeType - The node type to check (e.g., "n8n-nodes-base.executeWorkflowTrigger")
+ * @returns true if node is any type of trigger
+ */
+export function isTriggerNode(nodeType: string): boolean {
+  const normalized = normalizeNodeType(nodeType);
+  const lowerType = normalized.toLowerCase();
+
+  // Check for trigger pattern in node type name
+  if (lowerType.includes('trigger')) {
+    return true;
+  }
+
+  // Check for webhook nodes (excluding respondToWebhook which is NOT a trigger)
+  if (lowerType.includes('webhook') && !lowerType.includes('respond')) {
+    return true;
+  }
+
+  // Check for specific trigger types that don't have 'trigger' in their name
+  const specificTriggers = [
+    'nodes-base.start',
+    'nodes-base.manualTrigger',
+    'nodes-base.formTrigger'
+  ];
+
+  return specificTriggers.includes(normalized);
+}
+
+/**
+ * Check if a node is an ACTIVATABLE trigger (excludes executeWorkflowTrigger)
+ *
+ * This function determines if a node can be used to activate a workflow.
+ * Returns true for:
+ * - Webhook triggers (webhook, webhookTrigger)
+ * - Time-based triggers (schedule, cron)
+ * - Poll-based triggers (emailTrigger, slackTrigger, etc.)
+ * - Manual triggers (manualTrigger, start, formTrigger)
+ *
+ * Returns FALSE for:
+ * - executeWorkflowTrigger (can only be invoked by other workflows)
+ *
+ * Used for: Activation validation (active workflows need activatable triggers)
+ *
+ * @param nodeType - The node type to check
+ * @returns true if node can activate a workflow
+ */
+export function isActivatableTrigger(nodeType: string): boolean {
+  const normalized = normalizeNodeType(nodeType);
+  const lowerType = normalized.toLowerCase();
+
+  // executeWorkflowTrigger cannot activate a workflow (invoked by other workflows)
+  if (lowerType.includes('executeworkflow')) {
+    return false;
+  }
+
+  // All other triggers can activate workflows
+  return isTriggerNode(nodeType);
+}
+
+/**
+ * Get human-readable description of trigger type
+ *
+ * @param nodeType - The node type
+ * @returns Description of what triggers this node
+ */
+export function getTriggerTypeDescription(nodeType: string): string {
+  const normalized = normalizeNodeType(nodeType);
+  const lowerType = normalized.toLowerCase();
+
+  if (lowerType.includes('executeworkflow')) {
+    return 'Execute Workflow Trigger (invoked by other workflows)';
+  }
+
+  if (lowerType.includes('webhook')) {
+    return 'Webhook Trigger (HTTP requests)';
+  }
+
+  if (lowerType.includes('schedule') || lowerType.includes('cron')) {
+    return 'Schedule Trigger (time-based)';
+  }
+
+  if (lowerType.includes('manual') || normalized === 'nodes-base.start') {
+    return 'Manual Trigger (manual execution)';
+  }
+
+  if (lowerType.includes('email') || lowerType.includes('imap') || lowerType.includes('gmail')) {
+    return 'Email Trigger (polling)';
+  }
+
+  if (lowerType.includes('form')) {
+    return 'Form Trigger (form submissions)';
+  }
+
+  if (lowerType.includes('trigger')) {
+    return 'Trigger (event-based)';
+  }
+
+  return 'Unknown trigger type';
 }