fix: AI Agent validator not executing due to nodeType format mismatch (Critical)

Fixed critical bug where AI Agent validator never executed, missing 179 configuration errors (30% of all telemetry-identified failures).

The Bug:
- Switch case checked for '@n8n/n8n-nodes-langchain.agent' (full package format)
- But nodeType was normalized to 'nodes-langchain.agent' before reaching switch
- Result: AI Agent validator never matched, never executed

The Fix:
- Changed case to 'nodes-langchain.agent' to match normalized format
- Now correctly catches prompt configuration, maxIterations, error handling issues

Files Changed:
- src/services/enhanced-config-validator.ts:322 - Fixed nodeType format
- tests/unit/services/enhanced-config-validator.test.ts - Added validateAIAgent to mock and verification test
- CHANGELOG.md - Added bug fix section to 2.22.13 (not separate version)

Testing:
- npm test -- tests/unit/services/enhanced-config-validator.test.ts
- ✓ All 51 tests pass including new AI Agent validation test

Discovery:
Discovered by n8n-mcp-tester agent during post-deployment verification of 2.22.13 improvements. The agent attempted to validate an AI Agent node configuration and discovered the validator was never being called.

Impact:
- Without fix: 179 AI Agent configuration errors (30%) go undetected
- With fix: All AI Agent validation rules now execute correctly

Version: 2.22.13 (kept under same version as original implementation)

Concieved by Romuald Członkowski - www.aiadvisors.pl/en

tests/unit/services/enhanced-config-validator.test.ts

@@ -14,7 +14,8 @@ vi.mock('@/services/node-specific-validators', () => ({
     validateMongoDB: vi.fn(),
     validateWebhook: vi.fn(),
     validatePostgres: vi.fn(),
-    validateMySQL: vi.fn()
+    validateMySQL: vi.fn(),
+    validateAIAgent: vi.fn()
   }
 }));
 
@@ -1132,5 +1133,39 @@ describe('EnhancedConfigValidator', () => {
         }).not.toThrow();
       });
     });
+
+    describe('AI Agent node validation', () => {
+      it('should call validateAIAgent for AI Agent nodes', () => {
+        const nodeType = 'nodes-langchain.agent';
+        const config = {
+          promptType: 'define',
+          text: 'You are a helpful assistant'
+        };
+        const properties = [
+          { name: 'promptType', type: 'options', required: true },
+          { name: 'text', type: 'string', required: false }
+        ];
+
+        EnhancedConfigValidator.validateWithMode(
+          nodeType,
+          config,
+          properties,
+          'operation',
+          'ai-friendly'
+        );
+
+        // Verify the validator was called (fix for issue where it wasn't being called at all)
+        expect(NodeSpecificValidators.validateAIAgent).toHaveBeenCalledTimes(1);
+
+        // Verify it was called with a context object containing our config
+        const callArgs = (NodeSpecificValidators.validateAIAgent as any).mock.calls[0][0];
+        expect(callArgs).toHaveProperty('config');
+        expect(callArgs.config).toEqual(config);
+        expect(callArgs).toHaveProperty('errors');
+        expect(callArgs).toHaveProperty('warnings');
+        expect(callArgs).toHaveProperty('suggestions');
+        expect(callArgs).toHaveProperty('autofix');
+      });
+    });
   });
 });