feat: implement webhook path autofixer and improve node similarity service

- Add webhook path auto-generation for nodes missing path configuration
  - Generates UUID for both 'path' parameter and 'webhookId' field
  - Conditionally updates typeVersion to 2.1 only when < 2.1
  - High confidence fix (95%) as UUID generation is deterministic

- Fix critical security and performance issues in NodeSimilarityService:
  - Replace regex patterns with string-based matching to prevent ReDoS attacks
  - Add cache invalidation with version tracking to prevent memory leaks
  - Optimize Levenshtein distance algorithm from O(m*n) space to O(n)
  - Add early termination for performance improvement
  - Extract magic numbers into named constants

- Add comprehensive documentation for n8n_autofix_workflow tool
  - Document all fix types including new webhook-missing-path
  - Include examples, best practices, and warnings
  - Integrate with MCP tool documentation system

- Create node-type-utils for centralized type normalization
  - Eliminate code duplication across services
  - Consistent handling of package prefixes

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/mcp/tool-docs/workflow_management/n8n-autofix-workflow.ts

@@ -0,0 +1,125 @@
+import { ToolDocumentation } from '../types';
+
+export const n8nAutofixWorkflowDoc: ToolDocumentation = {
+  name: 'n8n_autofix_workflow',
+  category: 'workflow_management',
+  essentials: {
+    description: 'Automatically fix common workflow validation errors - expression formats, typeVersions, error outputs, webhook paths',
+    keyParameters: ['id', 'applyFixes'],
+    example: 'n8n_autofix_workflow({id: "wf_abc123", applyFixes: false})',
+    performance: 'Network-dependent (200-1000ms) - fetches, validates, and optionally updates workflow',
+    tips: [
+      'Use applyFixes: false to preview changes before applying',
+      'Set confidenceThreshold to control fix aggressiveness (high/medium/low)',
+      'Supports fixing expression formats, typeVersion issues, error outputs, node type corrections, and webhook paths',
+      'High-confidence fixes (≥90%) are safe for auto-application'
+    ]
+  },
+  full: {
+    description: `Automatically detects and fixes common workflow validation errors in n8n workflows. This tool:
+
+- Fetches the workflow from your n8n instance
+- Runs comprehensive validation to detect issues
+- Generates targeted fixes for common problems
+- Optionally applies the fixes back to the workflow
+
+The auto-fixer can resolve:
+1. **Expression Format Issues**: Missing '=' prefix in n8n expressions (e.g., {{ $json.field }} → ={{ $json.field }})
+2. **TypeVersion Corrections**: Downgrades nodes with unsupported typeVersions to maximum supported
+3. **Error Output Configuration**: Removes conflicting onError settings when error connections are missing
+4. **Node Type Corrections**: Intelligently fixes unknown node types using similarity matching:
+   - Handles deprecated package prefixes (n8n-nodes-base. → nodes-base.)
+   - Corrects capitalization mistakes (HttpRequest → httpRequest)
+   - Suggests correct packages (nodes-base.openai → nodes-langchain.openAi)
+   - Uses multi-factor scoring: name similarity, category match, package match, pattern match
+   - Only auto-fixes suggestions with ≥90% confidence
+   - Leverages NodeSimilarityService with 5-minute caching for performance
+5. **Webhook Path Generation**: Automatically generates UUIDs for webhook nodes missing path configuration:
+   - Generates a unique UUID for webhook path
+   - Sets both 'path' parameter and 'webhookId' field to the same UUID
+   - Ensures webhook nodes become functional with valid endpoints
+   - High confidence fix as UUID generation is deterministic
+
+The tool uses a confidence-based system to ensure safe fixes:
+- **High (≥90%)**: Safe to auto-apply (exact matches, known patterns)
+- **Medium (70-89%)**: Generally safe but review recommended
+- **Low (<70%)**: Manual review strongly recommended
+
+Requires N8N_API_URL and N8N_API_KEY environment variables to be configured.`,
+    parameters: {
+      id: {
+        type: 'string',
+        required: true,
+        description: 'The workflow ID to fix in your n8n instance'
+      },
+      applyFixes: {
+        type: 'boolean',
+        required: false,
+        description: 'Whether to apply fixes to the workflow (default: false - preview mode). When false, returns proposed fixes without modifying the workflow.'
+      },
+      fixTypes: {
+        type: 'array',
+        required: false,
+        description: 'Types of fixes to apply. Options: ["expression-format", "typeversion-correction", "error-output-config", "node-type-correction", "webhook-missing-path"]. Default: all types.'
+      },
+      confidenceThreshold: {
+        type: 'string',
+        required: false,
+        description: 'Minimum confidence level for fixes: "high" (≥90%), "medium" (≥70%), "low" (any). Default: "medium".'
+      },
+      maxFixes: {
+        type: 'number',
+        required: false,
+        description: 'Maximum number of fixes to apply (default: 50). Useful for limiting scope of changes.'
+      }
+    },
+    returns: `AutoFixResult object containing:
+- operations: Array of diff operations that will be/were applied
+- fixes: Detailed list of individual fixes with before/after values
+- summary: Human-readable summary of fixes
+- stats: Statistics by fix type and confidence level
+- applied: Boolean indicating if fixes were applied (when applyFixes: true)`,
+    examples: [
+      'n8n_autofix_workflow({id: "wf_abc123"}) - Preview all possible fixes',
+      'n8n_autofix_workflow({id: "wf_abc123", applyFixes: true}) - Apply all medium+ confidence fixes',
+      'n8n_autofix_workflow({id: "wf_abc123", applyFixes: true, confidenceThreshold: "high"}) - Only apply high-confidence fixes',
+      'n8n_autofix_workflow({id: "wf_abc123", fixTypes: ["expression-format"]}) - Only fix expression format issues',
+      'n8n_autofix_workflow({id: "wf_abc123", fixTypes: ["webhook-missing-path"]}) - Only fix webhook path issues',
+      'n8n_autofix_workflow({id: "wf_abc123", applyFixes: true, maxFixes: 10}) - Apply up to 10 fixes'
+    ],
+    useCases: [
+      'Fixing workflows imported from older n8n versions',
+      'Correcting expression syntax after manual edits',
+      'Resolving typeVersion conflicts after n8n upgrades',
+      'Cleaning up workflows before production deployment',
+      'Batch fixing common issues across multiple workflows',
+      'Migrating workflows between n8n instances with different versions',
+      'Repairing webhook nodes that lost their path configuration'
+    ],
+    performance: 'Depends on workflow size and number of issues. Preview mode: 200-500ms. Apply mode: 500-1000ms for medium workflows. Node similarity matching is cached for 5 minutes for improved performance on repeated validations.',
+    bestPractices: [
+      'Always preview fixes first (applyFixes: false) before applying',
+      'Start with high confidence threshold for production workflows',
+      'Review the fix summary to understand what changed',
+      'Test workflows after auto-fixing to ensure expected behavior',
+      'Use fixTypes parameter to target specific issue categories',
+      'Keep maxFixes reasonable to avoid too many changes at once'
+    ],
+    pitfalls: [
+      'Some fixes may change workflow behavior - always test after fixing',
+      'Low confidence fixes might not be the intended solution',
+      'Expression format fixes assume standard n8n syntax requirements',
+      'Node type corrections only work for known node types in the database',
+      'Cannot fix structural issues like missing nodes or invalid connections',
+      'TypeVersion downgrades might remove node features added in newer versions',
+      'Generated webhook paths are new UUIDs - existing webhook URLs will change'
+    ],
+    relatedTools: [
+      'n8n_validate_workflow',
+      'validate_workflow',
+      'n8n_update_partial_workflow',
+      'validate_workflow_expressions',
+      'validate_node_operation'
+    ]
+  }
+};