feat: add MCP tool annotations to all 20 tools (#512 )

* feat: add MCP tool annotations to all 20 tools Add MCP tool annotations per specification to help AI assistants understand tool behavior and capabilities. Documentation tools (7): - tools_documentation, search_nodes, get_node, validate_node, get_template, search_templates, validate_workflow - All marked readOnlyHint=true (local database queries) Management tools (13): - n8n_create_workflow, n8n_get_workflow, n8n_update_full_workflow, n8n_update_partial_workflow, n8n_delete_workflow, n8n_list_workflows, n8n_validate_workflow, n8n_autofix_workflow, n8n_test_workflow, n8n_executions, n8n_health_check, n8n_workflow_versions, n8n_deploy_template - All marked openWorldHint=true (n8n API access) - Destructive operations (delete_workflow, executions delete, workflow_versions delete/truncate) marked destructiveHint=true Annotations follow MCP spec: https://spec.modelcontextprotocol.io/specification/2025-03-26/server/tools/#annotations 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * feat: add idempotentHint to all read-only tools Adds idempotentHint: true annotation to all read-only tools that produce the same output when called multiple times: - 7 documentation tools (tools.ts) - 4 management tools (tools-n8n-manager.ts): n8n_get_workflow, n8n_list_workflows, n8n_validate_workflow, n8n_health_check Also adds trailing newline to tools-n8n-manager.ts. Conceived by Romuald Członkowski - www.aiadvisors.pl/en 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * feat: add idempotentHint to update operations, bump to 2.31.5 Adds idempotentHint: true to update operations that produce the same result when called repeatedly with the same arguments: - n8n_update_full_workflow - n8n_update_partial_workflow - n8n_autofix_workflow Also bumps version to 2.31.5 and updates CHANGELOG.md with complete documentation of all MCP tool annotations added in this PR. Conceived by Romuald Członkowski - www.aiadvisors.pl/en 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> --------- Co-authored-by: triepod-ai <noreply@github.com> Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com> Co-authored-by: Romuald Członkowski <romualdczlonkowski@MacBook-Pro-Romuald.local>
fix: preserve workflow data during serialization (Issue #517 ) (#519 )
2026-01-30 14:32:04 +00:00 · 2026-01-02 15:48:47 +01:00 · 2026-01-02 10:44:13 +01:00
7 changed files with 499 additions and 37 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,66 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

 ## [Unreleased]

+## [2.31.5] - 2026-01-02
+
+### Added
+
+**MCP Tool Annotations (PR #512)**
+
+Added MCP tool annotations to all 20 tools following the [MCP specification](https://spec.modelcontextprotocol.io/specification/2025-03-26/server/tools/#annotations). These annotations help AI assistants understand tool behavior and capabilities.
+
+**Annotations added:**
+- `title`: Human-readable name for each tool
+- `readOnlyHint`: True for tools that don't modify state (11 tools)
+- `destructiveHint`: True for delete operations (3 tools)
+- `idempotentHint`: True for operations that produce same result when called repeatedly (14 tools)
+- `openWorldHint`: True for tools accessing external n8n API (13 tools)
+
+**Documentation tools** (7): All marked `readOnlyHint=true`, `idempotentHint=true`
+- `tools_documentation`, `search_nodes`, `get_node`, `validate_node`, `get_template`, `search_templates`, `validate_workflow`
+
+**Management tools** (13): All marked `openWorldHint=true`
+- Read-only: `n8n_get_workflow`, `n8n_list_workflows`, `n8n_validate_workflow`, `n8n_health_check`
+- Idempotent updates: `n8n_update_full_workflow`, `n8n_update_partial_workflow`, `n8n_autofix_workflow`
+- Destructive: `n8n_delete_workflow`, `n8n_executions` (delete action), `n8n_workflow_versions` (delete/truncate)
+
+## [2.31.4] - 2026-01-02
+
+### Fixed
+
+**Workflow Data Mangled During Serialization: snake_case Conversion (Issue #517)**
+
+Fixed a critical bug where workflow mutation data was corrupted during serialization to Supabase, making 98.9% of collected workflow data invalid for n8n API operations.
+
+**Problem:**
+The `toSnakeCase()` function in `batch-processor.ts` was applied **recursively** to the entire mutation object, including nested workflow data that should be preserved exactly as-is:
+
+- **Connection keys mangled**: Node names like `"Webhook"` became `"_webhook"`, `"AI Agent"` became `"_a_i _agent"`
+- **Node field names mangled**: n8n camelCase fields like `typeVersion`, `webhookId`, `onError` became `type_version`, `webhook_id`, `on_error`
+
+**Root Cause:**
+```javascript
+// Old code - recursive conversion corrupted nested data
+result[snakeKey] = toSnakeCase(obj[key]); // WRONG
+```
+
+**Solution:**
+Replaced recursive `toSnakeCase()` with selective `mutationToSupabaseFormat()` that:
+- Converts **only** top-level field names to snake_case (for Supabase columns)
+- Preserves all nested data (workflow JSON, operations, validations) **exactly as-is**
+
+```javascript
+// New code - preserves nested workflow structure
+for (const [key, value] of Object.entries(mutation)) {
+  result[keyToSnakeCase(key)] = value; // Value preserved as-is
+}
+```
+
+**Impact:**
+- Workflow mutation data now maintains n8n API compatibility
+- Deployability rate improved from ~21% to ~68%
+- Added 3 regression tests to prevent future occurrences
+
 ## [2.31.3] - 2025-12-26

 ### Fixed
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
  "name": "n8n-mcp",
-  "version": "2.31.3",
+  "version": "2.31.5",
  "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
--- a/src/mcp/tools-n8n-manager.ts
+++ b/src/mcp/tools-n8n-manager.ts
@@ -66,7 +66,13 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['name', 'nodes', 'connections']
-    }
+    },
+    annotations: {
+      title: 'Create Workflow',
+      readOnlyHint: false,
+      destructiveHint: false,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_get_workflow',
@@ -86,7 +92,13 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['id']
-    }
+    },
+    annotations: {
+      title: 'Get Workflow',
+      readOnlyHint: true,
+      idempotentHint: true,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_update_full_workflow',
@@ -120,7 +132,14 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['id']
-    }
+    },
+    annotations: {
+      title: 'Update Full Workflow',
+      readOnlyHint: false,
+      destructiveHint: false,
+      idempotentHint: true,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_update_partial_workflow',
@@ -151,7 +170,14 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['id', 'operations']
-    }
+    },
+    annotations: {
+      title: 'Update Partial Workflow',
+      readOnlyHint: false,
+      destructiveHint: false,
+      idempotentHint: true,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_delete_workflow',
@@ -165,7 +191,13 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['id']
-    }
+    },
+    annotations: {
+      title: 'Delete Workflow',
+      readOnlyHint: false,
+      destructiveHint: true,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_list_workflows',
@@ -194,12 +226,18 @@ export const n8nManagementTools: ToolDefinition[] = [
          type: 'string', 
          description: 'Filter by project ID (enterprise feature)' 
        },
-        excludePinnedData: { 
-          type: 'boolean', 
-          description: 'Exclude pinned data from response (default: true)' 
+        excludePinnedData: {
+          type: 'boolean',
+          description: 'Exclude pinned data from response (default: true)'
        }
      }
-    }
+    },
+    annotations: {
+      title: 'List Workflows',
+      readOnlyHint: true,
+      idempotentHint: true,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_validate_workflow',
@@ -227,16 +265,22 @@ export const n8nManagementTools: ToolDefinition[] = [
              type: 'boolean', 
              description: 'Validate n8n expressions (default: true)' 
            },
-            profile: { 
-              type: 'string', 
+            profile: {
+              type: 'string',
              enum: ['minimal', 'runtime', 'ai-friendly', 'strict'],
-              description: 'Validation profile to use (default: runtime)' 
+              description: 'Validation profile to use (default: runtime)'
            }
          }
        }
      },
      required: ['id']
-    }
+    },
+    annotations: {
+      title: 'Validate Workflow',
+      readOnlyHint: true,
+      idempotentHint: true,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_autofix_workflow',
@@ -271,7 +315,14 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['id']
-    }
+    },
+    annotations: {
+      title: 'Autofix Workflow',
+      readOnlyHint: false,
+      destructiveHint: false,
+      idempotentHint: true,
+      openWorldHint: true,
+    },
  },

  // Execution Management Tools
@@ -328,7 +379,13 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['workflowId']
-    }
+    },
+    annotations: {
+      title: 'Test Workflow',
+      readOnlyHint: false,
+      destructiveHint: false,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_executions',
@@ -410,7 +467,13 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['action']
-    }
+    },
+    annotations: {
+      title: 'Manage Executions',
+      readOnlyHint: false,
+      destructiveHint: true,
+      openWorldHint: true,
+    },
  },

  // System Tools
@@ -431,7 +494,13 @@ export const n8nManagementTools: ToolDefinition[] = [
          description: 'Include extra details in diagnostic mode (default: false)'
        }
      }
-    }
+    },
+    annotations: {
+      title: 'Health Check',
+      readOnlyHint: true,
+      idempotentHint: true,
+      openWorldHint: true,
+    },
  },
  {
    name: 'n8n_workflow_versions',
@@ -485,7 +554,13 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['mode']
-    }
+    },
+    annotations: {
+      title: 'Workflow Versions',
+      readOnlyHint: false,
+      destructiveHint: true,
+      openWorldHint: true,
+    },
  },

  // Template Deployment Tool
@@ -520,6 +595,12 @@ export const n8nManagementTools: ToolDefinition[] = [
        }
      },
      required: ['templateId']
-    }
+    },
+    annotations: {
+      title: 'Deploy Template',
+      readOnlyHint: false,
+      destructiveHint: false,
+      openWorldHint: true,
+    },
  }
-];
+];
--- a/src/mcp/tools.ts
+++ b/src/mcp/tools.ts
@@ -25,6 +25,11 @@ export const n8nDocumentationToolsFinal: ToolDefinition[] = [
        },
      },
    },
+    annotations: {
+      title: 'Tools Documentation',
+      readOnlyHint: true,
+      idempotentHint: true,
+    },
  },
  {
    name: 'search_nodes',
@@ -55,6 +60,11 @@ export const n8nDocumentationToolsFinal: ToolDefinition[] = [
      },
      required: ['query'],
    },
+    annotations: {
+      title: 'Search Nodes',
+      readOnlyHint: true,
+      idempotentHint: true,
+    },
  },
  {
    name: 'get_node',
@@ -108,6 +118,11 @@ export const n8nDocumentationToolsFinal: ToolDefinition[] = [
      },
      required: ['nodeType'],
    },
+    annotations: {
+      title: 'Get Node Info',
+      readOnlyHint: true,
+      idempotentHint: true,
+    },
  },
  {
    name: 'validate_node',
@@ -188,6 +203,11 @@ export const n8nDocumentationToolsFinal: ToolDefinition[] = [
      },
      required: ['nodeType', 'displayName', 'valid']
    },
+    annotations: {
+      title: 'Validate Node Config',
+      readOnlyHint: true,
+      idempotentHint: true,
+    },
  },
  {
    name: 'get_template',
@@ -208,6 +228,11 @@ export const n8nDocumentationToolsFinal: ToolDefinition[] = [
      },
      required: ['templateId'],
    },
+    annotations: {
+      title: 'Get Template',
+      readOnlyHint: true,
+      idempotentHint: true,
+    },
  },
  {
    name: 'search_templates',
@@ -303,6 +328,11 @@ export const n8nDocumentationToolsFinal: ToolDefinition[] = [
        },
      },
    },
+    annotations: {
+      title: 'Search Templates',
+      readOnlyHint: true,
+      idempotentHint: true,
+    },
  },
  {
    name: 'validate_workflow',
@@ -388,6 +418,11 @@ export const n8nDocumentationToolsFinal: ToolDefinition[] = [
      },
      required: ['valid', 'summary']
    },
+    annotations: {
+      title: 'Validate Workflow',
+      readOnlyHint: true,
+      idempotentHint: true,
+    },
  },
 ];

--- a/src/telemetry/batch-processor.ts
+++ b/src/telemetry/batch-processor.ts
@@ -9,23 +9,34 @@ import { TelemetryError, TelemetryErrorType, TelemetryCircuitBreaker } from './t
 import { logger } from '../utils/logger';

 /**
- * Convert camelCase object keys to snake_case
- * Needed because Supabase PostgREST doesn't auto-convert
+ * Convert camelCase key to snake_case
 */
-function toSnakeCase(obj: any): any {
-  if (obj === null || obj === undefined) return obj;
-  if (Array.isArray(obj)) return obj.map(toSnakeCase);
-  if (typeof obj !== 'object') return obj;
+function keyToSnakeCase(key: string): string {
+  return key.replace(/[A-Z]/g, letter => `_${letter.toLowerCase()}`);
+}

-  const result: any = {};
-  for (const key in obj) {
-    if (obj.hasOwnProperty(key)) {
-      // Convert camelCase to snake_case
-      const snakeKey = key.replace(/[A-Z]/g, letter => `_${letter.toLowerCase()}`);
-      // Recursively convert nested objects
-      result[snakeKey] = toSnakeCase(obj[key]);
-    }
+/**
+ * Convert WorkflowMutationRecord to Supabase-compatible format.
+ *
+ * IMPORTANT: Only converts top-level field names to snake_case.
+ * Nested workflow data (workflowBefore, workflowAfter, operations, etc.)
+ * is preserved EXACTLY as-is to maintain n8n API compatibility.
+ *
+ * The Supabase workflow_mutations table stores workflow_before and
+ * workflow_after as JSONB columns, which preserve the original structure.
+ * Only the top-level columns (user_id, session_id, etc.) require snake_case.
+ *
+ * Issue #517: Previously this used recursive conversion which mangled:
+ * - Connection keys (node names like "Webhook" → "_webhook")
+ * - Node field names (typeVersion → type_version)
+ */
+function mutationToSupabaseFormat(mutation: WorkflowMutationRecord): Record<string, any> {
+  const result: Record<string, any> = {};
+
+  for (const [key, value] of Object.entries(mutation)) {
+    result[keyToSnakeCase(key)] = value;
  }
+
  return result;
 }

@@ -266,7 +277,7 @@ export class TelemetryBatchProcessor {
      for (const batch of batches) {
        const result = await this.executeWithRetry(async () => {
          // Convert camelCase to snake_case for Supabase
-          const snakeCaseBatch = batch.map(mutation => toSnakeCase(mutation));
+          const snakeCaseBatch = batch.map(mutation => mutationToSupabaseFormat(mutation));

          const { error } = await this.supabase!
            .from('workflow_mutations')
--- a/src/types/index.ts
+++ b/src/types/index.ts
@@ -10,6 +10,23 @@ export interface MCPServerConfig {
  authToken?: string;
 }

+/**
+ * MCP Tool annotations to help AI assistants understand tool behavior.
+ * Per MCP spec: https://spec.modelcontextprotocol.io/specification/2025-03-26/server/tools/#annotations
+ */
+export interface ToolAnnotations {
+  /** Human-readable title for the tool */
+  title?: string;
+  /** If true, the tool does not modify its environment */
+  readOnlyHint?: boolean;
+  /** If true, the tool may perform destructive updates to its environment */
+  destructiveHint?: boolean;
+  /** If true, calling the tool repeatedly with the same arguments has no additional effect */
+  idempotentHint?: boolean;
+  /** If true, the tool may interact with external entities (APIs, services) */
+  openWorldHint?: boolean;
+}
+
 export interface ToolDefinition {
  name: string;
  description: string;
@@ -25,6 +42,8 @@ export interface ToolDefinition {
    required?: string[];
    additionalProperties?: boolean | Record<string, any>;
  };
+  /** Tool behavior hints for AI assistants */
+  annotations?: ToolAnnotations;
 }

 export interface ResourceDefinition {
--- a/tests/unit/telemetry/batch-processor.test.ts
+++ b/tests/unit/telemetry/batch-processor.test.ts
@@ -1,7 +1,9 @@
 import { describe, it, expect, beforeEach, vi, afterEach, beforeAll, afterAll, type MockInstance } from 'vitest';
 import { TelemetryBatchProcessor } from '../../../src/telemetry/batch-processor';
-import { TelemetryEvent, WorkflowTelemetry, TELEMETRY_CONFIG } from '../../../src/telemetry/telemetry-types';
+import { TelemetryEvent, WorkflowTelemetry, WorkflowMutationRecord, TELEMETRY_CONFIG } from '../../../src/telemetry/telemetry-types';
 import { TelemetryError, TelemetryErrorType } from '../../../src/telemetry/telemetry-error';
+import { IntentClassification, MutationToolName } from '../../../src/telemetry/mutation-types';
+import { AddNodeOperation } from '../../../src/types/workflow-diff';
 import type { SupabaseClient } from '@supabase/supabase-js';

 // Mock logger to avoid console output in tests
@@ -679,4 +681,258 @@ describe('TelemetryBatchProcessor', () => {
      expect(mockProcessExit).toHaveBeenCalledWith(0);
    });
  });
+
+  describe('Issue #517: workflow data preservation', () => {
+    // This test verifies that workflow mutation data is NOT recursively converted to snake_case
+    // Previously, the toSnakeCase function was applied recursively which caused:
+    // - Connection keys like "Webhook" to become "_webhook"
+    // - Node fields like "typeVersion" to become "type_version"
+
+    it('should preserve connection keys exactly as-is (node names)', async () => {
+      const mutation: WorkflowMutationRecord = {
+        userId: 'user1',
+        sessionId: 'session1',
+        workflowBefore: {
+          nodes: [],
+          connections: {}
+        },
+        workflowAfter: {
+          nodes: [
+            { id: '1', name: 'Webhook', type: 'n8n-nodes-base.webhook', typeVersion: 1, position: [0, 0], parameters: {} }
+          ],
+          // Connection keys are NODE NAMES - must be preserved exactly
+          connections: {
+            'Webhook': { main: [[{ node: 'AI Agent', type: 'main', index: 0 }]] },
+            'AI Agent': { main: [[{ node: 'HTTP Request', type: 'main', index: 0 }]] },
+            'HTTP Request': { main: [[{ node: 'Send Email', type: 'main', index: 0 }]] }
+          }
+        },
+        workflowHashBefore: 'hash1',
+        workflowHashAfter: 'hash2',
+        userIntent: 'Test',
+        intentClassification: IntentClassification.ADD_FUNCTIONALITY,
+        toolName: MutationToolName.UPDATE_PARTIAL,
+        operations: [],
+        operationCount: 0,
+        operationTypes: [],
+        validationImproved: null,
+        errorsResolved: 0,
+        errorsIntroduced: 0,
+        nodesAdded: 1,
+        nodesRemoved: 0,
+        nodesModified: 0,
+        connectionsAdded: 3,
+        connectionsRemoved: 0,
+        propertiesChanged: 0,
+        mutationSuccess: true,
+        durationMs: 100
+      };
+
+      let capturedData: any = null;
+      vi.mocked(mockSupabase.from).mockImplementation((table) => ({
+        insert: vi.fn().mockImplementation((data) => {
+          if (table === 'workflow_mutations') {
+            capturedData = data;
+          }
+          return Promise.resolve(createMockSupabaseResponse());
+        }),
+        url: { href: '' },
+        headers: {},
+        select: vi.fn(),
+        upsert: vi.fn(),
+        update: vi.fn(),
+        delete: vi.fn()
+      } as any));
+
+      await batchProcessor.flush(undefined, undefined, [mutation]);
+
+      expect(capturedData).toBeDefined();
+      expect(capturedData).toHaveLength(1);
+
+      const savedMutation = capturedData[0];
+
+      // Top-level keys should be snake_case for Supabase
+      expect(savedMutation).toHaveProperty('user_id');
+      expect(savedMutation).toHaveProperty('session_id');
+      expect(savedMutation).toHaveProperty('workflow_after');
+
+      // Connection keys should be preserved EXACTLY (not "_webhook", "_a_i _agent", etc.)
+      const connections = savedMutation.workflow_after.connections;
+      expect(connections).toHaveProperty('Webhook');  // NOT "_webhook"
+      expect(connections).toHaveProperty('AI Agent'); // NOT "_a_i _agent"
+      expect(connections).toHaveProperty('HTTP Request'); // NOT "_h_t_t_p _request"
+    });
+
+    it('should preserve node field names in camelCase', async () => {
+      const mutation: WorkflowMutationRecord = {
+        userId: 'user1',
+        sessionId: 'session1',
+        workflowBefore: { nodes: [], connections: {} },
+        workflowAfter: {
+          nodes: [
+            {
+              id: '1',
+              name: 'Webhook',
+              type: 'n8n-nodes-base.webhook',
+              // These fields MUST remain in camelCase for n8n API compatibility
+              typeVersion: 2,
+              webhookId: 'abc123',
+              onError: 'continueOnFail',
+              alwaysOutputData: true,
+              continueOnFail: false,
+              retryOnFail: true,
+              maxTries: 3,
+              notesInFlow: true,
+              waitBetweenTries: 1000,
+              executeOnce: false,
+              position: [100, 200],
+              parameters: {}
+            }
+          ],
+          connections: {}
+        },
+        workflowHashBefore: 'hash1',
+        workflowHashAfter: 'hash2',
+        userIntent: 'Test',
+        intentClassification: IntentClassification.ADD_FUNCTIONALITY,
+        toolName: MutationToolName.UPDATE_PARTIAL,
+        operations: [],
+        operationCount: 0,
+        operationTypes: [],
+        validationImproved: null,
+        errorsResolved: 0,
+        errorsIntroduced: 0,
+        nodesAdded: 1,
+        nodesRemoved: 0,
+        nodesModified: 0,
+        connectionsAdded: 0,
+        connectionsRemoved: 0,
+        propertiesChanged: 0,
+        mutationSuccess: true,
+        durationMs: 100
+      };
+
+      let capturedData: any = null;
+      vi.mocked(mockSupabase.from).mockImplementation((table) => ({
+        insert: vi.fn().mockImplementation((data) => {
+          if (table === 'workflow_mutations') {
+            capturedData = data;
+          }
+          return Promise.resolve(createMockSupabaseResponse());
+        }),
+        url: { href: '' },
+        headers: {},
+        select: vi.fn(),
+        upsert: vi.fn(),
+        update: vi.fn(),
+        delete: vi.fn()
+      } as any));
+
+      await batchProcessor.flush(undefined, undefined, [mutation]);
+
+      expect(capturedData).toBeDefined();
+      const savedNode = capturedData[0].workflow_after.nodes[0];
+
+      // Node fields should be preserved in camelCase (NOT snake_case)
+      expect(savedNode).toHaveProperty('typeVersion');        // NOT type_version
+      expect(savedNode).toHaveProperty('webhookId');          // NOT webhook_id
+      expect(savedNode).toHaveProperty('onError');            // NOT on_error
+      expect(savedNode).toHaveProperty('alwaysOutputData');   // NOT always_output_data
+      expect(savedNode).toHaveProperty('continueOnFail');     // NOT continue_on_fail
+      expect(savedNode).toHaveProperty('retryOnFail');        // NOT retry_on_fail
+      expect(savedNode).toHaveProperty('maxTries');           // NOT max_tries
+      expect(savedNode).toHaveProperty('notesInFlow');        // NOT notes_in_flow
+      expect(savedNode).toHaveProperty('waitBetweenTries');   // NOT wait_between_tries
+      expect(savedNode).toHaveProperty('executeOnce');        // NOT execute_once
+
+      // Verify values are preserved
+      expect(savedNode.typeVersion).toBe(2);
+      expect(savedNode.webhookId).toBe('abc123');
+      expect(savedNode.maxTries).toBe(3);
+    });
+
+    it('should convert only top-level mutation record fields to snake_case', async () => {
+      const mutation: WorkflowMutationRecord = {
+        userId: 'user1',
+        sessionId: 'session1',
+        workflowBefore: { nodes: [], connections: {} },
+        workflowAfter: { nodes: [], connections: {} },
+        workflowHashBefore: 'hash1',
+        workflowHashAfter: 'hash2',
+        workflowStructureHashBefore: 'struct1',
+        workflowStructureHashAfter: 'struct2',
+        isTrulySuccessful: true,
+        userIntent: 'Test intent',
+        intentClassification: IntentClassification.ADD_FUNCTIONALITY,
+        toolName: MutationToolName.UPDATE_PARTIAL,
+        operations: [{ type: 'addNode', node: { name: 'Test', type: 'n8n-nodes-base.set', position: [0, 0] } } as AddNodeOperation],
+        operationCount: 1,
+        operationTypes: ['addNode'],
+        validationBefore: { valid: false, errors: [] },
+        validationAfter: { valid: true, errors: [] },
+        validationImproved: true,
+        errorsResolved: 1,
+        errorsIntroduced: 0,
+        nodesAdded: 1,
+        nodesRemoved: 0,
+        nodesModified: 0,
+        connectionsAdded: 0,
+        connectionsRemoved: 0,
+        propertiesChanged: 0,
+        mutationSuccess: true,
+        mutationError: undefined,
+        durationMs: 150
+      };
+
+      let capturedData: any = null;
+      vi.mocked(mockSupabase.from).mockImplementation((table) => ({
+        insert: vi.fn().mockImplementation((data) => {
+          if (table === 'workflow_mutations') {
+            capturedData = data;
+          }
+          return Promise.resolve(createMockSupabaseResponse());
+        }),
+        url: { href: '' },
+        headers: {},
+        select: vi.fn(),
+        upsert: vi.fn(),
+        update: vi.fn(),
+        delete: vi.fn()
+      } as any));
+
+      await batchProcessor.flush(undefined, undefined, [mutation]);
+
+      expect(capturedData).toBeDefined();
+      const saved = capturedData[0];
+
+      // Top-level fields should be converted to snake_case
+      expect(saved).toHaveProperty('user_id', 'user1');
+      expect(saved).toHaveProperty('session_id', 'session1');
+      expect(saved).toHaveProperty('workflow_before');
+      expect(saved).toHaveProperty('workflow_after');
+      expect(saved).toHaveProperty('workflow_hash_before', 'hash1');
+      expect(saved).toHaveProperty('workflow_hash_after', 'hash2');
+      expect(saved).toHaveProperty('workflow_structure_hash_before', 'struct1');
+      expect(saved).toHaveProperty('workflow_structure_hash_after', 'struct2');
+      expect(saved).toHaveProperty('is_truly_successful', true);
+      expect(saved).toHaveProperty('user_intent', 'Test intent');
+      expect(saved).toHaveProperty('intent_classification');
+      expect(saved).toHaveProperty('tool_name');
+      expect(saved).toHaveProperty('operation_count', 1);
+      expect(saved).toHaveProperty('operation_types');
+      expect(saved).toHaveProperty('validation_before');
+      expect(saved).toHaveProperty('validation_after');
+      expect(saved).toHaveProperty('validation_improved', true);
+      expect(saved).toHaveProperty('errors_resolved', 1);
+      expect(saved).toHaveProperty('errors_introduced', 0);
+      expect(saved).toHaveProperty('nodes_added', 1);
+      expect(saved).toHaveProperty('nodes_removed', 0);
+      expect(saved).toHaveProperty('nodes_modified', 0);
+      expect(saved).toHaveProperty('connections_added', 0);
+      expect(saved).toHaveProperty('connections_removed', 0);
+      expect(saved).toHaveProperty('properties_changed', 0);
+      expect(saved).toHaveProperty('mutation_success', true);
+      expect(saved).toHaveProperty('duration_ms', 150);
+    });
+  });
 });