fix: code validator false positives and null property removal (#294 , #293 , #611 ) (#637 )

- Fix $() node reference triggering "Invalid $ usage" warning by adding ( and _ to regex lookahead - Fix helper function primitive returns triggering "Cannot return primitive values" error - Fix null values in diff engine causing Zod validation errors — null now deletes properties - Update property removal docs from undefined to null Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-16 23:43:07 +00:00 · 2026-03-15 11:26:44 +01:00
16 changed files with 339 additions and 89 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

 ## [Unreleased]

+## [2.37.2] - 2026-03-15
+
+### Fixed
+
+- **Code validator `$()` false positive** (Issue #294): `$('Previous Node').first().json` no longer triggers "Invalid $ usage detected" warning. Added `(` and `_` to the regex negative lookahead to support standard n8n cross-node references and valid JS identifiers like `$_var`
+- **Code validator helper function return false positive** (Issue #293): `function isValid(item) { return false; }` no longer triggers "Cannot return primitive values directly" error. Added helper function detection to skip primitive return checks when named functions or arrow function assignments are present
+- **Null property removal in diff engine** (Issue #611): `{continueOnFail: null}` no longer causes Zod validation error "Expected boolean, received null". The diff engine now treats `null` values as property deletion (`delete` operator), and documentation updated from `undefined` to `null` for property removal
+
+Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en
+
 ## [2.37.1] - 2026-03-14

 ### Fixed
--- a/dist/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.js
+++ b/dist/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.js
@@ -195,12 +195,12 @@ Please choose a different name.
 - Can rename a node and add/remove connections using the new name in the same batch
 - Use \`validateOnly: true\` to preview effects before applying

-## Removing Properties with undefined
+## Removing Properties with null

-To remove a property from a node, set its value to \`undefined\` in the updates object. This is essential when migrating from deprecated properties or cleaning up optional configuration fields.
+To remove a property from a node, set its value to \`null\` in the updates object. This is essential when migrating from deprecated properties or cleaning up optional configuration fields.

-### Why Use undefined?
- **Property removal vs. null**: Setting a property to \`undefined\` removes it completely from the node object, while \`null\` sets the property to a null value
+### Why Use null?
+- **Property removal**: Setting a property to \`null\` removes it completely from the node object
 - **Validation constraints**: Some properties are mutually exclusive (e.g., \`continueOnFail\` and \`onError\`). Simply setting one without removing the other will fail validation
 - **Deprecated property migration**: When n8n deprecates properties, you must remove the old property before the new one will work

@@ -212,7 +212,7 @@ n8n_update_partial_workflow({
  operations: [{
    type: "updateNode",
    nodeName: "HTTP Request",
-    updates: { onError: undefined }
+    updates: { onError: null }
  }]
 });

@@ -222,7 +222,7 @@ n8n_update_partial_workflow({
  operations: [{
    type: "updateNode",
    nodeId: "node_abc",
-    updates: { disabled: undefined }
+    updates: { disabled: null }
  }]
 });
 \`\`\`
@@ -236,7 +236,7 @@ n8n_update_partial_workflow({
  operations: [{
    type: "updateNode",
    nodeName: "API Request",
-    updates: { "parameters.authentication": undefined }
+    updates: { "parameters.authentication": null }
  }]
 });

@@ -246,7 +246,7 @@ n8n_update_partial_workflow({
  operations: [{
    type: "updateNode",
    nodeName: "HTTP Request",
-    updates: { "parameters.headers": undefined }
+    updates: { "parameters.headers": null }
  }]
 });
 \`\`\`
@@ -272,7 +272,7 @@ n8n_update_partial_workflow({
    type: "updateNode",
    nodeName: "HTTP Request",
    updates: {
-      continueOnFail: undefined,
+      continueOnFail: null,
      onError: "continueErrorOutput"
    }
  }]
@@ -288,15 +288,15 @@ n8n_update_partial_workflow({
    type: "updateNode",
    nodeName: "Data Processor",
    updates: {
-      continueOnFail: undefined,
-      alwaysOutputData: undefined,
-      "parameters.legacy_option": undefined
+      continueOnFail: null,
+      alwaysOutputData: null,
+      "parameters.legacy_option": null
    }
  }]
 });
 \`\`\`

-### When to Use undefined
+### When to Use null
 - Removing deprecated properties during migration
 - Cleaning up optional configuration flags
 - Resolving mutual exclusivity validation errors
@@ -342,11 +342,11 @@ n8n_update_partial_workflow({
            '// Rewire AI Agent to use different language model\nn8n_update_partial_workflow({id: "ai9", operations: [{type: "rewireConnection", source: "AI Agent", from: "OpenAI Chat Model", to: "Anthropic Chat Model", sourceOutput: "ai_languageModel"}]})',
            '// Replace all AI tools for an agent\nn8n_update_partial_workflow({id: "ai10", operations: [\n  {type: "removeConnection", source: "Old Tool 1", target: "AI Agent", sourceOutput: "ai_tool"},\n  {type: "removeConnection", source: "Old Tool 2", target: "AI Agent", sourceOutput: "ai_tool"},\n  {type: "addConnection", source: "New HTTP Tool", target: "AI Agent", sourceOutput: "ai_tool"},\n  {type: "addConnection", source: "New Code Tool", target: "AI Agent", sourceOutput: "ai_tool"}\n]})',
            '\n// ============ REMOVING PROPERTIES EXAMPLES ============',
-            '// Remove a simple property\nn8n_update_partial_workflow({id: "rm1", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {onError: undefined}}]})',
-            '// Migrate from deprecated continueOnFail to onError\nn8n_update_partial_workflow({id: "rm2", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {continueOnFail: undefined, onError: "continueErrorOutput"}}]})',
-            '// Remove nested property\nn8n_update_partial_workflow({id: "rm3", operations: [{type: "updateNode", nodeName: "API Request", updates: {"parameters.authentication": undefined}}]})',
-            '// Remove multiple properties\nn8n_update_partial_workflow({id: "rm4", operations: [{type: "updateNode", nodeName: "Data Processor", updates: {continueOnFail: undefined, alwaysOutputData: undefined, "parameters.legacy_option": undefined}}]})',
-            '// Remove entire array property\nn8n_update_partial_workflow({id: "rm5", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {"parameters.headers": undefined}}]})'
+            '// Remove a simple property\nn8n_update_partial_workflow({id: "rm1", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {onError: null}}]})',
+            '// Migrate from deprecated continueOnFail to onError\nn8n_update_partial_workflow({id: "rm2", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {continueOnFail: null, onError: "continueErrorOutput"}}]})',
+            '// Remove nested property\nn8n_update_partial_workflow({id: "rm3", operations: [{type: "updateNode", nodeName: "API Request", updates: {"parameters.authentication": null}}]})',
+            '// Remove multiple properties\nn8n_update_partial_workflow({id: "rm4", operations: [{type: "updateNode", nodeName: "Data Processor", updates: {continueOnFail: null, alwaysOutputData: null, "parameters.legacy_option": null}}]})',
+            '// Remove entire array property\nn8n_update_partial_workflow({id: "rm5", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {"parameters.headers": null}}]})'
        ],
        useCases: [
            'Rewire connections when replacing nodes',
@@ -384,9 +384,9 @@ n8n_update_partial_workflow({
            'Use targetIndex for fallback models (primary=0, fallback=1)',
            'Batch AI component connections in a single operation for atomicity',
            'Validate AI workflows after connection changes to catch configuration errors',
-            'To remove properties, set them to undefined (not null) in the updates object',
+            'To remove properties, set them to null in the updates object',
            'When migrating from deprecated properties, remove the old property and add the new one in the same operation',
-            'Use undefined to resolve mutual exclusivity validation errors between properties',
+            'Use null to resolve mutual exclusivity validation errors between properties',
            'Batch multiple property removals in a single updateNode operation for efficiency'
        ],
        pitfalls: [
@@ -408,8 +408,8 @@ n8n_update_partial_workflow({
            '**Auto-sanitization runs on ALL nodes**: When ANY update is made, ALL nodes in the workflow are sanitized (not just modified ones)',
            '**Auto-sanitization cannot fix everything**: It fixes operator structures and missing metadata, but cannot fix broken connections or branch mismatches',
            '**Corrupted workflows beyond repair**: Workflows in paradoxical states (API returns corrupt, API rejects updates) cannot be fixed via API - must be recreated',
-            'Setting a property to null does NOT remove it - use undefined instead',
-            'When properties are mutually exclusive (e.g., continueOnFail and onError), setting only the new property will fail - you must remove the old one with undefined',
+            'To remove a property, set it to null in the updates object',
+            'When properties are mutually exclusive (e.g., continueOnFail and onError), setting only the new property will fail - you must remove the old one with null',
            'Removing a required property may cause validation errors - check node documentation first',
            'Nested property removal with dot notation only removes the specific nested field, not the entire parent object',
            'Array index notation (e.g., "parameters.headers[0]") is not supported - remove the entire array property instead'
--- a/dist/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.js.map
+++ b/dist/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.js.map
@@ -1 +1 @@
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--- a/dist/services/node-specific-validators.d.ts.map
+++ b/dist/services/node-specific-validators.d.ts.map
@@ -1 +1 @@
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+{"version":3,"file":"node-specific-validators.d.ts","sourceRoot":"","sources":["../../src/services/node-specific-validators.ts"],"names":[],"mappings":"AAOA,OAAO,EAAE,eAAe,EAAE,iBAAiB,EAAE,MAAM,oBAAoB,CAAC;AAExE,MAAM,WAAW,qBAAqB;IACpC,MAAM,EAAE,MAAM,CAAC,MAAM,EAAE,GAAG,CAAC,CAAC;IAC5B,MAAM,EAAE,eAAe,EAAE,CAAC;IAC1B,QAAQ,EAAE,iBAAiB,EAAE,CAAC;IAC9B,WAAW,EAAE,MAAM,EAAE,CAAC;IACtB,OAAO,EAAE,MAAM,CAAC,MAAM,EAAE,GAAG,CAAC,CAAC;CAC9B;AAED,qBAAa,sBAAsB;IAIjC,MAAM,CAAC,aAAa,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IAqE1D,OAAO,CAAC,MAAM,CAAC,wBAAwB;IAkDvC,OAAO,CAAC,MAAM,CAAC,0BAA0B;IAsBzC,OAAO,CAAC,MAAM,CAAC,0BAA0B;IA4BzC,OAAO,CAAC,MAAM,CAAC,0BAA0B;IA2CzC,MAAM,CAAC,oBAAoB,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IAiDjE,OAAO,CAAC,MAAM,CAAC,0BAA0B;IA0BzC,OAAO,CAAC,MAAM,CAAC,wBAAwB;IAkBvC,OAAO,CAAC,MAAM,CAAC,0BAA0B;IAsBzC,OAAO,CAAC,MAAM,CAAC,0BAA0B;IA4BzC,OAAO,CAAC,MAAM,CAAC,yBAAyB;IAwCxC,MAAM,CAAC,cAAc,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IAwF3D,MAAM,CAAC,eAAe,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IAyG5D,MAAM,CAAC,gBAAgB,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IAkI7D,MAAM,CAAC,eAAe,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IAmG5D,MAAM,CAAC,aAAa,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IA6F1D,OAAO,CAAC,MAAM,CAAC,gBAAgB;IAkF/B,MAAM,CAAC,mBAAmB,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IAiGhE,MAAM,CAAC,eAAe,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IA6D5D,MAAM,CAAC,YAAY,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;IA8DzD,OAAO,CAAC,MAAM,CAAC,sBAAsB;IAuDrC,OAAO,CAAC,MAAM,CAAC,kBAAkB;IAuDjC,OAAO,CAAC,MAAM,CAAC,uBAAuB;IAyFtC,OAAO,CAAC,MAAM,CAAC,oBAAoB;IAuKnC,OAAO,CAAC,MAAM,CAAC,oBAAoB;IA2EnC,MAAM,CAAC,WAAW,CAAC,OAAO,EAAE,qBAAqB,GAAG,IAAI;CAoDzD"}
--- a/dist/services/node-specific-validators.js
+++ b/dist/services/node-specific-validators.js
@@ -1067,7 +1067,8 @@ class NodeSpecificValidators {
                    fix: 'Wrap in array: return [{json: yourObject}]'
                });
            }
-            if (/return\s+(true|false|null|undefined|\d+|['"`])/m.test(code)) {
+            const hasHelperFunctions = /(?:function\s+\w+\s*\(|(?:const|let|var)\s+\w+\s*=\s*(?:async\s+)?(?:function|\([^)]*\)\s*=>|\w+\s*=>))/.test(code);
+            if (!hasHelperFunctions && /return\s+(true|false|null|undefined|\d+|['"`])/m.test(code)) {
                errors.push({
                    type: 'invalid_value',
                    property: 'jsCode',
@@ -1149,7 +1150,7 @@ class NodeSpecificValidators {
            }
        });
        if (language === 'javaScript') {
-            if (/\$(?![a-zA-Z])/.test(code) && !code.includes('${')) {
+            if (/\$(?![a-zA-Z_(])/.test(code) && !code.includes('${')) {
                warnings.push({
                    type: 'best_practice',
                    message: 'Invalid $ usage detected',
--- a/dist/services/node-specific-validators.js.map
+++ b/dist/services/node-specific-validators.js.map
--- a/dist/services/workflow-diff-engine.d.ts
+++ b/dist/services/workflow-diff-engine.d.ts
@@ -3,6 +3,10 @@ import { Workflow } from '../types/n8n-api';
 export declare class WorkflowDiffEngine {
    private renameMap;
    private warnings;
+    private modifiedNodeIds;
+    private removedNodeNames;
+    private tagsToAdd;
+    private tagsToRemove;
    applyDiff(workflow: Workflow, request: WorkflowDiffRequest): Promise<WorkflowDiffResult>;
    private validateOperation;
    private applyOperation;
--- a/dist/services/workflow-diff-engine.d.ts.map
+++ b/dist/services/workflow-diff-engine.d.ts.map
@@ -1 +1 @@
-{"version":3,"file":"workflow-diff-engine.d.ts","sourceRoot":"","sources":["../../src/services/workflow-diff-engine.ts"],"names":[],"mappings":"AAMA,OAAO,EAEL,mBAAmB,EACnB,kBAAkB,EAsBnB,MAAM,wBAAwB,CAAC;AAChC,OAAO,EAAE,QAAQ,EAAoC,MAAM,kBAAkB,CAAC;AAQ9E,qBAAa,kBAAkB;IAE7B,OAAO,CAAC,SAAS,CAAkC;IAEnD,OAAO,CAAC,QAAQ,CAAqC;IAK/C,SAAS,CACb,QAAQ,EAAE,QAAQ,EAClB,OAAO,EAAE,mBAAmB,GAC3B,OAAO,CAAC,kBAAkB,CAAC;IA0M9B,OAAO,CAAC,iBAAiB;IAwCzB,OAAO,CAAC,cAAc;IAyDtB,OAAO,CAAC,eAAe;IAwBvB,OAAO,CAAC,kBAAkB;IAuB1B,OAAO,CAAC,kBAAkB;IAoC1B,OAAO,CAAC,gBAAgB;IAQxB,OAAO,CAAC,kBAAkB;IAU1B,OAAO,CAAC,qBAAqB;IAkD7B,OAAO,CAAC,wBAAwB;IAuChC,OAAO,CAAC,wBAAwB;IAmDhC,OAAO,CAAC,YAAY;IA2BpB,OAAO,CAAC,eAAe;IAkCvB,OAAO,CAAC,eAAe;IAwBvB,OAAO,CAAC,aAAa;IAOrB,OAAO,CAAC,eAAe;IAOvB,OAAO,CAAC,gBAAgB;IAWxB,OAAO,CAAC,sBAAsB;IAgD9B,OAAO,CAAC,kBAAkB;IA4C1B,OAAO,CAAC,qBAAqB;IA2C7B,OAAO,CAAC,qBAAqB;IA0B7B,OAAO,CAAC,mBAAmB;IAW3B,OAAO,CAAC,eAAe;IAIvB,OAAO,CAAC,WAAW;IASnB,OAAO,CAAC,cAAc;IAUtB,OAAO,CAAC,wBAAwB;IAchC,OAAO,CAAC,0BAA0B;IAMlC,OAAO,CAAC,qBAAqB;IAM7B,OAAO,CAAC,uBAAuB;IAO/B,OAAO,CAAC,6BAA6B;IAKrC,OAAO,CAAC,0BAA0B;IA0BlC,OAAO,CAAC,0BAA0B;IA0ElC,OAAO,CAAC,uBAAuB;IAe/B,OAAO,CAAC,0BAA0B;IAkElC,OAAO,CAAC,iBAAiB;IAkBzB,OAAO,CAAC,QAAQ;IAsChB,OAAO,CAAC,uBAAuB;IAW/B,OAAO,CAAC,iBAAiB;CAc1B"}
+{"version":3,"file":"workflow-diff-engine.d.ts","sourceRoot":"","sources":["../../src/services/workflow-diff-engine.ts"],"names":[],"mappings":"AAMA,OAAO,EAEL,mBAAmB,EACnB,kBAAkB,EAsBnB,MAAM,wBAAwB,CAAC;AAChC,OAAO,EAAE,QAAQ,EAAoC,MAAM,kBAAkB,CAAC;AAY9E,qBAAa,kBAAkB;IAE7B,OAAO,CAAC,SAAS,CAAkC;IAEnD,OAAO,CAAC,QAAQ,CAAqC;IAErD,OAAO,CAAC,eAAe,CAAqB;IAE5C,OAAO,CAAC,gBAAgB,CAAqB;IAE7C,OAAO,CAAC,SAAS,CAAgB;IACjC,OAAO,CAAC,YAAY,CAAgB;IAK9B,SAAS,CACb,QAAQ,EAAE,QAAQ,EAClB,OAAO,EAAE,mBAAmB,GAC3B,OAAO,CAAC,kBAAkB,CAAC;IAqN9B,OAAO,CAAC,iBAAiB;IAwCzB,OAAO,CAAC,cAAc;IAyDtB,OAAO,CAAC,eAAe;IAwBvB,OAAO,CAAC,kBAAkB;IAuB1B,OAAO,CAAC,kBAAkB;IAoC1B,OAAO,CAAC,gBAAgB;IAQxB,OAAO,CAAC,kBAAkB;IAU1B,OAAO,CAAC,qBAAqB;IAkD7B,OAAO,CAAC,wBAAwB;IA6ChC,OAAO,CAAC,wBAAwB;IAmDhC,OAAO,CAAC,YAAY;IA4BpB,OAAO,CAAC,eAAe;IAwCvB,OAAO,CAAC,eAAe;IA0BvB,OAAO,CAAC,aAAa;IAOrB,OAAO,CAAC,eAAe;IAOvB,OAAO,CAAC,gBAAgB;IAWxB,OAAO,CAAC,sBAAsB;IAwD9B,OAAO,CAAC,kBAAkB;IA6C1B,OAAO,CAAC,qBAAqB;IAuC7B,OAAO,CAAC,qBAAqB;IA0B7B,OAAO,CAAC,mBAAmB;IAW3B,OAAO,CAAC,eAAe;IAIvB,OAAO,CAAC,WAAW;IAYnB,OAAO,CAAC,cAAc;IAatB,OAAO,CAAC,wBAAwB;IAchC,OAAO,CAAC,0BAA0B;IAMlC,OAAO,CAAC,qBAAqB;IAM7B,OAAO,CAAC,uBAAuB;IAO/B,OAAO,CAAC,6BAA6B;IAKrC,OAAO,CAAC,0BAA0B;IA0BlC,OAAO,CAAC,0BAA0B;IA+ElC,OAAO,CAAC,uBAAuB;IAe/B,OAAO,CAAC,0BAA0B;IAkElC,OAAO,CAAC,iBAAiB;IAkBzB,OAAO,CAAC,QAAQ;IAsChB,OAAO,CAAC,uBAAuB;IAW/B,OAAO,CAAC,iBAAiB;CAoB1B"}
--- a/dist/services/workflow-diff-engine.js
+++ b/dist/services/workflow-diff-engine.js
@@ -10,11 +10,19 @@ class WorkflowDiffEngine {
    constructor() {
        this.renameMap = new Map();
        this.warnings = [];
+        this.modifiedNodeIds = new Set();
+        this.removedNodeNames = new Set();
+        this.tagsToAdd = [];
+        this.tagsToRemove = [];
    }
    async applyDiff(workflow, request) {
        try {
            this.renameMap.clear();
            this.warnings = [];
+            this.modifiedNodeIds.clear();
+            this.removedNodeNames.clear();
+            this.tagsToAdd = [];
+            this.tagsToRemove = [];
            const workflowCopy = JSON.parse(JSON.stringify(workflow));
            const nodeOperationTypes = ['addNode', 'removeNode', 'updateNode', 'moveNode', 'enableNode', 'disableNode'];
            const nodeOperations = [];
@@ -82,7 +90,9 @@ class WorkflowDiffEngine {
                    errors: errors.length > 0 ? errors : undefined,
                    warnings: this.warnings.length > 0 ? this.warnings : undefined,
                    applied: appliedIndices,
-                    failed: failedIndices
+                    failed: failedIndices,
+                    tagsToAdd: this.tagsToAdd.length > 0 ? this.tagsToAdd : undefined,
+                    tagsToRemove: this.tagsToRemove.length > 0 ? this.tagsToRemove : undefined
                };
            }
            else {
@@ -142,8 +152,15 @@ class WorkflowDiffEngine {
                        };
                    }
                }
-                workflowCopy.nodes = workflowCopy.nodes.map((node) => (0, node_sanitizer_1.sanitizeNode)(node));
-                logger.debug('Applied full-workflow sanitization to all nodes');
+                if (this.modifiedNodeIds.size > 0) {
+                    workflowCopy.nodes = workflowCopy.nodes.map((node) => {
+                        if (this.modifiedNodeIds.has(node.id)) {
+                            return (0, node_sanitizer_1.sanitizeNode)(node);
+                        }
+                        return node;
+                    });
+                    logger.debug(`Sanitized ${this.modifiedNodeIds.size} modified nodes`);
+                }
                if (request.validateOnly) {
                    return {
                        success: true,
@@ -162,7 +179,9 @@ class WorkflowDiffEngine {
                    message: `Successfully applied ${operationsApplied} operations (${nodeOperations.length} node ops, ${otherOperations.length} other ops)`,
                    warnings: this.warnings.length > 0 ? this.warnings : undefined,
                    shouldActivate: shouldActivate || undefined,
-                    shouldDeactivate: shouldDeactivate || undefined
+                    shouldDeactivate: shouldDeactivate || undefined,
+                    tagsToAdd: this.tagsToAdd.length > 0 ? this.tagsToAdd : undefined,
+                    tagsToRemove: this.tagsToRemove.length > 0 ? this.tagsToRemove : undefined
                };
            }
        }
@@ -302,7 +321,7 @@ class WorkflowDiffEngine {
            return `Invalid parameter 'changes'. The updateNode operation requires 'updates' (not 'changes'). Example: {type: "updateNode", nodeId: "abc", updates: {name: "New Name", "parameters.url": "https://example.com"}}`;
        }
        if (!operation.updates) {
-            return `Missing required parameter 'updates'. The updateNode operation requires an 'updates' object containing properties to modify. Example: {type: "updateNode", nodeId: "abc", updates: {name: "New Name"}}`;
+            return `Missing required parameter 'updates'. The updateNode operation requires an 'updates' object. Correct structure: {type: "updateNode", nodeId: "abc-123" OR nodeName: "My Node", updates: {name: "New Name", "parameters.url": "https://example.com"}}`;
        }
        const node = this.findNode(workflow, operation.nodeId, operation.nodeName);
        if (!node) {
@@ -382,12 +401,18 @@ class WorkflowDiffEngine {
        const sourceNode = this.findNode(workflow, operation.source, operation.source);
        const targetNode = this.findNode(workflow, operation.target, operation.target);
        if (!sourceNode) {
+            if (this.removedNodeNames.has(operation.source)) {
+                return `Source node "${operation.source}" was already removed by a prior removeNode operation. Its connections were automatically cleaned up — no separate removeConnection needed.`;
+            }
            const availableNodes = workflow.nodes
                .map(n => `"${n.name}" (id: ${n.id.substring(0, 8)}...)`)
                .join(', ');
            return `Source node not found: "${operation.source}". Available nodes: ${availableNodes}. Tip: Use node ID for names with special characters.`;
        }
        if (!targetNode) {
+            if (this.removedNodeNames.has(operation.target)) {
+                return `Target node "${operation.target}" was already removed by a prior removeNode operation. Its connections were automatically cleaned up — no separate removeConnection needed.`;
+            }
            const availableNodes = workflow.nodes
                .map(n => `"${n.name}" (id: ${n.id.substring(0, 8)}...)`)
                .join(', ');
@@ -461,34 +486,40 @@ class WorkflowDiffEngine {
            executeOnce: operation.node.executeOnce
        };
        const sanitizedNode = (0, node_sanitizer_1.sanitizeNode)(newNode);
+        this.modifiedNodeIds.add(sanitizedNode.id);
        workflow.nodes.push(sanitizedNode);
    }
    applyRemoveNode(workflow, operation) {
        const node = this.findNode(workflow, operation.nodeId, operation.nodeName);
        if (!node)
            return;
+        this.removedNodeNames.add(node.name);
        const index = workflow.nodes.findIndex(n => n.id === node.id);
        if (index !== -1) {
            workflow.nodes.splice(index, 1);
        }
        delete workflow.connections[node.name];
-        Object.keys(workflow.connections).forEach(sourceName => {
-            const sourceConnections = workflow.connections[sourceName];
-            Object.keys(sourceConnections).forEach(outputName => {
-                sourceConnections[outputName] = sourceConnections[outputName].map(connections => connections.filter(conn => conn.node !== node.name)).filter(connections => connections.length > 0);
-                if (sourceConnections[outputName].length === 0) {
+        for (const [sourceName, sourceConnections] of Object.entries(workflow.connections)) {
+            for (const [outputName, outputConns] of Object.entries(sourceConnections)) {
+                sourceConnections[outputName] = outputConns.map(connections => connections.filter(conn => conn.node !== node.name));
+                const trimmed = sourceConnections[outputName];
+                while (trimmed.length > 0 && trimmed[trimmed.length - 1].length === 0) {
+                    trimmed.pop();
+                }
+                if (trimmed.length === 0) {
                    delete sourceConnections[outputName];
                }
-            });
+            }
            if (Object.keys(sourceConnections).length === 0) {
                delete workflow.connections[sourceName];
            }
-        });
+        }
    }
    applyUpdateNode(workflow, operation) {
        const node = this.findNode(workflow, operation.nodeId, operation.nodeName);
        if (!node)
            return;
+        this.modifiedNodeIds.add(node.id);
        if (operation.updates.name && operation.updates.name !== node.name) {
            const oldName = node.name;
            const newName = operation.updates.name;
@@ -521,8 +552,13 @@ class WorkflowDiffEngine {
    }
    resolveSmartParameters(workflow, operation) {
        const sourceNode = this.findNode(workflow, operation.source, operation.source);
-        let sourceOutput = operation.sourceOutput ?? 'main';
+        let sourceOutput = String(operation.sourceOutput ?? 'main');
        let sourceIndex = operation.sourceIndex ?? 0;
+        if (/^\d+$/.test(sourceOutput) && operation.sourceIndex === undefined
+            && operation.branch === undefined && operation.case === undefined) {
+            sourceIndex = parseInt(sourceOutput, 10);
+            sourceOutput = 'main';
+        }
        if (operation.branch !== undefined && operation.sourceIndex === undefined) {
            if (sourceNode?.type === 'n8n-nodes-base.if') {
                sourceIndex = operation.branch === 'true' ? 0 : 1;
@@ -556,7 +592,7 @@ class WorkflowDiffEngine {
        if (!sourceNode || !targetNode)
            return;
        const { sourceOutput, sourceIndex } = this.resolveSmartParameters(workflow, operation);
-        const targetInput = operation.targetInput ?? sourceOutput;
+        const targetInput = String(operation.targetInput ?? sourceOutput);
        const targetIndex = operation.targetIndex ?? 0;
        if (!workflow.connections[sourceNode.name]) {
            workflow.connections[sourceNode.name] = {};
@@ -581,12 +617,9 @@ class WorkflowDiffEngine {
        const sourceNode = this.findNode(workflow, operation.source, operation.source);
        const targetNode = this.findNode(workflow, operation.target, operation.target);
        if (!sourceNode || !targetNode) {
-            if (operation.ignoreErrors) {
-                return;
-            }
            return;
        }
-        const sourceOutput = operation.sourceOutput || 'main';
+        const sourceOutput = String(operation.sourceOutput ?? 'main');
        const connections = workflow.connections[sourceNode.name]?.[sourceOutput];
        if (!connections)
            return;
@@ -633,19 +666,21 @@ class WorkflowDiffEngine {
        workflow.name = operation.name;
    }
    applyAddTag(workflow, operation) {
-        if (!workflow.tags) {
-            workflow.tags = [];
+        const removeIdx = this.tagsToRemove.indexOf(operation.tag);
+        if (removeIdx !== -1) {
+            this.tagsToRemove.splice(removeIdx, 1);
        }
-        if (!workflow.tags.includes(operation.tag)) {
-            workflow.tags.push(operation.tag);
+        if (!this.tagsToAdd.includes(operation.tag)) {
+            this.tagsToAdd.push(operation.tag);
        }
    }
    applyRemoveTag(workflow, operation) {
-        if (!workflow.tags)
-            return;
-        const index = workflow.tags.indexOf(operation.tag);
-        if (index !== -1) {
-            workflow.tags.splice(index, 1);
+        const addIdx = this.tagsToAdd.indexOf(operation.tag);
+        if (addIdx !== -1) {
+            this.tagsToAdd.splice(addIdx, 1);
+        }
+        if (!this.tagsToRemove.includes(operation.tag)) {
+            this.tagsToRemove.push(operation.tag);
        }
    }
    validateActivateWorkflow(workflow, operation) {
@@ -734,7 +769,10 @@ class WorkflowDiffEngine {
                        return false;
                    }
                    return true;
-                })).filter(conns => conns.length > 0);
+                }));
+                while (filteredConnections.length > 0 && filteredConnections[filteredConnections.length - 1].length === 0) {
+                    filteredConnections.pop();
+                }
                if (filteredConnections.length === 0) {
                    delete outputs[outputName];
                }
@@ -818,12 +856,20 @@ class WorkflowDiffEngine {
        let current = obj;
        for (let i = 0; i < keys.length - 1; i++) {
            const key = keys[i];
-            if (!(key in current) || typeof current[key] !== 'object') {
+            if (!(key in current) || typeof current[key] !== 'object' || current[key] === null) {
+                if (value === null)
+                    return;
                current[key] = {};
            }
            current = current[key];
        }
-        current[keys[keys.length - 1]] = value;
+        const finalKey = keys[keys.length - 1];
+        if (value === null) {
+            delete current[finalKey];
+        }
+        else {
+            current[finalKey] = value;
+        }
    }
 }
 exports.WorkflowDiffEngine = WorkflowDiffEngine;
--- a/dist/services/workflow-diff-engine.js.map
+++ b/dist/services/workflow-diff-engine.js.map
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
  "name": "n8n-mcp",
-  "version": "2.37.1",
+  "version": "2.37.2",
  "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
--- a/src/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.ts
+++ b/src/mcp/tool-docs/workflow_management/n8n-update-partial-workflow.ts
@@ -194,12 +194,12 @@ Please choose a different name.
 - Can rename a node and add/remove connections using the new name in the same batch
 - Use \`validateOnly: true\` to preview effects before applying

-## Removing Properties with undefined
+## Removing Properties with null

-To remove a property from a node, set its value to \`undefined\` in the updates object. This is essential when migrating from deprecated properties or cleaning up optional configuration fields.
+To remove a property from a node, set its value to \`null\` in the updates object. This is essential when migrating from deprecated properties or cleaning up optional configuration fields.

-### Why Use undefined?
- **Property removal vs. null**: Setting a property to \`undefined\` removes it completely from the node object, while \`null\` sets the property to a null value
+### Why Use null?
+- **Property removal**: Setting a property to \`null\` removes it completely from the node object
 - **Validation constraints**: Some properties are mutually exclusive (e.g., \`continueOnFail\` and \`onError\`). Simply setting one without removing the other will fail validation
 - **Deprecated property migration**: When n8n deprecates properties, you must remove the old property before the new one will work

@@ -211,7 +211,7 @@ n8n_update_partial_workflow({
  operations: [{
    type: "updateNode",
    nodeName: "HTTP Request",
-    updates: { onError: undefined }
+    updates: { onError: null }
  }]
 });

@@ -221,7 +221,7 @@ n8n_update_partial_workflow({
  operations: [{
    type: "updateNode",
    nodeId: "node_abc",
-    updates: { disabled: undefined }
+    updates: { disabled: null }
  }]
 });
 \`\`\`
@@ -235,7 +235,7 @@ n8n_update_partial_workflow({
  operations: [{
    type: "updateNode",
    nodeName: "API Request",
-    updates: { "parameters.authentication": undefined }
+    updates: { "parameters.authentication": null }
  }]
 });

@@ -245,7 +245,7 @@ n8n_update_partial_workflow({
  operations: [{
    type: "updateNode",
    nodeName: "HTTP Request",
-    updates: { "parameters.headers": undefined }
+    updates: { "parameters.headers": null }
  }]
 });
 \`\`\`
@@ -271,7 +271,7 @@ n8n_update_partial_workflow({
    type: "updateNode",
    nodeName: "HTTP Request",
    updates: {
-      continueOnFail: undefined,
+      continueOnFail: null,
      onError: "continueErrorOutput"
    }
  }]
@@ -287,15 +287,15 @@ n8n_update_partial_workflow({
    type: "updateNode",
    nodeName: "Data Processor",
    updates: {
-      continueOnFail: undefined,
-      alwaysOutputData: undefined,
-      "parameters.legacy_option": undefined
+      continueOnFail: null,
+      alwaysOutputData: null,
+      "parameters.legacy_option": null
    }
  }]
 });
 \`\`\`

-### When to Use undefined
+### When to Use null
 - Removing deprecated properties during migration
 - Cleaning up optional configuration flags
 - Resolving mutual exclusivity validation errors
@@ -341,11 +341,11 @@ n8n_update_partial_workflow({
      '// Rewire AI Agent to use different language model\nn8n_update_partial_workflow({id: "ai9", operations: [{type: "rewireConnection", source: "AI Agent", from: "OpenAI Chat Model", to: "Anthropic Chat Model", sourceOutput: "ai_languageModel"}]})',
      '// Replace all AI tools for an agent\nn8n_update_partial_workflow({id: "ai10", operations: [\n  {type: "removeConnection", source: "Old Tool 1", target: "AI Agent", sourceOutput: "ai_tool"},\n  {type: "removeConnection", source: "Old Tool 2", target: "AI Agent", sourceOutput: "ai_tool"},\n  {type: "addConnection", source: "New HTTP Tool", target: "AI Agent", sourceOutput: "ai_tool"},\n  {type: "addConnection", source: "New Code Tool", target: "AI Agent", sourceOutput: "ai_tool"}\n]})',
      '\n// ============ REMOVING PROPERTIES EXAMPLES ============',
-      '// Remove a simple property\nn8n_update_partial_workflow({id: "rm1", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {onError: undefined}}]})',
-      '// Migrate from deprecated continueOnFail to onError\nn8n_update_partial_workflow({id: "rm2", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {continueOnFail: undefined, onError: "continueErrorOutput"}}]})',
-      '// Remove nested property\nn8n_update_partial_workflow({id: "rm3", operations: [{type: "updateNode", nodeName: "API Request", updates: {"parameters.authentication": undefined}}]})',
-      '// Remove multiple properties\nn8n_update_partial_workflow({id: "rm4", operations: [{type: "updateNode", nodeName: "Data Processor", updates: {continueOnFail: undefined, alwaysOutputData: undefined, "parameters.legacy_option": undefined}}]})',
-      '// Remove entire array property\nn8n_update_partial_workflow({id: "rm5", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {"parameters.headers": undefined}}]})'
+      '// Remove a simple property\nn8n_update_partial_workflow({id: "rm1", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {onError: null}}]})',
+      '// Migrate from deprecated continueOnFail to onError\nn8n_update_partial_workflow({id: "rm2", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {continueOnFail: null, onError: "continueErrorOutput"}}]})',
+      '// Remove nested property\nn8n_update_partial_workflow({id: "rm3", operations: [{type: "updateNode", nodeName: "API Request", updates: {"parameters.authentication": null}}]})',
+      '// Remove multiple properties\nn8n_update_partial_workflow({id: "rm4", operations: [{type: "updateNode", nodeName: "Data Processor", updates: {continueOnFail: null, alwaysOutputData: null, "parameters.legacy_option": null}}]})',
+      '// Remove entire array property\nn8n_update_partial_workflow({id: "rm5", operations: [{type: "updateNode", nodeName: "HTTP Request", updates: {"parameters.headers": null}}]})'
    ],
    useCases: [
      'Rewire connections when replacing nodes',
@@ -383,9 +383,9 @@ n8n_update_partial_workflow({
      'Use targetIndex for fallback models (primary=0, fallback=1)',
      'Batch AI component connections in a single operation for atomicity',
      'Validate AI workflows after connection changes to catch configuration errors',
-      'To remove properties, set them to undefined (not null) in the updates object',
+      'To remove properties, set them to null in the updates object',
      'When migrating from deprecated properties, remove the old property and add the new one in the same operation',
-      'Use undefined to resolve mutual exclusivity validation errors between properties',
+      'Use null to resolve mutual exclusivity validation errors between properties',
      'Batch multiple property removals in a single updateNode operation for efficiency'
    ],
    pitfalls: [
@@ -407,8 +407,8 @@ n8n_update_partial_workflow({
      '**Auto-sanitization runs on ALL nodes**: When ANY update is made, ALL nodes in the workflow are sanitized (not just modified ones)',
      '**Auto-sanitization cannot fix everything**: It fixes operator structures and missing metadata, but cannot fix broken connections or branch mismatches',
      '**Corrupted workflows beyond repair**: Workflows in paradoxical states (API returns corrupt, API rejects updates) cannot be fixed via API - must be recreated',
-      'Setting a property to null does NOT remove it - use undefined instead',
-      'When properties are mutually exclusive (e.g., continueOnFail and onError), setting only the new property will fail - you must remove the old one with undefined',
+      'To remove a property, set it to null in the updates object',
+      'When properties are mutually exclusive (e.g., continueOnFail and onError), setting only the new property will fail - you must remove the old one with null',
      'Removing a required property may cause validation errors - check node documentation first',
      'Nested property removal with dot notation only removes the specific nested field, not the entire parent object',
      'Array index notation (e.g., "parameters.headers[0]") is not supported - remove the entire array property instead'
--- a/src/services/node-specific-validators.ts
+++ b/src/services/node-specific-validators.ts
@@ -1374,8 +1374,11 @@ export class NodeSpecificValidators {
        });
      }
      
-      // Check for primitive return
-      if (/return\s+(true|false|null|undefined|\d+|['"`])/m.test(code)) {
+      // Skip primitive return check when helper functions are present,
+      // since we can't distinguish top-level vs nested returns without AST.
+      // Matches: function name(), const/let/var name = [async] function/arrow
+      const hasHelperFunctions = /(?:function\s+\w+\s*\(|(?:const|let|var)\s+\w+\s*=\s*(?:async\s+)?(?:function|\([^)]*\)\s*=>|\w+\s*=>))/.test(code);
+      if (!hasHelperFunctions && /return\s+(true|false|null|undefined|\d+|['"`])/m.test(code)) {
        errors.push({
          type: 'invalid_value',
          property: 'jsCode',
@@ -1487,7 +1490,7 @@ export class NodeSpecificValidators {
    // Check for common variable mistakes
    if (language === 'javaScript') {
      // Using $ without proper variable
-      if (/\$(?![a-zA-Z])/.test(code) && !code.includes('${')) {
+      if (/\$(?![a-zA-Z_(])/.test(code) && !code.includes('${')) {
        warnings.push({
          type: 'best_practice',
          message: 'Invalid $ usage detected',
--- a/src/services/workflow-diff-engine.ts
+++ b/src/services/workflow-diff-engine.ts
@@ -1240,12 +1240,18 @@ export class WorkflowDiffEngine {

    for (let i = 0; i < keys.length - 1; i++) {
      const key = keys[i];
-      if (!(key in current) || typeof current[key] !== 'object') {
+      if (!(key in current) || typeof current[key] !== 'object' || current[key] === null) {
+        if (value === null) return; // parent path doesn't exist, nothing to delete
        current[key] = {};
      }
      current = current[key];
    }

-    current[keys[keys.length - 1]] = value;
+    const finalKey = keys[keys.length - 1];
+    if (value === null) {
+      delete current[finalKey];
+    } else {
+      current[finalKey] = value;
+    }
  }
 }
--- a/tests/unit/services/node-specific-validators.test.ts
+++ b/tests/unit/services/node-specific-validators.test.ts
@@ -1912,6 +1912,55 @@ return [{"json": {"result": result}}]
        });
      });

+      it('should not error on primitive return inside helper functions', () => {
+        context.config = {
+          language: 'javaScript',
+          jsCode: 'function isValid(item) { return false; }\nconst items = $input.all();\nreturn items.filter(isValid).map(i => ({json: i.json}));'
+        };
+
+        NodeSpecificValidators.validateCode(context);
+
+        const primitiveErrors = context.errors.filter(e => e.message === 'Cannot return primitive values directly');
+        expect(primitiveErrors).toHaveLength(0);
+      });
+
+      it('should not error on primitive return inside arrow function helpers', () => {
+        context.config = {
+          language: 'javaScript',
+          jsCode: 'const isValid = (item) => { return false; };\nreturn $input.all().filter(isValid).map(i => ({json: i.json}));'
+        };
+
+        NodeSpecificValidators.validateCode(context);
+
+        const primitiveErrors = context.errors.filter(e => e.message === 'Cannot return primitive values directly');
+        expect(primitiveErrors).toHaveLength(0);
+      });
+
+      it('should not error on primitive return inside async function helpers', () => {
+        context.config = {
+          language: 'javaScript',
+          jsCode: 'async function fetchData(url) { return null; }\nconst data = await fetchData("https://api.example.com");\nreturn [{json: {data}}];'
+        };
+
+        NodeSpecificValidators.validateCode(context);
+
+        const primitiveErrors = context.errors.filter(e => e.message === 'Cannot return primitive values directly');
+        expect(primitiveErrors).toHaveLength(0);
+      });
+
+      it('should still error on primitive return without helper functions', () => {
+        context.config = {
+          language: 'javaScript',
+          jsCode: 'return "success";'
+        };
+
+        NodeSpecificValidators.validateCode(context);
+
+        expect(context.errors).toContainEqual(expect.objectContaining({
+          message: 'Cannot return primitive values directly'
+        }));
+      });
+
      it('should error on Python primitive return', () => {
        context.config = {
          language: 'python',
@@ -2038,6 +2087,30 @@ return [{"json": {"result": result}}]
        });
      });

+      it('should not warn about $() node reference syntax', () => {
+        context.config = {
+          language: 'javaScript',
+          jsCode: 'const data = $("Previous Node").first().json;\nreturn [{json: data}];'
+        };
+
+        NodeSpecificValidators.validateCode(context);
+
+        const dollarWarnings = context.warnings.filter(w => w.message === 'Invalid $ usage detected');
+        expect(dollarWarnings).toHaveLength(0);
+      });
+
+      it('should not warn about $_ variables', () => {
+        context.config = {
+          language: 'javaScript',
+          jsCode: 'const $_temp = 1;\nreturn [{json: {value: $_temp}}];'
+        };
+
+        NodeSpecificValidators.validateCode(context);
+
+        const dollarWarnings = context.warnings.filter(w => w.message === 'Invalid $ usage detected');
+        expect(dollarWarnings).toHaveLength(0);
+      });
+
      it('should correct helpers usage', () => {
        context.config = {
          language: 'javaScript',
--- a/tests/unit/services/workflow-diff-engine.test.ts
+++ b/tests/unit/services/workflow-diff-engine.test.ts
@@ -4882,4 +4882,111 @@ describe('WorkflowDiffEngine', () => {
      expect(result.workflow.connections['Source Node']['main'][0][0].type).toBe('main');
    });
  });
+
+  describe('null value property deletion', () => {
+    it('should delete a property when value is null', async () => {
+      const node = baseWorkflow.nodes.find((n: any) => n.name === 'HTTP Request')!;
+      (node as any).continueOnFail = true;
+
+      const operation: UpdateNodeOperation = {
+        type: 'updateNode',
+        nodeName: 'HTTP Request',
+        updates: { continueOnFail: null }
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(baseWorkflow, request);
+
+      expect(result.success).toBe(true);
+      const updatedNode = result.workflow.nodes.find((n: any) => n.name === 'HTTP Request')!;
+      expect('continueOnFail' in updatedNode).toBe(false);
+    });
+
+    it('should delete a nested property when value is null', async () => {
+      const node = baseWorkflow.nodes.find((n: any) => n.name === 'HTTP Request')!;
+      (node as any).parameters = { url: 'https://example.com', authentication: 'basic' };
+
+      const operation: UpdateNodeOperation = {
+        type: 'updateNode',
+        nodeName: 'HTTP Request',
+        updates: { 'parameters.authentication': null }
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(baseWorkflow, request);
+
+      expect(result.success).toBe(true);
+      const updatedNode = result.workflow.nodes.find((n: any) => n.name === 'HTTP Request')!;
+      expect((updatedNode as any).parameters.url).toBe('https://example.com');
+      expect('authentication' in (updatedNode as any).parameters).toBe(false);
+    });
+
+    it('should set property normally when value is not null', async () => {
+      const operation: UpdateNodeOperation = {
+        type: 'updateNode',
+        nodeName: 'HTTP Request',
+        updates: { continueOnFail: true }
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(baseWorkflow, request);
+
+      expect(result.success).toBe(true);
+      const updatedNode = result.workflow.nodes.find((n: any) => n.name === 'HTTP Request')!;
+      expect((updatedNode as any).continueOnFail).toBe(true);
+    });
+
+    it('should be a no-op when deleting a non-existent property', async () => {
+      const node = baseWorkflow.nodes.find((n: any) => n.name === 'HTTP Request')!;
+      const originalKeys = Object.keys(node).sort();
+
+      const operation: UpdateNodeOperation = {
+        type: 'updateNode',
+        nodeName: 'HTTP Request',
+        updates: { nonExistentProp: null }
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(baseWorkflow, request);
+
+      expect(result.success).toBe(true);
+      const updatedNode = result.workflow.nodes.find((n: any) => n.name === 'HTTP Request')!;
+      expect('nonExistentProp' in updatedNode).toBe(false);
+    });
+
+    it('should skip intermediate object creation when deleting from non-existent parent path', async () => {
+      const operation: UpdateNodeOperation = {
+        type: 'updateNode',
+        nodeName: 'HTTP Request',
+        updates: { 'nonExistent.deeply.nested.prop': null }
+      };
+
+      const request: WorkflowDiffRequest = {
+        id: 'test-workflow',
+        operations: [operation]
+      };
+
+      const result = await diffEngine.applyDiff(baseWorkflow, request);
+
+      expect(result.success).toBe(true);
+      const updatedNode = result.workflow.nodes.find((n: any) => n.name === 'HTTP Request')!;
+      expect('nonExistent' in updatedNode).toBe(false);
+    });
+  });
 });