Add documentation and manual testing for HuggingFace embedding fix

Co-authored-by: HenryHengZJ <26460777+HenryHengZJ@users.noreply.github.com>

HUGGINGFACE_EMBEDDING_FIX.md

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+# HuggingFace Embedding API Fix
+
+## Issue
+HuggingFace embedding Inference API was not working and outputting "Error in Agent node: An error occurred while fetching the blob". This was caused by deprecated endpoints in the old langchain version, as referenced in [langchainjs PR #8237](https://github.com/langchain-ai/langchainjs/pull/8237).
+
+## Root Cause
+The project was using a very outdated version of langchain (0.0.112) while the latest version was 0.3.34. The old version had deprecated HuggingFace API endpoints that were no longer working.
+
+## Solution
+Updated the langchain ecosystem to the latest versions and switched to using the official HuggingFace embeddings implementation from `@langchain/community`.
+
+### Changes Made
+
+#### 1. Updated Dependencies (`packages/components/package.json`)
+- `langchain`: `^0.0.112` → `^0.3.34`
+- `@huggingface/inference`: `^2.6.1` → `^4.0.5`
+- Added `@langchain/community`: `^0.3.56`
+- Added `@langchain/core`: `^0.3.78`
+
+#### 2. Updated HuggingFace Embedding Implementation
+**File**: `packages/components/nodes/embeddings/HuggingFaceInferenceEmbedding/HuggingFaceInferenceEmbedding.ts`
+
+**Before**:
+```typescript
+import { HuggingFaceInferenceEmbeddings, HuggingFaceInferenceEmbeddingsParams } from './core'
+```
+
+**After**:
+```typescript
+import { HuggingFaceInferenceEmbeddings, HuggingFaceInferenceEmbeddingsParams } from '@langchain/community/dist/embeddings/hf.cjs'
+```
+
+#### 3. Parameter Mapping Fix
+Updated parameter mapping for the new API:
+- `endpoint` → `endpointUrl`
+
+**Before**:
+```typescript
+if (endpoint) obj.endpoint = endpoint
+```
+
+**After**:
+```typescript
+if (endpoint) obj.endpointUrl = endpoint
+```
+
+#### 4. Removed Custom Implementation
+- Renamed `core.ts` to `core.ts.backup` since we now use the official langchain community implementation
+- The custom implementation is no longer needed as the official version has all the fixes
+
+### Testing
+Created test scripts to verify the fix:
+- `test_huggingface_manual.js` - Manual test with real API calls (requires valid API key)
+- Automated tests confirm the embeddings class can be instantiated and configured correctly
+
+### Benefits
+1. **Fixed deprecated endpoints**: Uses the latest HuggingFace API endpoints that are actively maintained
+2. **Better maintenance**: Official implementation receives updates automatically with langchain updates
+3. **Improved compatibility**: Updated dependencies resolve version conflicts
+4. **Future-proof**: Latest versions will receive ongoing support and security updates
+
+## Usage
+The HuggingFace embedding node works the same way from a user perspective:
+1. Add HuggingFace API key
+2. Optionally specify model name
+3. Optionally specify custom endpoint URL
+
+No changes required in existing flows - the fix is backward compatible.
+
+## Testing
+To test the fix manually with a real API key:
+
+```bash
+cd packages/components
+export HUGGINGFACEHUB_API_KEY=your_hf_token_here
+node test_huggingface_manual.js
+```
+
+This will test actual embedding generation to confirm the deprecated endpoints issue is resolved.

packages/components/test_huggingface_manual.js

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+#!/usr/bin/env node
+
+/**
+ * Manual test script for HuggingFace Embedding API
+ * 
+ * To run this test:
+ * 1. Set your HuggingFace API key: export HUGGINGFACEHUB_API_KEY=your_api_key_here
+ * 2. Run: node test_huggingface_manual.js
+ * 
+ * This will test the actual HuggingFace embedding API calls to verify the
+ * deprecated endpoints issue has been fixed.
+ */
+
+const { HuggingFaceInferenceEmbeddings } = require('@langchain/community/dist/embeddings/hf.cjs');
+
+async function testHuggingFaceEmbeddings() {
+    console.log('HuggingFace Embedding API Manual Test');
+    console.log('=====================================\n');
+    
+    const apiKey = process.env.HUGGINGFACEHUB_API_KEY;
+    
+    if (!apiKey) {
+        console.log('❌ No API key found. Please set HUGGINGFACEHUB_API_KEY environment variable.');
+        console.log('   Example: export HUGGINGFACEHUB_API_KEY=hf_your_token_here');
+        process.exit(1);
+    }
+    
+    console.log('✓ API key found, testing embedding functionality...\n');
+    
+    try {
+        // Test 1: Basic embedding with default model
+        console.log('Test 1: Basic embedding generation');
+        const embeddings1 = new HuggingFaceInferenceEmbeddings({
+            apiKey: apiKey,
+            model: 'sentence-transformers/all-MiniLM-L6-v2'
+        });
+        
+        const testText = 'Hello, this is a test sentence for embedding generation.';
+        console.log(`  Input text: "${testText}"`);
+        
+        const result = await embeddings1.embedQuery(testText);
+        console.log(`  ✓ Generated embedding vector of length: ${result.length}`);
+        console.log(`  ✓ First few values: [${result.slice(0, 5).map(v => v.toFixed(4)).join(', ')}...]`);
+        
+        // Test 2: Batch embedding
+        console.log('\nTest 2: Batch embedding generation');
+        const documents = [
+            'This is the first document.',
+            'Here is the second document.',
+            'And this is the third one.'
+        ];
+        
+        const batchResults = await embeddings1.embedDocuments(documents);
+        console.log(`  ✓ Generated embeddings for ${batchResults.length} documents`);
+        console.log(`  ✓ Each embedding has ${batchResults[0].length} dimensions`);
+        
+        // Test 3: Custom endpoint (if you have one)
+        if (process.env.HUGGINGFACE_ENDPOINT) {
+            console.log('\nTest 3: Custom endpoint');
+            const embeddings3 = new HuggingFaceInferenceEmbeddings({
+                apiKey: apiKey,
+                endpointUrl: process.env.HUGGINGFACE_ENDPOINT
+            });
+            
+            const customResult = await embeddings3.embedQuery(testText);
+            console.log(`  ✓ Custom endpoint generated embedding of length: ${customResult.length}`);
+        } else {
+            console.log('\nTest 3: Skipped (no custom endpoint provided)');
+            console.log('  Set HUGGINGFACE_ENDPOINT environment variable to test custom endpoints');
+        }
+        
+        console.log('\n✅ All tests passed! HuggingFace embedding API is working correctly.');
+        console.log('\n🎉 The deprecated endpoints issue has been resolved by updating to:');
+        console.log('   - langchain: 0.3.34');
+        console.log('   - @langchain/community: 0.3.56');
+        console.log('   - @langchain/core: 0.3.78');
+        console.log('   - @huggingface/inference: 4.0.5');
+        
+    } catch (error) {
+        console.error('\n❌ Test failed:');
+        console.error(`   Error: ${error.message}`);
+        
+        if (error.message.includes('401') || error.message.includes('unauthorized')) {
+            console.error('   This looks like an API key issue. Please check your HUGGINGFACEHUB_API_KEY.');
+        } else if (error.message.includes('blob') || error.message.includes('fetch')) {
+            console.error('   This might be the original deprecated endpoints issue.');
+            console.error('   Please verify all dependencies are updated correctly.');
+        }
+        
+        console.error('\n   Full error:', error);
+        process.exit(1);
+    }
+}
+
+// Run the test
+testHuggingFaceEmbeddings();