fix: OCR API error

backend/src/features/ocr/external/ocr-client.ts

@@ -1,9 +1,8 @@
 /**
  * @ai-summary HTTP client for OCR service communication
  */
-import FormData from 'form-data';
 import { logger } from '../../../core/logging/logger';
-import type { JobResponse, OcrResponse } from '../domain/ocr.types';
+import type { JobResponse, OcrResponse, VinExtractionResponse } from '../domain/ocr.types';
 
 /** OCR service configuration */
 const OCR_SERVICE_URL = process.env.OCR_SERVICE_URL || 'http://mvp-ocr:8000';
@@ -32,12 +31,7 @@ export class OcrClient {
     contentType: string,
     preprocess: boolean = true
   ): Promise<OcrResponse> {
-    const formData = new FormData();
-    formData.append('file', fileBuffer, {
-      filename: this.getFilenameFromContentType(contentType),
-      contentType,
-    });
-
+    const formData = this.buildFormData(fileBuffer, contentType);
     const url = `${this.baseUrl}/extract?preprocess=${preprocess}`;
 
     logger.info('OCR extract request', {
@@ -50,8 +44,7 @@ export class OcrClient {
 
     const response = await this.fetchWithTimeout(url, {
       method: 'POST',
-      body: formData as any,
-      headers: formData.getHeaders(),
+      body: formData,
     });
 
     if (!response.ok) {
@@ -77,6 +70,55 @@ export class OcrClient {
     return result;
   }
 
+  /**
+   * Extract VIN from an image using VIN-specific OCR.
+   *
+   * @param fileBuffer - Image file buffer
+   * @param contentType - MIME type of the file
+   * @returns VIN extraction result
+   */
+  async extractVin(
+    fileBuffer: Buffer,
+    contentType: string
+  ): Promise<VinExtractionResponse> {
+    const formData = this.buildFormData(fileBuffer, contentType);
+    const url = `${this.baseUrl}/extract/vin`;
+
+    logger.info('OCR VIN extract request', {
+      operation: 'ocr.client.extractVin',
+      url,
+      contentType,
+      fileSize: fileBuffer.length,
+    });
+
+    const response = await this.fetchWithTimeout(url, {
+      method: 'POST',
+      body: formData,
+    });
+
+    if (!response.ok) {
+      const errorText = await response.text();
+      logger.error('OCR VIN extract failed', {
+        operation: 'ocr.client.extractVin.error',
+        status: response.status,
+        error: errorText,
+      });
+      throw new Error(`OCR service error: ${response.status} - ${errorText}`);
+    }
+
+    const result = (await response.json()) as VinExtractionResponse;
+
+    logger.info('OCR VIN extract completed', {
+      operation: 'ocr.client.extractVin.success',
+      success: result.success,
+      vin: result.vin,
+      confidence: result.confidence,
+      processingTimeMs: result.processingTimeMs,
+    });
+
+    return result;
+  }
+
   /**
    * Submit an async OCR job for large files.
    *
@@ -90,11 +132,7 @@ export class OcrClient {
     contentType: string,
     callbackUrl?: string
   ): Promise<JobResponse> {
-    const formData = new FormData();
-    formData.append('file', fileBuffer, {
-      filename: this.getFilenameFromContentType(contentType),
-      contentType,
-    });
+    const formData = this.buildFormData(fileBuffer, contentType);
     if (callbackUrl) {
       formData.append('callback_url', callbackUrl);
     }
@@ -111,8 +149,7 @@ export class OcrClient {
 
     const response = await this.fetchWithTimeout(url, {
       method: 'POST',
-      body: formData as any,
-      headers: formData.getHeaders(),
+      body: formData,
     });
 
     if (!response.ok) {
@@ -205,6 +242,14 @@ export class OcrClient {
     }
   }
 
+  private buildFormData(fileBuffer: Buffer, contentType: string): FormData {
+    const filename = this.getFilenameFromContentType(contentType);
+    const blob = new Blob([fileBuffer], { type: contentType });
+    const formData = new FormData();
+    formData.append('file', blob, filename);
+    return formData;
+  }
+
   private getFilenameFromContentType(contentType: string): string {
     const extensions: Record<string, string> = {
       'image/jpeg': 'image.jpg',