fix: Remove VIN Cache

backend/src/features/vehicles/domain/vehicles.service.ts

@@ -1,6 +1,6 @@
 /**
  * @ai-summary Business logic for vehicles feature
- * @ai-context Handles VIN decoding, caching, and business rules
+ * @ai-context Handles VIN decoding and business rules
  */
 
 import { Pool } from 'pg';
@@ -594,72 +594,6 @@ export class VehiclesService {
     await cacheService.del(cacheKey);
   }
 
-  /**
-   * Check vin_cache for existing VIN data.
-   * Format-aware: validates raw_data has `success` field (Gemini format).
-   * Old NHTSA-format entries are treated as cache misses and expire via TTL.
-   */
-  async getVinCached(vin: string): Promise<VinDecodeResponse | null> {
-    try {
-      const result = await this.pool.query<{
-        raw_data: any;
-        cached_at: Date;
-      }>(
-        `SELECT raw_data, cached_at
-         FROM vin_cache
-         WHERE vin = $1
-         AND cached_at > NOW() - INTERVAL '365 days'`,
-        [vin]
-      );
-
-      if (result.rows.length === 0) {
-        return null;
-      }
-
-      const rawData = result.rows[0].raw_data;
-
-      // Format-aware check: Gemini responses have `success` field,
-      // old NHTSA responses do not. Treat old format as cache miss.
-      if (!rawData || typeof rawData !== 'object' || !('success' in rawData)) {
-        logger.debug('VIN cache format mismatch (legacy NHTSA entry), treating as miss', { vin });
-        return null;
-      }
-
-      logger.debug('VIN cache hit', { vin });
-      return rawData as VinDecodeResponse;
-    } catch (error) {
-      logger.error('Failed to check VIN cache', { vin, error });
-      return null;
-    }
-  }
-
-  /**
-   * Save VIN decode response to cache with ON CONFLICT upsert.
-   */
-  async saveVinCache(vin: string, response: VinDecodeResponse): Promise<void> {
-    try {
-      await this.pool.query(
-        `INSERT INTO vin_cache (vin, make, model, year, engine_type, body_type, raw_data, cached_at)
-         VALUES ($1, $2, $3, $4, $5, $6, $7, NOW())
-         ON CONFLICT (vin) DO UPDATE SET
-           make = EXCLUDED.make,
-           model = EXCLUDED.model,
-           year = EXCLUDED.year,
-           engine_type = EXCLUDED.engine_type,
-           body_type = EXCLUDED.body_type,
-           raw_data = EXCLUDED.raw_data,
-           cached_at = NOW()
-         WHERE (vin_cache.raw_data->>'confidence')::float <= $8`,
-        [vin, response.make, response.model, response.year, response.engine, response.bodyType, JSON.stringify(response), response.confidence ?? 1]
-      );
-
-      logger.debug('VIN cached', { vin, confidence: response.confidence });
-    } catch (error) {
-      logger.error('Failed to cache VIN data', { vin, error });
-      // Don't throw - caching failure shouldn't break the decode flow
-    }
-  }
-  
   async getDropdownMakes(year: number): Promise<string[]> {
     const vehicleDataService = getVehicleDataService();
     const pool = getPool();