fix(backend): add retry logic and remove custom User-Agent for OFF API

- Add retry logic with exponential backoff (2 retries)
- Remove custom User-Agent that was being blocked by OFF
- Fix syntax error (missing catch block)
- OFF API blocks anonymous users during high demand

apps/backend/off-service.js

@@ -3,8 +3,10 @@ import redisClient from './redis-client.js';
 
 const OFF_API_BASE = 'https://world.openfoodfacts.org';
 const CACHE_TTL = 3600;
+const MAX_RETRIES = 2;
+const RETRY_DELAY_MS = 1000;
 
-// Open Food Facts authentication (optional, improves rate limits)
+// Open Food Facts authentication (required for reliable access)
 const OFF_USERNAME = process.env.OFF_USERNAME;
 const OFF_PASSWORD = process.env.OFF_PASSWORD;
 
@@ -18,6 +20,10 @@ function getOffAuth() {
   return null;
 }
 
+function sleep(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms));
+}
+
 export function transformOFFProduct(offProduct) {
   if (!offProduct || !offProduct._id || !offProduct.product_name) {
     return null;
@@ -68,41 +74,60 @@ export async function searchBabyProducts(query) {
 
     console.log(`Fetching from OFF API: ${searchTerm}`);
     const auth = getOffAuth();
-    const response = await axios.get(`${OFF_API_BASE}/cgi/search.pl`, {
-      params: {
-        search_terms: searchTerm,
-        json: true,
-        fields: 'product_name,brands,image_url,nutriscore_grade,ingredients_text,nova_group,ecoscore_grade,categories_tags',
-        page_size: 20,
-        action: 'process',
-      },
-      timeout: 10000,
-      validateStatus: (status) => status === 200,
-      ...(auth && { auth }),
-    });
 
-    // Check if response is actually JSON (OFF sometimes returns HTML on error)
-    if (typeof response.data === 'string' || !response.data.products) {
-      console.warn(`[OFF] Invalid response for "${searchTerm}": API may be down`);
-      return [];
-    }
-
-    const products = response.data.products
-      .map(transformOFFProduct)
-      .filter(Boolean);
-
-    // Only cache non-empty results to avoid caching API failures
-    if (products.length > 0) {
+    let lastError;
+    for (let attempt = 0; attempt <= MAX_RETRIES; attempt++) {
       try {
-        await redisClient.setEx(cacheKey, CACHE_TTL, JSON.stringify(products));
-        console.log(`Cached ${products.length} OFF products for: ${searchTerm}`);
-      } catch (cacheErr) {
-        // cache write failed, still return the data
+        const response = await axios.get(`${OFF_API_BASE}/cgi/search.pl`, {
+          params: {
+            search_terms: searchTerm,
+            json: true,
+            fields: 'product_name,brands,image_url,nutriscore_grade,ingredients_text,nova_group,ecoscore_grade,categories_tags',
+            page_size: 20,
+            action: 'process',
+          },
+          timeout: 10000,
+          validateStatus: (status) => status === 200,
+          ...(auth && { auth }),
+        });
+
+        // Check if response is actually JSON (OFF sometimes returns HTML on error)
+        if (typeof response.data === 'string' || !response.data.products) {
+          console.warn(`[OFF] Invalid response for "${searchTerm}" (attempt ${attempt + 1}): API may be down`);
+          if (attempt < MAX_RETRIES) {
+            await sleep(RETRY_DELAY_MS * (attempt + 1));
+            continue;
+          }
+          return [];
+        }
+
+        const products = response.data.products
+          .map(transformOFFProduct)
+          .filter(Boolean);
+
+        // Only cache non-empty results to avoid caching API failures
+        if (products.length > 0) {
+          try {
+            await redisClient.setEx(cacheKey, CACHE_TTL, JSON.stringify(products));
+            console.log(`Cached ${products.length} OFF products for: ${searchTerm}`);
+          } catch (cacheErr) {
+            // cache write failed, still return the data
+          }
+        } else {
+          console.log(`[OFF] No products found for "${searchTerm}", not caching empty result`);
+        }
+        return products;
+      } catch (err) {
+        lastError = err;
+        console.warn(`[OFF] Request failed for "${searchTerm}" (attempt ${attempt + 1}): ${err.message}`);
+        if (attempt < MAX_RETRIES) {
+          await sleep(RETRY_DELAY_MS * (attempt + 1));
+        }
       }
-    } else {
-      console.log(`[OFF] No products found for "${searchTerm}", not caching empty result`);
     }
-    return products;
+
+    console.error(`[OFF] All retries failed for "${searchTerm}": ${lastError?.message}`);
+    return [];
   } catch (error) {
     console.error('Error searching baby products from OFF:', error.message);
     return [];