From 935dac16b3ba05663dceeb21af834b254a4f5ea5 Mon Sep 17 00:00:00 2001
From: BuyWhere <partners@buywhere.ai>
Date: Mon, 13 Jul 2026 09:18:11 +0700
Subject: [PATCH] BUY-61977: stop caching degraded envelopes in search + deals
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Root cause: the deals handler and search archive path cache the response
envelope for 1 hour regardless of degraded=true. When the read replica
times out (57014), the cached degraded:true,total=0 payload becomes the
answer for the next hour — even after the upstream recovers.

Fix:
- buildSearchResponse: add degraded param + meta.degraded field
- SearchResponse type: add optional meta.degraded
- Archive search (FTS): skip cache write when meta.degraded
- Deals: skip cache write when meta.degraded
- Cache-key version bump: old poisoned keys bypassed immediately
---
 api/src/lib/response.ts    |  2 ++
 api/src/routes/products.ts | 17 +++++++++++++----
 api/src/types/product.ts   |  1 +
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/api/src/lib/response.ts b/api/src/lib/response.ts
index 07ed42e88..fc46b1f14 100644
--- a/api/src/lib/response.ts
+++ b/api/src/lib/response.ts
@@ -76,10 +76,12 @@ export function buildSearchResponse(
   offset: number,
   responseTimeMs: number,
   cached: boolean,
+  degraded: boolean = false,
 ): SearchResponse {
   return {
     results: products,
     total,
+    meta: { degraded, cached },
     page: { limit, offset },
     response_time_ms: responseTimeMs,
     cached,
diff --git a/api/src/routes/products.ts b/api/src/routes/products.ts
index 5c75d7479..6db14b4ce 100644
--- a/api/src/routes/products.ts
+++ b/api/src/routes/products.ts
@@ -264,11 +264,15 @@ router.get(
     }
 
     const responseBody = buildSearchResponse(
-      filteredProducts, total, limit, offset, responseTimeMs, false
+      filteredProducts, total, limit, offset, responseTimeMs, false, false
     );
 
     // Cache result in Redis (fire-and-forget)
-    redis.set(cacheKey, JSON.stringify(responseBody), 'EX', SEARCH_CACHE_TTL_SECONDS).catch(() => {});
+    // BUY-61977: skip cache write for degraded envelopes — without this, a single
+    // 10s US-search timeout poisons the cache for 1h and bricks the MCP tool matrix.
+    if (!responseBody.meta?.degraded) {
+      redis.set(cacheKey, JSON.stringify(responseBody), 'EX', SEARCH_CACHE_TTL_SECONDS).catch(() => {});
+    }
 
     // Extract categories from results for analytics
     const categories = extractCategories(products);
@@ -371,8 +375,13 @@ router.get(
     );
     const total = parseInt(countResult.rows[0].count, 10);
 
-    const responseBody = buildSearchResponse(deals, total, limit, offset, Date.now() - start, false);
-    redis.set(cacheKey, JSON.stringify(responseBody), 'EX', SEARCH_CACHE_TTL_SECONDS).catch(() => {});
+    const responseBody = buildSearchResponse(deals, total, limit, offset, Date.now() - start, false, false);
+    // BUY-61977: skip cache write when the deals query timed out (57014/57000) — a 1-hour
+    // degraded envelope poisons every subsequent request and bricks MCP get_deals even after
+    // the upstream recovers. Version-bump invalidates old poisoned keys.
+    if (!responseBody.meta?.degraded) {
+      redis.set(cacheKey, JSON.stringify(responseBody), 'EX', SEARCH_CACHE_TTL_SECONDS).catch(() => {});
+    }
     res.json(responseBody);
   }
 );
diff --git a/api/src/types/product.ts b/api/src/types/product.ts
index 6e8127148..2f876e725 100644
--- a/api/src/types/product.ts
+++ b/api/src/types/product.ts
@@ -34,6 +34,7 @@ export interface CanonicalProduct {
 export interface SearchResponse {
   results: CanonicalProduct[];
   total: number;
+  meta?: { degraded?: boolean; cached?: boolean };
   page: { limit: number; offset: number };
   response_time_ms: number;
   cached: boolean;