diff --git a/src/server/features/domain/services/DomainService.ts b/src/server/features/domain/services/DomainService.ts
index f7be38e0..23338519 100644
--- a/src/server/features/domain/services/DomainService.ts
+++ b/src/server/features/domain/services/DomainService.ts
@@ -1,3 +1,4 @@
+import { waitUntil } from "cloudflare:workers";
 import { buildCacheKey, getCached, setCached } from "@/server/lib/r2-cache";
 import { z } from "zod";
 import type { BillingCustomerContext } from "@/server/billing/subscription";
@@ -90,10 +91,14 @@ async function getOverview(
   };
 
   if (result.hasData) {
-    void setCached(cacheKey, result, DOMAIN_OVERVIEW_TTL_SECONDS).catch(
-      (error) => {
-        console.error("domain.overview.cache-write failed:", error);
-      },
+    // waitUntil, not void: workerd cancels unregistered pending I/O once the
+    // response is sent, so a fire-and-forget put never persists the cache.
+    waitUntil(
+      setCached(cacheKey, result, DOMAIN_OVERVIEW_TTL_SECONDS).catch(
+        (error) => {
+          console.error("domain.overview.cache-write failed:", error);
+        },
+      ),
     );
   }
 
@@ -174,10 +179,15 @@ async function getSuggestedKeywords(
     }));
 
   if (keywords.length > 0) {
-    void setCached(cacheKey, keywords, DOMAIN_OVERVIEW_TTL_SECONDS).catch(
-      (error) => {
-        console.error("domain.keyword-suggestions.cache-write failed:", error);
-      },
+    waitUntil(
+      setCached(cacheKey, keywords, DOMAIN_OVERVIEW_TTL_SECONDS).catch(
+        (error) => {
+          console.error(
+            "domain.keyword-suggestions.cache-write failed:",
+            error,
+          );
+        },
+      ),
     );
   }
 
diff --git a/src/server/features/domain/services/domainKeywordsPage.ts b/src/server/features/domain/services/domainKeywordsPage.ts
index d57bfeb6..995911ce 100644
--- a/src/server/features/domain/services/domainKeywordsPage.ts
+++ b/src/server/features/domain/services/domainKeywordsPage.ts
@@ -1,3 +1,4 @@
+import { waitUntil } from "cloudflare:workers";
 import { z } from "zod";
 import type { BillingCustomerContext } from "@/server/billing/subscription";
 import { createDataforseoClient } from "@/server/lib/dataforseo";
@@ -113,10 +114,14 @@ export async function getKeywordsPage(
     fetchedAt: new Date().toISOString(),
   };
 
-  void setCached(cacheKey, result, DOMAIN_KEYWORDS_PAGE_TTL_SECONDS).catch(
-    (error) => {
-      console.error("domain.keywords-page.cache-write failed:", error);
-    },
+  // waitUntil, not void: workerd cancels unregistered pending I/O once the
+  // response is sent, so a fire-and-forget put never persists the cache.
+  waitUntil(
+    setCached(cacheKey, result, DOMAIN_KEYWORDS_PAGE_TTL_SECONDS).catch(
+      (error) => {
+        console.error("domain.keywords-page.cache-write failed:", error);
+      },
+    ),
   );
 
   return result;
diff --git a/src/server/features/domain/services/domainPagesPage.ts b/src/server/features/domain/services/domainPagesPage.ts
index 4475ad87..1fbd9c0f 100644
--- a/src/server/features/domain/services/domainPagesPage.ts
+++ b/src/server/features/domain/services/domainPagesPage.ts
@@ -1,3 +1,4 @@
+import { waitUntil } from "cloudflare:workers";
 import { z } from "zod";
 import type { BillingCustomerContext } from "@/server/billing/subscription";
 import { createDataforseoClient } from "@/server/lib/dataforseo";
@@ -193,10 +194,14 @@ export async function getPagesPage(
     fetchedAt: new Date().toISOString(),
   };
 
-  void setCached(cacheKey, result, DOMAIN_PAGES_PAGE_TTL_SECONDS).catch(
-    (error) => {
-      console.error("domain.pages-page.cache-write failed:", error);
-    },
+  // waitUntil, not void: workerd cancels unregistered pending I/O once the
+  // response is sent, so a fire-and-forget put never persists the cache.
+  waitUntil(
+    setCached(cacheKey, result, DOMAIN_PAGES_PAGE_TTL_SECONDS).catch(
+      (error) => {
+        console.error("domain.pages-page.cache-write failed:", error);
+      },
+    ),
   );
 
   return result;
diff --git a/src/server/features/keywords/services/research/serp.ts b/src/server/features/keywords/services/research/serp.ts
index 2339d729..7fde9405 100644
--- a/src/server/features/keywords/services/research/serp.ts
+++ b/src/server/features/keywords/services/research/serp.ts
@@ -1,3 +1,4 @@
+import { waitUntil } from "cloudflare:workers";
 import { type SerpLiveItem } from "@/server/lib/dataforseo";
 import { buildCacheKey, getCached, setCached } from "@/server/lib/r2-cache";
 import type { SerpResultItem } from "@/types/keywords";
@@ -91,9 +92,13 @@ async function getSerpLiveAnalysis(
     result.reason = "no_organic_results";
   }
 
-  void setCached(cacheKey, result, SERP_CACHE_TTL_SECONDS).catch((error) => {
-    console.error("keywords.serp.cache-write failed:", error);
-  });
+  // waitUntil, not void: workerd cancels unregistered pending I/O once the
+  // response is sent, so a fire-and-forget put never persists the cache.
+  waitUntil(
+    setCached(cacheKey, result, SERP_CACHE_TTL_SECONDS).catch((error) => {
+      console.error("keywords.serp.cache-write failed:", error);
+    }),
+  );
 
   return result;
 }