diff --git a/public/sw.js b/public/sw.js
index fd60ece14..499698631 100644
--- a/public/sw.js
+++ b/public/sw.js
@@ -51,6 +51,16 @@ const PAGE_CACHE = `healthlog-pages-${CACHE_VERSION}`;
 // next paint. Network-first restores read-after-write freshness while keeping
 // the offline fallback.
 const DATA_CACHE = `healthlog-data-${CACHE_VERSION}`;
+// Keep this ownership contract aligned with
+// `clearOfflineCachesForSessionEnd()` in `query-persister.ts`. Cache cleanup
+// must cover every current/legacy HealthLog cache without deleting unrelated
+// CacheStorage namespaces owned by another app on the same origin.
+const HEALTHLOG_CACHE_NAME_RE = /^healthlog-(?:static|pages|data)-/;
+const CURRENT_HEALTHLOG_CACHES = new Set([
+  STATIC_CACHE,
+  PAGE_CACHE,
+  DATA_CACHE,
+]);
 const MAX_STATIC_ENTRIES = 150;
 const MAX_PAGE_ENTRIES = 30;
 const MAX_DATA_ENTRIES = 60;
@@ -136,7 +146,8 @@ self.addEventListener("activate", (event) => {
             keys
               .filter(
                 (k) =>
-                  k !== STATIC_CACHE && k !== PAGE_CACHE && k !== DATA_CACHE,
+                  HEALTHLOG_CACHE_NAME_RE.test(k) &&
+                  !CURRENT_HEALTHLOG_CACHES.has(k),
               )
               .map((k) => caches.delete(k)),
           ),
diff --git a/src/lib/pwa/query-persister.ts b/src/lib/pwa/query-persister.ts
index 3fc3e2067..805b44f04 100644
--- a/src/lib/pwa/query-persister.ts
+++ b/src/lib/pwa/query-persister.ts
@@ -39,6 +39,10 @@ const STORE = "kv";
 const KEY = "react-query";
 const VERSION_KEY = "react-query-version";
 const MAX_AGE_MS = 24 * 60 * 60 * 1000; // discard anything older than a day
+// Keep this ownership contract aligned with `public/sw.js`. Session-end
+// cleanup removes every current/legacy HealthLog cache family while leaving
+// unrelated CacheStorage namespaces on the same origin untouched.
+const HEALTHLOG_CACHE_NAME_RE = /^healthlog-(?:static|pages|data)-/;
 
 /**
  * Upper bound on the serialized snapshot. The allowlist already caps WHAT is
@@ -326,11 +330,7 @@ export async function clearOfflineCachesForSessionEnd(): Promise<void> {
       const keys = await caches.keys();
       await Promise.all(
         keys
-          .filter(
-            (k) =>
-              k.startsWith("healthlog-data-") ||
-              k.startsWith("healthlog-pages-"),
-          )
+          .filter((k) => HEALTHLOG_CACHE_NAME_RE.test(k))
           .map((k) => caches.delete(k)),
       );
     } catch {