diff --git a/src/main.jsx b/src/main.jsx
index 391bef8..8c23890 100644
--- a/src/main.jsx
+++ b/src/main.jsx
@@ -8,11 +8,15 @@ import { FontSettingsProvider } from "./context/FontSettingsContext";
 import ErrorBoundary from "./components/ErrorBoundary";
 import { initErrorLogging } from "./utils/errorLogger";
 import { registerPwaServiceWorker } from "./hooks/usePwaStatus";
+import { clearStalePwaCaches } from "./utils/pwaCacheCleanup";
 import "./index.css";
 import "./styles/fontSettings.css";
 
 registerPwaServiceWorker();
 initErrorLogging();
+// Purge stale PWA caches on every startup so bloated caches (up to 3GB from old
+// SW versions) are cleared even if the SW hasn't updated yet.
+clearStalePwaCaches();
 
 ReactDOM.createRoot(document.getElementById("root")).render(
   <ThemeProvider>
diff --git a/src/utils/pwaCacheCleanup.js b/src/utils/pwaCacheCleanup.js
new file mode 100644
index 0000000..18e9f35
--- /dev/null
+++ b/src/utils/pwaCacheCleanup.js
@@ -0,0 +1,34 @@
+// Clears stale PWA caches directly from the page context, independent of the
+// service worker. Runs on every app startup so that even users whose SW has not
+// yet updated to the version with the fixed `activate` handler get their bloated
+// (3GB) caches purged. Safe to run repeatedly: only `construction-delivery-*`
+// caches are removed; nothing else is touched.
+export const clearStalePwaCaches = async () => {
+  if (typeof caches === "undefined" || !("caches" in window)) {
+    return;
+  }
+
+  try {
+    const keys = await caches.keys();
+    const staleKeys = keys.filter(
+      (key) =>
+        key.startsWith("construction-delivery-") &&
+        // Keep only the current cache versions we ship with (v115). Any other
+        // version is stale and free to purge.
+        !["construction-delivery-static-v115", "construction-delivery-runtime-v115"].includes(key),
+    );
+    if (staleKeys.length === 0) return;
+
+    // Delete old caches first so the SW activation has less to scan next time.
+    await Promise.all(staleKeys.map((key) => caches.delete(key)));
+
+    // Kick the service worker to re-run its activate handler (which also prunes
+    // caches and reclaims control) now that old caches are gone.
+    if ("serviceWorker" in navigator && navigator.serviceWorker?.controller) {
+      navigator.serviceWorker.controller.postMessage({ type: "CLEAR_STALE_CACHES" });
+    }
+  } catch (err) {
+    // Best-effort cleanup — never block app startup on cache errors.
+    console.warn("[pwa] cache cleanup skipped:", err);
+  }
+};