fix: offline content for iOS

public/sw.js

@@ -48,14 +48,18 @@ self.addEventListener("fetch", (event) => {
 
   const url = new URL(req.url);
 
-  // 1. Page navigations: network-first, fall back to a saved copy, then to the
-  //    offline library. This is what makes a "saved" page open with no network.
+  // 1. Page navigations.
+  //    ONLINE: do NOT intercept — let the browser navigate natively. Proxying
+  //    a redirected response (the app server-`redirect()`s every book chapter
+  //    index to its first verse) or Next's streamed SSR through the SW makes
+  //    iOS/WebKit standalone PWAs render a blank page. Native handling is
+  //    identical to how the app behaved before this SW had a fetch handler.
+  //    OFFLINE: serve a saved copy, then the offline library, then a stub —
+  //    all plain stored/constructed Responses, which WebKit accepts.
   if (req.mode === "navigate") {
+    if (self.navigator.onLine) return;
     event.respondWith(
       (async () => {
-        try {
-          return await fetch(req);
-        } catch {
         const pages = await caches.open(PAGES_CACHE);
         const saved =
           (await pages.match(req.url)) || (await pages.match(url.pathname));
@@ -66,7 +70,6 @@ self.addEventListener("fetch", (event) => {
           "<!doctype html><meta charset=utf-8><title>Offline</title><body style=\"font-family:system-ui;padding:2rem\"><h1>You're offline</h1><p>This page hasn't been saved for offline use.</p>",
           { headers: { "Content-Type": "text/html; charset=utf-8" }, status: 503 },
         );
-        }
       })(),
     );
     return;
@@ -80,7 +83,15 @@ self.addEventListener("fetch", (event) => {
         const hit = await cache.match(req);
         if (hit) return hit;
         const res = await fetch(req);
-        if (res && res.ok) cache.put(req, res.clone());
+        // Only cache full, same-origin 200s. Guard put() so a 206/opaque/quota
+        // rejection can never fail the request (which could drop a JS chunk).
+        try {
+          if (res && res.status === 200 && res.type === "basic") {
+            await cache.put(req, res.clone());
+          }
+        } catch {
+          /* serve the response uncached */
+        }
         return res;
       })(),
     );