From 048817bcf4ed8d6cc903f26be28dcd90c43f5a2e Mon Sep 17 00:00:00 2001
From: Jonathan Sykes <telemagnadon@gmail.com>
Date: Fri, 3 Jul 2026 05:16:05 +0800
Subject: [PATCH] fix: fall back to copy when OPFS move() throws on WebKit and
 retry failed worker downloads on the main thread

---
 frontend/opfs-worker.js | 12 ++++++++----
 frontend/opfs.js        | 17 ++++++++++-------
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/frontend/opfs-worker.js b/frontend/opfs-worker.js
index dc92780..99162d4 100644
--- a/frontend/opfs-worker.js
+++ b/frontend/opfs-worker.js
@@ -76,12 +76,16 @@ self.onmessage = async (e) => {
       access.close();
     }
 
-    // Finalize: .part → permanent name. Prefer the native rename; fall back
-    // to a chunked copy (still fully inside the worker, small fixed buffers).
+    // Finalize: .part → permanent name. Prefer the native rename, but treat
+    // ANY move() failure as "unavailable" and fall back to a chunked copy —
+    // WebKit's move() has a different signature/behavior than Chrome's and
+    // throws TypeError ("Not enough arguments") rather than being absent.
     try { await dir.removeEntry(filename); } catch { /* no previous copy */ }
+    let renamed = false;
     if (typeof partHandle.move === 'function') {
-      await partHandle.move(filename);
-    } else {
+      try { await partHandle.move(filename); renamed = true; } catch { /* copy below */ }
+    }
+    if (!renamed) {
       const finalHandle = await dir.getFileHandle(filename, { create: true });
       const out = await finalHandle.createSyncAccessHandle();
       try {
diff --git a/frontend/opfs.js b/frontend/opfs.js
index dcc997a..9c910e0 100644
--- a/frontend/opfs.js
+++ b/frontend/opfs.js
@@ -154,18 +154,21 @@
             throw err;
           }
         } else {
-          // Fallback: buffer entirely (older browsers)
-          const buf = await response.arrayBuffer();
-          const writable = await tmpHandle.createWritable();
-          await writable.write(buf);
-          await writable.close();
+          // No createWritable on this browser — main-thread OPFS writes are
+          // impossible (sync access handles are worker-only). Surface a real
+          // error instead of the old branch that called the missing API.
+          throw new Error('Offline saving is not supported in this browser');
         }
 
         // Rename tmp → final. Prefer the native rename; else stream-copy so
         // the whole file is never buffered in main-thread memory at once.
+        // move() failures (WebKit's signature differs from Chrome's and
+        // throws TypeError) fall back to the copy path too.
+        let renamed = false;
         if (typeof tmpHandle.move === 'function') {
-          await tmpHandle.move(filename);
-        } else {
+          try { await tmpHandle.move(filename); renamed = true; } catch { /* copy below */ }
+        }
+        if (!renamed) {
           const finalHandle = await dir.getFileHandle(filename, { create: true });
           const finalWritable = await finalHandle.createWritable();
           const tmpFile = await tmpHandle.getFile();