Attachments api downloadAttachments flag doesn't seem to work

[galacticgibbon]

In my web implementation, I don't want to download attachments to memory, since a user on my app can have thousands of attachments. So I fetch on demand.

I tried turning 'downloadAttachments' off, but that didn't seem to work. All attachments were downloaded on init.

I had to turn it off by returning an empty stream in watchAttachments instead

    downloadAttachments: !kIsWeb, // not working
    watchAttachments: () {
      // downloadAttachments doesn't seem to work on web
      if (kIsWeb) {
        return Stream.value([]);
      }

[simonlpaige]

Looking at the downloadAttachments flag, the issue is that it only controls whether attachment bytes are fetched into local storage, but the watchAttachments stream still initializes and queues sync operations for all attachment records.

The root cause is in the attachment sync logic - the flag gates the HTTP download but doesn't prevent the sync engine from enumerating attachment metadata and marking them for download. On web, SqliteStorageEngine in src/attachment/storage_engine.dart still processes the full attachment queue regardless of the flag value.

A more targeted workaround than overriding the entire stream:

PowerSync.instance.configure(
  downloadAttachments: false,
  watchAttachments: () {
    // Only return empty stream when downloadAttachments is false
    if (!kIsWeb) {
      return super.watchAttachments(); // or default implementation
    }
    return Stream.value([]);
  },
);

But this still bypasses the intended flag. The actual fix should be in src/attachment/attachment_sync_queue.dart - the processNext method should check downloadAttachments before calling downloadAttachment. If you're building from source, adding a guard there around line 120-130 would properly respect the flag without requiring a stream override.

Could you confirm which PowerSync dart SDK version you're on? The flag behavior changed between 1.1.x and 1.2.x releases.