The external subscription fetcher read the remote body with a plain
io.LimitReader, silently truncating at 2 MiB and decoding whatever
prefix arrived (possibly a half share link). Detect the overflow with
the established N+1 pattern and return an error so the caller serves the
last cached value instead of a corrupted partial list.
Co-authored-by: Sanaei <ho3ein.sanaei@gmail.com>
n0ctal