Large files buffered entirely in RAM can OOM workers. Add
max_file_size to source config (default None = no limit).
FS checks stat().st_size before read_bytes(). HTTP and WebDAV issue
a HEAD request before GET when a limit is configured. S3 checks the
size from the existing head_async() call before get_async().
FileTooLargeError is classified as PermanentError so oversized files
go straight to the DLQ instead of retrying.
Both are OSError subclasses caught by the broad timeout/io handler
and classified as transient. Pointing at a directory instead of a
file or a broken path component will never succeed on retry.
PermissionError is a subclass of OSError, so it was caught by the
broad timeout/io handler and classified as transient. An unreadable
file would retry 5 times then DLQ — permissions don't fix themselves
without operator intervention.
Add an explicit PermissionError check before the OSError catch so
unreadable files go straight to the DLQ.
FileNotFoundError is a subclass of OSError, so it was caught by the
broad timeout/io handler and classified as transient. A file deleted
between discovery and fetch would retry 5 times on a file that's
permanently gone, then DLQ with a confusing error message.
Add an explicit FileNotFoundError check before the OSError catch so
deleted files go straight to the DLQ.
