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.
HTTP, S3, and WebDAV sources all check `revision is not None and
snapshot.get(uri) == revision` to decide UPSERT vs UNCHANGED. When
a server returns no ETag or Last-Modified, revision is None and the
condition always fails — every sweep emits UPSERT even though the
content hasn't changed.
Now emit UNCHANGED when revision is None and the URI is already
known (has been ingested before). A first-time discovery with no
revision still correctly emits UPSERT.
The bare `except Exception` in HTTPSource.discover() silently
swallowed all errors from HEAD requests — including configuration
errors (bad auth, invalid headers) and programming errors (TypeError,
AttributeError) — treating them identically to network failures by
emitting UPSERT with no revision.
Narrow the catch to httpx.TransportError (the umbrella for
ConnectError, TimeoutException, etc.) and add a debug log. Other
exceptions now propagate to the poller's circuit breaker where they
surface as failures instead of being silently retried forever.
