> given that software expects it to work consistently or not work at all
I mean... that's wrong? If you come across such software, do you at least file a bug?
Of course not, and it’s completely correct behaviour: if a server advertises it supports Range requests for a given URL, it’s expected to support it. Garbage in, garbage out.
It’s not clear how you’d expect to handle a webserver trying to send you 1Gb of data after you asked for a specific 10kb range other than aborting.
"Conversely, a client MUST NOT assume that receiving an Accept-Ranges field means that future range requests will return partial responses. The content might change, the server might only support range requests at certain times or under certain conditions, or a different intermediary might process the next request." -- RFC 9110
Sure, but that’s utterly useless in practice because there is no way to handle that gracefully.
To be clear: most software does handle it, because it detects this case and aborts.
But to a user who is explicitly asking to read a parquet file without buffering the entire file into memory, there is no distinction between a server that cannot handle any range requests and a server that can occasionally handle range requests.
Other than one being much, much more annoying.