Sending an image or file with no typed text to a model with skills
bound replaced the (empty) message text with the list of skill names,
so the model answered with its skill catalog instead of handling the
attachment. The empty-message guard added for #24929 fired on any
empty last user text without checking for attachments.
The guard now skips the fallback when the current message carries
files, read from the user_message object the frontend sends with the
request. Attachment-only messages then go out exactly as they do on
models without skills. A bare skill selection with no attachment still
gets the fallback, so the provider 400 from #24929 stays fixed.
Request-level files were not usable as the signal: that list carries
the model's knowledge and folder files, so a bare skill selection on a
knowledge model would have gone out empty again.
Fixes#30040
Classic298
3348f68778