The thumbnail daemon runs for every change though, not only publishing. Do you perform an additional check to see if the new revision is actually published? Also, what about custom thumbnails? I assume the webhook wouldn't work with those?

I assumed that too, but then I tested it and it seems to work anyway. Originally I did user agent sniffing but this seems simpler so long as it works.

Oh yeah your right though, it gets called on edit which includes publish but sometimes more.

I rename it to "on version" as it's easier to do the publish check downstream of this hook