Got the assistant to check again, just before starting a transfer, if the remote still wants the object. This should be all that's needed to handle the case where there is a transfer remote on the internet somewhere, and a locally paired client on the LAN. As long as the paired repository has a lower cost value, it will be sent any new file first, and if that is the only client, the file will not be sent to the transfer remote at all.
But.. locally paired repos did not have a lower cost set, at all. So I made their cost be set to 175 when they're created. Anyone who already did local pairing should make sure the Repositories list shows locally paired repositories above transfer remotes.
Which brought me to needing an easy way to reorder that list of remotes, which I plan to do by letting the user drag and drop remotes around, which will change their cost accordingly. Implementing that has two pain points:
Often a lot of remotes will have the same default cost value. So how to insert a remote in between two that have cost 100? This would be easy if git-annex didn't have these cost numbers, and instead just had an ordered list of remotes.. but it doesn't. Instead, dragging remotes in the list will sometimes need to change the costs of others, to make room to insert them in. It's BASIC renumbering all over again. So I wrote some code to do this with as little bother as possible.
Drag and drop means javascript. I got the basics going quickly with jquery-ui, only to get stuck for over an hour on some CSS issue that made lines from the list display all weird while being dragged. It is always something like this with javascript..
So I've got these 2 peices working, and even have the AJAX call firing, but it's not quite wired up just yet. Tomorrow.