> I think my proposed patch is more natural for implied-open tabs (with the
> tab bar showing or not, doesn't really matter) or explicitly opened ones.
> Just invoke when the tabs are created seems the best route and the one that
> people would expect reading the code.
>
> I'll have a look at the close hooks again in a bit. I do know the behavior
> of the pre-close hook is good for my uses.

Since the behavior of the pre-close hook is good for your uses,
then the best solution for you would be to introduce a new similar hook:
'tab-bar-tab-pre-open-functions' that will be called in the first tab as well.