The hole I fell into
Bamboo makes it easy to just make a big pile of files (during build) and copy them out to the places you’re deploying.
The problem is when you need to delete some of those files. I haven’t seen a good way with the Bamboo tasks available to do those deletions. The copy task is just that, with no options you can set to actually sync.
In my case, I was running Composer during that build stage and then just copying packages from Composer out to my deploy areas. Did I not see this coming? I probably did and had to move on to the next urgent item on the list after I had something working.