Each transform copies each selected root, in transform-major order. All
graph writes succeed together or leave records, journal and allocator intact.
The same selection policy is applied at preview and commit: selected hosted
children never create a second independent copy.
Each transform copies each selected root, in transform-major order. All graph writes succeed together or leave records, journal and allocator intact. The same selection policy is applied at preview and commit: selected hosted children never create a second independent copy.