Mikey Boldt

I can work on this

I can work on this

Per discussion, we will break up the Buildpack API changes and the Platform API changes. I've created #870 to capture the Buildpack API changes. I would like to keep this...

For details on the Platform API spec changes to be addressed in this issue, see https://github.com/buildpacks/spec/pull/306

Could we include this in the [Platform 0.10 milestone](https://github.com/buildpacks/spec/milestone/24)? I plan to submit a PR for this soon.

Could we target this for [Platform 0.10](https://github.com/buildpacks/spec/milestone/24) since it ties into #245 through the .profile buildpack? Happy to put the above in a PR.

I ran a couple experiments for buildpacks/lifecycle#703. Detecting which buildpacks modify which layers using a file system watcher was pretty efficient (added ~0.5 seconds to a ~12-second build of Spring...

> One tricky part is knowing ahead of time which buildpack should “own” a given layer. From a fresh build, it’s easy to see which buildpack creates a layer. But,...