Use case

Developers wanting to transform assets, based on the current target platform (i.e. flutter build web -> web; flutter build apk -> android), currently cannot infer the target platform during the asset transformation.

Proposal

I propose that the target platform of the flutter build invocation is provided as either an argument, or in Platform.environment. I initially tried checking what is inside Platform.environment and the FLUTTER_BUILD_MODE seems to be there already?

Then I think the easiest thing to do is to also add something like FLUTTER_BUILD_TARGET_PLATFORM to Platform.environment or the args that are passed to the asset transformer, whichever makes more sense / is cleaner from a tool perspective.

Context: I was initially exploring if I could work around the absence of #141371 using an asset transformer