Changing the subtype of an existing project adds support for project subtypes. For Maniphest tasks, the subtype can be changed via the “Change Subtype” action in the action dropbox. For projects, there doesn’t seem to be any equivalent action. Is there a way to change a project’s subtype?

I think there’s no UI option, but you should be able to apply the transaction with the project.edit API method.

Useless context:

The “Change Subtype” comment action is available globally, but Projects doesn’t have a comment area where you can use it.

And the “Change subtype to” bulk edit action is also available globally, but Projects doesn’t currently support bulk edits.

Finally, the “Change Subtype” API transaction is available globally, and Projects has a *.edit method, so that should work.