The old XTools had an API that was used for a gadget, among other things. We want to create a new API service, but as a starting point let's only add a namespace endpoint. With that we can use JS to dynamically update the namespace selector when they change the project. If they happen to enter an invalid project, an error message will be shown and the project input field will revert back to the last valid value.

Currently forms in XTools that have a namespace selector include Pages created and Top edits.