the dataset, task, and pipeline were under the same project name. i'm seeing what happens if the dataset project name was different ( f"{project_name}_data" ). which project would get deleted... the dataset one or the project of the task that kicked it off?

and the answer is...
the project is preserved, the dataset's project hidden.

so ... empty dataset names due to a small typo in parameter override + the choice for the dataset to have the same project name as the task that created it (which felt reasonable...) led to a frankenbug where the project disappeared.

thank you SO much for letting the UI have a toggle to show hidden stuff, without that I would have never had a chance of finding it!

and thank you for replying so quickly. it was clear that "projects becoming hidden" was not ever intentional.