works made for hire
Means you do not exist in a legal sense. Nothing which was created pursuant to the final designs/product is yours.
I am not now, nor have I ever been a lawyer. You need to seek legal advice if you wish clarification - or there's any dispute - regarding any contract terms.
To me.. work-for-hire means they own the native files as well. They were created in order to facilitate the final work.. and would be no different than preliminary sketches on paper. Work-for-hire essentially means you are only an agent for the company, not a separate entity, and nothing is yours. Copyright ownership or "authorship" under work-for-hire extends to the creation of all things not merely final designs. It would be similar to an employee. In fact, all employees are seen as work-for-hire. The company owns absolutely everything created which was initiated during the course of the contract - whether that's a sketch of a frog on a cocktail napkin, a 400 page InDesign file, Illustrator files for 3 logos designs they never used, a script created to process jpgs through Photoshop, etc.
.. this.. is why work-for-hire agreements are often not accepted, or incur more client costs when dealing with freelancers.
I have, in the past, entered work-for-hire agreements with special stipulations that no native application files would be part of any transfer and would remain the sole property of [my company]. This, essentially, limited the ability to easily reuse and repurpose any of the work. But I had to negotiate the inclusion of this, non-standard, clause.