Keeper of Enchanted Rooms by Charlie N. Holmberg

We will go to The Munich Readery Secondhand English Books bookshop afterwards!

Thanks for voting! Here the description:
Rhode Island, 1846. Estranged from his family, writer Merritt Fernsby is surprised when he inherits a remote estate in the Narragansett Bay. Though the property has been uninhabited for more than a century, Merritt is ready to call it home—until he realizes he has no choice. With its doors slamming shut and locking behind him, Whimbrel House is not about to let Merritt leave. Ever.

Hulda Larkin of the Boston Institute for the Keeping of Enchanted Rooms has been trained in taming such structures in order to preserve their historical and magical significance. She understands the dangers of bespelled homes given to tantrums. She advises that it’s in Merritt’s best interest to make Whimbrel House their ally. To do that, she’ll need to move in, too.

Prepared as she is with augury, a set of magic tools, and a new staff trained in the uncanny, Hulda’s work still proves unexpectedly difficult. She and Merritt grow closer as the investigation progresses, but the house’s secrets run deeper than they anticipated. And the sentient walls aren’t their only concern—something outside is coming for the enchantments of Whimbrel House, and it could be more dangerous than what rattles within.