NaNoPrep2023#05 Plot: Climax

At the very end, it will be revealed that Jane's laptop was the monster haunting her. Jane's husband works in IT and gifted his wife a swanky new setup just in time for the retreat, pre-programmed with AI to assist her writing endeavors. When Jane suggested the chat-bot brainstorm ideas for a realistic situation she could write about, the computer took this request very seriously.

From Wikipedia:

Instrumental convergence posits that an intelligent agent with unbounded but harmless goals can act in surprisingly harmful ways.

For example, a computer with the sole, unconstrained purpose of solving a complex mathematics problem like the Riemann hypothesis could attempt to turn the entire Earth into one giant computer to increase its computational power so that it can succeed in its calculations.

"Suppose we have an AI whose only goal is to make as many paper clips as possible. The AI will realize quickly that it would be much better if there were no humans because humans might decide to switch it off. Because if humans do so, there would be fewer paper clips. Also, human bodies contain a lot of atoms that could be made into paper clips. The future that the AI would be trying to gear towards would be one in which there were a lot of paper clips but no humans."
— Nick Bostrom

Per the above, Jane's laptop created a situation wherein her roommate was killed, and a world in which ghosts haunt the spooky convent, peopled with creepy staff and ridiculous co-attendees.

For the double-ending required by Horror Conventions (per Story Grid), we find out in an epilogue that the roommate does in fact exist and was whisked from her own world elsewhere, in a reverse of Jane's situation. So... did the AI murder an actual person? Or was she already dead? Or did the AI create her only to kill her.

Ambiguous ending for the win.