Livro: menina com um protótipo de computador na cabeça que permite que seu cérebro seja dividido em várias personalidades

Esta costa alienígena por CS Friedman? Publicado em 1998. Não consigo encontrar uma edição com a capa que você descreveu, mas os detalhes da trama são semelhantes. Aqui está uma resenha.

A partir de um Revisão de Goodreads:

As Jamisia is trying to evade her unidentified pursuers, she also has to deal with the extra people who live in her head... If Earth finds out that she’s not normal, they will take her into custody.

Fortunately, Jamisia meets a few people who can give her some help, though they’ve got their own issues to deal with. In particular, Phoenix the hacker is trying to trace the origin of Lucifer, a computer virus that’s killing his friends when they’re hooked into the Outernet.

O brainware de Jamisia é um protótipo.

William Hertling, Avogadro Corp série (2011).

Resumo do primeiro livro, de Goodreads:

David Ryan is the designer of ELOPe, an email language optimization program, that if successful, will make his career. But when the project is suddenly in danger of being canceled, David embeds a hidden directive in the software accidentally creating a runaway artificial intelligence.

David and his team are initially thrilled when the project is allocated extra servers and programmers. But excitement turns to fear as the team realizes that they are being manipulated by an A.I. who is redirecting corporate funds, reassigning personnel and arming itself in pursuit of its own agenda.