Historical Fiction
The past as a system you have to live inside — period constraint default, Western frontier subgenre.
What is Historical Fiction?
Period fiction (Follett, Hannah, Mantel) is lived-in constraint: the past has rules the protagonist cannot opt out of. Western (L'Amour, McCarthy, McMurtry) is the frontier split — land as ordeal and draw, honor, distance, and the coming of law. Costume is not enough; institution, custom, and consequence must be load-bearing.
How Bespoke Books implements it
In The Composer, pick Historical fiction, then Period (default, voice_id: historical_fiction) or Western (voice_id: western). The Western sample on the Historical Fiction genre page is The Catclaw Line.