Here is the extract from the Astraifort Estate walkthrough:
This battle has confused many players because it makes no difference whether you win or lose the battle against the jackal whether you chose to Negotiate or to threaten him. All four scenarios will always trigger a bad ending
The only option to win is to escape from the battle.
After being hit the first time by his mummification curse, move to the right tile of the front row where there is an unprotected picture window here. The option "This battle is impossible to win. Escape" and "Escape regardless of the risks" will be presented to you.
If you need help with more things, here's the link to the guide. Just be careful because it has spoilers everywhere:
https://docs.google.com/document/d/1siF5FKC30ClEGoCTtszGQcvPHqP-lsKpuYUThl18In0/...