Apologies if I simply couldn't find it, but with hexcasting-forge-1.19.2-0.10.3 I couldn't find a config to disable giving the patchouli book on first world join, in either common or server configs.

That's a very important feature for me.

@aaronhowser1, I think I'm found a fast solution.

The issuance of the book is made according to the guide from patchouli docs.
It is issued not by a mod, but through vanilla advancements.

To turn off the book, just open the mod's .jar and delete /data/hexcasting/advancements/grant_patchi_book.json file. That's all!

You can't share modified jars in modpacks, but I can just replace that file using a datapack. Thanks!

for anyone seeing this in the future there's also an existing datapack https://github.com/SamsTheNerd/hexaddons/tree/main/datapacks/#no-hexbook.

(closing since there are existing solutions and I don't think having it be specifically config is the highest priority)