Journaling

It does what the title says. It allows you to see and edit pages that overflow a book's length. This is a total of like 5 lines of code changed to enable what is technically a failsafe of vanilla behavior.

Mods that rely on books, such as Computed, still work fully with this extended text (as the page is just a massive String). This is extremely useful when programming for Computed.

It just happens that Minecraft's multiline text edit allows you to scroll if this ever happens, meaning that the 1024 character limit isn't actually a hard requirement. This is done by Mojang because scrolling a book looks relatively out of place in the skeumorphic UI they've already designed.

To assist with this, I decided to enable decorations for the editor as well. This means you can see how close you are to the character limit (19,000/page). Please note that while it's technically possible to go over the limit, the packet will likely be rejected by the server if you do.

The rendering is more messy on signed books since they use Components, so note that it will keep going off the page. Keep these books unsigned if possible to stay scrollable.

This mod is entirely client-sided, so it works on all servers. People without this mod also installed can still view/edit signed text via /data like before.

What's even more useful is that vanilla clients are also fully capable of scrolling these extended books! (as long as they're not signed). They won't be able to add text beyond the page-long limit, however.