ForceBlend

Original mod by Mauro0805. Maintained by Mauro0805 and SasnycoN

ForceBlend prepares existing Overworld chunks so Minecraft can blend new terrain beside them after seed or
terrain-generator changes, chunk imports, or deletions. Minecraft generates the terrain; ForceBlend marks the existing
side of the border.

Opening a world

ForceBlend defaults to once per world. A read-only client analysis shows affected chunks, regions, deferred work,
and estimated processing time. By default you get Prepare world (backup is on), Open without changes, or Cancel.
With automatic backup turned off, the backup option comes first, followed by Prepare without backup (risky).
Processing uses native Minecraft screens with progress and completion, not desktop dialogs.

Dedicated servers have no menu and always complete a full-world backup before applying. On clients the backup is on by
default and can be turned off in the settings. ZIPs go under backups/forceblend/<world>/, outside the source world.
They exclude only the root runtime session.lock. Keep your own restorable copy of important worlds.

Settings and migration

Edit config/forceblend.properties; Fabric Mod Menu optionally provides a settings screen.
Automatic analysis and client backup default on, detailed logging defaults off, the chunk limit defaults
to unlimited, and processing threads default to all available processors.

Once mode records successful, non-deferred completion in forceblend.json. Existing forceblendonce.json markers
are honored. Every-opening mode ignores those markers for later imports, seed changes, or deletions.
Replace the old ForceBlend Once JAR with the correct loader build; do not install both.

Source and permission

MIT-licensed, free, usable in any modpack without asking, and open to forks.
Updates, response times, and pull-request review are not guaranteed.

Source: Mauro0805/ForceBlend. Release notes and the changelog are on GitHub.