chunktreefix

NeoForge 1.21.1 fix for MC-224729: trees, structures, and any other world-gen feature that overhangs from an already-generated chunk into a neighboring chunk that hasn’t finished generating yet can get silently discarded when that neighbor chunk is saved — producing the “cut off at the chunk border” look on trees and structures.

This is a reimplementation (not a copy) of SuperCoder79’s chunksavingfix-fabric (MIT, originally for 1.16.5 Fabric), rebuilt against current NeoForge 1.21.1 internals.

Status: Beta

Confirmed working in real play across a ~350-mod pack, alongside several other mods that also touch chunk saving/caching (ServerCore, SmoothChunk, ModernFix, Lithium). One known risk: this patches ChunkMap#saveChunkIfNeeded with @Overwrite. If another mod in your pack also overwrites that exact method, the two will conflict and the game won’t start. Not yet tested on a dedicated server (only singleplayer/integrated server so far).

Note on performance

This is a correctness/bugfix mod, not a performance mod — it adds a small amount of extra disk I/O for chunks that were previously (incorrectly) skipped during save, bounded by vanilla’s existing per-chunk save cooldown.