Structure Gel API

Structure Gel API

Minecraft 1.20.1 / Forge: this page documents that build and its measurements. For the separate 170-control Minecraft 1.21.1 port, see Minecraft 1.21.1 NeoForge.

One control for Structure Gel API 1.20.1-2.16.2 (mod id structure_gel), a fix: its lake hook checks structures inside the generation region, which stops a server freeze. Background on Generation context fixes. The switch checks the code it would change against the tested build; another build is left untouched with one WARN line (see How the patches are applied).

Key	Target	Side	Since	Kind
structure_gel_lake_guard_region	Structure Gel API 2.16.2	BOTH	1.0.11	fix

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structure_gel_lake_guard_region

Target: Structure Gel API 2.16.2 · Side: BOTH · Since: 1.0.11 (first as a patched JAR 2026-09-09) · Kind: fix Patched: com.legacy.structure_gel.core.asm_hooks.LakeFeatureHooks.checkForStructures — 1.0.19 script bons_and_furious-LakeFeatureHooks.js Mixin (since 1.0.20): LakeFeatureHooksMixin

What upstream did. Structure Gel's lake hook, which keeps lakes out of Structure Gel structures, had the same defect as Ice and Fire's lake guard: it took the live ServerLevel's structure manager while a lake was being placed in a generation region, so its checks could force live chunks to load on the server thread.

What the patch does. Binds the structure manager to the supplied region with StructureManager.forWorldGenRegion.

What stays the same. Every lake-protection check and its result; non-region contexts take the original path.

Measured. Fixes a server freeze; it was the second of the two independent lake guards in the 2026-09-09 freeze (12 Structure Gel workers were blocked once Ice and Fire's guard was fixed). With both fixed: 3,700 ticks in 185.001 s (20 TPS), zero live-chunk waits.

Since 1.0.34. A lake placed off the centre chunk of its generation region (a jigsaw lake with an offset, such as Strayed Fates: Forsaken's) asks the live level as before. Looked up inside the region, such a lake could reach a structure start 9 chunks from the centre, outside the region, and stop world generation. Lakes in the centre chunk, and every lake in Distant Horizons' regions, keep the region lookup.