HZLib

1.0.0 — 2026-07-04

Minecraft 1.21.1

⚠️ Breaking changes. This release renames the core API classes across the entire framework. Any mod built against 0.1.0-alpha must update its imports. See the rename table below.

First stable release. Establishes the canonical Family / Variant / Appearance three-tier terminology across HZLib, adds the full NBT data pipeline, declarative bone visibility, and idle slot animation system.

Breaking: API Rename (ADR_018)

The Internal* prefix has been removed from all public API classes. Every name now reflects its tier and role directly.

Old name	New name
InternalEntity	NativeEntity
InternalEntityType<T>	NativeEntityFamily<T>
InternalLogic	EntityLogic
InternalParticle	EntityParticles
InternalLayerRenderer<T> (Common)	LayerRenderPipeline<T>
InternalAnimation (Fabric / Forge / NeoForge)	NativeAnimation
InternalModel<T> (Fabric / Forge / NeoForge)	NativeModel<T>
InternalLayerRenderer<T> (Fabric / Forge / NeoForge)	NativeRenderer<T>

Why: Internal had accumulated three unrelated meanings — entity base class, family descriptor, GeckoLib integration layer, and utility helpers. The new names encode both tier (Native* = HZLib root layer) and role (*Family = family descriptor, *Pipeline = render coordinator) so a class's responsibility is readable from its name alone.

Not yet renamed (deferred to a future release):

• IInternalRenderLayer — render layer interface
• nativeEntity field on NativeEntity — field rename is a higher blast-radius operation

New: NBT Data Pipeline (ADR_019)

A version-agnostic, type-safe entity data pipeline. All HZLib pipeline code now operates on DataCompound — a pure-Java wrapper — never directly on MC-native tag types. This is what makes HZLib backportable to 1.12.2 and 1.7.10 without rewriting the save/load layer.

• DataCompound — pure-Java version-agnostic NBT wrapper interface. The only point of contact with the MC NBT API is the adapter implementation, which lives in the version-specific source set.
• NbtAdapterFactory — registration point for the MC-version-specific DataCompound implementation. Registered once at mod init.
• CompoundTagDataCompound — the 1.21.1 CompoundTag implementation of DataCompound.
• DataType<T> — INT, FLOAT, BOOLEAN, STRING, UUID. UUID handling is version-safe — the adapter selects the correct storage strategy per MC version automatically.
• DataField<T> — typed field handles. The NBT string key is encapsulated inside the handle — zero string literals at call sites. A typo in a field reference is a compile error, not a silent default value.
• EntityDataSchema — declares the ordered set of DataField<?> handles that define an entity family's saved data. Write and read go through the schema — no field names appear in save/load methods.
• MigrationStep / MigrationChain — sole migration authority. Each step receives and returns a DataCompound, enabling cross-field migration. Per-field migrators are deliberately excluded — migration logic belongs here only.
• FieldValueProvider / FieldValueConsumer — typed interfaces for entity ↔ schema communication. No string keys at call sites.

New: Bone Visibility Feature (ADR_022)

• BoneVisibilityFeature — declarative per-bone show/hide rules attached to a NativeEntityFamily. Evaluated each frame in NativeModel.setCustomAnimations().
• BoneCondition — @FunctionalInterface, evaluated client-side per render frame. Must be fast — no world queries, no allocations.
• BoneRule — pairs a bone name with a BoneCondition and a hide/show polarity.

Replaces all reflection-based bone access (getBone / setHidden via reflection). GeckoLib types remain in loader modules where they belong — BoneVisibilityFeature and its conditions are pure Java in HZLib Common.

New: Idle Slot Animation System (ADR_022)

Replaces tick-driven standby logic (handleStandbyAnimation()) with a declarative idle state profile. Eliminates standby animation flicker structurally.

• IdleCondition — @FunctionalInterface evaluated per locomotion controller tick.
• IdleSlot — pairs an AnimationPool with an IdleCondition, a priority, and an activation threshold in ticks. Higher priority slots are evaluated first; a slot activates only once its condition has held for the threshold duration.
• idleStationaryTicks on NativeEntity — incremented each tick the entity is not moving and not in a vehicle; reset on movement. IdleSlot threshold comparisons operate on this counter — stable once crossed, no per-frame re-evaluation.
• AnimationProfile gains idleSlots — the existing .idle() shorthand implicitly creates a priority-0, always-true, zero-threshold slot, guaranteeing every profile has a fallback.
• onIdleSlotChanged() hook on NativeEntity — called when the winning idle slot changes; override in subclasses to react (e.g. update hitbox on sit/stand transition).

New: headBoneName on NativeEntityFamily

The head bone name used for look-tracking in NativeModel.setCustomAnimations() is now a configurable field on the family descriptor (.headBone("head_bone_name")). Eliminates the hardcoded "head" string that was embedded in model code. All existing families default to "head" — zero migration required.

New: Conditional and Composite Appearance Features

• ConditionalAppearanceFeature — switches the active appearance based on runtime conditions evaluated against entity state.
• CompositeAppearanceFeature — composes multiple appearance layers into a single resolved appearance.

Known Issues / Deferred

• hzlib.api.entity.dynamic.* and hzlib.api.entity.monsters.* packages contain confirmed dead code with zero consumers. They remain in this build and are flagged for deletion in a future cleanup release.
• IInternalRenderLayer rename deferred.
• nativeEntity field rename deferred.