hcapi

Calls something that is on Kiln's roadmap. Parts of it may already run.

Evidence

Ran on Kiln's test stand (2026-11-04): Hcapi did not start: java.lang.NoClassDefFoundError: net/fabricmc/fabric/impl/base/toposort/SortableNode; HcapiClient did not start: java.lang.NoClassDefFoundError: net/minecraft/network/protocol/common/custom/CustomPacketPayload.

What it needs from Kiln

an access widener
Mixin
io.netty.buffer.Unpooled
net.fabricmc.fabric.api.client.networking.v1.ClientConfigurationNetworking
net.fabricmc.fabric.api.client.networking.v1.ClientConfigurationNetworking.ConfigurationPayloadHandler
net.fabricmc.fabric.api.client.networking.v1.ClientConfigurationNetworking.Context
net.fabricmc.fabric.api.client.networking.v1.ClientPlayNetworking
net.fabricmc.fabric.api.client.networking.v1.ClientPlayNetworking.Context
net.fabricmc.fabric.api.client.networking.v1.ClientPlayNetworking.PlayPayloadHandler
net.fabricmc.fabric.api.networking.v1.FriendlyByteBufs
net.fabricmc.fabric.api.networking.v1.PacketSender
net.fabricmc.fabric.api.networking.v1.PayloadTypeRegistry
net.fabricmc.fabric.api.networking.v1.ServerPlayNetworking
net.fabricmc.fabric.api.networking.v1.context.PacketContext
net.fabricmc.fabric.api.networking.v1.context.PacketContext.ReadKey
net.fabricmc.fabric.api.resource.conditions.v1.ResourceCondition
net.fabricmc.fabric.impl.base.toposort.NodeSorting
net.fabricmc.fabric.impl.base.toposort.SortableNode
net.minecraft.core.HolderLookup.RegistryLookup
net.minecraft.core.IdMap
net.minecraft.core.LayeredRegistryAccess
net.minecraft.core.RegistryAccess
net.minecraft.core.RegistryAccess.Frozen
net.minecraft.core.RegistryAccess.RegistryEntry
net.minecraft.core.RegistrySynchronization
net.minecraft.core.component.DataComponentInitializers
net.minecraft.core.component.DataComponentInitializers.PendingComponents
net.minecraft.core.component.DataComponentMap
net.minecraft.core.component.DataComponentMap.Builder
net.minecraft.core.component.DataComponentPatch
net.minecraft.core.component.TypedDataComponent
net.minecraft.network.Connection
net.minecraft.network.RegistryFriendlyByteBuf
net.minecraft.network.VarInt
net.minecraft.network.codec.ByteBufCodecs
net.minecraft.network.codec.StreamCodec
net.minecraft.network.codec.StreamCodec.CodecOperation
net.minecraft.network.protocol.common.custom.CustomPacketPayload
net.minecraft.network.protocol.common.custom.CustomPacketPayload.Type
net.minecraft.network.protocol.common.custom.CustomPacketPayload.TypeAndCodec
net.minecraft.resources.FileToIdConverter
net.minecraft.resources.RegistryOps
and 14 more

On the roadmap: Minecraft's libraries and client API (0.2), Code next to data (0.3), Mixin (0.5)

In the author's words

Holder Component API - Allows conveniently attaching data to holders via datapack

Scan

Scanned on 4 November 2026 against Kiln 0.2.0, file hcapi-1.0.1+mc26.3.jar. The scan reads the mod's classes; it does not run them.

Reports from players

No reports from players yet.

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