Customizable Hearts

Evidence

Ran on Kiln's test stand (2026-11-04): CustomizableHearts did not start: java.lang.NoClassDefFoundError: net/minecraft/network/protocol/common/custom/CustomPacketPayload; CustomizableHeartsClient did not start: java.lang.NoClassDefFoundError: net/minecraft/network/protocol/common/custom/CustomPacketPayload$Type.

What it needs from Kiln

• Mixin
• 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.command.v2.CommandRegistrationCallback
• net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents
• net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents.EndTick
• net.fabricmc.fabric.api.networking.v1.PayloadTypeRegistry
• net.fabricmc.fabric.api.networking.v1.ServerPlayConnectionEvents
• net.fabricmc.fabric.api.networking.v1.ServerPlayConnectionEvents.Join
• net.fabricmc.fabric.api.networking.v1.ServerPlayNetworking
• net.fabricmc.fabric.api.networking.v1.ServerPlayNetworking.Context
• net.fabricmc.fabric.api.networking.v1.ServerPlayNetworking.PlayPayloadHandler
• net.minecraft.client.gui.components.AbstractSliderButton
• net.minecraft.client.gui.components.Button
• net.minecraft.client.gui.components.Button.Builder
• net.minecraft.client.gui.components.Button.OnPress
• net.minecraft.client.gui.components.EditBox
• net.minecraft.client.gui.screens.ConfirmScreen
• net.minecraft.commands.CommandSourceStack
• net.minecraft.commands.Commands
• net.minecraft.commands.Commands.CommandSelection
• net.minecraft.commands.arguments.EntityArgument
• net.minecraft.network.RegistryFriendlyByteBuf
• net.minecraft.network.codec.StreamCodec
• 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.server.MinecraftServer
• net.minecraft.server.network.ServerGamePacketListenerImpl
• net.minecraft.server.permissions.PermissionSet
• net.minecraft.server.permissions.Permissions
• net.minecraft.server.players.PlayerList
• net.minecraft.world.damagesource.DamageSource
• net.minecraft.world.damagesource.DamageSources
• net.minecraft.world.entity.ai.attributes.AttributeModifier
• net.minecraft.world.entity.ai.attributes.AttributeModifier.Operation
• Minecraft.execute()
• Minecraft.setScreenAndShow()
• GuiGraphicsExtractor.centeredText()
• Screen.extractRenderState()
• and 9 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

A server-side Fabric mod for customizing player and mob health, damage, shared life, linked damage, and XP-based bonus hearts.

Scan

Scanned on 4 November 2026 against Kiln 0.2.0, file customizable-hearts-mc26.3-1.0.0.jar. The scan reads the mod's classes; it does not run them.