FSit

Evidence

Ran on Kiln's test stand (2026-11-04): FSitMod did not start: java.lang.NoClassDefFoundError: net/minecraft/core/HolderSet; FSitModClient did not start: java.lang.NoClassDefFoundError: net/minecraft/core/HolderSet.

What it needs from Kiln

• an access widener
• Mixin
• net.fabricmc.fabric.api.client.networking.v1.ClientPlayConnectionEvents
• net.fabricmc.fabric.api.client.networking.v1.ClientPlayConnectionEvents.Disconnect
• net.fabricmc.fabric.api.client.networking.v1.ClientPlayConnectionEvents.Join
• 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.EventFactory
• net.fabricmc.fabric.api.event.player.BlockEvents
• net.fabricmc.fabric.api.event.player.BlockEvents.UseWithoutItemCallback
• net.fabricmc.fabric.api.event.player.UseEntityCallback
• net.fabricmc.fabric.api.networking.v1.PacketSender
• net.fabricmc.fabric.api.networking.v1.PayloadTypeRegistry
• net.fabricmc.fabric.api.networking.v1.ServerPlayConnectionEvents
• net.fabricmc.fabric.api.networking.v1.ServerPlayConnectionEvents.Disconnect
• 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.fabricmc.fabric.api.permission.v1.PermissionNode
• net.fabricmc.fabric.api.permission.v1.PermissionPredicates
• net.minecraft.advancements.triggers.CriteriaTriggers
• net.minecraft.advancements.triggers.StartRidingTrigger
• net.minecraft.client.OptionInstance
• net.minecraft.client.OptionInstance.CaptionBasedToString
• net.minecraft.client.OptionInstance.Enum
• net.minecraft.client.OptionInstance.IntRange
• net.minecraft.client.OptionInstance.TooltipSupplier
• net.minecraft.client.OptionInstance.ValueSet
• net.minecraft.client.OptionInstance.ValueUpdateListener
• net.minecraft.client.Options
• net.minecraft.client.gui.components.Tooltip
• net.minecraft.commands.CommandSourceStack
• net.minecraft.commands.Commands
• net.minecraft.commands.Commands.CommandSelection
• net.minecraft.commands.arguments.ResourceOrTagArgument
• net.minecraft.commands.arguments.ResourceOrTagArgument.Result
• net.minecraft.commands.arguments.coordinates.BlockPosArgument
• net.minecraft.core.Direction.Axis
• net.minecraft.core.HolderSet
• and 80 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

Sit anywhere!

Scan

Scanned on 4 November 2026 against Kiln 0.2.0, file fsit-3.1.0-alpha.2+mc26.3.jar. The scan reads the mod's classes; it does not run them.