Moveable Entity Block Module >=1.21.1 API redesigned in 26.1

The package dev.anvilcraft.lib.v2.piston solves the issue of vanilla pistons being unable to push blocks with block entities. Through a set of Mixins and interfaces, it allows blocks to carry custom NBT data during movement and write the data back to the block entity at the destination when the piston stops.

Document Index

Document	Content
Core Interfaces	IMoveableEntityBlock, IPistonMovingBlockEntityExtension
Mixin and Usage	Mixin modification points, complete usage example

Overview

In vanilla, a piston pushing a block with a block entity has no effect. This module injects into the piston movement logic:

1. Before movement -- Calls clearData to extract block entity data
2. During movement -- Data is temporarily stored in PistonMovingBlockEntity
3. After movement -- Calls setData to write data back to the block entity at the new position

The entire process is transparent to the server and requires no modification to the vanilla piston core logic.

Notes

• All data transfer occurs server-side; the client does not retain additional data
• clearData should return only the custom data that needs to be preserved, not serialize the entire block entity
• IMoveableEntityBlock extends EntityBlock; if your block is already a BaseEntityBlock subclass, you only need to additionally implement this interface
• Mixin priority is priority = 943; may need adjustment if conflicting with other piston-modifying mods