JumpDuplicator

When a player in survival or adventure mode starts a valid jump, the mod copies the non-player entities around that player and places each copy at the same X and Z position, with a configured vertical offset applied. Dropped item stacks within the configured radius are copied in the same way, such as oak logs lying near the player. By default each copied stack holds only one item, even when the original stack holds more.

The duplication can also be triggered by hand: an administrator runs the duplicate command, and the executing player starts the duplication. Administrative commands require a permission level set in the vanilla configuration. Values in the config file that fall outside their safe ranges are clamped back into those ranges while the config loads, and the reload command applies config changes without restarting the server.

Installation needs Fabric Loader 0.19.3 or newer and Fabric API on a server running Minecraft 26.2. The built JumpDuplicator JAR goes into the server's mods folder; the remapped JAR is written to build/libs/ by the build. Its logic executes on the logical server, so players connecting to it do not need anything installed. The code is open source under the MIT License and published for 26.2 only.