Copycats EMI Refresh Fix

Keeps Copycats+ 3.0.4 items in EMI 1.1.24 through the normal EMI registration and reload cycle. This is a client-side addon for Minecraft 1.21.1 on NeoForge.

The problem

Copycats+ items can disappear from the EMI index after leaving and rejoining a world. The upstream tracker documents this symptom in issue #270, with a related refresh error in issue #339.

Why it happens

The original Copycats EMI plugin stores its registry during registration, while its feature-controlled item-list edits happen later in refreshItemList. Its registration method does not populate those entries itself. This leaves list edits outside the normal registration cycle.

Scope of the fix

• Runs Copycats' original feature-filtered item-list operations during each EMI plugin registration.
• Requests an EMI reload for a refresh while a client world is open. Refresh requests with no world open do nothing.
• Applies only on the client, with guards for the exact Copycats and EMI target classes.

Copycats' enabled/disabled feature choices are preserved. This addon adds no blocks, recipes, configuration files, server restrictions or balance changes.

Compatibility

• Minecraft 1.21.1 and Java 21.
• NeoForge 21.1.235, the version used for local checks. The package accepts NeoForge versions from 21.1.235 up to, but excluding, 21.2; other loader builds have not been separately tested.
• Create: Copycats+ 3.0.4+mc.1.21.1-neoforge, installed separately. This is an exact dependency.
• EMI 1.1.24+1.21.1+neoforge, installed separately. This is an exact dependency.
• Create 6.0.10, used for local checks and required by Copycats+.

Install on clients only. The Mixin is excluded on dedicated servers, and servers do not need this addon. It does not require a Java agent or the Steam & Steel launcher.

This file targets the older Copycats+ 3.0.4 build. Copycats+ 3.0.9 is not supported by this file; matching target code in a later release does not widen the package's declared compatibility. Unknown target class bytes leave the patch inactive. Do not install another copy of this addon under a different filename or combine it with another patch to the same EMI integration without a separate compatibility check.

From Steam & Steel

The fix originated in the client compatibility layer of Steam & Steel SMP, our custom Minecraft 1.21.1 NeoForge server modpack. It was adapted from our launcher compatibility code into a standalone NeoForge addon and included in the unified launcher-based client pack.

The standalone addon requires the original mods listed above. It does not require SteamSteelCore, Companion, or the full Steam & Steel modpack.

Acknowledgements

Create: Copycats+ is by Lysine, Bennyboy1695, Redcat_XVIII and its contributors. EMI is by Emi / EmilyPloszaj and its contributors. Create is by simibubi and the Create contributors.

This is an independent community addon. Copycats+ retains its All Rights Reserved license; EMI retains its MIT license; Create retains its separate MIT code and All Rights Reserved asset licenses. No upstream JARs, classes or artwork are bundled in this addon.

Beta / Feedback

This is a beta release. Saved local checks use the exact native Copycats+ 3.0.4 implementation, actual Sponge Mixin application, all-method comparison with our launcher patch, and explicit test fixtures for registration, feature filtering and refresh behavior. Dedicated-server and unknown-target paths leave the target unchanged.

These checks did not launch Minecraft and do not establish gameplay, a full client startup, rendering, or compatibility with every modpack. The standalone gameplay stage remains unverified.

If you encounter a crash, an error or unexpected behaviour, please leave a comment with your Minecraft, NeoForge, Create, Copycats+, EMI and addon versions, plus steps to reproduce the problem. We will investigate reported bugs and work on fixes.

License

Addon code is licensed under BSD 3-Clause. Copyright (c) 2026, DanielBasov (Steam & Steel). Forks, fixes and redistribution are permitted; retain the author attribution, license conditions and disclaimer in source distributions and in the materials accompanying binary distributions. A fork may not imply endorsement by the original author. The full license is included in the JAR and source archive.

The original mods and their artwork keep their own licenses. Original project artwork, when supplied with this project, is covered by its accompanying provenance and license record.