Understanding What Core Lib Does So You Can Troubleshoot Dependent Mods

Knowing what the library provides tells you which symptoms point back to it.

What it supplies

Core Lib is shared plumbing for the author's mods: GUI screens and containers, block and tile entity base classes, network packet handling, and registry helpers such as wrappers for criterion trigger types. It is loaded on demand, meaning it activates because another mod needs it, not on its own.

Symptoms that trace back to it

• A machine or storage block opens but the interface is blank, misaligned, or unclickable — GUI code lives here.
• A block places but never ticks, never stores contents, or forgets its inventory on reload — tile entity code lives here.
• Multiplayer desync where a client sees different contents than the server — packet handling lives here.
• Advancements or custom triggers from a dependent mod never fire — trigger type registration lives here.

What it will never cause

Core Lib adds no world content. If you are missing a specific item, block, or recipe, that is the dependent mod's content, not the library's. Likewise, the library does not change vanilla behavior on its own. Use this split to decide whether to look at the library or at the mod that owns the content.