xSuite
More than thirty Minecraft server plugins that share one core library. Economy, land claims, pets, ranks, permissions, chat, crates, teams and minigames.
What it is
Thirty-odd plugins meant to be run together on one shared core. One command system. One config style. One permission model.
On their own they are ordinary. The value is that they agree with each other. A server owner who assembles six plugins from six different authors gets none of that.
The lesson it taught me
A shared core means a shared command registry. Names in it are first come, first served across every plugin on the server.
A duplicate name is not a warning. It takes a whole plugin down at startup, and load order decides which of the two loses.
I found this when a chat plugin claimed a moderation command. The staff plugin then never turned on at all. No bans, no reports, no staff mode, from one repeated word.
The failure was almost silent. That is the part worth remembering. A shared registry needs to fail loudly, because the thing it breaks is never the thing you were editing.