Auth-Limbo

A small Paper plugin I wrote because AuthMe's post-login teleport kept dumping my players at world spawn instead of where they last were. Tried every config flag, removed Multiverse, tried forks. Nothing fixed it. So this does.

Two jobs: hosts a void auth_limbo world (so I could stop running Multiverse-Core for one world I never visited) and replaces AuthMe's broken post-login teleport with one that actually works.

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The problem

Friend logs in, types /login, AuthMe is supposed to teleport them back to where they were. They land at world spawn instead. Every time.

Spent a day chasing this. Disabled Multiverse-Core. Disabled GrimAC. Disabled UnexpectedSpawn. Disabled Essentials. Even ran with just AuthMe loaded and the bug stayed.

Eventually traced it to PaperMC/Paper#4085 — Player#teleportAsync resolves before the destination chunk loads, Paper's safety logic snaps the player to the nearest loaded chunk, and that chunk is world spawn. AuthMe's teleportOnLogin flow walks right into it.

Filed a mental bug report against AuthMe, decided writing my own listener was faster than waiting on a fork.

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What it does

Two things and that's it.

1. Void auth_limbo world. A custom ChunkGenerator produces empty chunks. A 5x5 barrier platform sits under spawn so unauth players don't fall forever. No daylight cycle, no weather, no mob spawning, no PvP. AuthMe uses it as the pre-auth limbo. No Multiverse-Core needed.

2. Authoritative restore-teleport. A LoginEvent listener at MONITOR priority fires after AuthMe's broken teleport, reads the saved quit-location straight out of plugins/AuthMe/authme.db, pins the destination chunk with Chunk#addPluginChunkTicket, then chains World#getChunkAtAsyncUrgently into an authoritative Player#teleportAsync. Same pattern PaperLib's AsyncTeleportPaper uses, just narrower.

That's the whole surface area. No password handling, no permissions beyond admin commands, no register flow, no chat formatting. AuthMe owns all of that.

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Install

1. Download AuthLimbo-1.0.0.jar from the Releases page.
2. Drop it in your plugins/ directory.
3. Restart the server. Don't /reload — it'll break things. Just restart.

AuthMe-ReReloaded is a hard dependency. The plugin refuses to load without it.

For the itzg/minecraft-server Docker image, see docs/installation.md for the PLUGINS: environment-variable form.

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Configuration

Defaults work. plugins/AuthLimbo/config.yml is created on first start. If you want to tweak:

limbo:
  world: auth_limbo            # Bukkit world name
  spawn-x: 0.5
  spawn-y: 128.0
  spawn-z: 0.5
  build-platform: true         # 5x5 barrier under spawn
  platform-y: 127

authme:
  db-path: plugins/AuthMe/authme.db
  teleport-delay-ticks: 10     # ticks to wait after LoginEvent
  preload-chunks: true         # forceload chunk before teleport

debug: false                   # verbose logging

Full reference in docs/configuration.md.

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Commands

Command	Permission	Effect
/authlimbo reload	authlimbo.admin	Reload config.yml.
/authlimbo tp <player>	authlimbo.admin	Manually teleport a player to their saved location.

Aliases: /alimbo.

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What I tested

Component	Status	Notes
Paper 1.21.11	Yes	Primary target.
Purpur 1.21.11	Yes	Same Paper API surface.
Folia	Unknown	Untested. Login event threading may differ.
AuthMe-ReReloaded (HaHaWTH b49)	Yes	Verified on production.
AuthMe-ReReloaded other 5.x forks	Untested	Schema is the same, should work.
Multiverse-Core	Untested	Not required. Possible teleport-intercept conflict — see docs/compatibility.md.

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Build from source

mvn clean package

Shaded jar lands at target/AuthLimbo-1.0.0.jar. Java 21, Maven 3.9. Standard. The lib/AuthMe-5.6.0-FORK-Universal.jar is referenced as a system-scope dep so the build doesn't need any private repo credentials.

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Why not just use Multiverse-Core for the void world?

Multiverse-Core does a dozen things. I needed one void world. Also Multiverse intercepts teleports for portals and respawn, which is the exact contention I was running from. This plugin is ~400 lines and only manages the one world AuthMe needs. If you already run Multiverse for legit reasons, ignore the limbo manager and just use the teleport fix.

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License

AGPL-3.0. See LICENSE.

If you run a modified version of this plugin on a Minecraft server that players connect to over the network, AGPLv3 §13 requires you to offer the modified source to those players. Unmodified use carries no obligation beyond GPLv3 (no source-sharing required).

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Author

Built by s8n-ru. If this fixes your headache too, cool. If not, file an issue, I'll look.