Lumen — A modern scripting platform for Minecraft servers

Lumen is a scripting platform for Spigot and Paper. It's strict, statically checked, and compiles your .luma files directly to JVM bytecode. The script you write becomes the code your server runs. There is no interpreter, and no implicit type conversion changing your variables behind your back.

If you're coming from Skript, the general feel will be recognizable. The actual syntax and the way you write things is its own thing.

AI Native, designed for AI assistants from day one

Lumen ships with a first-class MCP server. Instead of pulling from outdated wikis or making up syntax, AI assistants go through the real Lumen parser, look up patterns with the same ranker the compiler uses, and read the docs that come with the platform. If something the model writes doesn't parse, it sees the exact error on the exact line and keeps trying until it does. Anything wrong gets caught before it ever reaches you.

Sonnet can write 2000+ line scripts in a single prompt with no human corrections. A nine-page shop GUI with three top-level categories, three subpages each, full navigation, and full purchase logic was generated on the first try in about twelve minutes. The MCP has produced 5000+ line scripts the same way.

A live debugger the AI can use

Once your script is running, the same MCP connects the AI to your live server. There's no pasting logs back and forth, no copying variable values out of the console, no walking through what went wrong. The AI runs your commands as you, fires Bukkit events the same way the game does, changes the world around you, takes full variable snapshots on any line without pausing the tick, and swaps out expressions or branches in memory while the server keeps running.

It can change your health, give you any item with any NBT, place or break blocks, switch your gamemode, teleport you, run commands using the player context from your last action, execute the compiled Java for any line of your script, read internal Bukkit fields through reflection, or trigger any custom event with whatever arguments it needs. Anything a regular plugin can do, to you, in real time.

Server-side support is available today. Client-side is coming. Once that ships, the AI runs code inside your Minecraft client too, not just the server. Test anti-cheats end to end. Simulate real player movement. Swing, click, sprint, crouch, place blocks at exact tick offsets. No other scripting ecosystem is even attempting this.

Native performance

Because Lumen compiles to JVM bytecode, your scripts run at the same speed as a hand-written Spigot plugin. There is no pattern re-parsing on every event, no dynamic type lookup on every variable read, and no interpreter loop between lines. The work happens once when you save the file, and after that it's just Java running on the JVM. On any non-trivial workload, the difference compared to dynamic scripting is significant.

Strict, but inferred

You don't write types. The compiler infers them from how you use the variable. Set something to a number once and it stays a number. Try to assign a string to the same variable later and the script will not load. That one rule eliminates an entire class of bugs that interpreters only catch when a real player triggers them. Every assignment, comparison, and pattern match is checked before the script touches your server.

Nullable as part of the type system

A variable is either nullable or it is not. There is no middle state, and nothing is implicit. Declare it as nullable player and the compiler tracks that wherever the value flows. Pass a possibly-null value to something that does not accept null, and the editor warns you on the line you wrote. Use if x is set and the type narrows to non-null inside the branch. No more silent failures on offline players, missing slots, or empty variables.

Diagnostics that tell you the fix

Good error messages are part of the design, not an afterthought. Unknown patterns, broken globals, broken data classes, type mismatches, and most other mistakes come back with the exact token underlined, a label describing what the compiler expected, and a suggestion for the closest valid pattern. The format is heavily inspired by Rust. The error tells you what to fix, not just that something is broken.

Hot reload, including open inventories

Save the file. There is no /reload command, no restart, and nothing to run. Lumen picks up the change on its own while players stay connected and keep playing. Commands, events, scheduled tasks, and inventories that players currently have open all update live. Title changes, slot layout changes, item changes, lore, and click handlers all apply in place without the inventory closing or flickering. Almost no other Minecraft scripting plugin offers this.

Editor-grade tooling

The VSCode extension runs the actual Lumen engine in the background. Every error, completion, hover, and go-to-definition comes from the same compiler that loads your scripts on the server. The diagnostics are not approximations, they are the real engine reporting back. Inlay hints show the type of every variable next to its name, so you can read through a script and understand it without hovering or scrolling.

500+ entries, fully extendable

Statements, expressions, conditions, blocks. Lumen ships with over five hundred first-party entries, and more are added every release. Need something that doesn't exist yet? The Java addon API is clean. You can write your own statements, expressions, events, and types, and use them alongside the built-in ones.

Get started

Download the jar from your preferred host (Modrinth, SpigotMC, or BuiltByBit). Put it in your plugins/ folder. Start the server. There are no companion plugins, no external libraries, and no extra setup. Place .luma files in the scripts folder and they reload as you save them. That is the whole installation.

Lumen is currently in beta. Some features are missing and bugs do exist, but the platform improves quickly and updates ship often.