Threading Model

Most event callbacks run on Minecraft’s client thread. Keep those callbacks short. Packet callbacks can run during networking dispatch. They are marked non-blocking: client-thread APIs that would have to wait are rejected from those scopes.

local cachedHealth = nil

Script.on("tick", function()
  cachedHealth = Player.health()
end)

Script.on("packet_receive", function(event)
  if event.type == "system_chat" and event.text ~= nil and string.find(event.text, "debug", 1, true) then
    Chat.log("cached hp: " .. tostring(cachedHealth or "?"))
  end
end)

Use Script.thread or Async.run for blocking waits:

Script.thread(function()
  Time.sleepTicks(20)
  Chat.log("one second later")
end)

Direct raw Java calls through Java.mc(), Java.type(...), or Reflect do not automatically marshal back to the client thread. Prefer the high-level APIs when possible.

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Getting Started

Scripting

Examples

API Reference

Troubleshooting

Threading Model