Make Two Scripts Talk

You have a player.lua and a global.lua. How do they exchange information?

Start with the receiver. Does it own an object? Does the message cross contexts? Is the other script publishing a capability rather than announcing an occurrence?

A local event tells one object something

The receiver is a local script attached to an object:

---@omw-context local

return {
    eventHandlers = {
        MyModSetMarked = function(marked)
            print('The attached object is marked:', marked)
        end,
    },
}

The sender needs a target object and sends to that object:

target:sendEvent('MyModSetMarked', true)

Use a local event when the target object naturally owns the behavior.

A global event crosses into global infrastructure

The player script can announce a world-level event:

---@omw-context player

local core = require 'openmw.core'

core.sendGlobalEvent('MyModVisitRecorded', { cellId = 'Balmora' })

The global script receives it:

---@omw-context global

return {
    eventHandlers = {
        MyModVisitRecorded = function(data)
            print('Visited:', data.cellId)
        end,
    },
}

Keep event payloads small and deliberate. An event is an engine-managed boundary, not a convenient pipe for every private table in your program.

An interface exposes a capability

An interface is for a provider that owns a stable thing another script wants to call or query. For example, a player script can consume H3's attached-object interface:

---@omw-context player

local interfaces = require 'openmw.interfaces'
local actor = interfaces.s3.lf.asActor()

if actor then
    print(actor.recordId)
end

The player is not announcing that something happened. It is asking an owner for a capability. That is an interface-shaped question.

The tiny decision table

For the formal version, read Events and Interfaces. Next, learn what the objects and records in those messages actually are in Objects, Records, and Cells.