Creating a GE Extension

lua/ge/extensions/mymod/myfeature.lua
                  ↓
Extension name: mymod_myfeature

-- From extensions.lua:52-59
local function luaPathToExtName(filepath)
  return (filepath:gsub('_', '__'):gsub('/', '_'))
end

local function extNameToLuaPath(extName)
  return extName:gsub('__', '#'):gsub('_', '/'):gsub('#', '_')
end

-- lua/ge/extensions/mymod/myfeature.lua
local M = {}

-- OPTIONAL: Declare dependencies (loaded before your extension)
M.dependencies = {'core_settings_settings', 'career_career'}

-- OPTIONAL: Called when YOUR extension loads (or VM reloads)
-- Receives deserialized state from previous VM session (Ctrl+L reload)
local function onExtensionLoaded(deserializedData)
  -- Initialize state, register callbacks
  -- Return false to abort loading (extension will be unloaded)
end

-- OPTIONAL: Called AFTER onExtensionLoaded, GE only
-- Good for second-phase init when all batch-loaded extensions are ready
local function onInit(deserializedData)
end

-- OPTIONAL: Per-frame update (called every frame, before physics)
local function onUpdate(dtReal, dtSim, dtRaw)
  -- dtReal = wall-clock delta, dtSim = simulation delta (affected by slow-mo), dtRaw = unscaled
end

-- OPTIONAL: Called when level finishes loading and objects are available
local function onClientPostStartMission(levelPath)
end

-- OPTIONAL: Called when world is fully ready (state=2 means all done)
local function onWorldReadyState(state)
  if state == 2 then
    -- Safe to query entities, spawn things, etc.
  end
end

-- OPTIONAL: Called when your extension is unloaded
local function onExtensionUnloaded()
  -- Cleanup
end

-- Export hooks by assigning to M
M.onExtensionLoaded = onExtensionLoaded
M.onInit = onInit
M.onUpdate = onUpdate
M.onClientPostStartMission = onClientPostStartMission
M.onWorldReadyState = onWorldReadyState
M.onExtensionUnloaded = onExtensionUnloaded

-- Export public API functions
-- M.myPublicFunction = myPublicFunction

return M

extensions.load('mymod_myfeature')

-- scripts/mymod/modScript.lua
setExtensionUnloadMode("mymod_myfeature", "manual")
loadManualUnloadExtensions()

local function cleanup()
  extensions.unload('mymod_myfeature')
end

M.dependencies = {'core_settings_settings', 'career_career'}

if m.dependencies then
  for _, depName in ipairs(m.dependencies) do
    if not extRequested[depName] then
      extRequested[depName] = true
      local dependencyLoaded = extensionLoadInternal(depName, nil, extRequested)
      if not dependencyLoaded and not luaMods[depName] then
        log('W', logTag, 'Failed to load dependency: '..depName)
      end
    end
  end
end

-- From extensions.lua:601-620 (processLoadedFreshList)
if m.onExtensionLoaded then
  res = m.onExtensionLoaded(deserializedData[m.__extensionName__])
  if res == false then
    -- Extension will be unloaded
  end
end
-- ... later, for GE only:
if m and type(m.onInit) == 'function' then
  m.onInit(deserializedData[m.__extensionName__])
end

if career_career then  -- Check it's loaded
  career_career.isActive()
end

extensions.hook('myCustomHookName', arg1, arg2)
-- Every loaded extension with M.myCustomHookName will be called

-- In onInit or later, check if an extension is loaded
local function onInit()
  if career_career then
    -- Career extension is available
  end
end

guihooks.trigger('MyCustomEvent', {data = "value"})

-- lua/ge/extensions/mymod/helloworld.lua
local M = {}
local initialized = false

local function onExtensionLoaded()
  log('I', 'mymod', 'Hello World extension loaded!')
  initialized = true
end

local function onWorldReadyState(state)
  if state == 2 and initialized then
    log('I', 'mymod', 'World is ready!')
    guihooks.trigger('MyModReady', {message = 'Hello from mymod!'})
  end
end

local function onExtensionUnloaded()
  log('I', 'mymod', 'Goodbye!')
  initialized = false
end

M.onExtensionLoaded = onExtensionLoaded
M.onWorldReadyState = onWorldReadyState
M.onExtensionUnloaded = onExtensionUnloaded

return M