metabuilder/.github/prompts/implement/backend/3-impl-lua-script.prompt.md

Write Lua Business Logic

Add business logic as a sandboxed Lua script:

Create Script

Location: packages/{pkg}/seed/scripts/ or src/lib/lua-snippets.ts

-- Sandbox restrictions: NO os, io, require, loadfile
function validateInput(value)
  if not value or value == "" then
    return false, "Value required"
  end
  return true, nil
end

Register Script

renderer.registerLuaScript('validate_input', {
  code: luaCode,
  parameters: [{ name: 'value', type: 'string' }],
  returnType: 'boolean'
})

Execute Script

const result = await renderer.executeLuaScript('validate_input', [userInput])

When to Use Lua

• Validation rules
• Data transformation
• Conditional rendering logic
• Business rules that change frequently