foo.rb

class Foo < ApplicationRecord
  def array
    self[:array] ? LimitedArray.new(self[:array]) : self[:array]
  end

  def array=(value)
    self[:array] = value ? LimitedArray.new(value.dup).to_a : value
  end
end

limited_array.rb

class LimitedArray
  def initialize(array, limit: 10)
    @array = array
    @array.slice!(limit..-1)
    @limit = 10
  end

  def method_missing(method, *args, &block)
    @array.public_send(method, *args, &block).tap do
      @array.slice!(@limit..-1)
    end
  end

  def respond_to_missing?(name, include_private = false)
    @array.respond_to?(name)
  end
end