Undefined method in my plugin...

I've got a plugin that is really a collection of plugins, and I want
one plugin to see methods from another.
I've tried to simplify what I've done and what I'm seeing

So my (simplified) file structure looks like this:
acts_as_foobar/
  - init.rb
  - lib/
    acts_as_foobar.rb
    foo.rb
    bar.rb

init.rb:
    require 'acts_as_foobar.rb'

acts_as_foobar.rb:
    require 'foo'
    require 'bar'

foo.rb:
    module Foo
      def self.included(base)
        base.extend(ClassMethods)
      end

      module ClassMethods
        def acts_as_foo
          class_eval do
            extend Foo::SingletonMethods
          end
        end
      end

      module SingletonMethods
        def static_foo_method
          ...do something foo-ish here...
        end
      end
    end

    ActiveRecord::Base.send(:include, Foo)

bar.rb:
    module Bar
      def self.included(base)
        base.extend(ClassMethods)
      end

      module ClassMethods
        def acts_as_bar
          include Bar::InstanceMethods
        end
      end

      module InstanceMethods
        def instance_bar_method
          X.static_foo_method
        end
      end
    end

    ActiveRecord::Base.send(:include, Bar)

Now, I have two model classes, X and Y
X.rb
    class X < ActiveRecord::Base
      acts_as_foo
    end

Y.rb
    class Y < ActiveRecord::Base
      acts_as_bar
    end

Now if I try this:
    Y.find(1).instance_bar_method

I'll get an error like this:
    'undefined method `static_foo_method' for Foo:Module
(NoMethodError)

But I can call
    X.static_foo_method
and get the results I expect.

(I know this use of a plugin may not be optimal)

Any clues as to how I can get this work?

Thanks,
-kevin