diff --git a/.yardopts b/.yardopts
index 5d51dac2..2f9018fa 100644
--- a/.yardopts
+++ b/.yardopts
@@ -1,4 +1,4 @@
 --markup markdown
+--plugin yard-metasploit-erd
 --protected
 {app,lib}/**/*.rb
-db/migrate/*.rb
\ No newline at end of file
diff --git a/Gemfile b/Gemfile
index 0bc306a3..69c35498 100755
--- a/Gemfile
+++ b/Gemfile
@@ -3,6 +3,11 @@ source "http://rubygems.org"
 # Specify your gem's dependencies in metasploit_data_models.gemspec
 gemspec
 
+group :development do
+  # embed ERDs on index, namespace Module and Class<ActiveRecord::Base> pages
+  gem 'yard-metasploit-erd', '~> 0.0.2'
+end
+
 # used by dummy application
 group :development, :test do
   # supplies factories for producing model instance for specs
@@ -12,7 +17,7 @@ group :development, :test do
   gem 'factory_girl_rails'
   # rails is only used for the dummy application in spec/dummy
   # restrict from rails 4.0 as it requires protected_attributes gem and other changes for compatibility
-  # @see https://www.pivotaltracker.com/story/show/52309083
+  # @see MSP-2971
   gem 'rails', '>= 3.2', '< 4.0.0'
   # Used to create fake data
   gem "faker"
diff --git a/app/models/mdm/client.rb b/app/models/mdm/client.rb
index 530d68f6..4e61d3b8 100755
--- a/app/models/mdm/client.rb
+++ b/app/models/mdm/client.rb
@@ -2,7 +2,9 @@ class Mdm::Client < ActiveRecord::Base
   #
   # Relations
   #
-  belongs_to :host, :class_name => 'Mdm::Host'
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             inverse_of: :clients
 
   ActiveSupport.run_load_hooks(:mdm_client, self)
 end
diff --git a/app/models/mdm/cred.rb b/app/models/mdm/cred.rb
index 2bcd9c03..01b74e3d 100755
--- a/app/models/mdm/cred.rb
+++ b/app/models/mdm/cred.rb
@@ -19,13 +19,18 @@ class Mdm::Cred < ActiveRecord::Base
   #   The service this cred is for
   #
   #   @return [Mdm::Service]
-  belongs_to :service, :class_name => "Mdm::Service"
+  belongs_to :service,
+             class_name: 'Mdm::Service',
+             inverse_of: :creds
 
   # @!attribute [rw] task_creds
   #   Details about what Tasks touched this cred
   #
   #   @return [Array<Mdm::TaskCred>]
-  has_many :task_creds, :dependent => :destroy, :class_name => "Mdm::TaskCred"
+  has_many :task_creds,
+           class_name: 'Mdm::TaskCred',
+           dependent: :destroy,
+           inverse_of: :cred
 
   # @!attribute [rw] tasks
   #   Tasks that touched this service
diff --git a/app/models/mdm/event.rb b/app/models/mdm/event.rb
index e4952723..68354b08 100755
--- a/app/models/mdm/event.rb
+++ b/app/models/mdm/event.rb
@@ -3,8 +3,13 @@ class Mdm::Event < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :host, :class_name => 'Mdm::Host'
-  belongs_to :workspace, :class_name => 'Mdm::Workspace'
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             inverse_of: :events
+
+  belongs_to :workspace,
+             class_name: 'Mdm::Workspace',
+             inverse_of: :events
 
   #
   # Scopes
diff --git a/app/models/mdm/exploit_attempt.rb b/app/models/mdm/exploit_attempt.rb
index edd42d6d..03325fde 100755
--- a/app/models/mdm/exploit_attempt.rb
+++ b/app/models/mdm/exploit_attempt.rb
@@ -1,8 +1,49 @@
 class Mdm::ExploitAttempt < ActiveRecord::Base
   #
-  # Relations
+  # Associations
   #
-  belongs_to :host, :class_name => 'Mdm::Host', :counter_cache => :exploit_attempt_count
+
+  # @!attribute host
+  #   Host that was attempted to be exploited.
+  #
+  #   @return [Mdm::Host]
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             counter_cache: :exploit_attempt_count,
+             inverse_of: :exploit_attempts
+
+  # @!attribute loot
+  #   Loot gathers from the successful exploit.
+  #
+  #   @return [Mdm::Loot, nil]
+  belongs_to :loot,
+             class_name: 'Mdm::Loot',
+             inverse_of: :exploit_attempt
+
+  # @!attribute service
+  #   The service being exploited on {#host}.
+  #
+  #   @return [Mdm::Service, nil]
+  belongs_to :service,
+             class_name: 'Mdm::Service',
+             inverse_of: :exploit_attempts
+
+  # @!attribute session
+  #   The session that was established when this attempt was successful.
+  #
+  #   @return [Mdm::Session]
+  #   @return [nil] if session was not established.
+  belongs_to :session,
+             class_name: 'Mdm::Session',
+             inverse_of: :exploit_attempt
+
+  # @!attribute vuln
+  #   The vulnerability that was attempted to be exploited.
+  #
+  #   @return [Mdm::Vuln, nil]
+  belongs_to :vuln,
+             class_name: 'Mdm::Vuln',
+             inverse_of: :exploit_attempts
 
   #
   # Validations
diff --git a/app/models/mdm/exploited_host.rb b/app/models/mdm/exploited_host.rb
index b0432357..ae71e5da 100755
--- a/app/models/mdm/exploited_host.rb
+++ b/app/models/mdm/exploited_host.rb
@@ -3,8 +3,13 @@ class Mdm::ExploitedHost < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :host, :class_name => 'Mdm::Host'
-  belongs_to :service, :class_name => 'Mdm::Service'
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             inverse_of: :exploited_hosts
+
+  belongs_to :service,
+             class_name: 'Mdm::Service',
+             inverse_of: :exploited_hosts
 
   ActiveSupport.run_load_hooks(:mdm_exploited_host, self)
 end
diff --git a/app/models/mdm/host.rb b/app/models/mdm/host.rb
index 6b9b2532..a7939b1e 100755
--- a/app/models/mdm/host.rb
+++ b/app/models/mdm/host.rb
@@ -57,83 +57,122 @@ class Mdm::Host < ActiveRecord::Base
   #   Users connected to this host
   #
   #   @return [Array<Mdm::Client>]
-  has_many :clients, class_name: 'Mdm::Client', dependent: :destroy
+  has_many :clients,
+           class_name: 'Mdm::Client',
+           dependent: :destroy,
+           inverse_of: :host
+
+  # @!attribute events
+  #   Events that occurred on this host.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::Event>]
+  has_many :events,
+           class_name: 'Mdm::Event',
+           dependent: :destroy,
+           inverse_of: :host
 
   # @!attribute [rw] task_hosts
   #   Details about what Tasks touched this host
   #
   #   @return [Array<Mdm::TaskHost>]
-  has_many :task_hosts, :dependent => :destroy, :class_name => 'Mdm::TaskHost'
-
-  # @!attribute [rw] tasks
-  #   Tasks that touched this service
-  #
-  #   @return [Array<Mdm::Task>]
-  has_many :tasks, :through => :task_hosts, :class_name => 'Mdm::Task'
+  has_many :task_hosts,
+           class_name: 'Mdm::TaskHost',
+           dependent: :destroy,
+           inverse_of: :host
 
   # @!attribute [rw] exploit_attempts
   #   Attempts to run exploits against this host.
   #
   #   @return [Array<Mdm::ExploitAttempt]
   has_many :exploit_attempts,
-           :class_name => 'Mdm::ExploitAttempt',
-           :dependent => :destroy
-
-  # @!attribute [rw] exploited_hosts
-  #   @todo https://www.pivotaltracker.com/story/show/48993731
-  #   @return [Array<Mdm::ExploitedHost>]
-  has_many :exploited_hosts, :class_name => 'Mdm::ExploitedHost', :dependent => :destroy
+           class_name: 'Mdm::ExploitAttempt',
+           dependent: :destroy,
+           inverse_of: :host
+
+  # @!attribute exploited_hosts
+  #   @todo MSP-2732
+  #   @return [ActiveRecord::Relation<Mdm::ExploitedHost>]
+  has_many :exploited_hosts,
+           class_name: 'Mdm::ExploitedHost',
+           dependent: :destroy,
+           inverse_of: :host
 
   # @!attribute [rw] host_details
   #   @return [Array<Mdm::HostDetail>]
-  has_many :host_details, :class_name => 'Mdm::HostDetail', :dependent => :destroy
+  has_many :host_details,
+           class_name: 'Mdm::HostDetail',
+           dependent: :destroy,
+           inverse_of: :host
 
-  # @!attribute [rw] hosts_tags
+  # @!attribute hosts_tags
   #   A join model between {Mdm::Tag} and {Mdm::Host}.  Use {#tags} to get the actual {Mdm::Tag Mdm::Tags} on this host.
-  #   {#hosts_tags} are cleaned up in a before_destroy: {#cleanup_tags}.
   #
-  #   @todo https://www.pivotaltracker.com/story/show/48923201
-  #   @return [Array<Mdm::HostTag>]
-  has_many :hosts_tags, :class_name => 'Mdm::HostTag'
+  #   @todo MSP-2723
+  #   @return [ActiveRecord::Relation<Mdm::HostTag>]
+  has_many :hosts_tags,
+           class_name: 'Mdm::HostTag',
+           dependent: :destroy,
+           inverse_of: :host
 
-  # @!attribute [rw] loots
+  # @!attribute loots
   #   Loot gathered from the host with {Mdm::Loot#created_at newest loot} first.
   #
-  #   @todo https://www.pivotaltracker.com/story/show/48991525
-  #   @return [Array<Mdm::Loot>]
-  has_many :loots, :class_name => 'Mdm::Loot', :dependent => :destroy, :order => 'loots.created_at DESC'
+  #   @todo MSP-3065
+  #   @return [ActiveRecord::Relation<Mdm::Loot>]
+  has_many :loots,
+           class_name: 'Mdm::Loot',
+           dependent: :destroy,
+           inverse_of: :host,
+           order: 'loots.created_at DESC'
 
   # @!attribute [rw] notes
   #   Notes about the host entered by a user with {Mdm::Note#created_at oldest notes} first.
   #
   #   @return [Array<Mdm::Note>]
-  has_many :notes, :class_name => 'Mdm::Note', :dependent => :delete_all, :order => 'notes.created_at'
+  has_many :notes,
+           class_name: 'Mdm::Note',
+           inverse_of: :host,
+           dependent: :delete_all,
+           order: 'notes.created_at'
 
   # @!attribute [rw] services
   #   The services running on {Mdm::Service#port ports} on the host with services ordered by {Mdm::Service#port port}
   #   and {Mdm::Service#proto protocol}.
   #
   #   @return [Array<Mdm::Service>]
-  has_many :services, :class_name => 'Mdm::Service', :dependent => :destroy, :order => 'services.port, services.proto'
+  has_many :services,
+           class_name: 'Mdm::Service',
+           dependent: :destroy,
+           inverse_of: :host,
+           order: 'services.port, services.proto'
 
   # @!attribute [rw] sessions
   #   Sessions that are open or previously were open on the host ordered by {Mdm::Session#opened_at when the session was
   #   opened}
   #
   #   @return [Array<Mdm::Session]
-  has_many :sessions, :class_name => 'Mdm::Session', :dependent => :destroy, :order => 'sessions.opened_at'
+  has_many :sessions,
+           class_name: 'Mdm::Session',
+           dependent: :destroy,
+           inverse_of: :host,
+           order: 'sessions.opened_at'
 
   # @!attribute [rw] vulns
   #   Vulnerabilities found on the host.
   #
   #   @return [Array<Mdm::Vuln>]
-  has_many :vulns, :class_name => 'Mdm::Vuln', :dependent => :delete_all
+  has_many :vulns,
+           class_name: 'Mdm::Vuln',
+           dependent: :delete_all,
+           inverse_of: :host
 
   # @!attribute [rw] workspace
   #   The workspace in which this host was found.
   #
   #   @return [Mdm::Workspace]
-  belongs_to :workspace, :class_name => 'Mdm::Workspace'
+  belongs_to :workspace,
+             class_name: 'Mdm::Workspace',
+             inverse_of: :hosts
 
   #
   # Through host_tags
@@ -162,7 +201,10 @@ class Mdm::Host < ActiveRecord::Base
   #
   #   @return [Array<Mdm::Note>]
   #   @see #services
-  has_many :service_notes, :class_name => 'Mdm::Note', :through => :services
+  has_many :service_notes,
+           class_name: 'Mdm::Note',
+           source: :notes,
+           through: :services
 
   # @!attribute [r] web_sites
   #   {Mdm::WebSite Web sites} running on top of {#services} on this host.
@@ -171,6 +213,18 @@ class Mdm::Host < ActiveRecord::Base
   #   @see services
   has_many :web_sites, :class_name => 'Mdm::WebSite', :through => :services
 
+  #
+  # through: :task_hosts
+  #
+
+  # @!attribute tasks
+  #   Tasks that touched this service
+  #
+  #   @return [ActiveRecord::Relation<Mdm::Task>]
+  has_many :tasks,
+           class_name: 'Mdm::Task',
+           through: :task_hosts
+
 	#
 	# Through vulns
 	#
@@ -351,12 +405,6 @@ class Mdm::Host < ActiveRecord::Base
   #
   #   @return [Integer]
 
-  #
-  # Callbacks
-  #
-
-  before_destroy :cleanup_tags
-
   #
   # Nested Attributes
   # @note Must be declared after relations being referenced.
@@ -423,18 +471,6 @@ def attribute_locked?(attr)
     n && n.data[:locked]
   end
 
-  # Destroys any {Mdm::Tag Mdm::Tags} that will have no {Mdm::Tag#hosts} left after this host is deleted.
-  #
-  # @return [void]
-  def cleanup_tags
-    # No need to keep tags with no hosts
-    tags.each do |tag|
-      tag.destroy if tag.hosts == [self]
-    end
-    # Clean up association table records
-    Mdm::HostTag.delete_all("host_id = #{self.id}")
-  end
-
   # This is replicated by the IpAddressValidator class. Had to put it here as well to avoid
   # SQL errors when checking address uniqueness.
   #
diff --git a/app/models/mdm/host_detail.rb b/app/models/mdm/host_detail.rb
index f99a6b32..ce4e2336 100755
--- a/app/models/mdm/host_detail.rb
+++ b/app/models/mdm/host_detail.rb
@@ -3,7 +3,10 @@ class Mdm::HostDetail < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :host, :class_name => 'Mdm::Host', :counter_cache => :host_detail_count
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             counter_cache: :host_detail_count,
+             inverse_of: :host_details
 
   #
   # Validations
diff --git a/app/models/mdm/host_tag.rb b/app/models/mdm/host_tag.rb
index 9301885d..e02229ea 100755
--- a/app/models/mdm/host_tag.rb
+++ b/app/models/mdm/host_tag.rb
@@ -2,11 +2,49 @@ class Mdm::HostTag < ActiveRecord::Base
   self.table_name = "hosts_tags"
 
   #
-  # Relations
+  # Associations
   #
 
-  belongs_to :host, :class_name => 'Mdm::Host'
-  belongs_to :tag, :class_name => 'Mdm::Tag'
+  # @!attribute host
+  #   Host with {#tag}.
+  #
+  #   @todo MSP-2723
+  #   @return [Mdm::Host]
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             inverse_of: :hosts_tags
+
+  # @!attribute tag
+  #   Tag on {#host}.
+  #
+  #   @todo MSP-2723
+  #   @return [Mdm::Tag]
+  belongs_to :tag,
+             class_name: 'Mdm::Tag',
+             inverse_of: :hosts_tags
+
+  #
+  # Callbacks
+  #
+
+  # @see http://stackoverflow.com/a/11694704
+  after_destroy :destroy_orphan_tag
+
+  #
+  # Instance Methods
+  #
+
+  private
+
+  # Destroys {#tag} if it is orphaned
+  #
+  # @see http://stackoverflow.com/a/11694704
+  # @return [void]
+  def destroy_orphan_tag
+    tag.destroy_if_orphaned
+  end
+
+  public
 
   ActiveSupport.run_load_hooks(:mdm_host_tag, self)
 end
diff --git a/app/models/mdm/listener.rb b/app/models/mdm/listener.rb
index 9960213a..5d02e4c3 100755
--- a/app/models/mdm/listener.rb
+++ b/app/models/mdm/listener.rb
@@ -3,8 +3,13 @@ class Mdm::Listener < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :task, :class_name => 'Mdm::Task'
-  belongs_to :workspace, :class_name => 'Mdm::Workspace'
+  belongs_to :task,
+             class_name: 'Mdm::Task',
+             inverse_of: :listeners
+
+  belongs_to :workspace,
+             class_name: 'Mdm::Workspace',
+             inverse_of: :listeners
 
   #
   # Serializations
diff --git a/app/models/mdm/loot.rb b/app/models/mdm/loot.rb
index 33a4d89f..ccc48e79 100755
--- a/app/models/mdm/loot.rb
+++ b/app/models/mdm/loot.rb
@@ -16,23 +16,45 @@ class Mdm::Loot < ActiveRecord::Base
   # Associations
   #
 
+  # @!attribute exploit_attempt
+  #   Exploit attempt where this loot was gathered.
+  #
+  #   @return [Mdm::ExploitAttempt]
+  has_one :exploit_attempt,
+          class_name: 'Mdm::ExploitAttempt',
+          inverse_of: :loot
+
   # @!attribute [rw] host
   #   The host from which the loot was gathered.
   #
   #   @return [Mdm::Host]
-  belongs_to :host, :class_name => 'Mdm::Host'
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             inverse_of: :loots
 
   # @!attribute [rw] service
   #   The service running on the {#host} from which the loot was gathered.
   #
   #   @return [Mdm::Service]
-  belongs_to :service, :class_name => 'Mdm::Service'
+  belongs_to :service,
+             class_name: 'Mdm::Service',
+             inverse_of: :loots
+
+  # @!attribute vuln_attempt
+  #   Vuln attempt that gathered this loot.
+  #
+  #   @return [Mdm::VulnAttempt]
+  has_one :vuln_attempt,
+          class_name: 'Mdm::VulnAttempt',
+          inverse_of: :loot
 
   # @!attribute [rw] workspace
   #   The workspace in which the loot is stored and the {#host} exists.
   #
   #   @return [Mdm::Workspace]
-  belongs_to :workspace, :class_name => 'Mdm::Workspace'
+  belongs_to :workspace,
+             class_name: 'Mdm::Workspace',
+             inverse_of: :loots
 
   #
   # Attributes
diff --git a/app/models/mdm/nexpose_console.rb b/app/models/mdm/nexpose_console.rb
index 529f585a..46b160e2 100755
--- a/app/models/mdm/nexpose_console.rb
+++ b/app/models/mdm/nexpose_console.rb
@@ -1,4 +1,17 @@
 class Mdm::NexposeConsole < ActiveRecord::Base
+  #
+  # Associations
+  #
+
+  # @!attribute vuln_details
+  #   Details for vulnerabilities supplied by this Nexpose console.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::VulnDetail>]
+  has_many :vuln_details,
+           class_name: 'Mdm::VulnDetail',
+           foreign_key: :nx_console_id,
+           inverse_of: :nexpose_console
+
   #
   # Serializations
   #
diff --git a/app/models/mdm/note.rb b/app/models/mdm/note.rb
index 0a4aa8a2..a23f85a6 100755
--- a/app/models/mdm/note.rb
+++ b/app/models/mdm/note.rb
@@ -9,20 +9,27 @@ class Mdm::Note < ActiveRecord::Base
   #
   #   @return [Mdm::Host] if note is attached to an {Mdm::Host}.
   #   @return [nil] if note is attached to an {Mdm::Service}.
-  belongs_to :host, :class_name => 'Mdm::Host', :counter_cache => :note_count
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             counter_cache: :note_count,
+             inverse_of: :notes
 
   # @!attribute [rw] service
   #   The service to which this note is attached.
   #
   #   @return [Mdm::Service] if note is attached to an {Mdm::Service}.
   #   @return [nil] if not is attached to an {Mdm::Host}.
-  belongs_to :service, :class_name => 'Mdm::Service'
+  belongs_to :service,
+             class_name: 'Mdm::Service',
+             inverse_of: :notes
 
   # @!attribute [rw] workspace
   #   The workspace in which the {#host} or {#service} exists.
   #
   #   @return [Mdm::Workspace]
-  belongs_to :workspace, :class_name => 'Mdm::Workspace'
+  belongs_to :workspace,
+             class_name: 'Mdm::Workspace',
+             inverse_of: :notes
 
   #
   # Attributes
diff --git a/app/models/mdm/ref.rb b/app/models/mdm/ref.rb
index 289e34b5..000f10f2 100755
--- a/app/models/mdm/ref.rb
+++ b/app/models/mdm/ref.rb
@@ -18,9 +18,11 @@ class Mdm::Ref < ActiveRecord::Base
   # @!attribute [rw] vulns_refs
   #   Join model to {Mdm::Vuln Mdm::Vulns}.  Use {#vulns} to get the actual {Mdm::Vuln Mdm::Vulns}.
   #
-	#   @todo https://www.pivotaltracker.com/story/show/48915453
+	#   @todo MSP-3066
   #   @return [Array<Mdm::VulnRef>]
-  has_many :vulns_refs, :class_name => 'Mdm::VulnRef'
+  has_many :vulns_refs,
+           :class_name => 'Mdm::VulnRef',
+           inverse_of: :ref
 
   #
   # Through :vuln_refs
diff --git a/app/models/mdm/route.rb b/app/models/mdm/route.rb
index 4d13ef2f..22beabb9 100755
--- a/app/models/mdm/route.rb
+++ b/app/models/mdm/route.rb
@@ -3,7 +3,13 @@ class Mdm::Route < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :session, :class_name => 'Mdm::Session'
+  # @!attribute [rw] session
+  #   The session over which this route traverses.
+  #
+  #   @return [Mdm::Session]
+  belongs_to :session,
+             class_name: 'Mdm::Session',
+             inverse_of: :routes
 
   ActiveSupport.run_load_hooks(:mdm_route, self)
 end
diff --git a/app/models/mdm/service.rb b/app/models/mdm/service.rb
index 0a748d7e..6bccb671 100755
--- a/app/models/mdm/service.rb
+++ b/app/models/mdm/service.rb
@@ -11,52 +11,95 @@ class Mdm::Service < ActiveRecord::Base
   # Associations
   #
 
-  # @!attribute [rw] task_services
-  #   Details about what Tasks touched this service
-  #
-  #   @return [Array<Mdm::TaskService>]
-  has_many :task_services, :dependent => :destroy, :class_name => 'Mdm::TaskService'
-
-  # @!attribute [rw] tasks
-  #   Tasks that touched this service
+  # @!attribute creds
+  #   Credentials gathered from this service.
   #
-  #   @return [Array<Mdm::Task>]
-  has_many :tasks, :through => :task_services, :class_name => 'Mdm::Task'
+  #   @return [ActiveRecord::Relation<Mdm::Cred>]
+  has_many :creds,
+           class_name: 'Mdm::Cred',
+           dependent: :destroy,
+           inverse_of: :service
 
-  # @!attribute [rw] creds
-  #   Credentials gathered from this service.
+  # @!attribute exploit_attempts
+  #   Exploit attempts against this service.
   #
-  #   @return [Array<Mdm::Cred>]
-  has_many :creds, :dependent => :destroy, :class_name => 'Mdm::Cred'
+  #   @return [ActiveRecord::Relation<Mdm::ExploitAttempt>]
+  has_many :exploit_attempts,
+           class_name: 'Mdm::ExploitAttempt',
+           dependent: :destroy,
+           inverse_of: :service
 
-  # @!attribute [rw] exploited_hosts
-  #   @todo https://www.pivotaltracker.com/story/show/48993731
+  # @!attribute exploited_hosts
+  #   @todo MSP-2732
   #   @return [Array<Mdm::ExploitHost>]
-  has_many :exploited_hosts, :dependent => :destroy, :class_name => 'Mdm::ExploitedHost'
+  has_many :exploited_hosts,
+           class_name: 'Mdm::ExploitedHost',
+           dependent: :destroy,
+           inverse_of: :service
 
-  # @!attribute [rw] host
+  # @!attribute host
   #   The host on which this service runs.
   #
   #   @return [Mdm::Host]
-  belongs_to :host, :class_name => 'Mdm::Host', :counter_cache => :service_count
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             counter_cache: :service_count,
+             inverse_of: :services
 
-  # @!attribute [rw] notes
+  # @!attribute loots
+  #   Loot gathers from this service.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::Loot>]
+  has_many :loots,
+           class_name: 'Mdm::Loot',
+           dependent: :destroy,
+           inverse_of: :service
+
+  # @!attribute notes
   #   Notes about this service.
   #
-  #   @return [Array<Mdm::Note>]
-  has_many :notes, :dependent => :destroy, :class_name => 'Mdm::Note'
+  #   @return [ActiveRecord::Relation<Mdm::Note>]
+  has_many :notes,
+           class_name: 'Mdm::Note',
+           dependent: :destroy,
+           inverse_of: :service
 
-  # @!attribute [rw] vulns
+  # @!attribute [rw] task_services
+  #   Details about what Tasks touched this service
+  #
+  #   @return [Array<Mdm::TaskService>]
+  has_many :task_services,
+           class_name: 'Mdm::TaskService',
+           dependent: :destroy,
+           inverse_of: :service
+
+  # @!attribute vulns
   #   Vulnerabilities found in this service.
   #
-  #   @return [Array<Mdm::Vuln>]
-  has_many :vulns, :dependent => :destroy, :class_name => 'Mdm::Vuln'
+  #   @return [ActiveRecord::Relation<Mdm::Vuln>]
+  has_many :vulns,
+           class_name: 'Mdm::Vuln',
+           dependent: :destroy,
+           inverse_of: :service
 
-  # @!attribute [rw] web_sites
+  # @!attribute web_sites
   #   Web sites running on top of this service.
   #
-  #   @return [Array<Mdm::WebSite>]
-  has_many :web_sites, :dependent => :destroy, :class_name => 'Mdm::WebSite'
+  #   @return [ActiveRecord::Relation<Mdm::WebSite>]
+  has_many :web_sites,
+           class_name: 'Mdm::WebSite',
+           dependent: :destroy,
+           inverse_of: :service
+
+  #
+  # through: :task_services
+  #
+
+  # @!attribute [rw] tasks
+  #   Tasks that touched this service
+  #
+  #   @return [Array<Mdm::Task>]
+  has_many :tasks, :through => :task_services, :class_name => 'Mdm::Task'
 
   #
   # Through :web_sites
diff --git a/app/models/mdm/session.rb b/app/models/mdm/session.rb
index 7d778603..2a204f26 100755
--- a/app/models/mdm/session.rb
+++ b/app/models/mdm/session.rb
@@ -9,19 +9,44 @@ class Mdm::Session < ActiveRecord::Base
   #   Events that occurred when this session was open.
   #
   #   @return [Array<Mdm::Event>]
-  has_many :events, :class_name => 'Mdm::SessionEvent', :order => 'created_at', :dependent => :delete_all
+  has_many :events,
+           class_name: 'Mdm::SessionEvent',
+           dependent: :delete_all,
+           inverse_of: :session,
+           order: 'created_at'
+
+  # @!attribute exploit_attempt
+  #   Exploit attempt that created this session.
+  #
+  #   @return [Mdm::ExploitAttempt]
+  has_one :exploit_attempt,
+          class_name: 'Mdm::ExploitAttempt',
+          inverse_of: :session
 
   # @!attribute [rw] host
   #   {Mdm::Host Host} on which this session was opened.
   #
   #   @return [Mdm::Host]
-  belongs_to :host, :class_name => 'Mdm::Host'
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             inverse_of: :sessions
 
   # @!attribute [rw] routes
   #   Routes tunneled throug this session.
   #
   #   @return [Array<Mdm::Route>]
-  has_many :routes, :class_name => 'Mdm::Route', :dependent => :delete_all
+  has_many :routes,
+           class_name: 'Mdm::Route',
+           dependent: :delete_all,
+           inverse_of: :session
+
+  # @!attribute vuln_attempt
+  #   Vulnerability attempt that created this session.
+  #
+  #   @return [Mdm::VulnAttempt]
+  has_one :vuln_attempt,
+          class_name: 'Mdm::VulnAttempt',
+          inverse_of: :session
 
   #
   # Through :host
diff --git a/app/models/mdm/session_event.rb b/app/models/mdm/session_event.rb
index 99cadd22..40de569c 100755
--- a/app/models/mdm/session_event.rb
+++ b/app/models/mdm/session_event.rb
@@ -3,7 +3,9 @@ class Mdm::SessionEvent < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :session, :class_name => 'Mdm::Session'
+  belongs_to :session,
+             class_name: 'Mdm::Session',
+             inverse_of: :events
 
   ActiveSupport.run_load_hooks(:mdm_session_event, self)
 end
diff --git a/app/models/mdm/tag.rb b/app/models/mdm/tag.rb
index 5f61c4da..5f556857 100755
--- a/app/models/mdm/tag.rb
+++ b/app/models/mdm/tag.rb
@@ -1,20 +1,29 @@
 class Mdm::Tag < ActiveRecord::Base
   #
-  # Callbacks
+  # Relations
   #
 
-  before_destroy :cleanup_hosts
-
-  #
-  # Relations
+  # @!attribute hosts_tags
+  #  Joins {#hosts} to this tag.
   #
+  #  @return [ActiveRecord::Relation<Mdm::HostTag>]
+  has_many :hosts_tags,
+           class_name: 'Mdm::HostTag',
+           dependent: :destroy,
+           inverse_of: :tag
 
-  has_many :hosts_tags, :class_name => 'Mdm::HostTag'
-  belongs_to :user, :class_name => 'Mdm::User'
+  belongs_to :user,
+             class_name: 'Mdm::User',
+             inverse_of: :tags
 
   #
   # Through :hosts_tags
   #
+
+  # @!attribute [r] hosts
+  #   Host that are tagged with this tag.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::Host>]
   has_many :hosts, :through => :hosts_tags, :class_name => 'Mdm::Host'
 
 
@@ -33,9 +42,19 @@ class Mdm::Tag < ActiveRecord::Base
             },
             :presence => true
 
-  def cleanup_hosts
-    # Clean up association table records
-    Mdm::HostTag.delete_all("tag_id = #{self.id}")
+  #
+  # Instance Methods
+  #
+
+  # Destroy this tag if it has no {#hosts_tags}
+  #
+  # @return [void]
+  def destroy_if_orphaned
+    self.class.transaction do
+      if hosts_tags.empty?
+        destroy
+      end
+    end
   end
 
   def to_s
diff --git a/app/models/mdm/task.rb b/app/models/mdm/task.rb
index d8860821..9015329d 100755
--- a/app/models/mdm/task.rb
+++ b/app/models/mdm/task.rb
@@ -9,17 +9,62 @@ class Mdm::Task < ActiveRecord::Base
   # Relations
   #
 
+  # @!attribute listeners
+  #   Listeners spawned by this task
+  #
+  #   @return [ActiveRecord::Relation<Mdm::Listener>]
+  has_many :listeners,
+           class_name: 'Mdm::Listener',
+           dependent: :destroy,
+           inverse_of: :task
+
+  # @!attribute [rw] task_creds
+  #   Joins this to {#creds}.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::TaskCred>]
+  has_many :task_creds,
+           class_name: 'Mdm::TaskCred',
+           dependent: :destroy,
+           inverse_of: :task
+
+  # @!attribute task_hosts
+  #   Joins this to {#hosts}.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::TaskHost>]
+  has_many :task_hosts,
+           class_name: 'Mdm::TaskHost',
+           dependent: :destroy,
+           inverse_of: :task
+
+  # @!attribute task_services
+  #   Joins this to {#services}.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::TaskService>]
+  has_many :task_services,
+           class_name: 'Mdm::TaskService',
+           dependent: :destroy,
+           inverse_of: :task
+
+  # @!attribute task_sessions
+  #   Joins this to {#sessions}.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::TaskSession>]
+  has_many :task_sessions,
+           class_name: 'Mdm::TaskSession',
+           dependent: :destroy,
+           inverse_of: :task
+
   # @!attribute [rw] workspace
   #   The Workspace the Task belongs to
   #
   #   @return [Mdm::Workspace]
-  belongs_to :workspace,  :class_name => "Mdm::Workspace"
+  belongs_to :workspace,
+             class_name: 'Mdm::Workspace',
+             inverse_of: :tasks
 
-  # @!attribute [rw] task_creds
-  #   Details about creds this task touched
   #
-  #   @return [Array<Mdm::TaskCred>]
-  has_many :task_creds, :dependent => :destroy, :class_name => 'Mdm::TaskCred'
+  # through: :task_creds
+  #
 
   # @!attribute [rw] creds
   #   Creds this task touched
@@ -27,11 +72,9 @@ class Mdm::Task < ActiveRecord::Base
   #   @return [Array<Mdm::Cred>]
   has_many :creds, :through => :task_creds, :class_name => 'Mdm::Cred'
 
-  # @!attribute [rw] task_hosts
-  #   Details about hosts this task touched
   #
-  #   @return [Array<Mdm::TaskHost>]
-  has_many :task_hosts, :dependent => :destroy, :class_name => 'Mdm::TaskHost'
+  # through: :task_hosts
+  #
 
   # @!attribute [rw] hosts
   #   Hosts this task touched
@@ -39,11 +82,9 @@ class Mdm::Task < ActiveRecord::Base
   #   @return [Array<Mdm::Host>
   has_many :hosts, :through => :task_hosts, :class_name => 'Mdm::Host'
 
-  # @!attribute [rw] task_services
-  #   Details about services this task touched
   #
-  #   @return [Array<Mdm::TaskService>]
-  has_many :task_services, :dependent => :destroy, :class_name => 'Mdm::TaskService'
+  # through: :task_services
+  #
 
   # @!attribute [rw] services
   #   Services this task touched
@@ -51,11 +92,9 @@ class Mdm::Task < ActiveRecord::Base
   #   @return [Array<Mdm::Service>
   has_many :services, :through => :task_services, :class_name => 'Mdm::Service'
 
-  # @!attribute [rw] task_sessions
-  #   Details about sessions this task touched
   #
-  #   @return [Array<Mdm::TaskSession>]
-  has_many :task_sessions, :dependent => :destroy, :class_name => 'Mdm::TaskSession'
+  # through: :task_sessions
+  #
 
   # @!attribute [rw] sessions
   #   Session this task touched
diff --git a/app/models/mdm/task_cred.rb b/app/models/mdm/task_cred.rb
index 9517ca5e..00e5012f 100644
--- a/app/models/mdm/task_cred.rb
+++ b/app/models/mdm/task_cred.rb
@@ -1,7 +1,11 @@
 class Mdm::TaskCred < ActiveRecord::Base
-  # attr_accessible :title, :body
-  belongs_to :cred, :class_name => 'Mdm::Cred'
-  belongs_to :task, :class_name =>  'Mdm::Task'
+  belongs_to :cred,
+             class_name: 'Mdm::Cred',
+             inverse_of: :task_creds
+
+  belongs_to :task,
+             class_name: 'Mdm::Task',
+             inverse_of: :task_creds
 
   validates :cred_id,
             :uniqueness => {
diff --git a/app/models/mdm/task_host.rb b/app/models/mdm/task_host.rb
index dc3ce165..dabd0ff4 100644
--- a/app/models/mdm/task_host.rb
+++ b/app/models/mdm/task_host.rb
@@ -1,7 +1,11 @@
 class Mdm::TaskHost < ActiveRecord::Base
-  # attr_accessible :title, :body
-  belongs_to :host, :class_name => 'Mdm::Host'
-  belongs_to :task, :class_name =>  'Mdm::Task'
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             inverse_of: :task_hosts
+
+  belongs_to :task,
+             class_name: 'Mdm::Task',
+             inverse_of: :task_hosts
 
   validates :host_id,
             :uniqueness => {
diff --git a/app/models/mdm/task_service.rb b/app/models/mdm/task_service.rb
index fda5a071..8c46dc49 100644
--- a/app/models/mdm/task_service.rb
+++ b/app/models/mdm/task_service.rb
@@ -1,7 +1,11 @@
 class Mdm::TaskService < ActiveRecord::Base
-  # attr_accessible :title, :body
-  belongs_to :service, :class_name => 'Mdm::Service'
-  belongs_to :task, :class_name =>  'Mdm::Task'
+  belongs_to :service,
+             class_name: 'Mdm::Service',
+             inverse_of: :task_services
+
+  belongs_to :task,
+             class_name: 'Mdm::Task',
+             inverse_of: :task_services
 
   validates :service_id,
             :uniqueness => {
diff --git a/app/models/mdm/task_session.rb b/app/models/mdm/task_session.rb
index 89152d1b..2b3a3995 100644
--- a/app/models/mdm/task_session.rb
+++ b/app/models/mdm/task_session.rb
@@ -1,6 +1,11 @@
 class Mdm::TaskSession < ActiveRecord::Base
-  belongs_to :session, :class_name => 'Mdm::Session'
-  belongs_to :task, :class_name =>  'Mdm::Task'
+  belongs_to :session,
+             class_name: 'Mdm::Session',
+             inverse_of: :task_sessions
+
+  belongs_to :task,
+             class_name: 'Mdm::Task',
+             inverse_of: :task_sessions
 
   validates :session_id,
             :uniqueness => {
diff --git a/app/models/mdm/user.rb b/app/models/mdm/user.rb
index c727f850..e4b7ee82 100755
--- a/app/models/mdm/user.rb
+++ b/app/models/mdm/user.rb
@@ -5,8 +5,15 @@ class Mdm::User < ActiveRecord::Base
   # Relations
   #
 
-  has_many :owned_workspaces, :foreign_key => 'owner_id', :class_name => 'Mdm::Workspace'
-  has_many :tags, :class_name => 'Mdm::Tag'
+  has_many :owned_workspaces,
+           class_name: 'Mdm::Workspace',
+           foreign_key: 'owner_id',
+           inverse_of: :owner
+
+  has_many :tags,
+           class_name: 'Mdm::Tag',
+           inverse_of: :user
+
   has_and_belongs_to_many :workspaces, :join_table => 'workspace_members', :uniq => true, :class_name => 'Mdm::Workspace'
 
   #
diff --git a/app/models/mdm/vuln.rb b/app/models/mdm/vuln.rb
index e82b45bc..3720c4a8 100755
--- a/app/models/mdm/vuln.rb
+++ b/app/models/mdm/vuln.rb
@@ -4,36 +4,57 @@ class Mdm::Vuln < ActiveRecord::Base
   # Associations
   #
 
+  # @!attribute exploit_attempts
+  #   Attempts to exploit this vulnerability.
+  #
+  #   @return [ActiveRecord::Relation<Mdm::ExploitAttempt>]
+  has_many :exploit_attempts,
+           class_name: 'Mdm::ExploitAttempt',
+           inverse_of: :vuln
+
   # @!attribute [rw] host
   #   The host with this vulnerability.
   #
   #   @return [Mdm::Host]
-  belongs_to :host, :class_name => 'Mdm::Host', :counter_cache => :vuln_count
+  belongs_to :host,
+             class_name: 'Mdm::Host',
+             counter_cache: :vuln_count,
+             inverse_of: :vulns
 
   # @!attribute [rw] service
   #   The service with the vulnerability.
   #
   #   @return [Mdm::Service]
-  belongs_to :service, :class_name => 'Mdm::Service'
+  belongs_to :service,
+             class_name: 'Mdm::Service',
+             inverse_of: :vulns
 
   # @!attribute [rw] vuln_attempts
   #   Attempts to exploit this vulnerability.
   #
   #   @return [Array<Mdm::VulnAttempt>]
-  has_many :vuln_attempts, :class_name => 'Mdm::VulnAttempt', :dependent => :destroy
+  has_many :vuln_attempts,
+           class_name: 'Mdm::VulnAttempt',
+           dependent: :destroy,
+           inverse_of: :vuln
 
   # @!attribute [rw] vuln_details
   #   Additional information about this vulnerability.
   #
   #   @return [Array<Mdm::VulnDetail>]
-  has_many :vuln_details, :class_name => 'Mdm::VulnDetail', :dependent => :destroy
+  has_many :vuln_details,
+           class_name: 'Mdm::VulnDetail',
+           dependent: :destroy,
+           inverse_of: :vuln
 
   # @!attribute [rw] vulns_refs
   #   Join model that joins this vuln to its {Mdm::Ref external references}.
   #
-  #   @todo https://www.pivotaltracker.com/story/show/49004623
   #   @return [Array<Mdm::VulnRef>]
-  has_many :vulns_refs, :class_name => 'Mdm::VulnRef', :dependent => :destroy
+  has_many :vulns_refs,
+           class_name: 'Mdm::VulnRef',
+           dependent: :destroy,
+           inverse_of: :vuln
 
   #
   # Through :vuln_refs
@@ -42,7 +63,6 @@ class Mdm::Vuln < ActiveRecord::Base
   # @!attribute [r] refs
   #   External references to this vulnerability.
   #
-  #   @todo https://www.pivotaltracker.com/story/show/49004623
   #   @return [Array<Mdm::Ref>]
   has_many :refs, :class_name => 'Mdm::Ref', :through => :vulns_refs
 
diff --git a/app/models/mdm/vuln_attempt.rb b/app/models/mdm/vuln_attempt.rb
index 7d258271..ce0b426f 100755
--- a/app/models/mdm/vuln_attempt.rb
+++ b/app/models/mdm/vuln_attempt.rb
@@ -1,9 +1,44 @@
 class Mdm::VulnAttempt < ActiveRecord::Base
   #
-  # Relations
+  # Associations
   #
 
-  belongs_to :vuln, :class_name => 'Mdm::Vuln', :counter_cache => :vuln_attempt_count
+  # @!attribute loot
+  #   Loot gathered from this attempt.
+  #
+  #   @return [Mdm::Loot] if {#exploited} is `true`.
+  #   @return [nil] if {#exploited} is `false`.
+  belongs_to :loot,
+             class_name: 'Mdm::Loot',
+             inverse_of: :vuln_attempt
+
+  # @!attribute session
+  #   The session opened by this attempt.
+  #
+  #   @return [Mdm::Session] if {#exploited} is `true`.
+  #   @return [nil] if {#exploited} is `false`.
+  belongs_to :session,
+             class_name: 'Mdm::Session',
+             inverse_of: :vuln_attempt
+
+  # @!attribute vuln
+  #   The {Mdm::Vuln vulnerability} that this attempt was exploiting.
+  #
+  #   @return [Mdm::Vuln]
+  belongs_to :vuln,
+             class_name: 'Mdm::Vuln',
+             counter_cache: :vuln_attempt_count,
+             inverse_of: :vuln_attempts
+
+  #
+  # Attributes
+  #
+
+  # @!attribute [rw] exploited
+  #   Whether this attempt was successful.
+  #
+  #   @return [true] if {#vuln} was exploited.
+  #   @return [false] if {#vuln} was not exploited.
 
   #
   # Validations
diff --git a/app/models/mdm/vuln_detail.rb b/app/models/mdm/vuln_detail.rb
index d0386728..3cc46c5a 100755
--- a/app/models/mdm/vuln_detail.rb
+++ b/app/models/mdm/vuln_detail.rb
@@ -2,7 +2,15 @@ class Mdm::VulnDetail < ActiveRecord::Base
   #
   # Relations
   #
-  belongs_to :vuln, :class_name => 'Mdm::Vuln', :counter_cache => :vuln_detail_count
+
+  belongs_to :nexpose_console,
+             class_name: 'Mdm::NexposeConsole',
+             inverse_of: :vuln_details
+
+  belongs_to :vuln,
+             class_name: 'Mdm::Vuln',
+             counter_cache: :vuln_detail_count,
+             inverse_of: :vuln_details
 
   #
   # Validations
diff --git a/app/models/mdm/vuln_ref.rb b/app/models/mdm/vuln_ref.rb
index f11f9b62..217741d5 100644
--- a/app/models/mdm/vuln_ref.rb
+++ b/app/models/mdm/vuln_ref.rb
@@ -5,8 +5,13 @@ class Mdm::VulnRef < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :ref, :class_name => 'Mdm::Ref'
-  belongs_to :vuln, :class_name => 'Mdm::Vuln'
+  belongs_to :ref,
+             class_name: 'Mdm::Ref',
+             inverse_of: :vulns_refs
+
+  belongs_to :vuln,
+             class_name: 'Mdm::Vuln',
+             inverse_of: :vulns_refs
 
   ActiveSupport.run_load_hooks(:mdm_vuln_ref, self)
 end
diff --git a/app/models/mdm/web_form.rb b/app/models/mdm/web_form.rb
index 5d8ac12e..41e07461 100755
--- a/app/models/mdm/web_form.rb
+++ b/app/models/mdm/web_form.rb
@@ -3,7 +3,9 @@ class Mdm::WebForm < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :web_site, :class_name => 'Mdm::WebSite'
+  belongs_to :web_site,
+             class_name: 'Mdm::WebSite',
+             inverse_of: :web_forms
 
   #
   # Serializations
diff --git a/app/models/mdm/web_page.rb b/app/models/mdm/web_page.rb
index 538e2b0e..e8169e36 100755
--- a/app/models/mdm/web_page.rb
+++ b/app/models/mdm/web_page.rb
@@ -3,7 +3,9 @@ class Mdm::WebPage < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :web_site, :class_name => 'Mdm::WebSite'
+  belongs_to :web_site,
+             class_name: 'Mdm::WebSite',
+             inverse_of: :web_pages
 
   #
   # Serializations
diff --git a/app/models/mdm/web_site.rb b/app/models/mdm/web_site.rb
index a99750ae..9967a009 100755
--- a/app/models/mdm/web_site.rb
+++ b/app/models/mdm/web_site.rb
@@ -3,10 +3,25 @@ class Mdm::WebSite < ActiveRecord::Base
   # Relations
   #
 
-  belongs_to :service, :class_name => 'Mdm::Service', :foreign_key => 'service_id'
-  has_many :web_forms, :dependent => :destroy, :class_name => 'Mdm::WebForm'
-  has_many :web_pages, :dependent => :destroy, :class_name => 'Mdm::WebPage'
-  has_many :web_vulns, :dependent => :destroy, :class_name => 'Mdm::WebVuln'
+  belongs_to :service,
+             class_name: 'Mdm::Service',
+             foreign_key: 'service_id',
+             inverse_of: :web_sites
+
+  has_many :web_forms,
+           class_name: 'Mdm::WebForm',
+           dependent: :destroy,
+           inverse_of: :web_site
+
+  has_many :web_pages,
+           class_name: 'Mdm::WebPage',
+           dependent: :destroy,
+           inverse_of: :web_site
+
+  has_many :web_vulns,
+           class_name: 'Mdm::WebVuln',
+           dependent: :destroy,
+           inverse_of: :web_site
 
   #
   # Serializations
diff --git a/app/models/mdm/web_vuln.rb b/app/models/mdm/web_vuln.rb
index 6695f192..206698e2 100755
--- a/app/models/mdm/web_vuln.rb
+++ b/app/models/mdm/web_vuln.rb
@@ -36,7 +36,9 @@ class Mdm::WebVuln < ActiveRecord::Base
   # Associations
   #
 
-  belongs_to :web_site, :class_name => 'Mdm::WebSite'
+  belongs_to :web_site,
+             class_name: 'Mdm::WebSite',
+             inverse_of: :web_vulns
 
   #
   # Attributes
diff --git a/lib/tasks/yard.rake b/lib/tasks/yard.rake
index fc535703..675de5e1 100644
--- a/lib/tasks/yard.rake
+++ b/lib/tasks/yard.rake
@@ -12,6 +12,9 @@ if defined? YARD
       }
     end
 
+    # need environment so that yard templates can load ActiveRecord::Base subclasses for Entity-Relationship Diagrams
+    task :doc => :eager_load
+
     desc "Shows stats for YARD Documentation including listing undocumented modules, classes, constants, and methods"
     task :stats => :environment do
       stats = YARD::CLI::Stats.new
@@ -23,4 +26,8 @@ if defined? YARD
   desc "Generate YARD documentation"
   # allow calling namespace to as a task that goes to default task for namespace
   task :yard => ['yard:doc']
+end
+
+task eager_load: :environment do
+  Rails.application.eager_load!
 end
\ No newline at end of file
diff --git a/metasploit_data_models.gemspec b/metasploit_data_models.gemspec
index 4d53e193..71fa7d27 100644
--- a/metasploit_data_models.gemspec
+++ b/metasploit_data_models.gemspec
@@ -34,7 +34,9 @@ Gem::Specification.new do |s|
   # debugging
   s.add_development_dependency 'pry'
 
-  s.add_runtime_dependency 'activerecord', '>= 3.2.13'
+  # restrict from rails 4.0 as it requires protected_attributes gem and other changes for compatibility
+  # @see MSP-2971
+  s.add_runtime_dependency 'activerecord', '>= 3.2.13', '< 4.0.0'
   s.add_runtime_dependency 'activesupport'
   
   if RUBY_PLATFORM =~ /java/
diff --git a/spec/app/models/mdm/host_spec.rb b/spec/app/models/mdm/host_spec.rb
index f259e70e..2da2f34d 100644
--- a/spec/app/models/mdm/host_spec.rb
+++ b/spec/app/models/mdm/host_spec.rb
@@ -202,73 +202,6 @@
     it { should belong_to(:workspace).class_name('Mdm::Workspace') }
 	end
 
-	context 'callbacks' do
-    context 'before destroy' do
-      context 'cleanup_tags' do
-        context 'with tags' do
-          let!(:tag) do
-            FactoryGirl.create(:mdm_tag)
-          end
-
-          let!(:host) do
-            FactoryGirl.create(:mdm_host)
-          end
-
-          context 'with only this host' do
-            before(:each) do
-              FactoryGirl.create(
-                  :mdm_host_tag,
-                  :host => host,
-                  :tag => tag
-              )
-            end
-
-            it 'should destroy the tags' do
-              expect {
-                host.destroy
-              }.to change(Mdm::Tag, :count).by(-1)
-            end
-
-            it 'should destroy the host tags' do
-              expect {
-                host.destroy
-              }.to change(Mdm::HostTag, :count).by(-1)
-            end
-          end
-
-          context 'with additional hosts' do
-            let(:other_host) do
-              FactoryGirl.create(:mdm_host)
-            end
-
-            before(:each) do
-              FactoryGirl.create(:mdm_host_tag, :host => host, :tag => tag)
-              FactoryGirl.create(:mdm_host_tag, :host => other_host, :tag => tag)
-            end
-
-            it 'should not destroy the tag' do
-              expect {
-                host.destroy
-              }.to_not change(Mdm::Tag, :count)
-            end
-
-            it 'should destroy the host tags' do
-              expect {
-                host.destroy
-              }.to change(Mdm::HostTag, :count).by(-1)
-            end
-
-            it "should not destroy the other host's tags" do
-              host.destroy
-
-              other_host.hosts_tags.count.should == 1
-            end
-          end
-        end
-      end
-    end
-	end
-
 	context 'CONSTANTS' do
     context 'ARCHITECTURES' do
       subject(:architectures) do
diff --git a/spec/app/models/mdm/host_tag_spec.rb b/spec/app/models/mdm/host_tag_spec.rb
index dd6445c6..6f894b26 100644
--- a/spec/app/models/mdm/host_tag_spec.rb
+++ b/spec/app/models/mdm/host_tag_spec.rb
@@ -25,15 +25,46 @@
   end
 
   context '#destroy' do
-    it 'should successfully destroy the object' do
-      host_tag = FactoryGirl.create(:mdm_host_tag)
+    let(:tag) do
+      FactoryGirl.create(
+          :mdm_tag
+      )
+    end
+
+    let!(:host_tag) do
+      FactoryGirl.create(
+          :mdm_host_tag,
+          :tag => tag
+      )
+    end
+
+    it 'should delete 1 Mdm::HostTag' do
       expect {
         host_tag.destroy
-      }.to_not raise_error
-      expect {
-        host_tag.reload
-      }.to raise_error(ActiveRecord::RecordNotFound)
+      }.to change(Mdm::HostTag, :count).by(-1)
+    end
+
+    context 'with multiple Mdm::HostTags using same Mdm::Tag' do
+      let!(:other_host_tag) do
+        FactoryGirl.create(
+            :mdm_host_tag,
+            :tag => tag
+        )
+      end
+
+      it 'should not delete Mdm::Tag' do
+        expect {
+          host_tag.destroy
+        }.to_not change(Mdm::Tag, :count)
+      end
     end
-  end
 
+    context 'with only one Mdm::HostTag using Mdm::Tag' do
+      it 'should delete Mdm::Tag' do
+        expect {
+          host_tag.destroy
+        }.to change(Mdm::Tag, :count).by(-1)
+      end
+    end
+  end
 end
\ No newline at end of file
diff --git a/spec/app/models/mdm/tag_spec.rb b/spec/app/models/mdm/tag_spec.rb
index 04d886de..8f45f37d 100644
--- a/spec/app/models/mdm/tag_spec.rb
+++ b/spec/app/models/mdm/tag_spec.rb
@@ -66,23 +66,6 @@
     end
   end
 
-  context 'callbacks' do
-    context 'before_destroy' do
-      it 'should call #cleanup_hosts' do
-        mytag = FactoryGirl.create(:mdm_tag)
-        mytag.should_receive(:cleanup_hosts)
-        mytag.destroy
-      end
-
-      it 'should destroy the host_tag joins' do
-        mytag = FactoryGirl.create(:mdm_tag)
-        FactoryGirl.create(:mdm_host_tag, :tag => mytag)
-        Mdm::HostTag.should_receive(:delete_all).with("tag_id = #{mytag.id}")
-        mytag.destroy
-      end
-    end
-  end
-
   context 'instance methods' do
     context '#to_s' do
       it 'should return the name of the tag as a string' do
@@ -103,15 +86,14 @@
   end
 
   context '#destroy' do
+    let!(:tag) do
+      FactoryGirl.create(:mdm_tag)
+    end
+
     it 'should successfully destroy the object' do
-      tag = FactoryGirl.create(:mdm_tag)
       expect {
         tag.destroy
-      }.to_not raise_error
-      expect {
-        tag.reload
-      }.to raise_error(ActiveRecord::RecordNotFound)
+      }.to change(Mdm::Tag, :count).by(-1)
     end
   end
-
 end
\ No newline at end of file