add agent capacity support

app/controllers/api/v1/accounts/assignment_policies_controller.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+class Api::V1::Accounts::AssignmentPoliciesController < Api::V1::Accounts::BaseController
+  before_action :fetch_assignment_policy, only: [:show, :update, :destroy]
+  before_action :check_authorization
+
+  def index
+    @assignment_policies = Current.account.assignment_policies.includes(:inboxes)
+    render json: { assignment_policies: serialize_assignment_policies(@assignment_policies) }
+  end
+
+  def show
+    render json: { assignment_policy: serialize_assignment_policy(@assignment_policy) }
+  end
+
+  def create
+    @assignment_policy = Current.account.assignment_policies.build(assignment_policy_params)
+
+    if @assignment_policy.save
+      render json: { assignment_policy: serialize_assignment_policy(@assignment_policy) }, status: :created
+    else
+      render json: { errors: @assignment_policy.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  def update
+    if @assignment_policy.update(assignment_policy_params)
+      render json: { assignment_policy: serialize_assignment_policy(@assignment_policy) }
+    else
+      render json: { errors: @assignment_policy.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  def destroy
+    if @assignment_policy.destroy
+      head :ok
+    else
+      render json: { errors: @assignment_policy.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  private
+
+  def fetch_assignment_policy
+    @assignment_policy = Current.account.assignment_policies.find(params[:id])
+  end
+
+  def assignment_policy_params
+    params.require(:assignment_policy).permit(
+      :name, :description, :assignment_order, :conversation_priority,
+      :fair_distribution_limit, :fair_distribution_window, :enabled
+    )
+  end
+
+  def serialize_assignment_policy(policy)
+    {
+      id: policy.id,
+      name: policy.name,
+      description: policy.description,
+      assignment_order: policy.assignment_order,
+      conversation_priority: policy.conversation_priority,
+      fair_distribution_limit: policy.fair_distribution_limit,
+      fair_distribution_window: policy.fair_distribution_window,
+      enabled: policy.enabled,
+      inbox_count: policy.inboxes.count,
+      inboxes: policy.inboxes.map { |inbox| { id: inbox.id, name: inbox.name } },
+      created_at: policy.created_at,
+      updated_at: policy.updated_at
+    }
+  end
+
+  def serialize_assignment_policies(policies)
+    policies.map { |policy| serialize_assignment_policy(policy) }
+  end
+
+  def check_authorization
+    authorize(AssignmentPolicy)
+  end
+end

app/controllers/api/v1/accounts/inbox_assignment_policies_controller.rb

@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+class Api::V1::Accounts::InboxAssignmentPoliciesController < Api::V1::Accounts::BaseController
+  before_action :fetch_inbox
+  before_action :check_authorization
+
+  def show
+    @inbox_assignment_policy = @inbox.inbox_assignment_policy
+
+    if @inbox_assignment_policy
+      render json: {
+        inbox_assignment_policy: serialize_inbox_assignment_policy(@inbox_assignment_policy)
+      }
+    else
+      render json: {
+        inbox_assignment_policy: nil,
+        message: 'No assignment policy assigned to this inbox'
+      }
+    end
+  end
+
+  def create
+    # Remove existing assignment if any
+    @inbox.inbox_assignment_policy&.destroy
+
+    @assignment_policy = Current.account.assignment_policies.find(params[:assignment_policy_id])
+    @inbox_assignment_policy = @inbox.build_inbox_assignment_policy(assignment_policy: @assignment_policy)
+
+    if @inbox_assignment_policy.save
+      render json: {
+        inbox_assignment_policy: serialize_inbox_assignment_policy(@inbox_assignment_policy)
+      }, status: :created
+    else
+      render json: { errors: @inbox_assignment_policy.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  def destroy
+    @inbox_assignment_policy = @inbox.inbox_assignment_policy
+
+    if @inbox_assignment_policy
+      if @inbox_assignment_policy.destroy
+        head :ok
+      else
+        render json: { errors: @inbox_assignment_policy.errors.full_messages }, status: :unprocessable_entity
+      end
+    else
+      render json: { error: 'No assignment policy found for this inbox' }, status: :not_found
+    end
+  end
+
+  private
+
+  def fetch_inbox
+    @inbox = Current.account.inboxes.find(params[:inbox_id])
+  end
+
+  def check_authorization
+    authorize(@inbox, :update?)
+  end
+
+  def serialize_inbox_assignment_policy(inbox_assignment_policy)
+    {
+      id: inbox_assignment_policy.id,
+      inbox_id: inbox_assignment_policy.inbox_id,
+      assignment_policy_id: inbox_assignment_policy.assignment_policy_id,
+      assignment_policy: {
+        id: inbox_assignment_policy.assignment_policy.id,
+        name: inbox_assignment_policy.assignment_policy.name,
+        description: inbox_assignment_policy.assignment_policy.description,
+        assignment_order: inbox_assignment_policy.assignment_policy.assignment_order,
+        conversation_priority: inbox_assignment_policy.assignment_policy.conversation_priority,
+        fair_distribution_limit: inbox_assignment_policy.assignment_policy.fair_distribution_limit,
+        fair_distribution_window: inbox_assignment_policy.assignment_policy.fair_distribution_window,
+        enabled: inbox_assignment_policy.assignment_policy.enabled
+      },
+      created_at: inbox_assignment_policy.created_at,
+      updated_at: inbox_assignment_policy.updated_at
+    }
+  end
+end

app/jobs/assignment_v2/assignment_job.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+class AssignmentV2::AssignmentJob < ApplicationJob
+  queue_as :low
+
+  def perform(inbox_id: nil, conversation_id: nil)
+    if conversation_id
+      assign_single_conversation(conversation_id)
+    elsif inbox_id
+      assign_inbox_conversations(inbox_id)
+    else
+      Rails.logger.error 'AssignmentV2::AssignmentJob: No inbox_id or conversation_id provided'
+    end
+  end
+
+  private
+
+  def assign_single_conversation(conversation_id)
+    conversation = Conversation.find_by(id: conversation_id)
+    return unless conversation
+
+    service = AssignmentV2::AssignmentService.new(inbox: conversation.inbox)
+    service.perform_for_conversation(conversation)
+  end
+
+  def assign_inbox_conversations(inbox_id)
+    inbox = Inbox.find_by(id: inbox_id)
+    return unless inbox
+    return unless inbox.assignment_v2_enabled?
+
+    service = AssignmentV2::AssignmentService.new(inbox: inbox)
+    assigned_count = service.perform_bulk_assignment
+
+    Rails.logger.info "AssignmentV2::AssignmentJob: Assigned #{assigned_count} conversations for inbox #{inbox_id}"
+  end
+end

app/models/account.rb

@@ -61,6 +61,7 @@ class Account < ApplicationRecord
   has_many :agent_bots, dependent: :destroy_async
   has_many :api_channels, dependent: :destroy_async, class_name: '::Channel::Api'
   has_many :articles, dependent: :destroy_async, class_name: '::Article'
+  has_many :assignment_policies, dependent: :destroy_async
   has_many :automation_rules, dependent: :destroy_async
   has_many :macros, dependent: :destroy_async
   has_many :campaigns, dependent: :destroy_async

app/models/assignment_policy.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: assignment_policies
+#
+#  id                       :bigint           not null, primary key
+#  assignment_order         :integer          default("round_robin"), not null
+#  conversation_priority    :integer          default("earliest_created"), not null
+#  description              :text
+#  enabled                  :boolean          default(TRUE), not null
+#  fair_distribution_limit  :integer          default(100), not null
+#  fair_distribution_window :integer          default(3600), not null
+#  name                     :string(255)      not null
+#  created_at               :datetime         not null
+#  updated_at               :datetime         not null
+#  account_id               :bigint           not null
+#
+# Indexes
+#
+#  index_assignment_policies_on_account_id           (account_id)
+#  index_assignment_policies_on_account_id_and_name  (account_id,name) UNIQUE
+#  index_assignment_policies_on_enabled              (enabled)
+#
+
+class AssignmentPolicy < ApplicationRecord
+  # Enums
+  enum assignment_order: { round_robin: 0 }
+  enum conversation_priority: { earliest_created: 0, longest_waiting: 1 }
+
+  # Associations
+  belongs_to :account
+  has_many :inbox_assignment_policies, dependent: :destroy
+  has_many :inboxes, through: :inbox_assignment_policies
+
+  # Validations
+  validates :name, presence: true, uniqueness: { scope: :account_id }
+  validates :name, length: { maximum: 255 }
+  validates :description, length: { maximum: 1000 }
+  validates :fair_distribution_limit, presence: true, numericality: { greater_than: 0, less_than_or_equal_to: 100 }
+  validates :fair_distribution_window, presence: true, numericality: { greater_than: 60, less_than_or_equal_to: 86_400 }
+  validates :assignment_order, inclusion: { in: assignment_orders.keys }
+  validates :conversation_priority, inclusion: { in: conversation_priorities.keys }
+
+  def webhook_data
+    {
+      id: id,
+      name: name,
+      description: description,
+      assignment_order: assignment_order,
+      conversation_priority: conversation_priority,
+      fair_distribution_limit: fair_distribution_limit,
+      fair_distribution_window: fair_distribution_window,
+      enabled: enabled
+    }
+  end
+end
+
+AssignmentPolicy.prepend_mod_with('AssignmentPolicy')

app/models/concerns/auto_assignment_handler.rb

@@ -14,11 +14,18 @@ module AutoAssignmentHandler
     return unless conversation_status_changed_to_open?
     return unless should_run_auto_assignment?
 
-    ::AutoAssignment::AgentAssignmentService.new(conversation: self, allowed_agent_ids: inbox.member_ids_with_assignment_capacity).perform
+    if inbox.assignment_v2_enabled?
+      # Use Assignment V2 system
+      AssignmentV2::AssignmentJob.perform_later(conversation_id: id)
+    else
+      # Use legacy assignment system
+      ::AutoAssignment::AgentAssignmentService.new(conversation: self, allowed_agent_ids: inbox.member_ids_with_assignment_capacity).perform
+    end
   end
 
   def should_run_auto_assignment?
-    return false unless inbox.enable_auto_assignment?
+    # Check auto assignment is enabled (either legacy or v2)
+    return false unless inbox.auto_assignment_enabled?
 
     # run only if assignee is blank or doesn't have access to inbox
     assignee.blank? || inbox.members.exclude?(assignee)

app/models/concerns/inbox_agent_availability.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module InboxAgentAvailability
+  extend ActiveSupport::Concern
+
+  def available_agents(options = {})
+    # Get online agent IDs
+    online_agent_ids = fetch_online_agent_ids
+    return inbox_members.none if online_agent_ids.empty?
+
+    # Base query - only online agents
+    scope = build_online_agents_scope(online_agent_ids)
+
+    # Apply filters
+    apply_agent_filters(scope, options)
+  end
+
+  def member_ids_with_assignment_capacity
+    member_ids
+  end
+
+  private
+
+  def build_online_agents_scope(online_agent_ids)
+    inbox_members
+      .joins(:user)
+      .where(users: { id: online_agent_ids })
+      .includes(:user)
+  end
+
+  def apply_agent_filters(scope, options)
+    # Exclude specific users if requested
+    scope = scope.where.not(users: { id: options[:exclude_user_ids] }) if options[:exclude_user_ids].present?
+
+    # Apply rate limiting if assignment policy is enabled
+    scope = filter_by_rate_limits(scope) if options[:check_rate_limits] && defined?(AssignmentV2::RateLimiter)
+
+    scope
+  end
+
+  def fetch_online_agent_ids
+    OnlineStatusTracker.get_available_users(account_id)
+                       .select { |_key, value| value.eql?('online') }
+                       .keys
+                       .map(&:to_i)
+  end
+
+  def filter_by_rate_limits(inbox_members_scope)
+    # Filter out agents who have exceeded rate limits
+    return inbox_members_scope unless assignment_policy&.enabled?
+
+    inbox_members_scope.select do |inbox_member|
+      rate_limiter = AssignmentV2::RateLimiter.new(inbox: self, user: inbox_member.user)
+      rate_limiter.within_limits?
+    end
+  end
+end

app/models/inbox.rb

@@ -44,6 +44,7 @@ class Inbox < ApplicationRecord
   include Avatarable
   include OutOfOffisable
   include AccountCacheRevalidator
+  include InboxAgentAvailability
 
   # Not allowing characters:
   validates :name, presence: true
@@ -72,6 +73,10 @@ class Inbox < ApplicationRecord
   has_many :webhooks, dependent: :destroy_async
   has_many :hooks, dependent: :destroy_async, class_name: 'Integrations::Hook'
 
+  # Assignment V2 associations
+  has_one :inbox_assignment_policy, dependent: :destroy
+  has_one :assignment_policy, through: :inbox_assignment_policy
+
   enum sender_name_type: { friendly: 0, professional: 1 }
 
   after_destroy :delete_round_robin_agents
@@ -184,6 +189,19 @@ class Inbox < ApplicationRecord
     members.ids
   end
 
+  # Assignment V2 methods
+  def assignment_v2_enabled?
+    account.feature_enabled?('assignment_v2') && assignment_policy.present? && assignment_policy.enabled?
+  end
+
+  def auto_assignment_enabled?
+    if assignment_v2_enabled?
+      assignment_policy.present? && assignment_policy.enabled?
+    else
+      enable_auto_assignment?
+    end
+  end
+
   private
 
   def default_name_for_blank_name

app/models/inbox_assignment_policy.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: inbox_assignment_policies
+#
+#  id                   :bigint           not null, primary key
+#  created_at           :datetime         not null
+#  updated_at           :datetime         not null
+#  assignment_policy_id :bigint           not null
+#  inbox_id             :bigint           not null
+#
+# Indexes
+#
+#  index_inbox_assignment_policies_on_assignment_policy_id  (assignment_policy_id)
+#  index_inbox_assignment_policies_on_inbox_id              (inbox_id) UNIQUE
+#
+
+class InboxAssignmentPolicy < ApplicationRecord
+  # Associations
+  belongs_to :inbox
+  belongs_to :assignment_policy
+
+  # Validations
+  validates :inbox_id, uniqueness: true
+  validate :inbox_belongs_to_same_account
+
+  # Delegations
+  delegate :account, to: :inbox
+  delegate :name, :description, :assignment_order, :conversation_priority,
+           :fair_distribution_limit, :fair_distribution_window, :enabled?,
+           to: :assignment_policy, prefix: :policy
+
+  def webhook_data
+    {
+      id: id,
+      inbox_id: inbox_id,
+      assignment_policy_id: assignment_policy_id,
+      policy: assignment_policy.webhook_data
+    }
+  end
+
+  private
+
+  def inbox_belongs_to_same_account
+    return unless inbox && assignment_policy
+
+    return if inbox.account_id == assignment_policy.account_id
+
+    errors.add(:inbox, 'must belong to the same account as the assignment policy')
+  end
+end

app/policies/assignment_policy_policy.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class AssignmentPolicyPolicy < ApplicationPolicy
+  def index?
+    @account_user.administrator?
+  end
+
+  def show?
+    @account_user.administrator?
+  end
+
+  def create?
+    @account_user.administrator?
+  end
+
+  def update?
+    @account_user.administrator?
+  end
+
+  def destroy?
+    @account_user.administrator?
+  end
+end

app/services/assignment_v2/assignment_service.rb

@@ -0,0 +1,102 @@
+# frozen_string_literal: true
+
+class AssignmentV2::AssignmentService
+  pattr_initialize [:inbox!]
+
+  def perform_for_conversation(conversation)
+    return false unless can_assign?(conversation)
+
+    agent = find_agent_for_conversation(conversation)
+    return false unless agent
+
+    assign_conversation_to_agent(conversation, agent)
+  end
+
+  def perform_bulk_assignment(limit: 50)
+    return 0 unless assignment_enabled?
+
+    conversations = unassigned_conversations(limit)
+    assigned_count = 0
+
+    conversations.find_each do |conversation|
+      assigned_count += 1 if perform_for_conversation(conversation)
+    end
+
+    assigned_count
+  end
+
+  private
+
+  def policy
+    @policy ||= inbox.assignment_policy
+  end
+
+  def assignment_enabled?
+    policy&.enabled?
+  end
+
+  def can_assign?(conversation)
+    assignment_enabled? &&
+      conversation.status == 'open' &&
+      conversation.assignee_id.nil?
+  end
+
+  def find_agent_for_conversation(_conversation)
+    available_agents = inbox.available_agents(check_rate_limits: true)
+
+    if available_agents.empty?
+      log_no_agents_available
+      return nil
+    end
+
+    selector_service.select_agent(available_agents)
+  end
+
+  def selector_service
+    @selector_service ||= AssignmentV2::RoundRobinSelector.new(inbox: inbox)
+  end
+
+  def unassigned_conversations(limit)
+    scope = inbox.conversations
+                 .unassigned
+                 .open
+
+    # Apply conversation priority ordering
+    scope = case policy.conversation_priority
+            when 'longest_waiting'
+              scope.order(last_activity_at: :asc, created_at: :asc)
+            else
+              scope.order(created_at: :asc)
+            end
+
+    scope.limit(limit)
+  end
+
+  def assign_conversation_to_agent(conversation, agent)
+    conversation.update!(assignee: agent)
+    create_assignment_activity(conversation, agent)
+    true
+  rescue ActiveRecord::RecordInvalid => e
+    Rails.logger.error "AssignmentV2: Failed to assign conversation #{conversation.id}: #{e.message}"
+    false
+  end
+
+  def create_assignment_activity(conversation, agent)
+    Rails.configuration.dispatcher.dispatch(
+      Events::Types::ASSIGNEE_CHANGED,
+      Time.zone.now,
+      conversation: conversation,
+      user: agent
+    )
+  end
+
+  def enterprise_enabled?
+    @enterprise_enabled ||= defined?(Enterprise)
+  end
+
+  def log_no_agents_available
+    Rails.logger.warn("AssignmentV2: No agents available for inbox #{inbox.id}")
+  end
+end
+
+AssignmentV2::AssignmentService.prepend_mod_with('AssignmentV2::AssignmentService')

app/services/assignment_v2/rate_limiter.rb

@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+# Rate limiter for assignment operations
+# Uses SQL to track assignment counts per agent per time window
+# based on assignment policy's fair_distribution_limit and fair_distribution_window
+class AssignmentV2::RateLimiter
+  pattr_initialize [:inbox!, :user!]
+
+  # Check if the user has exceeded rate limits
+  # @return [Boolean] true if within limits, false if exceeded
+  def within_limits?
+    return true unless policy_exists?
+
+    current_count < rate_limit
+  end
+
+  # Get current rate limit status for the user
+  # @return [Hash] Rate limit status information
+  def status
+    if policy_exists?
+      {
+        within_limits: within_limits?,
+        current_count: current_count,
+        limit: rate_limit,
+        reset_at: Time.zone.at(next_window_start)
+      }
+    else
+      {
+        within_limits: true,
+        current_count: 0,
+        limit: Float::INFINITY,
+        reset_at: nil
+      }
+    end
+  end
+
+  private
+
+  def policy
+    @policy ||= inbox.assignment_policy
+  end
+
+  def policy_exists?
+    policy.present? && policy.enabled?
+  end
+
+  def current_count
+    # Count conversations assigned to this user in the current time window
+    # from this inbox
+    window_start = Time.zone.at(current_window)
+
+    Conversation
+      .where(inbox_id: inbox.id)
+      .where(assignee_id: user.id)
+      .where('updated_at >= ?', window_start)
+      .where.not(assignee_id: nil)
+      .count
+  end
+
+  def rate_limit
+    policy&.fair_distribution_limit || 10
+  end
+
+  def time_window
+    policy&.fair_distribution_window || 3600
+  end
+
+  def current_window
+    (Time.current.to_i / time_window) * time_window
+  end
+
+  def next_window_start
+    current_window + time_window
+  end
+end

app/services/assignment_v2/round_robin_selector.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+class AssignmentV2::RoundRobinSelector
+  pattr_initialize [:inbox!]
+
+  def select_agent(available_agents)
+    return nil if available_agents.empty?
+
+    # Extract user IDs from inbox members
+    agent_user_ids = available_agents.map(&:user_id).map(&:to_s)
+
+    # Use Redis queue for round robin
+    selected_user_id = round_robin_service.available_agent(allowed_agent_ids: agent_user_ids)
+    return nil unless selected_user_id
+
+    # Return the user object
+    available_agents.find { |inbox_member| inbox_member.user_id.to_s == selected_user_id }&.user
+  end
+
+  def add_agent_to_queue(user_id)
+    round_robin_service.add_agent_to_queue(user_id)
+  end
+
+  def remove_agent_from_queue(user_id)
+    round_robin_service.remove_agent_from_queue(user_id)
+  end
+
+  def reset_queue
+    round_robin_service.reset_queue
+  end
+
+  private
+
+  def round_robin_service
+    @round_robin_service ||= AutoAssignment::InboxRoundRobinService.new(inbox: inbox)
+  end
+end

config/features.yml

@@ -191,3 +191,6 @@
   display_name: CRM V2
   enabled: false
   chatwoot_internal: true
+- name: assignment_v2
+  display_name: Assignment V2
+  enabled: false

config/routes.rb

@@ -50,6 +50,9 @@ Rails.application.routes.draw do
           resource :bulk_actions, only: [:create]
           resources :agents, only: [:index, :create, :update, :destroy] do
             post :bulk_create, on: :collection
+            member do
+              get 'capacity', to: 'agents/capacity#show'
+            end
           end
           namespace :captain do
             resources :assistants do
@@ -97,6 +100,13 @@ Rails.application.routes.draw do
           end
           resources :sla_policies, only: [:index, :create, :show, :update, :destroy]
           resources :custom_roles, only: [:index, :create, :show, :update, :destroy]
+          resources :agent_capacity_policies, only: [:index, :create, :show, :update, :destroy] do
+            member do
+              post 'users', to: 'agent_capacity_policies#assign_user'
+              delete 'users/:user_id', to: 'agent_capacity_policies#unassign_user'
+              put 'inbox_limits/:inbox_id', to: 'agent_capacity_policies#update_inbox_limit'
+            end
+          end
           resources :campaigns, only: [:index, :create, :show, :update, :destroy]
           resources :dashboard_apps, only: [:index, :show, :create, :update, :destroy]
           namespace :channels do
@@ -217,6 +227,13 @@ Rails.application.routes.draw do
             end
           end
 
+          # Assignment V2 Routes
+          resources :assignment_policies
+
+          resources :inboxes, only: [] do
+            resource :assignment_policy, only: [:show, :create, :destroy], controller: 'inbox_assignment_policies'
+          end
+
           namespace :twitter do
             resource :authorization, only: [:create]
           end

db/schema.rb

@@ -320,6 +320,7 @@ ActiveRecord::Schema[7.1].define(version: 2025_08_08_123008) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.integer "status", default: 0, null: false
+    t.jsonb "metadata", default: {}
     t.index ["account_id"], name: "index_captain_documents_on_account_id"
     t.index ["assistant_id", "external_link"], name: "index_captain_documents_on_assistant_id_and_external_link", unique: true
     t.index ["assistant_id"], name: "index_captain_documents_on_assistant_id"

enterprise/app/controllers/api/v1/accounts/agent_capacity_policies_controller.rb

@@ -0,0 +1,58 @@
+class Api::V1::Accounts::AgentCapacityPoliciesController < Api::V1::Accounts::EnterpriseAccountsController
+  before_action :fetch_policy, only: [:show, :update, :destroy, :assign_user, :unassign_user, :update_inbox_limit]
+  before_action :check_enterprise_authorization
+
+  def index
+    @agent_capacity_policies = Current.account.agent_capacity_policies
+  end
+
+  def show; end
+
+  def create
+    @agent_capacity_policy = Current.account.agent_capacity_policies.create!(permitted_params)
+  end
+
+  def update
+    @agent_capacity_policy.update!(permitted_params)
+  end
+
+  def destroy
+    @agent_capacity_policy.destroy!
+    head :ok
+  end
+
+  def assign_user
+    user = Current.account.users.find(params[:user_id])
+    account_user = Current.account.account_users.find_by!(user: user)
+    account_user.update!(agent_capacity_policy: @agent_capacity_policy)
+    render json: { message: 'User assigned successfully' }
+  end
+
+  def unassign_user
+    user = Current.account.users.find(params[:user_id])
+    account_user = Current.account.account_users.find_by!(user: user)
+    account_user.update!(agent_capacity_policy: nil)
+    render json: { message: 'User unassigned successfully' }
+  end
+
+  def update_inbox_limit
+    inbox = Current.account.inboxes.find(params[:inbox_id])
+    inbox_limit = @agent_capacity_policy.inbox_capacity_limits.find_or_initialize_by(inbox: inbox)
+    inbox_limit.update!(conversation_limit: params[:conversation_limit])
+    render json: inbox_limit
+  end
+
+  private
+
+  def permitted_params
+    params.require(:agent_capacity_policy).permit(:name, :description, exclusion_rules: {})
+  end
+
+  def fetch_policy
+    @agent_capacity_policy = Current.account.agent_capacity_policies.find(params[:id])
+  end
+
+  def check_enterprise_authorization
+    authorize(Enterprise::AgentCapacityPolicy)
+  end
+end

enterprise/app/controllers/api/v1/accounts/agents/capacity_controller.rb

@@ -0,0 +1,39 @@
+class Api::V1::Accounts::Agents::CapacityController < Api::V1::Accounts::EnterpriseAccountsController
+  before_action :fetch_agent
+
+  def show
+    account_user = Current.account.account_users.find_by!(user: @agent)
+    capacity_service = Enterprise::AssignmentV2::CapacityService.new(account_user)
+    inbox = fetch_inbox
+
+    render json: build_capacity_response(account_user, capacity_service, inbox)
+  end
+
+  private
+
+  def fetch_agent
+    @agent = Current.account.users.find(params[:id])
+  end
+
+  def fetch_inbox
+    return if params[:inbox_id].blank?
+
+    Current.account.inboxes.find(params[:inbox_id])
+  end
+
+  def build_capacity_response(account_user, capacity_service, inbox)
+    response = {
+      has_capacity: capacity_service.agent_has_capacity?(inbox),
+      overall_capacity: capacity_service.agent_overall_capacity,
+      inbox_capacity: inbox ? capacity_service.agent_capacity_for_inbox(inbox) : nil,
+      current_conversations_count: account_user.user.assigned_conversations.open.count
+    }
+
+    add_inbox_conversations_count(response, account_user, inbox) if inbox
+    response
+  end
+
+  def add_inbox_conversations_count(response, account_user, inbox)
+    response[:inbox_conversations_count] = account_user.user.assigned_conversations.open.where(inbox: inbox).count
+  end
+end

enterprise/app/models/enterprise/agent_capacity_policy.rb

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+class Enterprise::AgentCapacityPolicy < ApplicationRecord
+  self.table_name = 'agent_capacity_policies'
+
+  belongs_to :account, class_name: '::Account'
+  has_many :inbox_capacity_limits, class_name: 'Enterprise::InboxCapacityLimit', dependent: :destroy
+  has_many :inboxes, through: :inbox_capacity_limits, class_name: '::Inbox'
+  has_many :account_users, class_name: '::AccountUser', dependent: :nullify
+
+  validates :name, presence: true, length: { maximum: 255 }
+
+  def applicable_for_time?(time = Time.current)
+    return true if exclusion_rules.blank?
+
+    !excluded_for_time?(time)
+  end
+
+  def capacity_for_inbox(inbox)
+    inbox_capacity_limits.find_by(inbox: inbox)&.conversation_limit
+  end
+
+  def overall_capacity
+    exclusion_rules['overall_capacity'] || Float::INFINITY
+  end
+
+  private
+
+  def excluded_for_time?(time)
+    excluded_by_hours?(time) || excluded_by_days?(time)
+  end
+
+  def excluded_by_hours?(time)
+    return false if exclusion_rules['hours'].blank?
+
+    current_hour = time.hour
+    exclusion_rules['hours'].include?(current_hour)
+  end
+
+  def excluded_by_days?(time)
+    return false if exclusion_rules['days'].blank?
+
+    current_day = time.strftime('%A').downcase
+    exclusion_rules['days'].include?(current_day)
+  end
+end

enterprise/app/models/enterprise/assignment_policy.rb

@@ -0,0 +1,27 @@
+module Enterprise::AssignmentPolicy
+  # In enterprise, we extend the enum to include balanced
+  # However, since Rails enums are frozen after definition,
+  # we need to handle this differently
+
+  # Override assignment_order= to accept 'balanced'
+  def assignment_order=(value)
+    if value.to_s == 'balanced'
+      write_attribute(:assignment_order, 1)
+    else
+      super
+    end
+  end
+
+  # Override assignment_order getter to return 'balanced' for value 1
+  def assignment_order
+    value = read_attribute(:assignment_order)
+    return 'balanced' if value == 1
+
+    super
+  end
+
+  # Define balanced? method
+  def balanced?
+    self[:assignment_order] == 1
+  end
+end

enterprise/app/models/enterprise/concerns/account.rb

@@ -5,6 +5,7 @@ module Enterprise::Concerns::Account
     has_many :sla_policies, dependent: :destroy_async
     has_many :applied_slas, dependent: :destroy_async
     has_many :custom_roles, dependent: :destroy_async
+    has_many :agent_capacity_policies, dependent: :destroy_async, class_name: 'Enterprise::AgentCapacityPolicy'
 
     has_many :captain_assistants, dependent: :destroy_async, class_name: 'Captain::Assistant'
     has_many :captain_assistant_responses, dependent: :destroy_async, class_name: 'Captain::AssistantResponse'

enterprise/app/models/enterprise/concerns/account_user.rb

@@ -3,5 +3,6 @@ module Enterprise::Concerns::AccountUser
 
   included do
     belongs_to :custom_role, optional: true
+    belongs_to :agent_capacity_policy, class_name: 'Enterprise::AgentCapacityPolicy', optional: true
   end
 end

enterprise/app/models/enterprise/concerns/inbox_agent_availability.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+module Enterprise::Concerns::InboxAgentAvailability
+  def apply_agent_filters(scope, options)
+    scope = super(scope, options)
+
+    # Apply capacity filtering if requested
+    scope = filter_by_capacity(scope) if options[:check_capacity]
+
+    scope
+  end
+
+  private
+
+  def filter_by_capacity(inbox_members_scope)
+    return inbox_members_scope unless assignment_policy&.enabled?
+
+    inbox_members_scope.select do |inbox_member|
+      account_user = AccountUser.find_by(account: account, user: inbox_member.user)
+      next true if account_user&.agent_capacity_policy.blank?
+
+      capacity_service = Enterprise::AssignmentV2::CapacityService.new(account_user)
+      capacity_service.agent_has_capacity?(self)
+    end
+  end
+end

enterprise/app/models/enterprise/inbox.rb

@@ -2,9 +2,17 @@ module Enterprise::Inbox
   def member_ids_with_assignment_capacity
     return super unless enable_auto_assignment?
 
-    max_assignment_limit = auto_assignment_config['max_assignment_limit']
-    overloaded_agent_ids = max_assignment_limit.present? ? get_agent_ids_over_assignment_limit(max_assignment_limit) : []
-    super - overloaded_agent_ids
+    member_ids = apply_max_assignment_limit(super)
+    apply_capacity_policy_filter(member_ids)
+  end
+
+  def available_agents(options = {})
+    agents = super(options)
+
+    # Apply capacity filtering if requested and assignment policy is enabled
+    agents = filter_agents_by_capacity(agents) if options[:check_capacity] && assignment_policy&.enabled?
+
+    agents
   end
 
   def active_bot?
@@ -17,6 +25,36 @@ module Enterprise::Inbox
 
   private
 
+  def filter_agents_by_capacity(inbox_members_scope)
+    inbox_members_scope.select do |inbox_member|
+      account_user = AccountUser.find_by(account: account, user: inbox_member.user)
+      next true if account_user&.agent_capacity_policy.blank?
+
+      capacity_service = Enterprise::AssignmentV2::CapacityService.new(account_user)
+      capacity_service.agent_has_capacity?(self)
+    end
+  end
+
+  def apply_max_assignment_limit(member_ids)
+    max_assignment_limit = auto_assignment_config['max_assignment_limit']
+    return member_ids if max_assignment_limit.blank?
+
+    overloaded_agent_ids = get_agent_ids_over_assignment_limit(max_assignment_limit)
+    member_ids - overloaded_agent_ids
+  end
+
+  def apply_capacity_policy_filter(member_ids)
+    return member_ids unless assignment_policy&.enabled?
+
+    account_users = AccountUser.where(account_id: account_id, user_id: member_ids)
+    account_users.select do |account_user|
+      next true if account_user.agent_capacity_policy.blank?
+
+      capacity_service = Enterprise::AssignmentV2::CapacityService.new(account_user)
+      capacity_service.agent_has_capacity?(self)
+    end.map(&:user_id)
+  end
+
   def more_responses?
     account.usage_limits[:captain][:responses][:current_available].positive?
   end

enterprise/app/models/enterprise/inbox_capacity_limit.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class Enterprise::InboxCapacityLimit < ApplicationRecord
+  self.table_name = 'inbox_capacity_limits'
+
+  belongs_to :agent_capacity_policy, class_name: 'Enterprise::AgentCapacityPolicy'
+  belongs_to :inbox, class_name: '::Inbox'
+
+  validates :conversation_limit, presence: true, numericality: { greater_than_or_equal_to: 0 }
+  validates :inbox_id, uniqueness: { scope: :agent_capacity_policy_id }
+end

enterprise/app/policies/enterprise/agent_capacity_policy_policy.rb

@@ -0,0 +1,33 @@
+class Enterprise::AgentCapacityPolicyPolicy < ApplicationPolicy
+  def index?
+    @account_user.administrator? || @account_user.agent?
+  end
+
+  def update?
+    @account_user.administrator?
+  end
+
+  def show?
+    @account_user.administrator? || @account_user.agent?
+  end
+
+  def create?
+    @account_user.administrator?
+  end
+
+  def destroy?
+    @account_user.administrator?
+  end
+
+  def assign_user?
+    @account_user.administrator?
+  end
+
+  def unassign_user?
+    @account_user.administrator?
+  end
+
+  def update_inbox_limit?
+    @account_user.administrator?
+  end
+end

enterprise/app/services/enterprise/assignment_v2/assignment_service.rb

@@ -0,0 +1,25 @@
+module Enterprise::AssignmentV2::AssignmentService
+  # Override selector_service to use BalancedSelector when appropriate
+  def selector_service
+    @selector_service ||= if policy&.balanced?
+                            Enterprise::AssignmentV2::BalancedSelector.new(inbox: inbox)
+                          else
+                            super
+                          end
+  end
+
+  # Override find_agent_for_conversation to include capacity checks
+  def find_agent_for_conversation(_conversation)
+    available_agents = inbox.available_agents(
+      check_rate_limits: true,
+      check_capacity: true
+    )
+
+    if available_agents.empty?
+      log_no_agents_available
+      return nil
+    end
+
+    selector_service.select_agent(available_agents)
+  end
+end

enterprise/app/services/enterprise/assignment_v2/balanced_selector.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+class Enterprise::AssignmentV2::BalancedSelector
+  pattr_initialize [:inbox!]
+
+  def select_agent(available_agents)
+    return nil if available_agents.empty?
+
+    # Get current assignment counts for all available agents
+    agent_users = available_agents.map(&:user)
+    assignment_counts = fetch_assignment_counts(agent_users)
+
+    # Find the agent with the least assignments
+    selected_agent = agent_users.min_by { |user| assignment_counts[user.id] || 0 }
+
+    # Log the selection for debugging
+    Rails.logger.info "BalancedSelector: Selected agent #{selected_agent.id} with #{assignment_counts[selected_agent.id] || 0} assignments"
+
+    selected_agent
+  end
+
+  def add_agent_to_queue(user_id)
+    # No-op for balanced assignment - we don't maintain a queue
+  end
+
+  def remove_agent_from_queue(user_id)
+    # No-op for balanced assignment - we don't maintain a queue
+  end
+
+  def reset_queue
+    # No-op for balanced assignment - we don't maintain a queue
+  end
+
+  private
+
+  def fetch_assignment_counts(users)
+    # Get open conversation counts for each user
+    user_ids = users.map(&:id)
+
+    # Count open conversations assigned to each user in this inbox
+    counts = inbox.conversations
+                  .open
+                  .where(assignee_id: user_ids)
+                  .group(:assignee_id)
+                  .count
+
+    # Convert to hash with default value of 0
+    Hash.new(0).merge(counts)
+  end
+
+  def account
+    @account ||= inbox.account
+  end
+end

enterprise/app/services/enterprise/assignment_v2/capacity_service.rb

@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+class Enterprise::AssignmentV2::CapacityService
+  def initialize(account_user)
+    @account_user = account_user
+    @account = account_user.account
+  end
+
+  def agent_has_capacity?(inbox = nil)
+    return true unless capacity_policy_applicable?
+
+    if inbox
+      check_inbox_capacity(inbox)
+    else
+      check_overall_capacity
+    end
+  end
+
+  def agent_capacity_for_inbox(inbox)
+    return Float::INFINITY unless capacity_policy_applicable?
+
+    policy = @account_user.agent_capacity_policy
+    inbox_limit = policy.capacity_for_inbox(inbox)
+    return Float::INFINITY unless inbox_limit
+
+    current_count = current_conversations_count(inbox)
+    [inbox_limit - current_count, 0].max
+  end
+
+  def agent_overall_capacity
+    return Float::INFINITY unless capacity_policy_applicable?
+
+    policy = @account_user.agent_capacity_policy
+    overall_limit = policy.overall_capacity
+    return Float::INFINITY if overall_limit == Float::INFINITY
+
+    current_count = current_conversations_count
+    [overall_limit - current_count, 0].max
+  end
+
+  def current_conversations_count(inbox = nil)
+    scope = @account_user.user.conversations
+                         .joins(:account)
+                         .where(account: @account, status: :open)
+    scope = scope.where(inbox: inbox) if inbox
+    scope.count
+  end
+
+  private
+
+  def capacity_policy_applicable?
+    return false if @account_user.agent_capacity_policy.blank?
+
+    @account_user.agent_capacity_policy.applicable_for_time?
+  end
+
+  def check_inbox_capacity(inbox)
+    policy = @account_user.agent_capacity_policy
+    inbox_limit = policy.capacity_for_inbox(inbox)
+
+    return check_overall_capacity unless inbox_limit
+
+    current_count = current_conversations_count(inbox)
+    current_count < inbox_limit && check_overall_capacity
+  end
+
+  def check_overall_capacity
+    policy = @account_user.agent_capacity_policy
+    overall_limit = policy.overall_capacity
+
+    return true if overall_limit == Float::INFINITY
+
+    current_count = current_conversations_count
+    current_count < overall_limit
+  end
+end

enterprise/app/views/api/v1/accounts/agent_capacity_policies/create.json.jbuilder

@@ -0,0 +1,12 @@
+json.id @agent_capacity_policy.id
+json.name @agent_capacity_policy.name
+json.description @agent_capacity_policy.description
+json.exclusion_rules @agent_capacity_policy.exclusion_rules
+json.created_at @agent_capacity_policy.created_at
+json.updated_at @agent_capacity_policy.updated_at
+json.account_id @agent_capacity_policy.account_id
+json.inbox_capacity_limits @agent_capacity_policy.inbox_capacity_limits do |limit|
+  json.id limit.id
+  json.inbox_id limit.inbox_id
+  json.conversation_limit limit.conversation_limit
+end

enterprise/app/views/api/v1/accounts/agent_capacity_policies/index.json.jbuilder

@@ -0,0 +1,14 @@
+json.array! @agent_capacity_policies do |policy|
+  json.id policy.id
+  json.name policy.name
+  json.description policy.description
+  json.exclusion_rules policy.exclusion_rules
+  json.created_at policy.created_at
+  json.updated_at policy.updated_at
+  json.account_id policy.account_id
+  json.inbox_capacity_limits policy.inbox_capacity_limits do |limit|
+    json.id limit.id
+    json.inbox_id limit.inbox_id
+    json.conversation_limit limit.conversation_limit
+  end
+end

enterprise/app/views/api/v1/accounts/agent_capacity_policies/show.json.jbuilder

@@ -0,0 +1,12 @@
+json.id @agent_capacity_policy.id
+json.name @agent_capacity_policy.name
+json.description @agent_capacity_policy.description
+json.exclusion_rules @agent_capacity_policy.exclusion_rules
+json.created_at @agent_capacity_policy.created_at
+json.updated_at @agent_capacity_policy.updated_at
+json.account_id @agent_capacity_policy.account_id
+json.inbox_capacity_limits @agent_capacity_policy.inbox_capacity_limits do |limit|
+  json.id limit.id
+  json.inbox_id limit.inbox_id
+  json.conversation_limit limit.conversation_limit
+end

enterprise/app/views/api/v1/accounts/agent_capacity_policies/update.json.jbuilder

@@ -0,0 +1,12 @@
+json.id @agent_capacity_policy.id
+json.name @agent_capacity_policy.name
+json.description @agent_capacity_policy.description
+json.exclusion_rules @agent_capacity_policy.exclusion_rules
+json.created_at @agent_capacity_policy.created_at
+json.updated_at @agent_capacity_policy.updated_at
+json.account_id @agent_capacity_policy.account_id
+json.inbox_capacity_limits @agent_capacity_policy.inbox_capacity_limits do |limit|
+  json.id limit.id
+  json.inbox_id limit.inbox_id
+  json.conversation_limit limit.conversation_limit
+end

spec/enterprise/models/enterprise/agent_capacity_policy_spec.rb

@@ -0,0 +1,128 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Enterprise::AgentCapacityPolicy do
+  let(:account) { create(:account) }
+  let(:policy) { described_class.create!(account: account, name: 'Test Policy') }
+
+  describe 'associations' do
+    it 'belongs to account' do
+      expect(policy.account).to eq(account)
+    end
+
+    it 'has many inbox capacity limits' do
+      expect(policy).to respond_to(:inbox_capacity_limits)
+    end
+
+    it 'has many inboxes through inbox capacity limits' do
+      expect(policy).to respond_to(:inboxes)
+    end
+
+    it 'has many account users' do
+      expect(policy).to respond_to(:account_users)
+    end
+  end
+
+  describe 'validations' do
+    it 'validates presence of name' do
+      invalid_policy = described_class.new(account: account)
+      expect(invalid_policy).not_to be_valid
+      expect(invalid_policy.errors[:name]).to include("can't be blank")
+    end
+
+    it 'validates length of name' do
+      invalid_policy = described_class.new(account: account, name: 'a' * 256)
+      expect(invalid_policy).not_to be_valid
+      expect(invalid_policy.errors[:name]).to include('is too long (maximum is 255 characters)')
+    end
+  end
+
+  describe '#applicable_for_time?' do
+    context 'when no exclusion rules' do
+      it 'returns true' do
+        expect(policy.applicable_for_time?).to be true
+      end
+    end
+
+    context 'with hour exclusions' do
+      let(:policy) do
+        described_class.create!(
+          account: account,
+          name: 'Hour Exclusion Policy',
+          exclusion_rules: { 'hours' => [10, 11, 12] }
+        )
+      end
+
+      it 'returns false during excluded hours' do
+        time = Time.zone.parse('10:30')
+        expect(policy.applicable_for_time?(time)).to be false
+      end
+
+      it 'returns true outside excluded hours' do
+        time = Time.zone.parse('13:30')
+        expect(policy.applicable_for_time?(time)).to be true
+      end
+    end
+
+    context 'with day exclusions' do
+      let(:policy) do
+        described_class.create!(
+          account: account,
+          name: 'Day Exclusion Policy',
+          exclusion_rules: { 'days' => %w[saturday sunday] }
+        )
+      end
+
+      it 'returns false on excluded days' do
+        time = Time.zone.parse('2024-01-06 10:00') # Saturday
+        expect(policy.applicable_for_time?(time)).to be false
+      end
+
+      it 'returns true on non-excluded days' do
+        time = Time.zone.parse('2024-01-08 10:00') # Monday
+        expect(policy.applicable_for_time?(time)).to be true
+      end
+    end
+  end
+
+  describe '#capacity_for_inbox' do
+    let(:inbox) { create(:inbox, account: account) }
+
+    it 'returns the conversation limit for the inbox' do
+      Enterprise::InboxCapacityLimit.create!(
+        agent_capacity_policy: policy,
+        inbox: inbox,
+        conversation_limit: 10
+      )
+      expect(policy.capacity_for_inbox(inbox)).to eq(10)
+    end
+
+    it 'returns nil for inbox without limit' do
+      other_inbox = create(:inbox, account: account)
+      expect(policy.capacity_for_inbox(other_inbox)).to be_nil
+    end
+  end
+
+  describe '#overall_capacity' do
+    context 'when overall_capacity is set' do
+      let(:policy) do
+        described_class.create!(
+          account: account,
+          name: 'Overall Capacity Policy',
+          exclusion_rules: { 'overall_capacity' => 25 }
+        )
+      end
+
+      it 'returns the overall capacity' do
+        expect(policy.overall_capacity).to eq(25)
+      end
+    end
+
+    context 'when overall_capacity is not set' do
+      it 'returns infinity' do
+        expect(policy.overall_capacity).to eq(Float::INFINITY)
+      end
+    end
+  end
+end

spec/enterprise/services/enterprise/assignment_v2/assignment_with_capacity_spec.rb

@@ -0,0 +1,141 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Assignment with Capacity' do
+  let(:account) { create(:account) }
+  let(:inbox) { create(:inbox, account: account, enable_auto_assignment: false) }
+
+  let(:agent1) { create(:user, accounts: [account]) }
+  let(:agent2) { create(:user, accounts: [account]) }
+  let(:account_user1) { AccountUser.find_by(account: account, user: agent1) }
+  let(:account_user2) { AccountUser.find_by(account: account, user: agent2) }
+
+  let(:capacity_policy) do
+    Enterprise::AgentCapacityPolicy.create!(
+      account: account,
+      name: 'Test Capacity Policy',
+      exclusion_rules: { 'overall_capacity' => 5 }
+    )
+  end
+
+  let!(:inbox_capacity_limit) do
+    Enterprise::InboxCapacityLimit.create!(
+      agent_capacity_policy: capacity_policy,
+      inbox: inbox,
+      conversation_limit: 3
+    )
+  end
+
+  before do
+    # Create and setup assignment policy for the inbox
+    @assignment_policy = create(:assignment_policy, account: account, enabled: true)
+    create(:inbox_assignment_policy, inbox: inbox, assignment_policy: @assignment_policy)
+
+    # Add agents to inbox
+    create(:inbox_member, inbox: inbox, user: agent1)
+    create(:inbox_member, inbox: inbox, user: agent2)
+
+    # Set agents online using presence and status
+    OnlineStatusTracker.update_presence(account.id, 'User', agent1.id)
+    OnlineStatusTracker.update_presence(account.id, 'User', agent2.id)
+    OnlineStatusTracker.set_status(account.id, agent1.id, 'online')
+    OnlineStatusTracker.set_status(account.id, agent2.id, 'online')
+
+    # Also set account_user availability
+    account_user1.update!(availability: 'online')
+    account_user2.update!(availability: 'online')
+
+    # Assign capacity policy to agent1 only
+    account_user1.update!(agent_capacity_policy: capacity_policy)
+  end
+
+  describe 'capacity-based agent filtering' do
+    context 'when agent has capacity' do
+      it 'includes agent in available agents' do
+        available_agents = inbox.available_agents(check_capacity: true)
+        expect(available_agents.map(&:user)).to include(agent1, agent2)
+      end
+    end
+
+    context 'when agent reaches inbox capacity limit' do
+      before do
+        # Create 3 conversations for agent1 (at inbox limit)
+        create_list(:conversation, 3, account: account, inbox: inbox, assignee: agent1, status: :open)
+      end
+
+      it 'excludes agent from available agents for that inbox' do
+        available_agents = inbox.available_agents(check_capacity: true)
+        expect(available_agents.map(&:user)).not_to include(agent1)
+        expect(available_agents.map(&:user)).to include(agent2)
+      end
+    end
+
+    context 'when agent reaches overall capacity limit' do
+      before do
+        # Create 5 conversations for agent1 (at overall limit)
+        create_list(:conversation, 5, account: account, assignee: agent1, status: :open)
+      end
+
+      it 'excludes agent from all inbox assignments' do
+        available_agents = inbox.available_agents(check_capacity: true)
+        expect(available_agents.map(&:user)).not_to include(agent1)
+        expect(available_agents.map(&:user)).to include(agent2)
+      end
+    end
+
+    context 'when capacity policy is not applicable (time exclusion)' do
+      before do
+        capacity_policy.update!(exclusion_rules: {
+                                  'overall_capacity' => 5,
+                                  'hours' => [Time.current.hour]
+                                })
+        # Create 5 conversations for agent1 (would be at limit if policy was active)
+        create_list(:conversation, 5, account: account, assignee: agent1, status: :open)
+      end
+
+      it 'includes agent in available agents' do
+        available_agents = inbox.available_agents(check_capacity: true)
+        expect(available_agents.map(&:user)).to include(agent1, agent2)
+      end
+    end
+  end
+
+  describe 'capacity-aware assignment' do
+    let(:conversation) { create(:conversation, account: account, inbox: inbox, status: :open, assignee: nil) }
+
+    context 'when agents have capacity' do
+      it 'both agents are available for assignment' do
+        available = inbox.available_agents(check_capacity: true)
+        expect(available.map(&:user)).to include(agent1, agent2)
+      end
+    end
+
+    context 'when one agent is at capacity' do
+      before do
+        # Agent1 at inbox capacity
+        create_list(:conversation, 3, account: account, inbox: inbox, assignee: agent1, status: :open)
+      end
+
+      it 'only agent with capacity is available' do
+        available = inbox.available_agents(check_capacity: true)
+        expect(available.map(&:user)).not_to include(agent1)
+        expect(available.map(&:user)).to include(agent2)
+      end
+    end
+
+    context 'when all agents are at capacity' do
+      before do
+        # Both agents at capacity
+        account_user2.update!(agent_capacity_policy: capacity_policy)
+        create_list(:conversation, 3, account: account, inbox: inbox, assignee: agent1, status: :open)
+        create_list(:conversation, 3, account: account, inbox: inbox, assignee: agent2, status: :open)
+      end
+
+      it 'no agents are available' do
+        available = inbox.available_agents(check_capacity: true)
+        expect(available).to be_empty
+      end
+    end
+  end
+end

spec/enterprise/services/enterprise/assignment_v2/capacity_service_spec.rb

@@ -0,0 +1,168 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Enterprise::AssignmentV2::CapacityService do
+  let(:account) { create(:account) }
+  let(:user) { create(:user, accounts: [account]) }
+  let(:account_user) { AccountUser.find_by(account: account, user: user) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:service) { described_class.new(account_user) }
+
+  describe '#agent_has_capacity?' do
+    context 'without capacity policy' do
+      it 'returns true' do
+        expect(service.agent_has_capacity?).to be true
+        expect(service.agent_has_capacity?(inbox)).to be true
+      end
+    end
+
+    context 'with capacity policy' do
+      let(:policy) { Enterprise::AgentCapacityPolicy.create!(account: account, name: 'Test Policy') }
+
+      before do
+        account_user.update!(agent_capacity_policy: policy)
+      end
+
+      context 'when policy is not applicable' do
+        before do
+          allow(policy).to receive(:applicable_for_time?).and_return(false)
+        end
+
+        it 'returns true' do
+          expect(service.agent_has_capacity?).to be true
+        end
+      end
+
+      context 'when checking inbox capacity' do
+        let!(:inbox_limit) do
+          Enterprise::InboxCapacityLimit.create!(
+            agent_capacity_policy: policy,
+            inbox: inbox,
+            conversation_limit: 5
+          )
+        end
+
+        it 'returns true when under limit' do
+          create_list(:conversation, 3, account: account, inbox: inbox, assignee: user, status: :open)
+          expect(service.agent_has_capacity?(inbox)).to be true
+        end
+
+        it 'returns false when at limit' do
+          create_list(:conversation, 5, account: account, inbox: inbox, assignee: user, status: :open)
+          expect(service.agent_has_capacity?(inbox)).to be false
+        end
+
+        it 'checks overall capacity too' do
+          policy.update!(exclusion_rules: { 'overall_capacity' => 10 })
+          create_list(:conversation, 9, account: account, assignee: user, status: :open)
+
+          # Under inbox limit but close to overall limit
+          expect(service.agent_has_capacity?(inbox)).to be true
+
+          # Add one more to hit overall limit
+          create(:conversation, account: account, assignee: user, status: :open)
+          expect(service.agent_has_capacity?(inbox)).to be false
+        end
+      end
+
+      context 'when checking overall capacity' do
+        before do
+          policy.update!(exclusion_rules: { 'overall_capacity' => 10 })
+        end
+
+        it 'returns true when under limit' do
+          create_list(:conversation, 8, account: account, assignee: user, status: :open)
+          expect(service.agent_has_capacity?).to be true
+        end
+
+        it 'returns false when at limit' do
+          create_list(:conversation, 10, account: account, assignee: user, status: :open)
+          expect(service.agent_has_capacity?).to be false
+        end
+      end
+    end
+  end
+
+  describe '#agent_capacity_for_inbox' do
+    context 'without capacity policy' do
+      it 'returns infinity' do
+        expect(service.agent_capacity_for_inbox(inbox)).to eq(Float::INFINITY)
+      end
+    end
+
+    context 'with capacity policy and inbox limit' do
+      let(:policy) { Enterprise::AgentCapacityPolicy.create!(account: account, name: 'Test Policy') }
+      let!(:inbox_limit) do
+        Enterprise::InboxCapacityLimit.create!(
+          agent_capacity_policy: policy,
+          inbox: inbox,
+          conversation_limit: 5
+        )
+      end
+
+      before do
+        account_user.update!(agent_capacity_policy: policy)
+      end
+
+      it 'returns remaining capacity' do
+        create_list(:conversation, 2, account: account, inbox: inbox, assignee: user, status: :open)
+        expect(service.agent_capacity_for_inbox(inbox)).to eq(3)
+      end
+
+      it 'returns 0 when at capacity' do
+        create_list(:conversation, 5, account: account, inbox: inbox, assignee: user, status: :open)
+        expect(service.agent_capacity_for_inbox(inbox)).to eq(0)
+      end
+    end
+  end
+
+  describe '#agent_overall_capacity' do
+    context 'without capacity policy' do
+      it 'returns infinity' do
+        expect(service.agent_overall_capacity).to eq(Float::INFINITY)
+      end
+    end
+
+    context 'with capacity policy and overall limit' do
+      let(:policy) do
+        Enterprise::AgentCapacityPolicy.create!(
+          account: account,
+          name: 'Overall Policy',
+          exclusion_rules: { 'overall_capacity' => 10 }
+        )
+      end
+
+      before do
+        account_user.update!(agent_capacity_policy: policy)
+      end
+
+      it 'returns remaining capacity' do
+        create_list(:conversation, 6, account: account, assignee: user, status: :open)
+        expect(service.agent_overall_capacity).to eq(4)
+      end
+
+      it 'returns 0 when at capacity' do
+        create_list(:conversation, 10, account: account, assignee: user, status: :open)
+        expect(service.agent_overall_capacity).to eq(0)
+      end
+    end
+  end
+
+  describe '#current_conversations_count' do
+    it 'counts open conversations assigned to user' do
+      create_list(:conversation, 3, account: account, assignee: user, status: :open)
+      create(:conversation, account: account, assignee: user, status: :resolved)
+      create(:conversation, account: account, status: :open)
+
+      expect(service.current_conversations_count).to eq(3)
+    end
+
+    it 'counts inbox-specific conversations when inbox provided' do
+      create_list(:conversation, 2, account: account, inbox: inbox, assignee: user, status: :open)
+      create(:conversation, account: account, assignee: user, status: :open)
+
+      expect(service.current_conversations_count(inbox)).to eq(2)
+    end
+  end
+end

spec/factories/agent_capacity_policies.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :agent_capacity_policy, class: 'Enterprise::AgentCapacityPolicy' do
+    account
+    name { Faker::Name.name }
+    description { Faker::Lorem.sentence }
+    exclusion_rules { {} }
+  end
+end

spec/factories/assignment_policies.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :assignment_policy do
+    account
+    sequence(:name) { |n| "Assignment Policy #{n}" }
+    description { 'Test assignment policy' }
+    assignment_order { :round_robin }
+    conversation_priority { :earliest_created }
+    fair_distribution_limit { 10 }
+    fair_distribution_window { 3600 }
+    enabled { true }
+
+    trait :balanced do
+      assignment_order { :balanced }
+    end
+
+    trait :disabled do
+      enabled { false }
+    end
+
+    trait :longest_waiting do
+      conversation_priority { :longest_waiting }
+    end
+
+    trait :with_high_limit do
+      fair_distribution_limit { 50 }
+    end
+
+    trait :with_short_window do
+      fair_distribution_window { 300 } # 5 minutes
+    end
+  end
+end

spec/factories/inbox_assignment_policies.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :inbox_assignment_policy do
+    inbox
+    assignment_policy
+
+    # Ensure inbox and policy belong to same account
+    after(:build) do |inbox_policy|
+      inbox_policy.assignment_policy.account = inbox_policy.inbox.account if inbox_policy.inbox && inbox_policy.assignment_policy
+    end
+  end
+end

spec/factories/inbox_capacity_limits.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :inbox_capacity_limit, class: 'Enterprise::InboxCapacityLimit' do
+    association :agent_capacity_policy, factory: :agent_capacity_policy
+    inbox
+    conversation_limit { 10 }
+  end
+end

spec/jobs/assignment_v2/assignment_job_spec.rb

@@ -0,0 +1,196 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe AssignmentV2::AssignmentJob, type: :job do
+  before do
+    # Mock GlobalConfig to avoid InstallationConfig issues
+    allow(GlobalConfig).to receive(:get).and_return({})
+  end
+
+  let(:account) { create(:account) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:conversation) { create(:conversation, inbox: inbox, assignee: nil) }
+  let(:assignment_policy) { create(:assignment_policy, account: account, enabled: true) }
+  let!(:inbox_assignment_policy) { create(:inbox_assignment_policy, inbox: inbox, assignment_policy: assignment_policy) }
+
+  describe '#perform' do
+    context 'with conversation_id' do
+      it 'assigns a single conversation' do
+        service = instance_double(AssignmentV2::AssignmentService)
+        expect(AssignmentV2::AssignmentService).to receive(:new).with(inbox: inbox).and_return(service)
+        expect(service).to receive(:perform_for_conversation).with(conversation)
+
+        described_class.new.perform(conversation_id: conversation.id)
+      end
+
+      it 'handles non-existent conversation gracefully' do
+        expect(AssignmentV2::AssignmentService).not_to receive(:new)
+
+        # Should not raise error
+        expect do
+          described_class.new.perform(conversation_id: 999_999)
+        end.not_to raise_error
+      end
+    end
+
+    context 'with inbox_id' do
+      let!(:agent) { create(:user, account: account, role: :agent, availability: :online) }
+
+      before do
+        create_list(:conversation, 3, inbox: inbox, assignee: nil)
+        create(:inbox_member, inbox: inbox, user: agent)
+      end
+
+      it 'assigns multiple conversations for inbox' do
+        # Mock the feature flag for assignment_v2
+        allow(inbox.account).to receive(:feature_enabled?).with('assignment_v2').and_return(true)
+        allow(Inbox).to receive(:find_by).with(id: inbox.id).and_return(inbox)
+
+        service = instance_double(AssignmentV2::AssignmentService)
+        expect(AssignmentV2::AssignmentService).to receive(:new).with(inbox: inbox).and_return(service)
+        expect(service).to receive(:perform_bulk_assignment).and_return(3)
+
+        described_class.new.perform(inbox_id: inbox.id)
+      end
+
+      it 'logs the number of assigned conversations' do
+        # Mock the feature flag for assignment_v2
+        allow(inbox.account).to receive(:feature_enabled?).with('assignment_v2').and_return(true)
+        allow(Inbox).to receive(:find_by).with(id: inbox.id).and_return(inbox)
+
+        service = instance_double(AssignmentV2::AssignmentService)
+        allow(AssignmentV2::AssignmentService).to receive(:new).with(inbox: inbox).and_return(service)
+        allow(service).to receive(:perform_bulk_assignment).and_return(2)
+
+        expect(Rails.logger).to receive(:info).with("AssignmentV2::AssignmentJob: Assigned 2 conversations for inbox #{inbox.id}")
+
+        described_class.new.perform(inbox_id: inbox.id)
+      end
+
+      it 'skips assignment when inbox has no policy' do
+        inbox_assignment_policy.destroy!
+
+        expect(AssignmentV2::AssignmentService).not_to receive(:new)
+
+        described_class.new.perform(inbox_id: inbox.id)
+      end
+
+      it 'skips assignment when policy is disabled' do
+        assignment_policy.update!(enabled: false)
+
+        expect(AssignmentV2::AssignmentService).not_to receive(:new)
+
+        described_class.new.perform(inbox_id: inbox.id)
+      end
+
+      it 'handles non-existent inbox gracefully' do
+        expect(AssignmentV2::AssignmentService).not_to receive(:new)
+
+        # Should not raise error
+        expect do
+          described_class.new.perform(inbox_id: 999_999)
+        end.not_to raise_error
+      end
+    end
+
+    context 'without parameters' do
+      it 'logs error when no parameters provided' do
+        expect(Rails.logger).to receive(:error).with('AssignmentV2::AssignmentJob: No inbox_id or conversation_id provided')
+
+        described_class.new.perform
+      end
+
+      it 'does not attempt assignment' do
+        expect(AssignmentV2::AssignmentService).not_to receive(:new)
+
+        described_class.new.perform
+      end
+    end
+
+    context 'with both parameters' do
+      it 'prioritizes conversation_id over inbox_id' do
+        service = instance_double(AssignmentV2::AssignmentService)
+        expect(AssignmentV2::AssignmentService).to receive(:new).with(inbox: inbox).and_return(service)
+        expect(service).to receive(:perform_for_conversation).with(conversation)
+        expect(service).not_to receive(:perform_bulk_assignment)
+
+        described_class.new.perform(conversation_id: conversation.id, inbox_id: inbox.id)
+      end
+    end
+  end
+
+  describe 'job configuration' do
+    it 'uses the low queue' do
+      expect(described_class.new.queue_name).to eq('low')
+    end
+  end
+
+  describe 'error handling' do
+    context 'when assignment service raises error' do
+      it 'propagates the error for retry' do
+        service = instance_double(AssignmentV2::AssignmentService)
+        allow(AssignmentV2::AssignmentService).to receive(:new).and_return(service)
+        allow(service).to receive(:perform_for_conversation).and_raise(StandardError, 'Assignment failed')
+
+        expect do
+          described_class.new.perform(conversation_id: conversation.id)
+        end.to raise_error(StandardError, 'Assignment failed')
+      end
+    end
+
+    context 'when database connection fails' do
+      it 'raises error for retry' do
+        allow(Conversation).to receive(:find_by).and_raise(ActiveRecord::ConnectionNotEstablished)
+
+        expect do
+          described_class.new.perform(conversation_id: conversation.id)
+        end.to raise_error(ActiveRecord::ConnectionNotEstablished)
+      end
+    end
+  end
+
+  describe 'concurrency and idempotency' do
+    it 'handles concurrent job execution safely' do
+      # Create multiple jobs for same inbox
+      jobs = []
+      3.times { jobs << described_class.new }
+
+      # All should execute without issues
+      expect do
+        jobs.each { |job| job.perform(inbox_id: inbox.id) }
+      end.not_to raise_error
+    end
+
+    it 'is idempotent for conversation assignment' do
+      service = instance_double(AssignmentV2::AssignmentService)
+      allow(AssignmentV2::AssignmentService).to receive(:new).and_return(service)
+
+      # First call assigns
+      expect(service).to receive(:perform_for_conversation).and_return(true)
+      described_class.new.perform(conversation_id: conversation.id)
+
+      # Second call should handle already assigned conversation
+      expect(service).to receive(:perform_for_conversation).and_return(false)
+      expect { described_class.new.perform(conversation_id: conversation.id) }.not_to raise_error
+    end
+  end
+
+  describe 'performance considerations' do
+    it 'processes large inbox assignments in batches' do
+      # Create many unassigned conversations
+      create_list(:conversation, 100, inbox: inbox, assignee: nil)
+      # Mock the feature flag for assignment_v2
+      allow(inbox.account).to receive(:feature_enabled?).with('assignment_v2').and_return(true)
+      allow(Inbox).to receive(:find_by).with(id: inbox.id).and_return(inbox)
+
+      service = instance_double(AssignmentV2::AssignmentService)
+      allow(AssignmentV2::AssignmentService).to receive(:new).and_return(service)
+
+      # Service should be called with default limit
+      expect(service).to receive(:perform_bulk_assignment).with(no_args).and_return(50)
+
+      described_class.new.perform(inbox_id: inbox.id)
+    end
+  end
+end

spec/models/assignment_policy_spec.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe AssignmentPolicy, type: :model do
+  let(:account) { create(:account) }
+  let(:assignment_policy) { create(:assignment_policy, account: account) }
+
+  describe 'associations' do
+    it { is_expected.to belong_to(:account) }
+    it { is_expected.to have_many(:inbox_assignment_policies).dependent(:destroy) }
+    it { is_expected.to have_many(:inboxes).through(:inbox_assignment_policies) }
+  end
+
+  describe 'validations' do
+    subject { assignment_policy }
+
+    it { is_expected.to validate_presence_of(:name) }
+    it { is_expected.to validate_uniqueness_of(:name).scoped_to(:account_id) }
+    it { is_expected.to validate_length_of(:name).is_at_most(255) }
+    it { is_expected.to validate_length_of(:description).is_at_most(1000) }
+
+    it { is_expected.to validate_presence_of(:fair_distribution_limit) }
+    it { is_expected.to validate_numericality_of(:fair_distribution_limit).is_greater_than(0).is_less_than_or_equal_to(100) }
+
+    it { is_expected.to validate_presence_of(:fair_distribution_window) }
+    it { is_expected.to validate_numericality_of(:fair_distribution_window).is_greater_than(60).is_less_than_or_equal_to(86_400) }
+  end
+
+  describe 'enums' do
+    it { is_expected.to define_enum_for(:assignment_order).with_values(round_robin: 0) }
+    it { is_expected.to define_enum_for(:conversation_priority).with_values(earliest_created: 0, longest_waiting: 1) }
+  end
+
+  describe '#webhook_data' do
+    it 'returns correct data structure' do
+      data = assignment_policy.webhook_data
+
+      expect(data).to include(
+        id: assignment_policy.id,
+        name: assignment_policy.name,
+        description: assignment_policy.description,
+        assignment_order: assignment_policy.assignment_order,
+        conversation_priority: assignment_policy.conversation_priority,
+        fair_distribution_limit: assignment_policy.fair_distribution_limit,
+        fair_distribution_window: assignment_policy.fair_distribution_window,
+        enabled: assignment_policy.enabled
+      )
+    end
+  end
+end

spec/models/inbox_assignment_policy_spec.rb

@@ -0,0 +1,116 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe InboxAssignmentPolicy, type: :model do
+  let(:account) { create(:account) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:assignment_policy) { create(:assignment_policy, account: account) }
+  let(:inbox_assignment_policy) { create(:inbox_assignment_policy, inbox: inbox, assignment_policy: assignment_policy) }
+
+  describe 'associations' do
+    it { is_expected.to belong_to(:inbox) }
+    it { is_expected.to belong_to(:assignment_policy) }
+  end
+
+  describe 'validations' do
+    subject { inbox_assignment_policy }
+
+    it { is_expected.to validate_uniqueness_of(:inbox_id) }
+
+    context 'with inbox and policy from different accounts' do
+      let(:other_account) { create(:account) }
+      let(:other_policy) { create(:assignment_policy, account: other_account) }
+
+      it 'validates inbox belongs to same account as policy' do
+        # Build without the factory callback that sets the accounts to be the same
+        invalid_policy = described_class.new(inbox: inbox, assignment_policy: other_policy)
+
+        expect(invalid_policy).not_to be_valid
+        expect(invalid_policy.errors[:inbox]).to include('must belong to the same account as the assignment policy')
+      end
+    end
+  end
+
+  describe 'delegations' do
+    it 'delegates account to inbox' do
+      expect(inbox_assignment_policy.account).to eq(account)
+    end
+
+    it 'delegates policy attributes' do
+      expect(inbox_assignment_policy.policy_name).to eq(assignment_policy.name)
+      expect(inbox_assignment_policy.policy_description).to eq(assignment_policy.description)
+      expect(inbox_assignment_policy.policy_assignment_order).to eq(assignment_policy.assignment_order)
+      expect(inbox_assignment_policy.policy_conversation_priority).to eq(assignment_policy.conversation_priority)
+      expect(inbox_assignment_policy.policy_fair_distribution_limit).to eq(assignment_policy.fair_distribution_limit)
+      expect(inbox_assignment_policy.policy_fair_distribution_window).to eq(assignment_policy.fair_distribution_window)
+      expect(inbox_assignment_policy.policy_enabled?).to eq(assignment_policy.enabled?)
+    end
+  end
+
+  describe '#webhook_data' do
+    it 'returns correct data structure' do
+      data = inbox_assignment_policy.webhook_data
+
+      expect(data).to include(
+        id: inbox_assignment_policy.id,
+        inbox_id: inbox.id,
+        assignment_policy_id: assignment_policy.id
+      )
+
+      expect(data[:policy]).to eq(assignment_policy.webhook_data)
+    end
+  end
+
+  describe 'business logic constraints' do
+    it 'prevents multiple policies per inbox' do
+      # Ensure first policy exists
+      inbox_assignment_policy
+
+      policy2 = create(:assignment_policy, account: account)
+
+      # Try to create a second policy for the same inbox
+      duplicate_policy = described_class.new(inbox: inbox, assignment_policy: policy2)
+      expect(duplicate_policy).not_to be_valid
+      expect(duplicate_policy.errors[:inbox_id]).to include('has already been taken')
+    end
+
+    it 'allows reassigning to different policy' do
+      policy2 = create(:assignment_policy, account: account)
+
+      expect do
+        inbox_assignment_policy.update!(assignment_policy: policy2)
+      end.not_to raise_error
+
+      expect(inbox_assignment_policy.reload.assignment_policy).to eq(policy2)
+    end
+  end
+
+  describe 'edge cases' do
+    it 'handles nil associations gracefully' do
+      # Build without saving to test nil handling
+      policy = build(:inbox_assignment_policy, inbox: nil, assignment_policy: nil)
+
+      expect { policy.valid? }.not_to raise_error
+      expect(policy).not_to be_valid
+    end
+
+    it 'handles policy deletion cascade' do
+      inbox_policy_id = inbox_assignment_policy.id
+
+      # Deleting policy should delete inbox assignment
+      assignment_policy.destroy!
+
+      expect(described_class.find_by(id: inbox_policy_id)).to be_nil
+    end
+
+    it 'handles inbox deletion cascade' do
+      inbox_policy_id = inbox_assignment_policy.id
+
+      # Deleting inbox should delete inbox assignment
+      inbox.destroy!
+
+      expect(described_class.find_by(id: inbox_policy_id)).to be_nil
+    end
+  end
+end

spec/services/assignment_v2/assignment_service_spec.rb

@@ -0,0 +1,329 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe AssignmentV2::AssignmentService do
+  before do
+    # Mock the GlobalConfig to avoid InstallationConfig issues
+    allow(GlobalConfig).to receive(:get).and_return({})
+
+    # Define the constant if not already defined
+    stub_const('ASSIGNEE_CHANGED', 'assignee.changed') unless defined?(ASSIGNEE_CHANGED)
+    create(:inbox_member, inbox: inbox, user: agent1)
+    create(:inbox_member, inbox: inbox, user: agent2)
+    create(:inbox_member, inbox: inbox, user: agent3)
+
+    # Mock available agents to return inbox members
+    online_members = InboxMember.joins(:user).where(inbox: inbox, user: [agent1, agent2])
+    allow(inbox).to receive(:available_agents).and_return(online_members)
+  end
+
+  let(:account) { create(:account) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:assignment_policy) { create(:assignment_policy, account: account, enabled: true) }
+  let!(:inbox_assignment_policy) { create(:inbox_assignment_policy, inbox: inbox, assignment_policy: assignment_policy) }
+  let(:service) { described_class.new(inbox: inbox) }
+
+  # Create agents
+  let!(:agent1) { create(:user, account: account, role: :agent, availability: :online) }
+  let!(:agent2) { create(:user, account: account, role: :agent, availability: :online) }
+  let!(:agent3) { create(:user, account: account, role: :agent, availability: :offline) }
+
+  # Make agents members of inbox
+
+  describe '#perform_for_conversation' do
+    let(:conversation) { create(:conversation, inbox: inbox, assignee: nil) }
+
+    context 'when policy is enabled' do
+      before do
+        # Mock the selector to return an agent
+        selector = instance_double(AssignmentV2::RoundRobinSelector)
+        allow(AssignmentV2::RoundRobinSelector).to receive(:new).and_return(selector)
+        allow(selector).to receive(:select_agent).and_return(agent1)
+      end
+
+      it 'assigns conversation to an available agent' do
+        expect(service.perform_for_conversation(conversation)).to be true
+        expect(conversation.reload.assignee).to eq(agent1)
+      end
+
+      it 'dispatches assignment event' do
+        # The dispatcher is called from the assignment service and also from conversation model
+        allow(Rails.configuration.dispatcher).to receive(:dispatch)
+
+        service.perform_for_conversation(conversation)
+
+        expect(Rails.configuration.dispatcher).to have_received(:dispatch).with(
+          'assignee.changed',
+          anything,
+          hash_including(conversation: conversation, user: agent1)
+        ).at_least(:once)
+      end
+
+      it 'returns false when no agents are available' do
+        allow(inbox).to receive(:available_agents).and_return(InboxMember.none)
+        allow(Rails.logger).to receive(:warn)
+
+        expect(service.perform_for_conversation(conversation)).to be false
+        expect(conversation.reload.assignee).to be_nil
+      end
+    end
+
+    context 'when policy is disabled' do
+      before { assignment_policy.update!(enabled: false) }
+
+      it 'does not assign conversation' do
+        expect(service.perform_for_conversation(conversation)).to be false
+        expect(conversation.reload.assignee).to be_nil
+      end
+    end
+
+    context 'when conversation is already assigned' do
+      before { conversation.update!(assignee: agent1) }
+
+      it 'does not reassign conversation' do
+        expect(service.perform_for_conversation(conversation)).to be false
+        expect(conversation.reload.assignee).to eq(agent1)
+      end
+    end
+
+    context 'with round robin assignment' do
+      before do
+        assignment_policy.update!(assignment_order: :round_robin)
+
+        # Mock round robin selector to return agents in rotation
+        selector = instance_double(AssignmentV2::RoundRobinSelector)
+        allow(AssignmentV2::RoundRobinSelector).to receive(:new).and_return(selector)
+        agent_index = 0
+        allow(selector).to receive(:select_agent) do
+          agent = [agent1, agent2][agent_index % 2]
+          agent_index += 1
+          agent
+        end
+      end
+
+      it 'assigns agents in rotation' do
+        conversations = create_list(:conversation, 4, inbox: inbox, assignee: nil)
+
+        assignments = conversations.map do |conv|
+          service.perform_for_conversation(conv)
+          conv.reload.assignee
+        end
+
+        # Should rotate between available agents
+        expect(assignments[0]).to eq(agent1)
+        expect(assignments[1]).to eq(agent2)
+        expect(assignments[2]).to eq(agent1) # Back to first agent
+        expect(assignments[3]).to eq(agent2) # Back to second agent
+      end
+    end
+
+    context 'with balanced assignment' do
+      before do
+        # For now, just use round robin since balanced is enterprise only
+        # The test is verifying the service works, not the specific algorithm
+        selector = instance_double(AssignmentV2::RoundRobinSelector)
+        allow(AssignmentV2::RoundRobinSelector).to receive(:new).and_return(selector)
+        allow(selector).to receive(:select_agent).and_return(agent2)
+      end
+
+      it 'assigns conversations successfully' do
+        # Create existing assignments
+        create_list(:conversation, 3, inbox: inbox, assignee: agent1, status: :open)
+        create(:conversation, inbox: inbox, assignee: agent2, status: :open)
+
+        new_conversation = create(:conversation, inbox: inbox, assignee: nil)
+
+        expect(service.perform_for_conversation(new_conversation)).to be true
+        expect(new_conversation.reload.assignee).to eq(agent2)
+      end
+
+      it 'handles different conversation statuses' do
+        # Create resolved conversations (should not count)
+        create_list(:conversation, 5, inbox: inbox, assignee: agent1, status: :resolved)
+
+        # Create open conversation
+        create(:conversation, inbox: inbox, assignee: agent2, status: :open)
+
+        new_conversation = create(:conversation, inbox: inbox, assignee: nil)
+
+        expect(service.perform_for_conversation(new_conversation)).to be true
+        expect(new_conversation.reload.assignee).to eq(agent2) # Selected by mock
+      end
+    end
+
+    context 'when error occurs' do
+      before do
+        # Mock the selector to return an agent
+        selector = instance_double(AssignmentV2::RoundRobinSelector)
+        allow(AssignmentV2::RoundRobinSelector).to receive(:new).and_return(selector)
+        allow(selector).to receive(:select_agent).and_return(agent1)
+      end
+
+      it 'returns false and logs error on assignment failure' do
+        allow(conversation).to receive(:update!).and_raise(ActiveRecord::RecordInvalid.new(conversation))
+        expect(Rails.logger).to receive(:error).with(/Failed to assign conversation/)
+
+        expect(service.perform_for_conversation(conversation)).to be false
+      end
+    end
+  end
+
+  describe '#perform_bulk_assignment' do
+    before do
+      create_list(:conversation, 5, inbox: inbox, assignee: nil, status: :open)
+
+      # Mock the selector to return agents
+      selector = instance_double(AssignmentV2::RoundRobinSelector)
+      allow(AssignmentV2::RoundRobinSelector).to receive(:new).and_return(selector)
+      call_count = 0
+      allow(selector).to receive(:select_agent) do
+        call_count += 1
+        call_count.odd? ? agent1 : agent2
+      end
+    end
+
+    context 'when policy is enabled' do
+      it 'assigns multiple conversations' do
+        assigned_count = service.perform_bulk_assignment(limit: 3)
+
+        expect(assigned_count).to eq(3)
+        expect(inbox.conversations.unassigned.count).to eq(2)
+      end
+
+      it 'respects conversation priority order' do
+        # Clear existing conversations first
+        Conversation.destroy_all
+
+        # Create conversations with different timestamps
+        old_conversation = create(:conversation, inbox: inbox, assignee: nil, status: :open, created_at: 1.hour.ago)
+        new_conversation = create(:conversation, inbox: inbox, assignee: nil, status: :open, created_at: 1.minute.ago)
+
+        assignment_policy.update!(conversation_priority: :earliest_created)
+
+        # Re-create service after policy change
+        service_with_priority = described_class.new(inbox: inbox)
+
+        service_with_priority.perform_bulk_assignment(limit: 1)
+
+        expect(old_conversation.reload.assignee).not_to be_nil
+        expect(new_conversation.reload.assignee).to be_nil
+      end
+
+      it 'handles longest_waiting priority' do
+        # Clear existing conversations first
+        Conversation.destroy_all
+
+        # Create conversations with different last activity
+        inactive_conversation = create(:conversation, inbox: inbox, assignee: nil, status: :open, last_activity_at: 2.hours.ago)
+        active_conversation = create(:conversation, inbox: inbox, assignee: nil, status: :open, last_activity_at: 5.minutes.ago)
+
+        assignment_policy.update!(conversation_priority: :longest_waiting)
+
+        # Re-create service after policy change
+        service_with_priority = described_class.new(inbox: inbox)
+
+        service_with_priority.perform_bulk_assignment(limit: 1)
+
+        expect(inactive_conversation.reload.assignee).not_to be_nil
+        expect(active_conversation.reload.assignee).to be_nil
+      end
+
+      it 'returns 0 when no conversations to assign' do
+        Conversation.find_each { |c| c.update!(assignee_id: agent1.id) }
+
+        expect(service.perform_bulk_assignment).to eq(0)
+      end
+    end
+
+    context 'when policy is disabled' do
+      before { assignment_policy.update!(enabled: false) }
+
+      it 'does not assign any conversations' do
+        expect(service.perform_bulk_assignment).to eq(0)
+        expect(inbox.conversations.unassigned.count).to eq(5)
+      end
+    end
+  end
+
+  describe 'enterprise capacity features' do
+    let(:conversation) { create(:conversation, inbox: inbox, assignee: nil) }
+
+    before do
+      # Mock enterprise availability
+      stub_const('Enterprise', Module.new)
+      stub_const('Enterprise::AssignmentV2::CapacityManager', Class.new)
+
+      # Mock the selector to return agent1
+      selector = instance_double(AssignmentV2::RoundRobinSelector)
+      allow(AssignmentV2::RoundRobinSelector).to receive(:new).and_return(selector)
+      allow(selector).to receive(:select_agent).and_return(agent1)
+    end
+
+    it 'uses round robin when enterprise features are available' do
+      expect(service.perform_for_conversation(conversation)).to be true
+      expect(conversation.reload.assignee).to eq(agent1)
+    end
+
+    it 'handles absence of enterprise features gracefully' do
+      # Remove enterprise constant
+      hide_const('Enterprise')
+
+      # Service should still work with round robin
+      expect(service.perform_for_conversation(conversation)).to be true
+      expect(conversation.reload.assignee).to eq(agent1)
+    end
+  end
+
+  describe 'cache management' do
+    it 'uses cache for round robin state' do
+      assignment_policy.update!(assignment_order: :round_robin)
+
+      # Mock the selector and round robin service
+      selector = instance_double(AssignmentV2::RoundRobinSelector)
+      allow(AssignmentV2::RoundRobinSelector).to receive(:new).and_return(selector)
+      allow(selector).to receive(:select_agent).and_return(agent1)
+
+      # Create and assign conversations
+      conversation1 = create(:conversation, inbox: inbox, assignee: nil)
+      service.perform_for_conversation(conversation1)
+
+      conversation2 = create(:conversation, inbox: inbox, assignee: nil)
+      service.perform_for_conversation(conversation2)
+
+      # Just verify assignments worked
+      expect(conversation1.reload.assignee).to eq(agent1)
+      expect(conversation2.reload.assignee).to eq(agent1)
+    end
+  end
+
+  describe 'edge cases' do
+    it 'handles inbox without policy gracefully' do
+      inbox_assignment_policy.destroy!
+      conversation = create(:conversation, inbox: inbox, assignee: nil)
+
+      expect(service.perform_for_conversation(conversation)).to be false
+    end
+
+    it 'handles empty agent list' do
+      allow(inbox).to receive(:available_agents).and_return(InboxMember.none)
+      conversation = create(:conversation, inbox: inbox, assignee: nil)
+
+      expect(service.perform_for_conversation(conversation)).to be false
+    end
+
+    it 'filters out agents without inbox membership' do
+      non_member_agent = create(:user, account: account, role: :agent, availability: :online)
+      conversation = create(:conversation, inbox: inbox, assignee: nil)
+
+      # Mock selector to return agent1 (who is a member)
+      selector = instance_double(AssignmentV2::RoundRobinSelector)
+      allow(AssignmentV2::RoundRobinSelector).to receive(:new).and_return(selector)
+      allow(selector).to receive(:select_agent).and_return(agent1)
+
+      expect(service.perform_for_conversation(conversation)).to be true
+      expect(conversation.reload.assignee).not_to eq(non_member_agent)
+      expect(conversation.reload.assignee).to eq(agent1)
+    end
+  end
+end

spec/services/assignment_v2/rate_limiter_spec.rb

@@ -0,0 +1,328 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe AssignmentV2::RateLimiter, type: :service do
+  before do
+    # Mock GlobalConfig to avoid InstallationConfig issues
+    allow(GlobalConfig).to receive(:get).and_return({})
+
+    # Ensure inbox_assignment_policy exists so the inbox has a policy
+    inbox_assignment_policy
+  end
+
+  let(:account) { create(:account) }
+  let(:policy) { create(:assignment_policy, account: account, fair_distribution_limit: 5, fair_distribution_window: 3600) }
+  let(:agent) { create(:user, account: account) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:inbox_assignment_policy) { create(:inbox_assignment_policy, inbox: inbox, assignment_policy: policy) }
+  let(:rate_limiter) { described_class.new(inbox: inbox, user: agent) }
+
+  describe '#initialize' do
+    it 'sets up rate limiter with inbox and user' do
+      expect(rate_limiter.instance_variable_get(:@inbox)).to eq(inbox)
+      expect(rate_limiter.instance_variable_get(:@user)).to eq(agent)
+    end
+  end
+
+  describe '#within_limits?' do
+    context 'when agent has no assignments in current window' do
+      it 'returns true' do
+        expect(rate_limiter.within_limits?).to be true
+      end
+    end
+
+    context 'when agent is below limit' do
+      before do
+        # Create 3 conversations assigned to agent in current window
+        3.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+        end
+      end
+
+      it 'returns true' do
+        expect(rate_limiter.within_limits?).to be true
+      end
+    end
+
+    context 'when agent reaches limit' do
+      before do
+        # Create 5 conversations assigned to agent (at the limit)
+        5.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+        end
+      end
+
+      it 'returns false' do
+        expect(rate_limiter.within_limits?).to be false
+      end
+    end
+
+    context 'when agent exceeds limit' do
+      before do
+        # Create 6 conversations assigned to agent (exceeding the limit)
+        6.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+        end
+      end
+
+      it 'returns false' do
+        expect(rate_limiter.within_limits?).to be false
+      end
+    end
+
+    context 'when assignments are from different inbox' do
+      let(:other_inbox) { create(:inbox, account: account) }
+
+      before do
+        # Create assignments in different inbox
+        5.times do
+          create(:conversation, inbox: other_inbox, assignee: agent, updated_at: Time.current)
+        end
+        # Create assignments in current inbox
+        2.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+        end
+      end
+
+      it 'only counts assignments from current inbox' do
+        expect(rate_limiter.within_limits?).to be true
+      end
+    end
+
+    context 'when assignments are outside time window' do
+      before do
+        # Create old assignments outside the window
+        5.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: 2.hours.ago)
+        end
+        # Create recent assignments within the window
+        2.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+        end
+      end
+
+      it 'only counts assignments within time window' do
+        expect(rate_limiter.within_limits?).to be true
+      end
+    end
+  end
+
+  describe '#status' do
+    it 'returns correct status for agent with no assignments' do
+      status = rate_limiter.status
+      expect(status[:current_count]).to eq(0)
+      expect(status[:within_limits]).to be true
+      expect(status[:limit]).to eq(5)
+    end
+
+    it 'returns correct count after assignments' do
+      3.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+      status = rate_limiter.status
+      expect(status[:current_count]).to eq(3)
+      expect(status[:within_limits]).to be true
+    end
+
+    it 'includes reset_at time' do
+      status = rate_limiter.status
+      expect(status[:reset_at]).to be_a(Time)
+      expect(status[:reset_at]).to be > Time.current
+    end
+
+    context 'when policy is disabled' do
+      before do
+        policy.update!(enabled: false)
+      end
+
+      it 'returns unlimited status' do
+        status = rate_limiter.status
+        expect(status[:within_limits]).to be true
+        expect(status[:current_count]).to eq(0)
+        expect(status[:limit]).to eq(Float::INFINITY)
+        expect(status[:reset_at]).to be_nil
+      end
+    end
+
+    context 'when no policy exists' do
+      let(:inbox_without_policy) { create(:inbox, account: account) }
+      let(:rate_limiter_no_policy) { described_class.new(inbox: inbox_without_policy, user: agent) }
+
+      it 'returns unlimited status' do
+        status = rate_limiter_no_policy.status
+        expect(status[:within_limits]).to be true
+        expect(status[:current_count]).to eq(0)
+        expect(status[:limit]).to eq(Float::INFINITY)
+        expect(status[:reset_at]).to be_nil
+      end
+    end
+  end
+
+  describe 'remaining assignments' do
+    it 'returns full limit when no assignments made' do
+      status = rate_limiter.status
+      expect(status[:limit] - status[:current_count]).to eq(5)
+    end
+
+    it 'returns correct remaining count' do
+      2.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+      status = rate_limiter.status
+      expect(status[:limit] - status[:current_count]).to eq(3)
+    end
+
+    it 'returns 0 when limit reached' do
+      5.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+      status = rate_limiter.status
+      expect(status[:limit] - status[:current_count]).to eq(0)
+    end
+
+    it 'returns negative when limit exceeded' do
+      6.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+      status = rate_limiter.status
+      expect(status[:limit] - status[:current_count]).to eq(-1)
+    end
+  end
+
+  describe 'assignment capacity checks' do
+    it 'returns true when agent has remaining capacity' do
+      2.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+      expect(rate_limiter.within_limits?).to be true
+    end
+
+    it 'returns false when agent has no capacity' do
+      5.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+      expect(rate_limiter.within_limits?).to be false
+    end
+
+    it 'correctly tracks multiple assignments' do
+      3.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+
+      status = rate_limiter.status
+      expect(status[:current_count]).to eq(3)
+      expect(status[:within_limits]).to be true
+      expect(status[:limit] - status[:current_count]).to eq(2)
+    end
+  end
+
+  describe 'multiple agents' do
+    let(:agent2) { create(:user, account: account) }
+    let(:rate_limiter2) { described_class.new(inbox: inbox, user: agent2) }
+
+    before do
+      2.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+      4.times do
+        create(:conversation, inbox: inbox, assignee: agent2, updated_at: Time.current)
+      end
+    end
+
+    it 'tracks status independently for each agent' do
+      status1 = rate_limiter.status
+      status2 = rate_limiter2.status
+
+      expect(status1[:current_count]).to eq(2)
+      expect(status1[:within_limits]).to be true
+      expect(status1[:limit] - status1[:current_count]).to eq(3)
+
+      expect(status2[:current_count]).to eq(4)
+      expect(status2[:within_limits]).to be true
+      expect(status2[:limit] - status2[:current_count]).to eq(1)
+    end
+  end
+
+  describe 'window timing' do
+    it 'calculates reset time correctly' do
+      # Mock current time to make test predictable
+      travel_to(Time.zone.parse('2024-01-01 10:30:00')) do
+        status = rate_limiter.status
+        reset_time = status[:reset_at]
+
+        expect(reset_time).to be_a(Time)
+        expect(reset_time).to be > Time.current
+        expect(reset_time - Time.current).to be <= 3600
+      end
+    end
+  end
+
+  describe 'window boundaries' do
+    it 'resets count in new window' do
+      # Set up assignments in current window
+      2.times do
+        create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+      end
+      expect(rate_limiter.status[:current_count]).to eq(2)
+
+      # Travel to next window (advance by window size)
+      travel(3601.seconds) do
+        expect(rate_limiter.status[:current_count]).to eq(0)
+        expect(rate_limiter.within_limits?).to be true
+      end
+    end
+
+    it 'does not count assignments from previous window' do
+      # Create assignments in previous window
+      travel_to(2.hours.ago) do
+        3.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+        end
+      end
+
+      # Check current window
+      expect(rate_limiter.status[:current_count]).to eq(0)
+      expect(rate_limiter.within_limits?).to be true
+    end
+  end
+
+  describe 'policy configuration' do
+    context 'with different fair_distribution_limit' do
+      let(:policy) { create(:assignment_policy, account: account, fair_distribution_limit: 10, fair_distribution_window: 3600) }
+
+      it 'uses policy limit' do
+        8.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+        end
+        expect(rate_limiter.within_limits?).to be true
+
+        2.times do
+          create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+        end
+        expect(rate_limiter.within_limits?).to be false
+      end
+    end
+
+    context 'with different fair_distribution_window' do
+      let(:policy) { create(:assignment_policy, account: account, fair_distribution_limit: 5, fair_distribution_window: 7200) }
+
+      it 'uses policy window' do
+        # Calculate the current window start based on the 2-hour window
+        current_time = Time.current
+        window_start_timestamp = (current_time.to_i / 7200) * 7200
+
+        # Create assignments 30 minutes after window start (definitely within window)
+        travel_to(Time.zone.at(window_start_timestamp + 30.minutes)) do
+          3.times do
+            create(:conversation, inbox: inbox, assignee: agent, updated_at: Time.current)
+          end
+        end
+
+        # These should still count toward the limit
+        expect(rate_limiter.status[:current_count]).to eq(3)
+        expect(rate_limiter.within_limits?).to be true
+      end
+    end
+  end
+end

spec/services/assignment_v2/round_robin_selector_spec.rb

@@ -0,0 +1,145 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe AssignmentV2::RoundRobinSelector, type: :service do
+  before do
+    # Mock GlobalConfig to avoid InstallationConfig issues
+    allow(GlobalConfig).to receive(:get).and_return({})
+    create(:inbox_member, inbox: inbox, user: user1)
+    create(:inbox_member, inbox: inbox, user: user2)
+    create(:inbox_member, inbox: inbox, user: user3)
+  end
+
+  let(:account) { create(:account) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:policy) { create(:assignment_policy, account: account) }
+  let(:user1) { create(:user, account: account, availability: :online) }
+  let(:user2) { create(:user, account: account, availability: :online) }
+  let(:user3) { create(:user, account: account, availability: :offline) }
+
+  describe '#select_agent' do
+    let(:selector) { described_class.new(inbox: inbox) }
+    let(:round_robin_service) { instance_double(AutoAssignment::InboxRoundRobinService) }
+    let(:available_agents) { InboxMember.where(inbox: inbox, user: [user1, user2]) }
+
+    before do
+      allow(AutoAssignment::InboxRoundRobinService).to receive(:new).with(inbox: inbox).and_return(round_robin_service)
+    end
+
+    context 'when Redis is available' do
+      before do
+        allow(round_robin_service).to receive(:available_agent).with(allowed_agent_ids: [user1.id.to_s, user2.id.to_s]).and_return(user1.id.to_s)
+      end
+
+      it 'returns an online agent' do
+        result = selector.select_agent(available_agents)
+        expect(result).to eq(user1)
+      end
+
+      it 'excludes offline agents' do
+        result = selector.select_agent(available_agents)
+        expect(result).not_to eq(user3)
+      end
+
+      it 'handles no available agent gracefully' do
+        allow(round_robin_service).to receive(:available_agent).with(allowed_agent_ids: [user1.id.to_s, user2.id.to_s]).and_return(nil)
+        result = selector.select_agent(available_agents)
+        expect(result).to be_nil
+      end
+    end
+
+    context 'when Redis fails' do
+      before do
+        allow(round_robin_service).to receive(:available_agent).and_raise(Redis::CannotConnectError)
+      end
+
+      it 'raises the error' do
+        expect { selector.select_agent(available_agents) }.to raise_error(Redis::CannotConnectError)
+      end
+    end
+
+    context 'with empty available agents' do
+      it 'returns nil when no agents are available' do
+        result = selector.select_agent(InboxMember.none)
+        expect(result).to be_nil
+      end
+    end
+
+    context 'with different user IDs' do
+      it 'correctly finds the inbox member by user_id' do
+        allow(round_robin_service).to receive(:available_agent).with(allowed_agent_ids: [user1.id.to_s, user2.id.to_s]).and_return(user2.id.to_s)
+
+        result = selector.select_agent(available_agents)
+        expect(result).to eq(user2)
+      end
+    end
+  end
+
+  describe '#add_agent_to_queue' do
+    let(:selector) { described_class.new(inbox: inbox) }
+    let(:round_robin_service) { instance_double(AutoAssignment::InboxRoundRobinService) }
+
+    before do
+      allow(AutoAssignment::InboxRoundRobinService).to receive(:new).with(inbox: inbox).and_return(round_robin_service)
+    end
+
+    it 'delegates to round robin service' do
+      expect(round_robin_service).to receive(:add_agent_to_queue).with(user1.id)
+      selector.add_agent_to_queue(user1.id)
+    end
+  end
+
+  describe '#remove_agent_from_queue' do
+    let(:selector) { described_class.new(inbox: inbox) }
+    let(:round_robin_service) { instance_double(AutoAssignment::InboxRoundRobinService) }
+
+    before do
+      allow(AutoAssignment::InboxRoundRobinService).to receive(:new).with(inbox: inbox).and_return(round_robin_service)
+    end
+
+    it 'delegates to round robin service' do
+      expect(round_robin_service).to receive(:remove_agent_from_queue).with(user1.id)
+      selector.remove_agent_from_queue(user1.id)
+    end
+  end
+
+  describe '#reset_queue' do
+    let(:selector) { described_class.new(inbox: inbox) }
+    let(:round_robin_service) { instance_double(AutoAssignment::InboxRoundRobinService) }
+
+    before do
+      allow(AutoAssignment::InboxRoundRobinService).to receive(:new).with(inbox: inbox).and_return(round_robin_service)
+    end
+
+    it 'delegates to round robin service' do
+      expect(round_robin_service).to receive(:reset_queue)
+      selector.reset_queue
+    end
+  end
+
+  describe 'edge cases' do
+    let(:selector) { described_class.new(inbox: inbox) }
+    let(:round_robin_service) { instance_double(AutoAssignment::InboxRoundRobinService) }
+    let(:available_agents) { InboxMember.where(inbox: inbox, user: [user1, user2]) }
+
+    before do
+      allow(AutoAssignment::InboxRoundRobinService).to receive(:new).with(inbox: inbox).and_return(round_robin_service)
+    end
+
+    it 'handles invalid user_id from round robin service' do
+      allow(round_robin_service).to receive(:available_agent).and_return('invalid_id')
+
+      result = selector.select_agent(available_agents)
+      expect(result).to be_nil
+    end
+
+    it 'handles user_id not in available agents' do
+      other_user = create(:user, account: account)
+      allow(round_robin_service).to receive(:available_agent).and_return(other_user.id.to_s)
+
+      result = selector.select_agent(available_agents)
+      expect(result).to be_nil
+    end
+  end
+end