add crew and crew_membership models with migrations

- crews table with name, gamertag, granblue_crew_id, description
- crew_memberships with role enum (member/vice_captain/captain)
- partial unique index ensures one active crew per user
- updated User model with crew associations and helper methods

app/models/crew.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+class Crew < ApplicationRecord
+  has_many :crew_memberships, dependent: :destroy
+  has_many :users, through: :crew_memberships
+  has_many :active_memberships, -> { where(retired: false) }, class_name: 'CrewMembership'
+  has_many :active_members, through: :active_memberships, source: :user
+
+  validates :name, presence: true, length: { maximum: 100 }
+  validates :gamertag, length: { maximum: 50 }, allow_nil: true
+  validates :granblue_crew_id, uniqueness: true, allow_nil: true
+
+  def captain
+    crew_memberships.find_by(role: :captain, retired: false)&.user
+  end
+
+  def vice_captains
+    crew_memberships.where(role: :vice_captain, retired: false).includes(:user).map(&:user)
+  end
+
+  def officers
+    crew_memberships.where(role: [:captain, :vice_captain], retired: false).includes(:user).map(&:user)
+  end
+
+  def member_count
+    active_memberships.count
+  end
+
+  def blueprint
+    CrewBlueprint
+  end
+end

app/models/crew_membership.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+class CrewMembership < ApplicationRecord
+  belongs_to :crew
+  belongs_to :user
+
+  enum :role, { member: 0, vice_captain: 1, captain: 2 }
+
+  validates :user_id, uniqueness: { scope: :crew_id }
+  validate :one_active_crew_per_user, on: :create
+  validate :captain_limit
+  validate :vice_captain_limit
+
+  scope :active, -> { where(retired: false) }
+  scope :retired, -> { where(retired: true) }
+
+  def retire!
+    update!(retired: true, retired_at: Time.current, role: :member)
+  end
+
+  def blueprint
+    CrewMembershipBlueprint
+  end
+
+  private
+
+  def one_active_crew_per_user
+    return if retired
+
+    if CrewMembership.where(user_id: user_id, retired: false).where.not(id: id).exists?
+      errors.add(:user, 'can only be in one active crew')
+    end
+  end
+
+  def captain_limit
+    return unless captain? && !retired
+
+    existing = crew.crew_memberships.where(role: :captain, retired: false).where.not(id: id)
+    errors.add(:role, 'crew can only have one captain') if existing.exists?
+  end
+
+  def vice_captain_limit
+    return unless vice_captain? && !retired
+
+    existing = crew.crew_memberships.where(role: :vice_captain, retired: false).where.not(id: id)
+    errors.add(:role, 'crew can only have up to 3 vice captains') if existing.count >= 3
+  end
+end

app/models/user.rb

@@ -12,8 +12,10 @@ class User < ApplicationRecord
   has_many :collection_job_accessories, dependent: :destroy
   has_many :collection_artifacts, dependent: :destroy
 
-  # Note: The crew association will be added when crews feature is implemented
-  # belongs_to :crew, optional: true
+  # Crew associations
+  has_many :crew_memberships, dependent: :destroy
+  has_one :active_crew_membership, -> { where(retired: false) }, class_name: 'CrewMembership'
+  has_one :crew, through: :active_crew_membership
 
   ##### ActiveRecord Validations
   validates :username,
@@ -76,9 +78,7 @@ class User < ApplicationRecord
     when 'everyone'
       true
     when 'crew_only'
-      # Will be implemented when crew feature is added:
-      # viewer.present? && crew.present? && viewer.crew_id == crew_id
-      false # For now, crew_only acts like private until crews are implemented
+      viewer.present? && in_same_crew_as?(viewer)
     when 'private_collection'
       false
     else
@@ -86,11 +86,26 @@ class User < ApplicationRecord
     end
   end
 
-  # Helper method to check if user is in same crew (placeholder for future)
+  # Check if user is in same crew as another user
   def in_same_crew_as?(other_user)
-    # Will be implemented when crew feature is added:
-    # return false unless other_user.present?
-    # crew.present? && other_user.crew_id == crew_id
-    false
+    return false unless other_user.present?
+    return false unless crew.present? && other_user.crew.present?
+
+    crew.id == other_user.crew.id
+  end
+
+  # Get the user's crew role
+  def crew_role
+    active_crew_membership&.role
+  end
+
+  # Check if user is a crew officer (captain or vice captain)
+  def crew_officer?
+    crew_role.in?(%w[captain vice_captain])
+  end
+
+  # Check if user is a crew captain
+  def crew_captain?
+    crew_role == 'captain'
   end
 end

db/migrate/20251204063628_create_crews.rb

@@ -0,0 +1,15 @@
+class CreateCrews < ActiveRecord::Migration[8.0]
+  def change
+    create_table :crews, id: :uuid do |t|
+      t.string :name, null: false
+      t.string :gamertag
+      t.string :granblue_crew_id
+      t.text :description
+
+      t.timestamps
+    end
+
+    add_index :crews, :name
+    add_index :crews, :granblue_crew_id, unique: true, where: "granblue_crew_id IS NOT NULL"
+  end
+end

db/migrate/20251204063649_create_crew_memberships.rb

@@ -0,0 +1,20 @@
+class CreateCrewMemberships < ActiveRecord::Migration[8.0]
+  def change
+    create_table :crew_memberships, id: :uuid do |t|
+      t.references :crew, type: :uuid, null: false, foreign_key: true
+      t.references :user, type: :uuid, null: false, foreign_key: true
+      t.integer :role, default: 0, null: false
+      t.boolean :retired, default: false, null: false
+      t.datetime :retired_at
+
+      t.timestamps
+    end
+
+    add_index :crew_memberships, [:crew_id, :user_id], unique: true
+    add_index :crew_memberships, [:crew_id, :role]
+    add_index :crew_memberships, [:user_id],
+              unique: true,
+              where: "retired = false",
+              name: "index_crew_memberships_on_active_user"
+  end
+end

db/migrate/20251204063711_add_show_gamertag_to_users.rb

@@ -0,0 +1,5 @@
+class AddShowGamertagToUsers < ActiveRecord::Migration[8.0]
+  def change
+    add_column :users, :show_gamertag, :boolean, default: true, null: false
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_12_03_221115) do
+ActiveRecord::Schema[8.0].define(version: 2025_12_04_063711) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "btree_gin"
   enable_extension "pg_catalog.plpgsql"
@@ -234,6 +234,32 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_03_221115) do
     t.index ["weapon_key4_id"], name: "index_collection_weapons_on_weapon_key4_id"
   end
 
+  create_table "crew_memberships", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
+    t.uuid "crew_id", null: false
+    t.uuid "user_id", null: false
+    t.integer "role", default: 0, null: false
+    t.boolean "retired", default: false, null: false
+    t.datetime "retired_at"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["crew_id", "role"], name: "index_crew_memberships_on_crew_id_and_role"
+    t.index ["crew_id", "user_id"], name: "index_crew_memberships_on_crew_id_and_user_id", unique: true
+    t.index ["crew_id"], name: "index_crew_memberships_on_crew_id"
+    t.index ["user_id"], name: "index_crew_memberships_on_active_user", unique: true, where: "(retired = false)"
+    t.index ["user_id"], name: "index_crew_memberships_on_user_id"
+  end
+
+  create_table "crews", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
+    t.string "name", null: false
+    t.string "gamertag"
+    t.string "granblue_crew_id"
+    t.text "description"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["granblue_crew_id"], name: "index_crews_on_granblue_crew_id", unique: true, where: "(granblue_crew_id IS NOT NULL)"
+    t.index ["name"], name: "index_crews_on_name"
+  end
+
   create_table "data_migrations", primary_key: "version", id: :string, force: :cascade do |t|
   end
 
@@ -718,6 +744,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_03_221115) do
     t.string "theme", default: "system", null: false
     t.integer "role", default: 1, null: false
     t.integer "collection_privacy", default: 0, null: false
+    t.boolean "show_gamertag", default: true, null: false
     t.index ["collection_privacy"], name: "index_users_on_collection_privacy"
   end
 
@@ -847,6 +874,8 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_03_221115) do
   add_foreign_key "collection_weapons", "weapon_keys", column: "weapon_key3_id"
   add_foreign_key "collection_weapons", "weapon_keys", column: "weapon_key4_id"
   add_foreign_key "collection_weapons", "weapons"
+  add_foreign_key "crew_memberships", "crews"
+  add_foreign_key "crew_memberships", "users"
   add_foreign_key "effects", "effects", column: "effect_family_id"
   add_foreign_key "favorites", "parties"
   add_foreign_key "favorites", "users"