From 5597cab95c266b2ac6c6f34e97d87034d5822c1b Mon Sep 17 00:00:00 2001
From: Justin Edmund <justin@jedmund.com>
Date: Mon, 5 Jan 2026 02:39:32 -0800
Subject: [PATCH] Party sharing into crews (#207)

* add party_shares table and model with associations

* add party share errors and blueprint

* add party shares controller and routes

* include shared parties in listings and show

* add party share factory and model specs

* add party shares controller specs

* include shares in party response for owners

* add crew shared_parties endpoint
---
 app/blueprints/api/v1/party_blueprint.rb      |  15 ++
 .../api/v1/party_share_blueprint.rb           |  57 +++++++
 app/controllers/api/v1/api_controller.rb      |   5 +
 app/controllers/api/v1/crews_controller.rb    |  20 ++-
 app/controllers/api/v1/parties_controller.rb  |   8 +-
 .../api/v1/party_shares_controller.rb         |  67 +++++++++
 app/errors/party_share_errors.rb              |  77 ++++++++++
 app/models/crew.rb                            |   2 +
 app/models/party.rb                           |  34 +++++
 app/models/party_share.rb                     |  63 ++++++++
 app/models/user.rb                            |   1 +
 app/services/party_query_builder.rb           |  19 ++-
 config/routes.rb                              |   6 +
 db/data_schema.rb                             |   2 +-
 .../20260105053753_create_party_shares.rb     |  21 +++
 db/schema.rb                                  |  19 ++-
 spec/factories/party_shares.rb                |  17 +++
 spec/models/party_share_spec.rb               | 121 +++++++++++++++
 spec/requests/api/v1/crews_spec.rb            |  55 +++++++
 spec/requests/api/v1/party_shares_spec.rb     | 139 ++++++++++++++++++
 20 files changed, 739 insertions(+), 9 deletions(-)
 create mode 100644 app/blueprints/api/v1/party_share_blueprint.rb
 create mode 100644 app/controllers/api/v1/party_shares_controller.rb
 create mode 100644 app/errors/party_share_errors.rb
 create mode 100644 app/models/party_share.rb
 create mode 100644 db/migrate/20260105053753_create_party_shares.rb
 create mode 100644 spec/factories/party_shares.rb
 create mode 100644 spec/models/party_share_spec.rb
 create mode 100644 spec/requests/api/v1/party_shares_spec.rb

diff --git a/app/blueprints/api/v1/party_blueprint.rb b/app/blueprints/api/v1/party_blueprint.rb
index 395b699..2e8df6b 100644
--- a/app/blueprints/api/v1/party_blueprint.rb
+++ b/app/blueprints/api/v1/party_blueprint.rb
@@ -52,6 +52,21 @@ module Api
         include_view :nested_objects # Characters, Weapons, Summons
         include_view :remix_metadata # Remixes, Source party
         include_view :job_metadata # Accessory, Skills, Guidebooks
+
+        # Shares (only visible to owner)
+        field :shares, if: ->(_field_name, party, options) {
+          options[:current_user] && party.user_id == options[:current_user].id
+        } do |party|
+          party.party_shares.includes(:shareable).map do |share|
+            {
+              id: share.id,
+              shareable_type: share.shareable_type.downcase,
+              shareable_id: share.shareable_id,
+              shareable_name: share.shareable.try(:name),
+              created_at: share.created_at
+            }
+          end
+        end
       end
 
       # Primary object associations
diff --git a/app/blueprints/api/v1/party_share_blueprint.rb b/app/blueprints/api/v1/party_share_blueprint.rb
new file mode 100644
index 0000000..4bbc73d
--- /dev/null
+++ b/app/blueprints/api/v1/party_share_blueprint.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module Api
+  module V1
+    class PartyShareBlueprint < ApiBlueprint
+      identifier :id
+
+      fields :created_at
+
+      field :shareable_type do |share|
+        share.shareable_type.downcase
+      end
+
+      field :shareable_id do |share|
+        share.shareable_id
+      end
+
+      view :with_shareable do
+        fields :created_at
+
+        field :shareable_type do |share|
+          share.shareable_type.downcase
+        end
+
+        field :shareable do |share|
+          case share.shareable_type
+          when 'Crew'
+            CrewBlueprint.render_as_hash(share.shareable, view: :minimal)
+          end
+        end
+
+        field :shared_by do |share|
+          UserBlueprint.render_as_hash(share.shared_by, view: :minimal)
+        end
+      end
+
+      view :with_party do
+        fields :created_at
+
+        field :shareable_type do |share|
+          share.shareable_type.downcase
+        end
+
+        field :party do |share|
+          PartyBlueprint.render_as_hash(share.party, view: :preview)
+        end
+
+        field :shareable do |share|
+          case share.shareable_type
+          when 'Crew'
+            CrewBlueprint.render_as_hash(share.shareable, view: :minimal)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/app/controllers/api/v1/api_controller.rb b/app/controllers/api/v1/api_controller.rb
index 1efc0bf..e57a07b 100644
--- a/app/controllers/api/v1/api_controller.rb
+++ b/app/controllers/api/v1/api_controller.rb
@@ -44,6 +44,11 @@ module Api
         render json: e.to_hash, status: e.http_status
       end
 
+      # Party share errors
+      rescue_from PartyShareErrors::PartyShareError do |e|
+        render json: e.to_hash, status: e.http_status
+      end
+
       rescue_from GranblueError do |e|
         render_error(e)
       end
diff --git a/app/controllers/api/v1/crews_controller.rb b/app/controllers/api/v1/crews_controller.rb
index 7879063..89ac110 100644
--- a/app/controllers/api/v1/crews_controller.rb
+++ b/app/controllers/api/v1/crews_controller.rb
@@ -6,9 +6,9 @@ module Api
       include CrewAuthorizationConcern
 
       before_action :restrict_access
-      before_action :set_crew, only: %i[show update members roster leave transfer_captain]
-      before_action :require_crew!, only: %i[show update members roster]
-      before_action :authorize_crew_member!, only: %i[show members]
+      before_action :set_crew, only: %i[show update members roster leave transfer_captain shared_parties]
+      before_action :require_crew!, only: %i[show update members roster shared_parties]
+      before_action :authorize_crew_member!, only: %i[show members shared_parties]
       before_action :authorize_crew_officer!, only: %i[update roster]
       before_action :authorize_crew_captain!, only: %i[transfer_captain]
 
@@ -106,6 +106,20 @@ module Api
         render json: CrewBlueprint.render(@crew.reload, view: :full, root: :crew, current_user: current_user)
       end
 
+      # GET /crew/shared_parties
+      # Returns parties that have been shared with this crew
+      def shared_parties
+        parties = @crew.shared_parties
+                       .includes(:user, :job, :raid)
+                       .order(created_at: :desc)
+                       .paginate(page: params[:page], per_page: page_size)
+
+        render json: {
+          parties: PartyBlueprint.render_as_hash(parties, view: :preview, current_user: current_user),
+          meta: pagination_meta(parties)
+        }
+      end
+
       private
 
       def set_crew
diff --git a/app/controllers/api/v1/parties_controller.rb b/app/controllers/api/v1/parties_controller.rb
index 229e772..d9fa825 100644
--- a/app/controllers/api/v1/parties_controller.rb
+++ b/app/controllers/api/v1/parties_controller.rb
@@ -56,11 +56,15 @@ module Api
       end
 
       # Shows a specific party.
+      # Uses viewable_by? to check visibility including crew sharing.
+      # Also allows access via edit_key for anonymous parties.
       def show
-        return render_unauthorized_response if @party.private? && (!current_user || not_owner?)
+        unless @party.viewable_by?(current_user) || !not_owner?
+          return render_unauthorized_response
+        end
 
         if @party
-          render json: PartyBlueprint.render(@party, view: :full, root: :party)
+          render json: PartyBlueprint.render(@party, view: :full, root: :party, current_user: current_user)
         else
           render_not_found_response('project')
         end
diff --git a/app/controllers/api/v1/party_shares_controller.rb b/app/controllers/api/v1/party_shares_controller.rb
new file mode 100644
index 0000000..915c765
--- /dev/null
+++ b/app/controllers/api/v1/party_shares_controller.rb
@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+module Api
+  module V1
+    class PartySharesController < Api::V1::ApiController
+      before_action :restrict_access
+      before_action :set_party
+      before_action :authorize_party_owner!
+      before_action :set_party_share, only: [:destroy]
+
+      # GET /parties/:party_id/shares
+      # List all shares for a party (only for owner)
+      def index
+        shares = @party.party_shares.includes(:shareable, :shared_by)
+        render json: PartyShareBlueprint.render(shares, view: :with_shareable, root: :shares)
+      end
+
+      # POST /parties/:party_id/shares
+      # Share a party with the current user's crew
+      def create
+        crew = current_user.crew
+        raise PartyShareErrors::NotInCrewError unless crew
+
+        # For now, users can only share to their own crew
+        # Future: support party_share_params[:crew_id] for sharing to other crews
+        share = PartyShare.new(
+          party: @party,
+          shareable: crew,
+          shared_by: current_user
+        )
+
+        if share.save
+          render json: PartyShareBlueprint.render(share, view: :with_shareable, root: :share), status: :created
+        else
+          render_validation_error_response(share)
+        end
+      end
+
+      # DELETE /parties/:party_id/shares/:id
+      # Remove a share
+      def destroy
+        @party_share.destroy!
+        head :no_content
+      end
+
+      private
+
+      def set_party
+        @party = Party.find(params[:party_id])
+      end
+
+      def set_party_share
+        @party_share = @party.party_shares.find(params[:id])
+      end
+
+      def authorize_party_owner!
+        return if @party.user_id == current_user.id
+
+        raise Api::V1::UnauthorizedError
+      end
+
+      def party_share_params
+        params.require(:share).permit(:crew_id)
+      end
+    end
+  end
+end
diff --git a/app/errors/party_share_errors.rb b/app/errors/party_share_errors.rb
new file mode 100644
index 0000000..a2f591c
--- /dev/null
+++ b/app/errors/party_share_errors.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+module PartyShareErrors
+  # Base class for all party share-related errors
+  class PartyShareError < StandardError
+    def http_status
+      :unprocessable_entity
+    end
+
+    def code
+      self.class.name.demodulize.underscore
+    end
+
+    def to_hash
+      {
+        message: message,
+        code: code
+      }
+    end
+  end
+
+  class NotInCrewError < PartyShareError
+    def http_status
+      :unprocessable_entity
+    end
+
+    def code
+      'not_in_crew'
+    end
+
+    def message
+      'You must be in a crew to share parties'
+    end
+  end
+
+  class NotPartyOwnerError < PartyShareError
+    def http_status
+      :forbidden
+    end
+
+    def code
+      'not_party_owner'
+    end
+
+    def message
+      'Only the party owner can share this party'
+    end
+  end
+
+  class AlreadySharedError < PartyShareError
+    def http_status
+      :conflict
+    end
+
+    def code
+      'already_shared'
+    end
+
+    def message
+      'This party is already shared with this crew'
+    end
+  end
+
+  class CanOnlyShareToOwnCrewError < PartyShareError
+    def http_status
+      :forbidden
+    end
+
+    def code
+      'can_only_share_to_own_crew'
+    end
+
+    def message
+      'You can only share parties with your own crew'
+    end
+  end
+end
diff --git a/app/models/crew.rb b/app/models/crew.rb
index 915c14a..c59ceae 100644
--- a/app/models/crew.rb
+++ b/app/models/crew.rb
@@ -10,6 +10,8 @@ class Crew < ApplicationRecord
   has_many :crew_gw_participations, dependent: :destroy
   has_many :gw_events, through: :crew_gw_participations
   has_many :phantom_players, dependent: :destroy
+  has_many :party_shares, as: :shareable, dependent: :destroy
+  has_many :shared_parties, through: :party_shares, source: :party
 
   validates :name, presence: true, length: { maximum: 100 }
   validates :gamertag, length: { maximum: 50 }, allow_nil: true
diff --git a/app/models/party.rb b/app/models/party.rb
index 17780e6..bd55f36 100644
--- a/app/models/party.rb
+++ b/app/models/party.rb
@@ -156,6 +156,8 @@ class Party < ApplicationRecord
            inverse_of: :party
 
   has_many :favorites, dependent: :destroy
+  has_many :party_shares, dependent: :destroy
+  has_many :shared_crews, through: :party_shares, source: :shareable, source_type: 'Crew'
 
   accepts_nested_attributes_for :characters
   accepts_nested_attributes_for :summons
@@ -261,6 +263,38 @@ class Party < ApplicationRecord
     visibility == 3
   end
 
+  ##
+  # Checks if the party is shared with a specific crew.
+  #
+  # @param crew [Crew] the crew to check.
+  # @return [Boolean] true if shared with the crew; false otherwise.
+  def shared_with_crew?(crew)
+    return false unless crew
+
+    party_shares.exists?(shareable_type: 'Crew', shareable_id: crew.id)
+  end
+
+  ##
+  # Checks if a user can view this party based on visibility and sharing rules.
+  # A user can view if:
+  # - The party is public
+  # - The party is unlisted (accessible via direct link)
+  # - They own the party
+  # - They are an admin
+  # - The party is shared with a crew they belong to
+  #
+  # @param user [User, nil] the user to check.
+  # @return [Boolean] true if the user can view the party; false otherwise.
+  def viewable_by?(user)
+    return true if public?
+    return true if unlisted?
+    return true if user && user_id == user.id
+    return true if user&.admin?
+    return true if user&.crew && shared_with_crew?(user.crew)
+
+    false
+  end
+
   ##
   # Checks if the party is favorited by a given user.
   #
diff --git a/app/models/party_share.rb b/app/models/party_share.rb
new file mode 100644
index 0000000..ef735dc
--- /dev/null
+++ b/app/models/party_share.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+##
+# PartyShare represents a sharing relationship between a party and a group (e.g., a crew).
+# It allows party owners to share their parties with specific groups, granting view access
+# to members of those groups without changing the party's base visibility.
+#
+# @!attribute [rw] party
+#   @return [Party] the party being shared.
+# @!attribute [rw] shareable
+#   @return [Crew] the polymorphic group the party is shared with.
+# @!attribute [rw] shared_by
+#   @return [User] the user who created this share.
+class PartyShare < ApplicationRecord
+  # Associations
+  belongs_to :party
+  belongs_to :shareable, polymorphic: true
+  belongs_to :shared_by, class_name: 'User'
+
+  # Validations
+  validates :party_id, uniqueness: {
+    scope: [:shareable_type, :shareable_id],
+    message: 'has already been shared with this group'
+  }
+  validate :owner_can_share
+  validate :sharer_is_member_of_shareable
+
+  # Scopes
+  scope :for_crew, ->(crew) { where(shareable_type: 'Crew', shareable_id: crew.id) }
+  scope :for_crews, ->(crew_ids) { where(shareable_type: 'Crew', shareable_id: crew_ids) }
+  scope :for_party, ->(party) { where(party_id: party.id) }
+
+  ##
+  # Returns the blueprint class for serialization.
+  #
+  # @return [Class] the PartyShareBlueprint class.
+  def blueprint
+    PartyShareBlueprint
+  end
+
+  private
+
+  ##
+  # Validates that only the party owner can share the party.
+  #
+  # @return [void]
+  def owner_can_share
+    return if party&.user_id == shared_by_id
+
+    errors.add(:shared_by, 'must be the party owner')
+  end
+
+  ##
+  # Validates that the sharer is a member of the group they're sharing to.
+  #
+  # @return [void]
+  def sharer_is_member_of_shareable
+    return unless shareable_type == 'Crew'
+    return if shareable&.active_memberships&.exists?(user_id: shared_by_id)
+
+    errors.add(:shareable, 'you must be a member of this crew')
+  end
+end
diff --git a/app/models/user.rb b/app/models/user.rb
index ac2c8aa..9f24428 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -19,6 +19,7 @@ class User < ApplicationRecord
   has_many :crew_invitations, dependent: :destroy
   has_many :pending_crew_invitations, -> { where(status: :pending) }, class_name: 'CrewInvitation'
   has_many :sent_crew_invitations, class_name: 'CrewInvitation', foreign_key: :invited_by_id, dependent: :nullify
+  has_many :party_shares, foreign_key: :shared_by_id, dependent: :destroy
 
   ##### ActiveRecord Validations
   validates :username,
diff --git a/app/services/party_query_builder.rb b/app/services/party_query_builder.rb
index 600ed9c..2b77f2c 100644
--- a/app/services/party_query_builder.rb
+++ b/app/services/party_query_builder.rb
@@ -61,15 +61,30 @@ class PartyQueryBuilder
   end
 
   # Applies privacy settings based on whether the current user is an admin.
+  # Also includes parties shared with the current user's crew.
   def apply_privacy_settings(query)
     # If the options say to skip privacy filtering (e.g. when viewing your own profile),
     # then return the query unchanged.
     return query if @options[:skip_privacy]
 
-    # Otherwise, if not admin, only show public parties.
+    # Admins can see everything
     return query if @current_user&.admin?
 
-    query.where('visibility = ?', 1)
+    # Build conditions for what the user can see:
+    # 1. Public parties (visibility = 1)
+    # 2. Parties shared with their crew (if they're in a crew)
+    if @current_user&.crew
+      # User is in a crew - include public parties OR parties shared with their crew
+      query.where(<<-SQL.squish, 1, 'Crew', @current_user.crew.id)
+        visibility = ? OR parties.id IN (
+          SELECT party_id FROM party_shares
+          WHERE shareable_type = ? AND shareable_id = ?
+        )
+      SQL
+    else
+      # User is not in a crew - only show public parties
+      query.where('visibility = ?', 1)
+    end
   end
 
   # Builds a hash of filtering conditions from the params.
diff --git a/config/routes.rb b/config/routes.rb
index 9cf0772..189b5cb 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -70,6 +70,11 @@ Rails.application.routes.draw do
     post 'parties/:id/regenerate_preview', to: 'parties#regenerate_preview'
     post 'parties/:id/remix', to: 'parties#remix'
 
+    # Party shares
+    resources :parties, only: [] do
+      resources :shares, controller: 'party_shares', only: [:index, :create, :destroy]
+    end
+
     put 'parties/:id/jobs', to: 'jobs#update_job'
     put 'parties/:id/job_skills', to: 'jobs#update_job_skills'
     delete 'parties/:id/job_skills', to: 'jobs#destroy_job_skill'
@@ -180,6 +185,7 @@ Rails.application.routes.draw do
       member do
         get :members
         get :roster
+        get :shared_parties
         post :leave
       end
     end
diff --git a/db/data_schema.rb b/db/data_schema.rb
index bb71a21..bc95d29 100644
--- a/db/data_schema.rb
+++ b/db/data_schema.rb
@@ -1 +1 @@
-DataMigrate::Data.define(version: 20251230000002)
+DataMigrate::Data.define(version: 20260104000002)
diff --git a/db/migrate/20260105053753_create_party_shares.rb b/db/migrate/20260105053753_create_party_shares.rb
new file mode 100644
index 0000000..a1de39a
--- /dev/null
+++ b/db/migrate/20260105053753_create_party_shares.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+class CreatePartyShares < ActiveRecord::Migration[8.0]
+  def change
+    create_table :party_shares, id: :uuid do |t|
+      t.references :party, type: :uuid, null: false, foreign_key: true
+      t.references :shareable, type: :uuid, null: false, polymorphic: true
+      t.references :shared_by, type: :uuid, null: false, foreign_key: { to_table: :users }
+
+      t.timestamps
+    end
+
+    # Prevent duplicate shares of the same party to the same group
+    add_index :party_shares, [:party_id, :shareable_type, :shareable_id],
+              unique: true,
+              name: 'index_party_shares_unique_per_shareable'
+
+    # Quick lookup of all parties shared with a specific group
+    add_index :party_shares, [:shareable_type, :shareable_id]
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 9442424..7bcee92 100644
--- a/db/schema.rb
+++ b/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_30_000004) do
+ActiveRecord::Schema[8.0].define(version: 2026_01_05_053753) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "btree_gin"
   enable_extension "pg_catalog.plpgsql"
@@ -677,6 +677,20 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_30_000004) do
     t.index ["weapons_count", "characters_count", "summons_count"], name: "index_parties_on_counters"
   end
 
+  create_table "party_shares", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
+    t.uuid "party_id", null: false
+    t.string "shareable_type", null: false
+    t.uuid "shareable_id", null: false
+    t.uuid "shared_by_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["party_id", "shareable_type", "shareable_id"], name: "index_party_shares_unique_per_shareable", unique: true
+    t.index ["party_id"], name: "index_party_shares_on_party_id"
+    t.index ["shareable_type", "shareable_id"], name: "index_party_shares_on_shareable"
+    t.index ["shareable_type", "shareable_id"], name: "index_party_shares_on_shareable_type_and_shareable_id"
+    t.index ["shared_by_id"], name: "index_party_shares_on_shared_by_id"
+  end
+
   create_table "pg_search_documents", force: :cascade do |t|
     t.text "content"
     t.string "granblue_id"
@@ -1029,6 +1043,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_30_000004) do
     t.string "forged_from"
     t.uuid "forge_chain_id"
     t.integer "forge_order"
+    t.integer "max_exorcism_level"
     t.index ["forge_chain_id"], name: "index_weapons_on_forge_chain_id"
     t.index ["forged_from"], name: "index_weapons_on_forged_from"
     t.index ["gacha"], name: "index_weapons_on_gacha"
@@ -1111,6 +1126,8 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_30_000004) do
   add_foreign_key "parties", "parties", column: "source_party_id"
   add_foreign_key "parties", "raids"
   add_foreign_key "parties", "users"
+  add_foreign_key "party_shares", "parties"
+  add_foreign_key "party_shares", "users", column: "shared_by_id"
   add_foreign_key "phantom_players", "crew_memberships", column: "claimed_from_membership_id"
   add_foreign_key "phantom_players", "crews"
   add_foreign_key "phantom_players", "users", column: "claimed_by_id"
diff --git a/spec/factories/party_shares.rb b/spec/factories/party_shares.rb
new file mode 100644
index 0000000..1c506ea
--- /dev/null
+++ b/spec/factories/party_shares.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :party_share do
+    party
+    association :shareable, factory: :crew
+    association :shared_by, factory: :user
+
+    # Ensure the shared_by user owns the party and is in the crew
+    after(:build) do |party_share|
+      party_share.party.user = party_share.shared_by
+      unless party_share.shareable.crew_memberships.exists?(user: party_share.shared_by, retired: false)
+        create(:crew_membership, crew: party_share.shareable, user: party_share.shared_by)
+      end
+    end
+  end
+end
diff --git a/spec/models/party_share_spec.rb b/spec/models/party_share_spec.rb
new file mode 100644
index 0000000..79f4de8
--- /dev/null
+++ b/spec/models/party_share_spec.rb
@@ -0,0 +1,121 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe PartyShare, type: :model do
+  describe 'associations' do
+    it { should belong_to(:party) }
+    it { should belong_to(:shareable) }
+    it { should belong_to(:shared_by).class_name('User') }
+  end
+
+  describe 'validations' do
+    let(:crew) { create(:crew) }
+    let(:user) { create(:user) }
+    let(:party) { create(:party, user: user) }
+
+    before do
+      create(:crew_membership, crew: crew, user: user)
+    end
+
+    it 'validates uniqueness of party scoped to shareable' do
+      create(:party_share, party: party, shareable: crew, shared_by: user)
+
+      duplicate = build(:party_share, party: party, shareable: crew, shared_by: user)
+      expect(duplicate).not_to be_valid
+      expect(duplicate.errors[:party_id]).to include('has already been shared with this group')
+    end
+
+    it 'allows same party to be shared with different crews' do
+      crew2 = create(:crew)
+      create(:crew_membership, crew: crew2, user: user)
+
+      share1 = create(:party_share, party: party, shareable: crew, shared_by: user)
+      share2 = build(:party_share, party: party, shareable: crew2, shared_by: user)
+
+      expect(share2).to be_valid
+    end
+  end
+
+  describe 'owner validation' do
+    let(:crew) { create(:crew) }
+    let(:owner) { create(:user) }
+    let(:other_user) { create(:user) }
+    let(:party) { create(:party, user: owner) }
+
+    before do
+      create(:crew_membership, crew: crew, user: owner)
+      create(:crew_membership, crew: crew, user: other_user)
+    end
+
+    it 'allows owner to share their party' do
+      share = build(:party_share, party: party, shareable: crew, shared_by: owner)
+      expect(share).to be_valid
+    end
+
+    it 'prevents non-owner from sharing the party' do
+      share = build(:party_share, party: party, shareable: crew, shared_by: other_user)
+      expect(share).not_to be_valid
+      expect(share.errors[:shared_by]).to include('must be the party owner')
+    end
+  end
+
+  describe 'crew membership validation' do
+    let(:crew) { create(:crew) }
+    let(:user) { create(:user) }
+    let(:party) { create(:party, user: user) }
+
+    it 'allows sharing to a crew the user belongs to' do
+      create(:crew_membership, crew: crew, user: user)
+      share = build(:party_share, party: party, shareable: crew, shared_by: user)
+      expect(share).to be_valid
+    end
+
+    it 'prevents sharing to a crew the user does not belong to' do
+      share = build(:party_share, party: party, shareable: crew, shared_by: user)
+      expect(share).not_to be_valid
+      expect(share.errors[:shareable]).to include('you must be a member of this crew')
+    end
+
+    it 'prevents sharing if user has retired from crew' do
+      membership = create(:crew_membership, crew: crew, user: user)
+      membership.retire!
+
+      share = build(:party_share, party: party, shareable: crew, shared_by: user)
+      expect(share).not_to be_valid
+    end
+  end
+
+  describe 'scopes' do
+    let(:crew1) { create(:crew) }
+    let(:crew2) { create(:crew) }
+    let(:user) { create(:user) }
+    let(:party1) { create(:party, user: user) }
+    let(:party2) { create(:party, user: user) }
+
+    before do
+      create(:crew_membership, crew: crew1, user: user)
+      create(:crew_membership, crew: crew2, user: user)
+    end
+
+    describe '.for_crew' do
+      it 'returns shares for a specific crew' do
+        share1 = create(:party_share, party: party1, shareable: crew1, shared_by: user)
+        share2 = create(:party_share, party: party2, shareable: crew2, shared_by: user)
+
+        expect(PartyShare.for_crew(crew1)).to include(share1)
+        expect(PartyShare.for_crew(crew1)).not_to include(share2)
+      end
+    end
+
+    describe '.for_party' do
+      it 'returns shares for a specific party' do
+        share1 = create(:party_share, party: party1, shareable: crew1, shared_by: user)
+        share2 = create(:party_share, party: party2, shareable: crew1, shared_by: user)
+
+        expect(PartyShare.for_party(party1)).to include(share1)
+        expect(PartyShare.for_party(party1)).not_to include(share2)
+      end
+    end
+  end
+end
diff --git a/spec/requests/api/v1/crews_spec.rb b/spec/requests/api/v1/crews_spec.rb
index a21038c..7cbcdc5 100644
--- a/spec/requests/api/v1/crews_spec.rb
+++ b/spec/requests/api/v1/crews_spec.rb
@@ -261,4 +261,59 @@ RSpec.describe 'Api::V1::Crews', type: :request do
       end
     end
   end
+
+  describe 'GET /api/v1/crew/shared_parties' do
+    let(:crew) { create(:crew) }
+    let!(:membership) { create(:crew_membership, crew: crew, user: user, role: :member) }
+
+    context 'as crew member' do
+      it 'returns parties shared with the crew' do
+        other_user = create(:user)
+        create(:crew_membership, crew: crew, user: other_user)
+        party = create(:party, user: other_user, visibility: 3) # private
+        create(:party_share, party: party, shareable: crew, shared_by: other_user)
+
+        get '/api/v1/crew/shared_parties', headers: auth_headers
+
+        expect(response).to have_http_status(:ok)
+        json = JSON.parse(response.body)
+        expect(json['parties'].length).to eq(1)
+        expect(json['parties'][0]['id']).to eq(party.id)
+      end
+
+      it 'returns empty array when no shared parties' do
+        get '/api/v1/crew/shared_parties', headers: auth_headers
+
+        expect(response).to have_http_status(:ok)
+        json = JSON.parse(response.body)
+        expect(json['parties']).to eq([])
+      end
+
+      it 'includes pagination meta' do
+        get '/api/v1/crew/shared_parties', headers: auth_headers
+
+        expect(response).to have_http_status(:ok)
+        json = JSON.parse(response.body)
+        expect(json['meta']).to include('count', 'total_pages', 'per_page')
+      end
+    end
+
+    context 'when not in a crew' do
+      before { membership.retire! }
+
+      it 'returns not found' do
+        get '/api/v1/crew/shared_parties', headers: auth_headers
+
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+
+    context 'without authentication' do
+      it 'returns unauthorized' do
+        get '/api/v1/crew/shared_parties'
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+  end
 end
diff --git a/spec/requests/api/v1/party_shares_spec.rb b/spec/requests/api/v1/party_shares_spec.rb
new file mode 100644
index 0000000..64ba752
--- /dev/null
+++ b/spec/requests/api/v1/party_shares_spec.rb
@@ -0,0 +1,139 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Api::V1::PartyShares', type: :request do
+  let(:user) { create(:user) }
+  let(:access_token) do
+    Doorkeeper::AccessToken.create!(resource_owner_id: user.id, expires_in: 30.days, scopes: 'public')
+  end
+  let(:auth_headers) { { 'Authorization' => "Bearer #{access_token.token}" } }
+
+  let(:crew) { create(:crew) }
+  let(:party) { create(:party, user: user) }
+
+  before do
+    create(:crew_membership, crew: crew, user: user)
+  end
+
+  describe 'GET /api/v1/parties/:party_id/shares' do
+    context 'as party owner' do
+      it 'returns list of shares' do
+        share = create(:party_share, party: party, shareable: crew, shared_by: user)
+
+        get "/api/v1/parties/#{party.id}/shares", headers: auth_headers
+
+        expect(response).to have_http_status(:ok)
+        json = JSON.parse(response.body)
+        expect(json['shares'].length).to eq(1)
+        expect(json['shares'][0]['id']).to eq(share.id)
+      end
+
+      it 'returns empty array when no shares' do
+        get "/api/v1/parties/#{party.id}/shares", headers: auth_headers
+
+        expect(response).to have_http_status(:ok)
+        json = JSON.parse(response.body)
+        expect(json['shares']).to eq([])
+      end
+    end
+
+    context 'as non-owner' do
+      let(:other_user) { create(:user) }
+      let(:other_token) do
+        Doorkeeper::AccessToken.create!(resource_owner_id: other_user.id, expires_in: 30.days, scopes: 'public')
+      end
+      let(:other_headers) { { 'Authorization' => "Bearer #{other_token.token}" } }
+
+      it 'returns unauthorized' do
+        get "/api/v1/parties/#{party.id}/shares", headers: other_headers
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'without authentication' do
+      it 'returns unauthorized' do
+        get "/api/v1/parties/#{party.id}/shares"
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+  end
+
+  describe 'POST /api/v1/parties/:party_id/shares' do
+    context 'as party owner in a crew' do
+      it 'shares the party with their crew' do
+        post "/api/v1/parties/#{party.id}/shares", headers: auth_headers
+
+        expect(response).to have_http_status(:created)
+        json = JSON.parse(response.body)
+        expect(json['share']['shareable_type']).to eq('crew')
+        expect(json['share']['shareable']['id']).to eq(crew.id)
+      end
+
+      it 'returns error when already shared' do
+        create(:party_share, party: party, shareable: crew, shared_by: user)
+
+        post "/api/v1/parties/#{party.id}/shares", headers: auth_headers
+
+        expect(response).to have_http_status(:unprocessable_entity)
+      end
+    end
+
+    context 'as party owner not in a crew' do
+      before do
+        user.active_crew_membership.retire!
+      end
+
+      it 'returns not_in_crew error' do
+        post "/api/v1/parties/#{party.id}/shares", headers: auth_headers
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        json = JSON.parse(response.body)
+        expect(json['code']).to eq('not_in_crew')
+      end
+    end
+
+    context 'as non-owner' do
+      let(:other_user) { create(:user) }
+      let(:other_token) do
+        Doorkeeper::AccessToken.create!(resource_owner_id: other_user.id, expires_in: 30.days, scopes: 'public')
+      end
+      let(:other_headers) { { 'Authorization' => "Bearer #{other_token.token}" } }
+
+      it 'returns unauthorized' do
+        post "/api/v1/parties/#{party.id}/shares", headers: other_headers
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+  end
+
+  describe 'DELETE /api/v1/parties/:party_id/shares/:id' do
+    let!(:share) { create(:party_share, party: party, shareable: crew, shared_by: user) }
+
+    context 'as party owner' do
+      it 'removes the share' do
+        delete "/api/v1/parties/#{party.id}/shares/#{share.id}", headers: auth_headers
+
+        expect(response).to have_http_status(:no_content)
+        expect(PartyShare.exists?(share.id)).to be false
+      end
+    end
+
+    context 'as non-owner' do
+      let(:other_user) { create(:user) }
+      let(:other_token) do
+        Doorkeeper::AccessToken.create!(resource_owner_id: other_user.id, expires_in: 30.days, scopes: 'public')
+      end
+      let(:other_headers) { { 'Authorization' => "Bearer #{other_token.token}" } }
+
+      it 'returns unauthorized' do
+        delete "/api/v1/parties/#{party.id}/shares/#{share.id}", headers: other_headers
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+  end
+end