merge next-main, keep both modifier associations and orphan handling

app/blueprints/api/v1/grid_artifact_blueprint.rb

@@ -3,7 +3,7 @@
 module Api
   module V1
     class GridArtifactBlueprint < ApiBlueprint
-      fields :level, :reroll_slot
+      fields :level, :reroll_slot, :orphaned
 
       field :collection_artifact_id
       field :out_of_sync, if: ->(_field, ga, _options) { ga.collection_artifact_id.present? } do |ga|

app/blueprints/api/v1/grid_summon_blueprint.rb

@@ -3,7 +3,7 @@
 module Api
   module V1
     class GridSummonBlueprint < ApiBlueprint
-      fields :main, :friend, :position, :quick_summon, :uncap_level, :transcendence_step
+      fields :main, :friend, :position, :quick_summon, :uncap_level, :transcendence_step, :orphaned
 
       field :collection_summon_id
       field :out_of_sync, if: ->(_field, gs, _options) { gs.collection_summon_id.present? } do |gs|

app/blueprints/api/v1/grid_weapon_blueprint.rb

@@ -3,7 +3,7 @@
 module Api
   module V1
     class GridWeaponBlueprint < ApiBlueprint
-      fields :mainhand, :position, :uncap_level, :transcendence_step, :element
+      fields :mainhand, :position, :uncap_level, :transcendence_step, :element, :orphaned
 
       field :collection_weapon_id
       field :out_of_sync, if: ->(_field, gw, _options) { gw.collection_weapon_id.present? } do |gw|

app/blueprints/api/v1/party_blueprint.rb

@@ -36,6 +36,10 @@ module Api
         end
       end
 
+      field :has_orphaned_items do |party|
+        party.has_orphaned_items?
+      end
+
       # For collection views
       view :preview do
         include_view :preview_objects # Characters, Weapons, Summons

app/controllers/api/v1/collection_artifacts_controller.rb

@@ -9,7 +9,7 @@ module Api
       before_action :set_collection_artifact_for_read, only: %i[show]
 
       # Write actions: require auth, use current_user
-      before_action :restrict_access, only: %i[create update destroy batch batch_destroy import]
+      before_action :restrict_access, only: %i[create update destroy batch batch_destroy import preview_sync]
       before_action :set_collection_artifact_for_write, only: %i[update destroy]
 
       def index
@@ -109,6 +109,8 @@ module Api
       #
       # @param data [Hash] Game data containing artifact list
       # @param update_existing [Boolean] Whether to update existing artifacts (default: false)
+      # @param is_full_inventory [Boolean] Whether this represents the user's complete inventory (default: false)
+      # @param reconcile_deletions [Boolean] Whether to delete items not in the import (default: false)
       def import
         game_data = import_params[:data]
 
@@ -119,7 +121,9 @@ module Api
         service = ArtifactImportService.new(
           current_user,
           game_data,
-          update_existing: import_params[:update_existing] == true
+          update_existing: import_params[:update_existing] == true,
+          is_full_inventory: import_params[:is_full_inventory] == true,
+          reconcile_deletions: import_params[:reconcile_deletions] == true
         )
 
         result = service.import
@@ -131,10 +135,41 @@ module Api
           created: result.created&.size || 0,
           updated: result.updated&.size || 0,
           skipped: result.skipped&.size || 0,
-          errors: result.errors || []
+          errors: result.errors || [],
+          reconciliation: result.reconciliation
         }, status: status
       end
 
+      # POST /collection/artifacts/preview_sync
+      # Previews what would be deleted in a full sync operation
+      #
+      # @param data [Hash] Game data containing artifact list
+      # @return [JSON] List of items that would be deleted
+      def preview_sync
+        game_data = import_params[:data]
+
+        unless game_data.present?
+          return render json: { error: 'No data provided' }, status: :bad_request
+        end
+
+        service = ArtifactImportService.new(current_user, game_data)
+        items_to_delete = service.preview_deletions
+
+        render json: {
+          will_delete: items_to_delete.map do |ca|
+            {
+              id: ca.id,
+              game_id: ca.game_id,
+              name: ca.artifact&.name_en,
+              granblue_id: ca.artifact&.granblue_id,
+              element: ca.element,
+              level: ca.level
+            }
+          end,
+          count: items_to_delete.size
+        }
+      end
+
       # DELETE /collection/artifacts/batch_destroy
       # Deletes multiple collection artifacts in a single request
       def batch_destroy
@@ -197,6 +232,8 @@ module Api
       def import_params
         {
           update_existing: params[:update_existing],
+          is_full_inventory: params[:is_full_inventory],
+          reconcile_deletions: params[:reconcile_deletions],
           data: params[:data]&.to_unsafe_h
         }
       end

app/controllers/api/v1/collection_summons_controller.rb

@@ -7,7 +7,7 @@ module Api
       before_action :set_collection_summon_for_read, only: %i[show]
 
       # Write actions: require auth, use current_user
-      before_action :restrict_access, only: %i[create update destroy batch batch_destroy import]
+      before_action :restrict_access, only: %i[create update destroy batch batch_destroy import preview_sync]
       before_action :set_collection_summon_for_write, only: %i[update destroy]
 
       def index
@@ -113,6 +113,8 @@ module Api
       #
       # @param data [Hash] Game data containing summon list
       # @param update_existing [Boolean] Whether to update existing summons (default: false)
+      # @param is_full_inventory [Boolean] Whether this represents the user's complete inventory (default: false)
+      # @param reconcile_deletions [Boolean] Whether to delete items not in the import (default: false)
       def import
         game_data = import_params[:data]
 
@@ -123,7 +125,9 @@ module Api
         service = SummonImportService.new(
           current_user,
           game_data,
-          update_existing: import_params[:update_existing] == true
+          update_existing: import_params[:update_existing] == true,
+          is_full_inventory: import_params[:is_full_inventory] == true,
+          reconcile_deletions: import_params[:reconcile_deletions] == true
         )
 
         result = service.import
@@ -135,10 +139,41 @@ module Api
           created: result.created.size,
           updated: result.updated.size,
           skipped: result.skipped.size,
-          errors: result.errors
+          errors: result.errors,
+          reconciliation: result.reconciliation
         }, status: status
       end
 
+      # POST /collection/summons/preview_sync
+      # Previews what would be deleted in a full sync operation
+      #
+      # @param data [Hash] Game data containing summon list
+      # @return [JSON] List of items that would be deleted
+      def preview_sync
+        game_data = import_params[:data]
+
+        unless game_data.present?
+          return render json: { error: 'No data provided' }, status: :bad_request
+        end
+
+        service = SummonImportService.new(current_user, game_data)
+        items_to_delete = service.preview_deletions
+
+        render json: {
+          will_delete: items_to_delete.map do |cs|
+            {
+              id: cs.id,
+              game_id: cs.game_id,
+              name: cs.summon&.name_en,
+              granblue_id: cs.summon&.granblue_id,
+              uncap_level: cs.uncap_level,
+              transcendence_step: cs.transcendence_step
+            }
+          end,
+          count: items_to_delete.size
+        }
+      end
+
       private
 
       def set_target_user
@@ -181,6 +216,8 @@ module Api
       def import_params
         {
           update_existing: params[:update_existing],
+          is_full_inventory: params[:is_full_inventory],
+          reconcile_deletions: params[:reconcile_deletions],
           data: params[:data]&.to_unsafe_h
         }
       end

app/controllers/api/v1/collection_weapons_controller.rb

@@ -7,7 +7,7 @@ module Api
       before_action :set_collection_weapon_for_read, only: %i[show]
 
       # Write actions: require auth, use current_user
-      before_action :restrict_access, only: %i[create update destroy batch batch_destroy import]
+      before_action :restrict_access, only: %i[create update destroy batch batch_destroy import preview_sync]
       before_action :set_collection_weapon_for_write, only: %i[update destroy]
 
       def index
@@ -121,6 +121,8 @@ module Api
       #
       # @param data [Hash] Game data containing weapon list
       # @param update_existing [Boolean] Whether to update existing weapons (default: false)
+      # @param is_full_inventory [Boolean] Whether this represents the user's complete inventory (default: false)
+      # @param reconcile_deletions [Boolean] Whether to delete items not in the import (default: false)
       def import
         game_data = import_params[:data]
 
@@ -131,7 +133,9 @@ module Api
         service = WeaponImportService.new(
           current_user,
           game_data,
-          update_existing: import_params[:update_existing] == true
+          update_existing: import_params[:update_existing] == true,
+          is_full_inventory: import_params[:is_full_inventory] == true,
+          reconcile_deletions: import_params[:reconcile_deletions] == true
         )
 
         result = service.import
@@ -143,10 +147,41 @@ module Api
           created: result.created.size,
           updated: result.updated.size,
           skipped: result.skipped.size,
-          errors: result.errors
+          errors: result.errors,
+          reconciliation: result.reconciliation
         }, status: status
       end
 
+      # POST /collection/weapons/preview_sync
+      # Previews what would be deleted in a full sync operation
+      #
+      # @param data [Hash] Game data containing weapon list
+      # @return [JSON] List of items that would be deleted
+      def preview_sync
+        game_data = import_params[:data]
+
+        unless game_data.present?
+          return render json: { error: 'No data provided' }, status: :bad_request
+        end
+
+        service = WeaponImportService.new(current_user, game_data)
+        items_to_delete = service.preview_deletions
+
+        render json: {
+          will_delete: items_to_delete.map do |cw|
+            {
+              id: cw.id,
+              game_id: cw.game_id,
+              name: cw.weapon&.name_en,
+              granblue_id: cw.weapon&.granblue_id,
+              uncap_level: cw.uncap_level,
+              transcendence_step: cw.transcendence_step
+            }
+          end,
+          count: items_to_delete.size
+        }
+      end
+
       private
 
       def set_target_user
@@ -199,6 +234,8 @@ module Api
       def import_params
         {
           update_existing: params[:update_existing],
+          is_full_inventory: params[:is_full_inventory],
+          reconcile_deletions: params[:reconcile_deletions],
           data: params[:data]&.to_unsafe_h
         }
       end

app/models/collection_artifact.rb

@@ -7,6 +7,10 @@ class CollectionArtifact < ApplicationRecord
   belongs_to :user
   belongs_to :artifact
 
+  has_many :grid_artifacts, dependent: :nullify
+
+  before_destroy :orphan_grid_items
+
   # Enums - using GranblueEnums::ELEMENTS values (excluding Null)
   # Wind: 1, Fire: 2, Water: 3, Earth: 4, Dark: 5, Light: 6
   enum :element, {
@@ -77,4 +81,12 @@ class CollectionArtifact < ApplicationRecord
   def quirk_artifact?
     artifact&.quirk?
   end
+
+  ##
+  # Marks all linked grid artifacts as orphaned before destroying this collection artifact.
+  #
+  # @return [void]
+  def orphan_grid_items
+    grid_artifacts.update_all(orphaned: true, collection_artifact_id: nil)
+  end
 end

app/models/collection_summon.rb

@@ -2,6 +2,10 @@ class CollectionSummon < ApplicationRecord
   belongs_to :user
   belongs_to :summon
 
+  has_many :grid_summons, dependent: :nullify
+
+  before_destroy :orphan_grid_items
+
   validates :uncap_level, inclusion: { in: 0..5 }
   validates :transcendence_step, inclusion: { in: 0..10 }
 
@@ -31,4 +35,12 @@ class CollectionSummon < ApplicationRecord
       errors.add(:transcendence_step, "not available for this summon")
     end
   end
+
+  ##
+  # Marks all linked grid summons as orphaned before destroying this collection summon.
+  #
+  # @return [void]
+  def orphan_grid_items
+    grid_summons.update_all(orphaned: true, collection_summon_id: nil)
+  end
 end

app/models/collection_weapon.rb

@@ -12,6 +12,10 @@ class CollectionWeapon < ApplicationRecord
   belongs_to :ax_modifier2, class_name: 'WeaponStatModifier', optional: true
   belongs_to :befoulment_modifier, class_name: 'WeaponStatModifier', optional: true
 
+  has_many :grid_weapons, dependent: :nullify
+
+  before_destroy :orphan_grid_items
+
   # Set defaults before validation so database defaults don't cause validation failures
   attribute :awakening_level, :integer, default: 1
 
@@ -162,4 +166,12 @@ class CollectionWeapon < ApplicationRecord
       errors.add(:transcendence_step, "not available for this weapon") if transcendence_step > 0
     end
   end
+
+  ##
+  # Marks all linked grid weapons as orphaned before destroying this collection weapon.
+  #
+  # @return [void]
+  def orphan_grid_items
+    grid_weapons.update_all(orphaned: true, collection_weapon_id: nil)
+  end
 end

app/models/grid_artifact.rb

@@ -11,6 +11,10 @@ class GridArtifact < ApplicationRecord
   has_one :party, through: :grid_character
   has_one :character, through: :grid_character
 
+  # Orphan status scopes
+  scope :orphaned, -> { where(orphaned: true) }
+  scope :not_orphaned, -> { where(orphaned: false) }
+
   # Enums - using GranblueEnums::ELEMENTS values (excluding Null)
   # Wind: 1, Fire: 2, Water: 3, Earth: 4, Dark: 5, Light: 6
   enum :element, {
@@ -55,6 +59,14 @@ class GridArtifact < ApplicationRecord
     quirk_artifact? ? proficiency : artifact&.proficiency
   end
 
+  ##
+  # Marks this grid artifact as orphaned and clears its collection link.
+  #
+  # @return [Boolean] true if the update succeeded
+  def mark_orphaned!
+    update!(orphaned: true, collection_artifact_id: nil)
+  end
+
   ##
   # Syncs customizations from the linked collection artifact.
   #

app/models/grid_summon.rb

@@ -19,6 +19,10 @@ class GridSummon < ApplicationRecord
   belongs_to :collection_summon, optional: true
   validates_presence_of :party
 
+  # Orphan status scopes
+  scope :orphaned, -> { where(orphaned: true) }
+  scope :not_orphaned, -> { where(orphaned: false) }
+
   # Validate that position is provided.
   validates :position, presence: true
   validate :compatible_with_position, on: :create
@@ -40,6 +44,14 @@ class GridSummon < ApplicationRecord
     GridSummonBlueprint
   end
 
+  ##
+  # Marks this grid summon as orphaned and clears its collection link.
+  #
+  # @return [Boolean] true if the update succeeded
+  def mark_orphaned!
+    update!(orphaned: true, collection_summon_id: nil)
+  end
+
   ##
   # Syncs customizations from the linked collection summon.
   #

app/models/grid_weapon.rb

@@ -43,6 +43,10 @@ class GridWeapon < ApplicationRecord
   belongs_to :ax_modifier2, class_name: 'WeaponStatModifier', optional: true
   belongs_to :befoulment_modifier, class_name: 'WeaponStatModifier', optional: true
 
+  # Orphan status scopes
+  scope :orphaned, -> { where(orphaned: true) }
+  scope :not_orphaned, -> { where(orphaned: false) }
+
   # Validate that uncap_level is present and numeric, transcendence_step is optional but must be numeric if present.
   validates :uncap_level, presence: true, numericality: { only_integer: true }
   validates :transcendence_step, numericality: { only_integer: true }, allow_nil: true
@@ -100,6 +104,14 @@ class GridWeapon < ApplicationRecord
     true
   end
 
+  ##
+  # Marks this grid weapon as orphaned and clears its collection link.
+  #
+  # @return [Boolean] true if the update succeeded
+  def mark_orphaned!
+    update!(orphaned: true, collection_weapon_id: nil)
+  end
+
   ##
   # Checks if grid weapon is out of sync with collection.
   #

app/models/party.rb

@@ -274,6 +274,19 @@ class Party < ApplicationRecord
     end
   end
 
+  ##
+  # Checks if the party has any orphaned grid items.
+  #
+  # An orphaned item is one whose linked collection item has been deleted,
+  # indicating the user no longer has that item in their game inventory.
+  #
+  # @return [Boolean] true if the party has orphaned weapons, summons, or artifacts.
+  def has_orphaned_items?
+    weapons.orphaned.exists? ||
+      summons.orphaned.exists? ||
+      characters.joins(:grid_artifact).where(grid_artifacts: { orphaned: true }).exists?
+  end
+
   ##
   # Determines if the party meets the minimum requirements for preview generation.
   #

app/services/artifact_import_service.rb

@@ -12,7 +12,7 @@
 #   end
 #
 class ArtifactImportService
-  Result = Struct.new(:success?, :created, :updated, :skipped, :errors, keyword_init: true)
+  Result = Struct.new(:success?, :created, :updated, :skipped, :errors, :reconciliation, keyword_init: true)
 
   # Game element values to our element enum values
   # Game: 1=Fire, 2=Water, 3=Earth, 4=Wind, 5=Light, 6=Dark
@@ -30,10 +30,38 @@ class ArtifactImportService
     @user = user
     @game_data = game_data
     @update_existing = options[:update_existing] || false
+    @is_full_inventory = options[:is_full_inventory] || false
+    @reconcile_deletions = options[:reconcile_deletions] || false
     @created = []
     @updated = []
     @skipped = []
     @errors = []
+    @processed_game_ids = []
+  end
+
+  ##
+  # Previews what would be deleted in a sync operation.
+  # Does not modify any data, just returns items that would be removed.
+  #
+  # @return [Array<CollectionArtifact>] Collection artifacts that would be deleted
+  def preview_deletions
+    items = extract_items
+    return [] if items.empty?
+
+    # Extract all game_ids from the import data
+    # Artifacts use 'id' directly (not nested in 'param')
+    game_ids = items.filter_map do |item|
+      data = item.is_a?(Hash) ? item.with_indifferent_access : item
+      data['id'].to_s if data['id'].present?
+    end
+
+    return [] if game_ids.empty?
+
+    # Find collection artifacts with game_ids NOT in the import
+    @user.collection_artifacts
+         .includes(:artifact)
+         .where.not(game_id: nil)
+         .where.not(game_id: game_ids)
   end
 
   ##
@@ -43,7 +71,14 @@ class ArtifactImportService
   def import
     items = extract_items
     if items.empty?
-      return Result.new(success?: false, created: [], updated: [], skipped: [], errors: ['No artifact items found in data'])
+      return Result.new(
+        success?: false,
+        created: [],
+        updated: [],
+        skipped: [],
+        errors: ['No artifact items found in data'],
+        reconciliation: nil
+      )
     end
 
     # Preload artifacts and existing collection artifacts to avoid N+1 queries
@@ -58,12 +93,19 @@ class ArtifactImportService
       end
     end
 
+    # Handle deletion reconciliation if requested
+    reconciliation_result = nil
+    if @reconcile_deletions && @is_full_inventory && @processed_game_ids.any?
+      reconciliation_result = reconcile_deletions
+    end
+
     Result.new(
       success?: @errors.empty?,
       created: @created,
       updated: @updated,
       skipped: @skipped,
-      errors: @errors
+      errors: @errors,
+      reconciliation: reconciliation_result
     )
   end
 
@@ -92,6 +134,10 @@ class ArtifactImportService
     # Handle both string and symbol keys from params
     data = item.is_a?(Hash) ? item.with_indifferent_access : item
 
+    # Track this game_id as processed (for reconciliation)
+    game_id = data['id']
+    @processed_game_ids << game_id.to_s if game_id.present?
+
     artifact = find_artifact(data['artifact_id'])
     unless artifact
       @errors << { game_id: data['id'], artifact_id: data['artifact_id'], error: 'Artifact not found' }
@@ -193,4 +239,34 @@ class ArtifactImportService
       'level' => level.to_i
     }
   end
+
+  ##
+  # Reconciles deletions by removing collection artifacts not in the processed list.
+  # Only called when @is_full_inventory and @reconcile_deletions are both true.
+  #
+  # @return [Hash] Reconciliation result with deleted count and orphaned grid item IDs
+  def reconcile_deletions
+    # Find collection artifacts with game_ids NOT in our processed list
+    missing = @user.collection_artifacts
+                   .where.not(game_id: nil)
+                   .where.not(game_id: @processed_game_ids)
+
+    deleted_count = 0
+    orphaned_grid_item_ids = []
+
+    missing.find_each do |coll_artifact|
+      # Collect IDs of grid items that will be orphaned
+      grid_artifact_ids = GridArtifact.where(collection_artifact_id: coll_artifact.id).pluck(:id)
+      orphaned_grid_item_ids.concat(grid_artifact_ids)
+
+      # The before_destroy callback on CollectionArtifact will mark grid items as orphaned
+      coll_artifact.destroy
+      deleted_count += 1
+    end
+
+    {
+      deleted: deleted_count,
+      orphaned_grid_items: orphaned_grid_item_ids
+    }
+  end
 end

app/services/summon_import_service.rb

@@ -12,16 +12,43 @@
 #   end
 #
 class SummonImportService
-  Result = Struct.new(:success?, :created, :updated, :skipped, :errors, keyword_init: true)
+  Result = Struct.new(:success?, :created, :updated, :skipped, :errors, :reconciliation, keyword_init: true)
 
   def initialize(user, game_data, options = {})
     @user = user
     @game_data = game_data
     @update_existing = options[:update_existing] || false
+    @is_full_inventory = options[:is_full_inventory] || false
+    @reconcile_deletions = options[:reconcile_deletions] || false
     @created = []
     @updated = []
     @skipped = []
     @errors = []
+    @processed_game_ids = []
+  end
+
+  ##
+  # Previews what would be deleted in a sync operation.
+  # Does not modify any data, just returns items that would be removed.
+  #
+  # @return [Array<CollectionSummon>] Collection summons that would be deleted
+  def preview_deletions
+    items = extract_items
+    return [] if items.empty?
+
+    # Extract all game_ids from the import data
+    game_ids = items.filter_map do |item|
+      param = item['param'] || {}
+      param['id'].to_s if param['id'].present?
+    end
+
+    return [] if game_ids.empty?
+
+    # Find collection summons with game_ids NOT in the import
+    @user.collection_summons
+         .includes(:summon)
+         .where.not(game_id: nil)
+         .where.not(game_id: game_ids)
   end
 
   ##
@@ -30,7 +57,16 @@ class SummonImportService
   # @return [Result] Import result with counts and errors
   def import
     items = extract_items
-    return Result.new(success?: false, created: [], updated: [], skipped: [], errors: ['No summon items found in data']) if items.empty?
+    if items.empty?
+      return Result.new(
+        success?: false,
+        created: [],
+        updated: [],
+        skipped: [],
+        errors: ['No summon items found in data'],
+        reconciliation: nil
+      )
+    end
 
     ActiveRecord::Base.transaction do
       items.each_with_index do |item, index|
@@ -40,12 +76,19 @@ class SummonImportService
       end
     end
 
+    # Handle deletion reconciliation if requested
+    reconciliation_result = nil
+    if @reconcile_deletions && @is_full_inventory && @processed_game_ids.any?
+      reconciliation_result = reconcile_deletions
+    end
+
     Result.new(
       success?: @errors.empty?,
       created: @created,
       updated: @updated,
       skipped: @skipped,
-      errors: @errors
+      errors: @errors,
+      reconciliation: reconciliation_result
     )
   end
 
@@ -68,6 +111,9 @@ class SummonImportService
     granblue_id = image_id || master['id']
     game_id = param['id']
 
+    # Track this game_id as processed (for reconciliation)
+    @processed_game_ids << game_id.to_s if game_id.present?
+
     summon = find_summon(granblue_id)
     unless summon
       @errors << { game_id: game_id, granblue_id: granblue_id, error: 'Summon not found' }
@@ -143,4 +189,34 @@ class SummonImportService
     value = phase.to_i
     value.clamp(0, 10)
   end
+
+  ##
+  # Reconciles deletions by removing collection summons not in the processed list.
+  # Only called when @is_full_inventory and @reconcile_deletions are both true.
+  #
+  # @return [Hash] Reconciliation result with deleted count and orphaned grid item IDs
+  def reconcile_deletions
+    # Find collection summons with game_ids NOT in our processed list
+    missing = @user.collection_summons
+                   .where.not(game_id: nil)
+                   .where.not(game_id: @processed_game_ids)
+
+    deleted_count = 0
+    orphaned_grid_item_ids = []
+
+    missing.find_each do |coll_summon|
+      # Collect IDs of grid items that will be orphaned
+      grid_summon_ids = GridSummon.where(collection_summon_id: coll_summon.id).pluck(:id)
+      orphaned_grid_item_ids.concat(grid_summon_ids)
+
+      # The before_destroy callback on CollectionSummon will mark grid items as orphaned
+      coll_summon.destroy
+      deleted_count += 1
+    end
+
+    {
+      deleted: deleted_count,
+      orphaned_grid_items: orphaned_grid_item_ids
+    }
+  end
 end

app/services/weapon_import_service.rb

@@ -12,7 +12,7 @@
 #   end
 #
 class WeaponImportService
-  Result = Struct.new(:success?, :created, :updated, :skipped, :errors, keyword_init: true)
+  Result = Struct.new(:success?, :created, :updated, :skipped, :errors, :reconciliation, keyword_init: true)
 
   # Game awakening form to our slug mapping
   AWAKENING_FORM_MAPPING = {
@@ -28,12 +28,39 @@ class WeaponImportService
     @user = user
     @game_data = game_data
     @update_existing = options[:update_existing] || false
+    @is_full_inventory = options[:is_full_inventory] || false
+    @reconcile_deletions = options[:reconcile_deletions] || false
     @created = []
     @updated = []
     @skipped = []
     @errors = []
     @awakening_cache = {}
     @modifier_cache = {}
+    @processed_game_ids = []
+  end
+
+  ##
+  # Previews what would be deleted in a sync operation.
+  # Does not modify any data, just returns items that would be removed.
+  #
+  # @return [Array<CollectionWeapon>] Collection weapons that would be deleted
+  def preview_deletions
+    items = extract_items
+    return [] if items.empty?
+
+    # Extract all game_ids from the import data
+    game_ids = items.filter_map do |item|
+      param = item['param'] || {}
+      param['id'].to_s if param['id'].present?
+    end
+
+    return [] if game_ids.empty?
+
+    # Find collection weapons with game_ids NOT in the import
+    @user.collection_weapons
+         .includes(:weapon)
+         .where.not(game_id: nil)
+         .where.not(game_id: game_ids)
   end
 
   ##
@@ -42,7 +69,16 @@ class WeaponImportService
   # @return [Result] Import result with counts and errors
   def import
     items = extract_items
-    return Result.new(success?: false, created: [], updated: [], skipped: [], errors: ['No weapon items found in data']) if items.empty?
+    if items.empty?
+      return Result.new(
+        success?: false,
+        created: [],
+        updated: [],
+        skipped: [],
+        errors: ['No weapon items found in data'],
+        reconciliation: nil
+      )
+    end
 
     ActiveRecord::Base.transaction do
       items.each_with_index do |item, index|
@@ -52,12 +88,19 @@ class WeaponImportService
       end
     end
 
+    # Handle deletion reconciliation if requested
+    reconciliation_result = nil
+    if @reconcile_deletions && @is_full_inventory && @processed_game_ids.any?
+      reconciliation_result = reconcile_deletions
+    end
+
     Result.new(
       success?: @errors.empty?,
       created: @created,
       updated: @updated,
       skipped: @skipped,
-      errors: @errors
+      errors: @errors,
+      reconciliation: reconciliation_result
     )
   end
 
@@ -78,6 +121,9 @@ class WeaponImportService
     granblue_id = param['image_id'] || master['id']
     game_id = param['id']
 
+    # Track this game_id as processed (for reconciliation)
+    @processed_game_ids << game_id.to_s if game_id.present?
+
     weapon = find_weapon(granblue_id)
     unless weapon
       @errors << { game_id: game_id, granblue_id: granblue_id, error: 'Weapon not found' }
@@ -307,4 +353,34 @@ class WeaponImportService
 
     nil
   end
+
+  ##
+  # Reconciles deletions by removing collection weapons not in the processed list.
+  # Only called when @is_full_inventory and @reconcile_deletions are both true.
+  #
+  # @return [Hash] Reconciliation result with deleted count and orphaned grid item IDs
+  def reconcile_deletions
+    # Find collection weapons with game_ids NOT in our processed list
+    missing = @user.collection_weapons
+                   .where.not(game_id: nil)
+                   .where.not(game_id: @processed_game_ids)
+
+    deleted_count = 0
+    orphaned_grid_item_ids = []
+
+    missing.find_each do |coll_weapon|
+      # Collect IDs of grid items that will be orphaned
+      grid_weapon_ids = GridWeapon.where(collection_weapon_id: coll_weapon.id).pluck(:id)
+      orphaned_grid_item_ids.concat(grid_weapon_ids)
+
+      # The before_destroy callback on CollectionWeapon will mark grid items as orphaned
+      coll_weapon.destroy
+      deleted_count += 1
+    end
+
+    {
+      deleted: deleted_count,
+      orphaned_grid_items: orphaned_grid_item_ids
+    }
+  end
 end

config/routes.rb

@@ -276,6 +276,7 @@ Rails.application.routes.draw do
           post :batch
           delete :batch_destroy
           post :import
+          post :preview_sync
         end
       end
       resources :summons, only: [:create, :update, :destroy], controller: '/api/v1/collection_summons' do
@@ -283,6 +284,7 @@ Rails.application.routes.draw do
           post :batch
           delete :batch_destroy
           post :import
+          post :preview_sync
         end
       end
       resources :job_accessories, controller: '/api/v1/collection_job_accessories',
@@ -292,6 +294,7 @@ Rails.application.routes.draw do
           post :batch
           delete :batch_destroy
           post :import
+          post :preview_sync
         end
       end
     end

db/migrate/20251223000000_add_orphaned_to_grid_items.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class AddOrphanedToGridItems < ActiveRecord::Migration[8.0]
+  def change
+    add_column :grid_weapons, :orphaned, :boolean, default: false, null: false
+    add_column :grid_summons, :orphaned, :boolean, default: false, null: false
+    add_column :grid_artifacts, :orphaned, :boolean, default: false, null: false
+
+    add_index :grid_weapons, :orphaned
+    add_index :grid_summons, :orphaned
+    add_index :grid_artifacts, :orphaned
+  end
+end