AI: address issue #479

Co-authored-by: Codex Night Worker <codex-night@localhost>
Reviewed-on: #480
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/AGENTS.md

@@ -424,7 +424,7 @@ races according to the target constraint's business meaning.
   and JSON keys are generally snake_case.
 - Preserve existing HTTP status conventions:
   `:unauthorized` for no user, `:forbidden` for insufficient role or banned
-  user, `:not_found` for missing records, and `:unprocessable_entity` for
+  user, `:not_found` for missing records, and `:unprocessable_content` for
   validation failures.
 - For diagnostic or internal helper JSON, prefer a deliberately light response
   shape over full representation classes when callers only need identifiers,

backend/app/controllers/application_controller.rb

@@ -95,7 +95,7 @@ class ApplicationController < ActionController::API
     render_validation_error base: ['すでに存在してゐます．']
   end
 
-  def render_validation_error record = nil, fields: { }, base: [], status: :unprocessable_entity
+  def render_validation_error record = nil, fields: { }, base: [], status: :unprocessable_content
     errors = { }
 
     if record

backend/app/controllers/counts_exports_controller.rb

@@ -18,7 +18,7 @@ class CountsExportsController < ApplicationController
     render json: { error: 'private_condition' }, status: :forbidden
   rescue CountsTableQuery::TooManyColumns
     render json: { error: 'too_many_columns', max_columns: CountsTableQuery::MAX_COLUMNS },
-           status: :unprocessable_entity
+           status: :unprocessable_content
   rescue ActiveRecord::StatementTimeout
     render json: { error: 'counts_query_timeout' }, status: :service_unavailable
   rescue ArgumentError, TypeError, KeyError, JSON::ParserError
@@ -63,7 +63,7 @@ class CountsExportsController < ApplicationController
     render json: { error: 'private_condition' }, status: :forbidden
   rescue CountsTableQuery::TooManyColumns
     render json: { error: 'too_many_columns', max_columns: CountsTableQuery::MAX_COLUMNS },
-        status: :unprocessable_entity
+        status: :unprocessable_content
   rescue ActiveRecord::StatementTimeout
     render json: { error: 'counts_query_timeout' }, status: :service_unavailable
   rescue ArgumentError, TypeError, KeyError, JSON::ParserError
@@ -107,7 +107,7 @@ class CountsExportsController < ApplicationController
     render json: { error: 'private_condition' }, status: :forbidden
   rescue CountsTableQuery::TooManyColumns
     render json: { error: 'too_many_columns', max_columns: CountsTableQuery::MAX_COLUMNS },
-        status: :unprocessable_entity
+        status: :unprocessable_content
   rescue ActiveRecord::StatementTimeout
     render json: { error: 'counts_query_timeout' }, status: :service_unavailable
   rescue ArgumentError, TypeError, KeyError, JSON::ParserError

backend/app/controllers/counts_tables_controller.rb

@@ -24,7 +24,7 @@ class CountsTablesController < ApplicationController
     render json: { error: 'private_condition' }, status: :forbidden
   rescue CountsTableQuery::TooManyColumns
     render json: { error: 'too_many_columns', max_columns: CountsTableQuery::MAX_COLUMNS },
-           status: :unprocessable_entity
+           status: :unprocessable_content
   rescue CountsPivotTotals::TimedOut
     Rails.logger.warn('counts_query_timeout: pivot_totals')
     render json: { error: 'counts_query_timeout', stage: 'totals',

backend/app/controllers/gekanator_games_controller.rb

@@ -15,7 +15,7 @@ class GekanatorGamesController < ApplicationController
         answers:)
 
     if game.invalid?
-      render json: { errors: game.errors.full_messages }, status: :unprocessable_entity
+      render json: { errors: game.errors.full_messages }, status: :unprocessable_content
       return
     end
 
@@ -31,7 +31,7 @@ class GekanatorGamesController < ApplicationController
       learned_example_count:
     }, status: :created
   rescue ActiveRecord::RecordInvalid => e
-    render json: { errors: e.record.errors.full_messages }, status: :unprocessable_entity
+    render json: { errors: e.record.errors.full_messages }, status: :unprocessable_content
   end
 
   def extra_questions

backend/app/controllers/materials_controller.rb

@@ -536,7 +536,7 @@ class MaterialsController < ApplicationController
                    errors: { },
                    base_errors: ['ZIP export に必要な素材ファイルが欠損しています．'],
                    missing_files: },
-           status: :unprocessable_entity
+           status: :unprocessable_content
   end
 
   def build_uploaded_material_blob! file, file_sha256

backend/app/controllers/posts_controller.rb

@@ -429,7 +429,7 @@ class PostsController < ApplicationController
     filters = literals.map do |literal|
       internal, = source_ids.fetch(literal[:name])
       name = internal.empty? ? literal[:name] : names[internal.first]
-      return head :unprocessable_entity unless name && internal.length <= 1
+      return head :unprocessable_content unless name && internal.length <= 1
 
       literal[:negative] ? "not:#{ name }" : name
     end
@@ -438,7 +438,7 @@ class PostsController < ApplicationController
     literals.zip(translated).each do |literal, translation|
       unless (source_ids.fetch(literal[:name]).map(&:sort) ==
           target_ids.fetch(translation[:name]).map(&:sort))
-        return head :unprocessable_entity
+        return head :unprocessable_content
       end
     end
     index = 0

backend/app/controllers/theatres_controller.rb

@@ -55,7 +55,7 @@ class TheatresController < ApplicationController
     theatre = Theatre.find_by(id: params[:id])
     return head :not_found unless theatre
     requested_post_id = params[:post_id].to_i
-    return head :unprocessable_entity if requested_post_id <= 0
+    return head :unprocessable_content if requested_post_id <= 0
 
     skipped = false
     conflicted = false
@@ -95,7 +95,7 @@ class TheatresController < ApplicationController
     theatre = Theatre.find_by(id: params[:id])
     return head :not_found unless theatre
     requested_post_id = params[:post_id].to_i
-    return head :unprocessable_entity if requested_post_id <= 0
+    return head :unprocessable_content if requested_post_id <= 0
 
     conflicted = false
 

backend/spec/requests/error_responses_spec.rb

@@ -20,7 +20,7 @@ RSpec.describe 'error responses', type: :request do
 
       patch "/tags/#{ tag.id }", params: { category: 'nico' }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json).to include(
           'type' => 'validation_error',
           'message' => '入力内容を確認してください．',
@@ -37,7 +37,7 @@ RSpec.describe 'error responses', type: :request do
 
       put "/users/#{ user.id }", params: { name: 'a' * 256 }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json).to include(
           'type' => 'validation_error',
           'message' => '入力内容を確認してください．')