Enable frozen string literals.

Make all string literals immutable by default.

app/jobs/amcheck_database_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs hourly to check the database for corruption. Spawned by {DanbooruMaintenance}.
 # Requires at least PostgreSQL 14.0 to be installed for pg_amcheck to be available.
 #

app/jobs/application_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # The base class for all background jobs on Danbooru.
 #
 # @see https://guides.rubyonrails.org/active_job_basics.html

app/jobs/bigquery_export_all_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs daily to export all tables to BigQuery. Spawned by {DanbooruMaintenance}.
 class BigqueryExportAllJob < ApplicationJob
   def perform

app/jobs/bigquery_export_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that exports a database table to Google Cloud Storage and to Google
 # BigQuery. Spawned daily by {DanbooruMaintenance}.
 #

app/jobs/delete_favorites_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that deletes a user's favorites when they delete their account.
 class DeleteFavoritesJob < ApplicationJob
   queue_as :default

app/jobs/discord_notification_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that sends notifications about new forum posts to Discord. Spawned by
 # the {ForumPost} class when a new forum post is created.
 class DiscordNotificationJob < ApplicationJob

app/jobs/dmail_inactive_approvers_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs weekly to warn inactive approvers before they're demoted.
 # Spawned by {DanbooruMaintenance}.
 class DmailInactiveApproversJob < ApplicationJob

app/jobs/iqdb_add_post_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that adds a post to IQDB when a new post is uploaded, or when a post is
 # regenerated. Spawned by the {Post} class.
 class IqdbAddPostJob < ApplicationJob

app/jobs/iqdb_remove_post_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that removes a post from IQDB when it is deleted. Spawned by the {Post}
 # class.
 class IqdbRemovePostJob < ApplicationJob

app/jobs/populate_saved_search_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that updates a user's saved searches when they do a search for
 # `search:all` or `search:<label>`.
 class PopulateSavedSearchJob < ApplicationJob

app/jobs/process_bulk_update_request_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that applies a bulk update request after it is approved.
 #
 # @see {BulkUpdateRequestProcessor}

app/jobs/prune_approvers_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs monthly to demote all inactive approvers. Spawned by
 # {DanbooruMaintenance}.
 class PruneApproversJob < ApplicationJob

app/jobs/prune_bans_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs daily to remove expired bans. Spawned by
 # {DanbooruMaintenance}.
 class PruneBansJob < ApplicationJob

app/jobs/prune_bulk_update_requests_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs daily to reject expired bulk update requests. Spawned by
 # {DanbooruMaintenance}.
 class PruneBulkUpdateRequestsJob < ApplicationJob

app/jobs/prune_delayed_jobs_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs daily to delete all stale delayed jobs. Spawned by
 # {DanbooruMaintenance}.
 class PruneDelayedJobsJob < ApplicationJob

app/jobs/prune_post_disapprovals_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs daily to remove old post disapprovals. Spawned by
 # {DanbooruMaintenance}.
 class PrunePostDisapprovalsJob < ApplicationJob

app/jobs/prune_posts_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs hourly to delete all expired pending, flagged, and appealed
 # posts. Spawned by {DanbooruMaintenance}.
 class PrunePostsJob < ApplicationJob

app/jobs/prune_rate_limits_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs hourly to delete all state rate limit objects from the
 # database. Spawned by {DanbooruMaintenance}.
 class PruneRateLimitsJob < ApplicationJob

app/jobs/prune_uploads_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs hourly to delete all completed, stale, or failed uploads.
 # Spawned by {DanbooruMaintenance}.
 class PruneUploadsJob < ApplicationJob

app/jobs/regenerate_post_counts_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs hourly to fix all incorrect tag counts.
 # Spawned by {DanbooruMaintenance}.
 class RegeneratePostCountsJob < ApplicationJob

app/jobs/regenerate_post_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that regenerates a post's images and IQDB when a moderator requests it.
 class RegeneratePostJob < ApplicationJob
   queue_as :default

app/jobs/retire_tag_relationships_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs weekly to retire inactive aliases and implications. Spawned
 # by {DanbooruMaintenance}.
 class RetireTagRelationshipsJob < ApplicationJob

app/jobs/upload_preprocessor_delayed_start_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that downloads and generates thumbnails in the background for an image
 # uploaded with the upload bookmarklet.
 class UploadPreprocessorDelayedStartJob < ApplicationJob

app/jobs/upload_service_delayed_start_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that tries to resume a preprocessed image upload job.
 class UploadServiceDelayedStartJob < ApplicationJob
   queue_as :default

app/jobs/vacuum_database_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A job that runs daily to vacuum the database. Spawned by {DanbooruMaintenance}.
 class VacuumDatabaseJob < ApplicationJob
   def perform