Change media description length limit for remote media attachments from 1500 to 10000 characters (mastodon#37921)

Author: ClearlyClaire

FEDERATION.md

@@ -68,6 +68,6 @@ The following table summarizes those limits.
 | Account `attributionDomains`                                  | 256        | List will be truncated             |
 | Account aliases (actor `alsoKnownAs`)                         | 256        | List will be truncated             |
 | Custom emoji shortcode (`Emoji` `name`)                       | 2048       | Emoji will be rejected             |
-| Media and avatar/header descriptions (`name`/`summary`)       | 1500       | Description will be truncated      |
+| Media and avatar/header descriptions (`name`/`summary`)       | 10000      | Description will be truncated      |
 | Collection name (`FeaturedCollection` `name`)                 | 256        | Name will be truncated             |
 | Collection description (`FeaturedCollection` `summary`)       | 2048       | Description will be truncated      |

app/lib/activitypub/parser/media_attachment_parser.rb

@@ -30,7 +30,7 @@ def thumbnail_remote_url
 
   def description
     str = @json['summary'].presence || @json['name'].presence
-    str = str.strip[0...MediaAttachment::MAX_DESCRIPTION_LENGTH] if str.present?
+    str = str.strip[0...MediaAttachment::MAX_DESCRIPTION_HARD_LENGTH_LIMIT] if str.present?
     str
   end
 

app/models/concerns/account/avatar.rb

@@ -25,7 +25,7 @@ def avatar_styles(file)
     validates_attachment_size :avatar, less_than: AVATAR_LIMIT
     remotable_attachment :avatar, AVATAR_LIMIT, suppress_errors: false
 
-    validates :avatar_description, length: { maximum: MediaAttachment::MAX_DESCRIPTION_LENGTH }
+    validates :avatar_description, length: { maximum: MediaAttachment::MAX_DESCRIPTION_LENGTH }, if: -> { local? && will_save_change_to_avatar_description? }
   end
 
   def avatar_original_url

app/models/concerns/account/header.rb

@@ -26,7 +26,7 @@ def header_styles(file)
     validates_attachment_size :header, less_than: HEADER_LIMIT
     remotable_attachment :header, HEADER_LIMIT, suppress_errors: false
 
-    validates :header_description, length: { maximum: MediaAttachment::MAX_DESCRIPTION_LENGTH }
+    validates :header_description, length: { maximum: MediaAttachment::MAX_DESCRIPTION_LENGTH }, if: -> { local? && will_save_change_to_header_description? }
   end
 
   def header_original_url

app/models/media_attachment.rb

@@ -39,6 +39,7 @@ class MediaAttachment < ApplicationRecord
   enum :processing, { queued: 0, in_progress: 1, complete: 2, failed: 3 }, prefix: true
 
   MAX_DESCRIPTION_LENGTH = 1_500
+  MAX_DESCRIPTION_HARD_LENGTH_LIMIT = 10_000
 
   IMAGE_LIMIT = 16.megabytes
   VIDEO_LIMIT = 99.megabytes

app/services/activitypub/process_account_service.rb

@@ -238,7 +238,7 @@ def image_url_and_description(key)
       url = first_of_value(value['url'])
       url = url['href'] if url.is_a?(Hash)
       description = value['summary'].presence || value['name'].presence
-      description = description.strip[0...MediaAttachment::MAX_DESCRIPTION_LENGTH] if description.present?
+      description = description.strip[0...MediaAttachment::MAX_DESCRIPTION_HARD_LENGTH_LIMIT] if description.present?
     else
       url = value
     end