extract email assets

app/mailers/submitter_mailer.rb

@@ -16,7 +16,7 @@ class SubmitterMailer < ApplicationMailer
 
     template_submitters_index = @email_message.blank? ? build_submitter_preferences_index(@submitter) : {}
 
-    @body = @email_message&.body.presence ||
+    @body = @email_message&.normalized_body.presence ||
             template_submitters_index.dig(@submitter.uuid, 'request_email_body').presence ||
             @submitter.template&.preferences&.dig('request_email_body').presence
 

app/models/account.rb

@@ -24,6 +24,7 @@ class Account < ApplicationRecord
   has_many :encrypted_configs, dependent: :destroy
   has_many :account_configs, dependent: :destroy
   has_many :email_messages, dependent: :destroy
+  has_many :email_message_assets, dependent: :destroy
   has_many :templates, dependent: :destroy
   has_many :template_folders, dependent: :destroy
   has_one :default_template_folder, -> { where(name: TemplateFolder::DEFAULT_NAME) },

app/models/email_message.rb

@@ -33,6 +33,15 @@ class EmailMessage < ApplicationRecord
 
   before_validation :set_sha1, on: :create
 
+  def normalized_body
+    @normalized_body ||=
+      if body&.include?(EmailMessages::ASSET_PREFIX)
+        EmailMessages.rebuild_body_with_assets(account_id, body)
+      else
+        body
+      end
+  end
+
   def set_sha1
     self.sha1 = Digest::SHA1.hexdigest({ subject:, body: }.to_json)
   end

app/models/email_message_asset.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: email_message_assets
+#
+#  id         :bigint           not null, primary key
+#  data       :text             not null
+#  sha1       :string           not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#  account_id :bigint           not null
+#
+# Indexes
+#
+#  index_email_message_assets_on_account_id_and_sha1  (account_id,sha1) UNIQUE
+#
+# Foreign Keys
+#
+#  fk_rails_...  (account_id => accounts.id)
+#
+class EmailMessageAsset < ApplicationRecord
+  belongs_to :account
+
+  before_validation :set_sha1, on: :create
+
+  def set_sha1
+    self.sha1 = Digest::SHA1.hexdigest(data.to_s)
+  end
+end

app/views/submissions/_send_email_base.html.erb

@@ -56,7 +56,7 @@
       <div class="form-control">
         <%= f.label :message, t('body'), class: 'label' %>
         <% body_variables = AccountConfig::EMAIL_VARIABLES[AccountConfig::SUBMITTER_INVITATION_EMAIL_KEY] %>
-        <%= render 'personalization_settings/markdown_editor', name: f.field_name(:body), value: local_assigns[:submitter_email_message]&.body.presence || submitter_preferences_index.dig(local_assigns[:submitter]&.uuid, 'request_email_body').presence || template&.preferences&.dig('request_email_body').presence || config.value['body'], variables: body_variables %>
+        <%= render 'personalization_settings/markdown_editor', name: f.field_name(:body), value: local_assigns[:submitter_email_message]&.normalized_body.presence || submitter_preferences_index.dig(local_assigns[:submitter]&.uuid, 'request_email_body').presence || template&.preferences&.dig('request_email_body').presence || config.value['body'], variables: body_variables %>
         <% unless local_assigns.fetch(:disable_save_as_default_template_option, false) %>
           <label for="<%= uuid = SecureRandom.uuid %>" class="flex items-center cursor-pointer">
             <%= check_box_tag :save_message, id: uuid, class: 'base-checkbox', checked: false %>
@@ -91,7 +91,7 @@
               </div>
               <div class="form-control">
                 <%= ff.label :message, t('body'), class: 'label' %>
-                <%= render 'personalization_settings/markdown_editor', name: ff.field_name(:body), value: local_assigns[:submitter_email_message]&.body.presence || submitter_preferences_index.dig(submitter['uuid'], 'request_email_body').presence || template&.preferences&.dig('request_email_body').presence || config.value['body'], variables: body_variables %>
+                <%= render 'personalization_settings/markdown_editor', name: ff.field_name(:body), value: local_assigns[:submitter_email_message]&.normalized_body.presence || submitter_preferences_index.dig(submitter['uuid'], 'request_email_body').presence || template&.preferences&.dig('request_email_body').presence || config.value['body'], variables: body_variables %>
               </div>
             </div>
           <% end %>

db/migrate/20260628120000_create_email_message_assets.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class CreateEmailMessageAssets < ActiveRecord::Migration[8.1]
+  def change
+    create_table :email_message_assets do |t|
+      t.references :account, null: false, foreign_key: true, index: false
+      t.text :data, null: false
+      t.string :sha1, null: false
+      t.timestamps
+    end
+
+    add_index :email_message_assets, %i[account_id sha1], unique: true
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.1].define(version: 2026_06_27_083558) do
+ActiveRecord::Schema[8.1].define(version: 2026_06_28_120000) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "btree_gin"
   enable_extension "pg_catalog.plpgsql"
@@ -214,6 +214,15 @@ ActiveRecord::Schema[8.1].define(version: 2026_06_27_083558) do
     t.index ["message_id"], name: "index_email_events_on_message_id"
   end
 
+  create_table "email_message_assets", force: :cascade do |t|
+    t.bigint "account_id", null: false
+    t.datetime "created_at", null: false
+    t.text "data", null: false
+    t.string "sha1", null: false
+    t.datetime "updated_at", null: false
+    t.index ["account_id", "sha1"], name: "index_email_message_assets_on_account_id_and_sha1", unique: true
+  end
+
   create_table "email_messages", force: :cascade do |t|
     t.bigint "account_id", null: false
     t.bigint "author_id", null: false
@@ -579,6 +588,7 @@ ActiveRecord::Schema[8.1].define(version: 2026_06_27_083558) do
   add_foreign_key "dynamic_document_versions", "dynamic_documents"
   add_foreign_key "dynamic_documents", "templates"
   add_foreign_key "email_events", "accounts"
+  add_foreign_key "email_message_assets", "accounts"
   add_foreign_key "email_messages", "accounts"
   add_foreign_key "email_messages", "users", column: "author_id"
   add_foreign_key "encrypted_configs", "accounts"

lib/email_messages.rb

@@ -1,13 +1,70 @@
 # frozen_string_literal: true
 
 module EmailMessages
+  MIN_BODY_SIZE = 2.kilobytes
+  MIN_ASSET_SIZE = 256.bytes
+  STYLE_REGEXP = %r{<style[^>]*>.*?</style>(?:\s*<style[^>]*>.*?</style>)*}mi
+  BASE64_REGEXP = %r{(data:[^,]*;base64,)([A-Za-z0-9+/=]+)}
+  ASSET_REGEXP = Regexp.union(STYLE_REGEXP, BASE64_REGEXP)
+  ASSET_PREFIX = '[[asset:'
+  PLACEHOLDER_REGEXP = /\[\[asset:(\h{40})\]\]/
+
   module_function
 
   def find_or_create_for_account_user(account, user, subject, body)
     subject = I18n.t(:you_are_invited_to_sign_a_document) if subject.blank?
 
-    message = account.email_messages.new(author: user, subject:, body:).tap(&:validate)
+    body, assets = maybe_extract_assets(account, body)
+
+    new_message = account.email_messages.new(author: user, subject:, body:).tap(&:validate)
+
+    message = account.email_messages.find_by(sha1: new_message.sha1)
+
+    message ||= new_message.tap do |m|
+      m.save!(validate: false)
+
+      save_new_assets!(account, assets)
+    end
+
+    message
+  end
+
+  def save_new_assets!(account, assets)
+    return if assets.blank?
+
+    existing_assets_sha1 = account.email_message_assets.where(sha1: assets.map(&:sha1)).pluck(:sha1)
+
+    assets.each do |asset|
+      asset.save!(validate: false) if existing_assets_sha1.exclude?(asset.sha1)
+    rescue ActiveRecord::RecordNotUnique
+      nil
+    end
+  end
+
+  def maybe_extract_assets(account, body)
+    return [body, []] if body.blank? || body.bytesize < MIN_BODY_SIZE
+
+    assets_index = {}
+
+    result = body.gsub(ASSET_REGEXP) do
+      match = Regexp.last_match
+      prefix, data = match[1] ? [match[1], match[2]] : ['', match[0]]
+
+      next match[0] if data.blank? || data.bytesize < MIN_ASSET_SIZE
+
+      asset = account.email_message_assets.new(data:).tap(&:validate)
+      assets_index[asset.sha1] = asset
+
+      "#{prefix}#{ASSET_PREFIX}#{asset.sha1}]]"
+    end
+
+    [result, assets_index.values]
+  end
+
+  def rebuild_body_with_assets(account_id, body)
+    shas = body.scan(PLACEHOLDER_REGEXP).flatten.uniq
+    data = EmailMessageAsset.where(account_id:, sha1: shas).pluck(:sha1, :data).to_h
 
-    account.email_messages.find_by(sha1: message.sha1) || message.tap { |m| m.save!(validate: false) }
+    body.gsub(PLACEHOLDER_REGEXP) { data[Regexp.last_match(1)] || Regexp.last_match(0) }
   end
 end