diff --git a/app/jobs/regular/detect_translate_topic.rb b/app/jobs/regular/detect_translate_topic.rb
new file mode 100644
index 00000000..a1c03cec
--- /dev/null
+++ b/app/jobs/regular/detect_translate_topic.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Jobs
+  class DetectTranslateTopic < ::Jobs::Base
+    def execute(args)
+      return unless SiteSetting.translator_enabled
+      return unless SiteSetting.experimental_content_translation
+      return if args[:topic_id].blank?
+
+      topic = Topic.find(args[:topic_id])
+      if topic.blank? || topic.title.blank? || topic.deleted_at.present? || topic.user_id <= 0
+        return
+      end
+
+      detected_locale = DiscourseTranslator::TopicLocaleDetector.detect_locale(topic)
+
+      locales = SiteSetting.automatic_translation_target_languages.split("|")
+      return if locales.blank?
+
+      locales.each do |locale|
+        next if locale == detected_locale
+
+        begin
+          DiscourseTranslator::TopicTranslator.translate(topic, locale)
+        rescue => e
+          Rails.logger.error(
+            "Discourse Translator: Failed to translate topic #{topic.id} to #{locale}: #{e.message}",
+          )
+        end
+      end
+    end
+  end
+end
diff --git a/app/jobs/regular/translate_topics.rb b/app/jobs/regular/translate_topics.rb
new file mode 100644
index 00000000..a2ba4033
--- /dev/null
+++ b/app/jobs/regular/translate_topics.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module Jobs
+  class TranslateTopics < ::Jobs::Base
+    cluster_concurrency 1
+    sidekiq_options retry: false
+
+    BATCH_SIZE = 50
+
+    def execute(args)
+      return unless SiteSetting.translator_enabled
+      return unless SiteSetting.experimental_content_translation
+
+      locales = SiteSetting.automatic_translation_target_languages.split("|")
+      return if locales.blank?
+
+      limit = args[:limit] || BATCH_SIZE
+
+      locales.each do |locale|
+        topics =
+          Topic
+            .joins(
+              "LEFT JOIN topic_localizations tl ON tl.topic_id = topics.id AND tl.locale = #{ActiveRecord::Base.connection.quote(locale)}",
+            )
+            .where(deleted_at: nil)
+            .where("topics.user_id > 0")
+            .where.not(locale: nil)
+            .where.not(locale: locale)
+            .where("tl.id IS NULL")
+            .limit(limit)
+
+        next if topics.empty?
+
+        topics.each do |topic|
+          begin
+            DiscourseTranslator::TopicTranslator.translate(topic, locale)
+          rescue => e
+            Rails.logger.error(
+              "Discourse Translator: Failed to translate topic #{topic.id} to #{locale}: #{e.message}",
+            )
+          end
+        end
+
+        DiscourseTranslator::VerboseLogger.log("Translated #{topics.size} topics to #{locale}")
+      end
+    end
+  end
+end
diff --git a/app/jobs/scheduled/automatic_category_translation.rb b/app/jobs/scheduled/category_translation_backfill.rb
similarity index 87%
rename from app/jobs/scheduled/automatic_category_translation.rb
rename to app/jobs/scheduled/category_translation_backfill.rb
index c0841577..0463edfc 100644
--- a/app/jobs/scheduled/automatic_category_translation.rb
+++ b/app/jobs/scheduled/category_translation_backfill.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module Jobs
-  class AutomaticCategoryTranslation < ::Jobs::Scheduled
+  class CategoryTranslationBackfill < ::Jobs::Scheduled
     every 12.hours
     cluster_concurrency 1
 
diff --git a/app/jobs/scheduled/topic_translation_backfill.rb b/app/jobs/scheduled/topic_translation_backfill.rb
new file mode 100644
index 00000000..0e5f3757
--- /dev/null
+++ b/app/jobs/scheduled/topic_translation_backfill.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module Jobs
+  class TopicTranslationBackfill < ::Jobs::Scheduled
+    every 5.minutes
+    cluster_concurrency 1
+
+    def execute(args)
+      return unless SiteSetting.translator_enabled
+      return unless SiteSetting.experimental_content_translation
+
+      return if SiteSetting.automatic_translation_target_languages.blank?
+      return if SiteSetting.automatic_translation_backfill_rate == 0
+
+      Jobs.enqueue(:translate_topics, limit: SiteSetting.automatic_translation_backfill_rate)
+    end
+  end
+end
diff --git a/app/jobs/scheduled/topics_locale_detection_backfill.rb b/app/jobs/scheduled/topics_locale_detection_backfill.rb
new file mode 100644
index 00000000..fb0d30b8
--- /dev/null
+++ b/app/jobs/scheduled/topics_locale_detection_backfill.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Jobs
+  class TopicsLocaleDetectionBackfill < ::Jobs::Scheduled
+    every 5.minutes
+    cluster_concurrency 1
+
+    def execute(args)
+      return unless SiteSetting.translator_enabled
+      return unless SiteSetting.experimental_content_translation
+      return if SiteSetting.automatic_translation_backfill_rate == 0
+
+      limit = SiteSetting.automatic_translation_backfill_rate
+      topics =
+        Topic
+          .where(locale: nil)
+          .where(deleted_at: nil)
+          .where("topics.user_id > 0")
+          .order(updated_at: :desc)
+          .limit(limit)
+      return if topics.empty?
+
+      topics.each do |topic|
+        begin
+          DiscourseTranslator::TopicLocaleDetector.detect_locale(topic)
+        rescue => e
+          Rails.logger.error(
+            "Discourse Translator: Failed to detect topic #{topic.id}'s locale: #{e.message}",
+          )
+        end
+      end
+
+      DiscourseTranslator::VerboseLogger.log("Detected #{topics.size} topic locales")
+    end
+  end
+end
diff --git a/app/services/discourse_translator/topic_locale_detector.rb b/app/services/discourse_translator/topic_locale_detector.rb
new file mode 100644
index 00000000..5be9d939
--- /dev/null
+++ b/app/services/discourse_translator/topic_locale_detector.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+module DiscourseTranslator
+  class TopicLocaleDetector
+    def self.detect_locale(topic)
+      return if topic.blank?
+
+      translator = DiscourseTranslator::Provider::TranslatorProvider.get
+      detected_locale = translator.detect!(topic)
+      locale = LocaleNormalizer.normalize_to_i18n(detected_locale)
+      topic.update!(locale:)
+      locale
+    end
+  end
+end
diff --git a/app/services/discourse_translator/topic_translator.rb b/app/services/discourse_translator/topic_translator.rb
new file mode 100644
index 00000000..3df5f547
--- /dev/null
+++ b/app/services/discourse_translator/topic_translator.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module DiscourseTranslator
+  class TopicTranslator
+    def self.translate(topic, target_locale = I18n.locale)
+      return if topic.blank? || target_locale.blank? || topic.locale == target_locale.to_s
+
+      target_locale_sym = target_locale.to_s.sub("-", "_").to_sym
+
+      translator = DiscourseTranslator::Provider::TranslatorProvider.get
+      translated_title = translator.translate_topic!(topic, target_locale_sym)
+
+      localization =
+        TopicLocalization.find_or_initialize_by(topic_id: topic.id, locale: target_locale_sym.to_s)
+
+      localization.title = translated_title
+      localization.fancy_title = Topic.fancy_title(translated_title)
+      localization.localizer_user_id = Discourse.system_user.id
+      localization.save!
+      localization
+    end
+  end
+end
diff --git a/lib/discourse_translator/automatic_translations.rb b/lib/discourse_translator/automatic_translations.rb
index e5944dc5..00111584 100644
--- a/lib/discourse_translator/automatic_translations.rb
+++ b/lib/discourse_translator/automatic_translations.rb
@@ -17,6 +17,10 @@ def inject(plugin)
         if translatable?(topic)
           Jobs.enqueue(:translate_translatable, type: "Topic", translatable_id: topic.id)
         end
+
+        if SiteSetting.experimental_content_localization
+          Jobs.enqueue(:detect_translate_topic, topic_id: topic.id)
+        end
       end
 
       plugin.on(:topic_edited) do |topic|
@@ -24,6 +28,12 @@ def inject(plugin)
           Jobs.enqueue(:translate_translatable, type: "Topic", translatable_id: topic.id)
         end
       end
+
+      plugin.on(:post_edited) do |post, topic_changed|
+        if SiteSetting.experimental_content_localization && topic_changed
+          Jobs.enqueue(:detect_translate_topic, topic_id: post.topic_id)
+        end
+      end
     end
 
     def translatable?(content)
diff --git a/spec/jobs/detect_translate_topic_spec.rb b/spec/jobs/detect_translate_topic_spec.rb
new file mode 100644
index 00000000..d2830485
--- /dev/null
+++ b/spec/jobs/detect_translate_topic_spec.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+describe Jobs::DetectTranslateTopic do
+  fab!(:topic)
+  subject(:job) { described_class.new }
+
+  let(:locales) { %w[en ja] }
+
+  before do
+    SiteSetting.translator_enabled = true
+    SiteSetting.experimental_content_translation = true
+    SiteSetting.automatic_translation_backfill_rate = 1
+    SiteSetting.automatic_translation_target_languages = locales.join("|")
+  end
+
+  it "does nothing when translator is disabled" do
+    SiteSetting.translator_enabled = false
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).never
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({ topic_id: topic.id })
+  end
+
+  it "does nothing when content translation is disabled" do
+    SiteSetting.experimental_content_translation = false
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).never
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({ topic_id: topic.id })
+  end
+
+  it "detects locale" do
+    SiteSetting.translator_enabled = true
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic).once
+    DiscourseTranslator::TopicTranslator.expects(:translate).twice
+
+    job.execute({ topic_id: topic.id })
+  end
+
+  it "skips bot topics" do
+    topic.update!(user: Discourse.system_user)
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({ topic_id: topic.id })
+  end
+
+  it "does not translate when no target languages are configured" do
+    SiteSetting.automatic_translation_target_languages = ""
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic).returns("en")
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({ topic_id: topic.id })
+  end
+
+  it "skips translating to the topic's language" do
+    topic.update(locale: "en")
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic).returns("en")
+    DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "en").never
+    DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "ja").once
+
+    job.execute({ topic_id: topic.id })
+  end
+
+  it "handles translation errors gracefully" do
+    topic.update(locale: "en")
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic).returns("en")
+    DiscourseTranslator::TopicTranslator.expects(:translate).raises(StandardError.new("API error"))
+
+    expect { job.execute({ topic_id: topic.id }) }.not_to raise_error
+  end
+end
diff --git a/spec/jobs/topics_locale_detection_backfill_spec.rb b/spec/jobs/topics_locale_detection_backfill_spec.rb
new file mode 100644
index 00000000..b0828d13
--- /dev/null
+++ b/spec/jobs/topics_locale_detection_backfill_spec.rb
@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+describe Jobs::TopicsLocaleDetectionBackfill do
+  fab!(:topic) { Fabricate(:topic, locale: nil) }
+  subject(:job) { described_class.new }
+
+  before do
+    SiteSetting.translator_enabled = true
+    SiteSetting.experimental_content_translation = true
+    SiteSetting.automatic_translation_backfill_rate = 100
+  end
+
+  it "does nothing when translator is disabled" do
+    SiteSetting.translator_enabled = false
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).never
+
+    job.execute({})
+  end
+
+  it "does nothing when content translation is disabled" do
+    SiteSetting.experimental_content_translation = false
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).never
+
+    job.execute({})
+  end
+
+  it "does nothing when there are no topics to detect" do
+    Topic.update_all(locale: "en")
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).never
+
+    job.execute({})
+  end
+
+  it "detects locale for topics with nil locale" do
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic).once
+    job.execute({})
+  end
+
+  it "detects most recently updated topics first" do
+    topic_2 = Fabricate(:topic, locale: nil)
+    topic_3 = Fabricate(:topic, locale: nil)
+
+    topic.update!(updated_at: 3.days.ago)
+    topic_2.update!(updated_at: 2.day.ago)
+    topic_3.update!(updated_at: 4.day.ago)
+
+    SiteSetting.automatic_translation_backfill_rate = 1
+
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic_2).once
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic).never
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic_3).never
+
+    job.execute({})
+  end
+
+  it "skips bot topics" do
+    topic.update!(user: Discourse.system_user)
+    DiscourseTranslator::TopicLocaleDetector.expects(:detect_locale).with(topic).never
+
+    job.execute({})
+  end
+
+  it "handles detection errors gracefully" do
+    DiscourseTranslator::TopicLocaleDetector
+      .expects(:detect_locale)
+      .with(topic)
+      .raises(StandardError.new("jiboomz"))
+      .once
+
+    expect { job.execute({}) }.not_to raise_error
+  end
+
+  it "logs a summary after running" do
+    DiscourseTranslator::TopicLocaleDetector.stubs(:detect_locale)
+    DiscourseTranslator::VerboseLogger.expects(:log).with(includes("Detected 1 topic locales"))
+
+    job.execute({})
+  end
+end
diff --git a/spec/jobs/translate_topics_spec.rb b/spec/jobs/translate_topics_spec.rb
new file mode 100644
index 00000000..318546b4
--- /dev/null
+++ b/spec/jobs/translate_topics_spec.rb
@@ -0,0 +1,122 @@
+# frozen_string_literal: true
+
+describe Jobs::TranslateTopics do
+  fab!(:topic)
+  subject(:job) { described_class.new }
+
+  let(:locales) { %w[en ja de] }
+
+  before do
+    SiteSetting.translator_enabled = true
+    SiteSetting.experimental_content_translation = true
+    SiteSetting.automatic_translation_backfill_rate = 1
+    SiteSetting.automatic_translation_target_languages = locales.join("|")
+  end
+
+  it "does nothing when translator is disabled" do
+    SiteSetting.translator_enabled = false
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({})
+  end
+
+  it "does nothing when content translation is disabled" do
+    SiteSetting.experimental_content_translation = false
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({})
+  end
+
+  it "does nothing when no target languages are configured" do
+    SiteSetting.automatic_translation_target_languages = ""
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({})
+  end
+
+  it "does nothing when there are no topics to translate" do
+    Topic.destroy_all
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({})
+  end
+
+  it "skips topics that already have localizations" do
+    Topic.all.each do |topic|
+      Fabricate(:topic_localization, topic:, locale: "en")
+      Fabricate(:topic_localization, topic:, locale: "ja")
+    end
+    DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+    job.execute({})
+  end
+
+  it "skips bot topics" do
+    topic.update!(user: Discourse.system_user)
+    DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "en").never
+    DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "ja").never
+
+    job.execute({})
+  end
+
+  it "handles translation errors gracefully" do
+    topic.update(locale: "es")
+    DiscourseTranslator::TopicTranslator
+      .expects(:translate)
+      .with(topic, "en")
+      .raises(StandardError.new("API error"))
+    DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "ja").once
+    DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "de").once
+
+    expect { job.execute({}) }.not_to raise_error
+  end
+
+  it "logs a summary after translation" do
+    topic.update(locale: "es")
+    DiscourseTranslator::TopicTranslator.stubs(:translate)
+    DiscourseTranslator::VerboseLogger.expects(:log).with(includes("Translated 1 topics to en"))
+    DiscourseTranslator::VerboseLogger.expects(:log).with(includes("Translated 1 topics to ja"))
+    DiscourseTranslator::VerboseLogger.expects(:log).with(includes("Translated 1 topics to de"))
+
+    job.execute({})
+  end
+
+  context "for translation scenarios" do
+    it "scenario 1: skips topic when locale is not set" do
+      DiscourseTranslator::TopicTranslator.expects(:translate).never
+
+      job.execute({})
+    end
+
+    it "scenario 2: returns topic with locale 'es' if localizations for en/ja/de do not exist" do
+      topic = Fabricate(:topic, locale: "es")
+
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "en").once
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "ja").once
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "de").once
+
+      job.execute({})
+    end
+
+    it "scenario 3: returns topic with locale 'en' if ja/de localization does not exist" do
+      topic = Fabricate(:topic, locale: "en")
+
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "ja").once
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "de").once
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "en").never
+
+      job.execute({})
+    end
+
+    it "scenario 4: skips topic with locale 'en' if 'ja' localization already exists" do
+      topic = Fabricate(:topic, locale: "en")
+      Fabricate(:topic_localization, topic: topic, locale: "ja")
+
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "en").never
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "ja").never
+      DiscourseTranslator::TopicTranslator.expects(:translate).with(topic, "de").once
+
+      job.execute({})
+    end
+  end
+end
diff --git a/spec/lib/automatic_translation_spec.rb b/spec/lib/automatic_translation_spec.rb
index b7756835..0e97f7fe 100644
--- a/spec/lib/automatic_translation_spec.rb
+++ b/spec/lib/automatic_translation_spec.rb
@@ -20,4 +20,59 @@
       expect(job_enqueued?(job: :detect_translate_post, args: { post_id: post.id })).to eq false
     end
   end
+
+  describe "upon topic created" do
+    it "enqueues detect topic locale and translate topic job" do
+      SiteSetting.experimental_content_localization = true
+      topic =
+        PostCreator.create!(
+          Fabricate(:admin),
+          raw: "post",
+          title: "topic",
+          skip_validations: true,
+        ).topic
+
+      expect_job_enqueued(job: :detect_translate_topic, args: { topic_id: topic.id })
+    end
+
+    it "does not enqueue if setting disabled" do
+      SiteSetting.experimental_content_localization = false
+      topic =
+        PostCreator.create!(
+          Fabricate(:admin),
+          raw: "post",
+          title: "topic",
+          skip_validations: true,
+        ).topic
+
+      expect(job_enqueued?(job: :detect_translate_topic, args: { topic_id: topic.id })).to eq false
+    end
+  end
+
+  describe "upon first post (topic) edited" do
+    fab!(:post) { Fabricate(:post, post_number: 1) }
+    fab!(:non_first_post) { Fabricate(:post, post_number: 2) }
+
+    it "enqueues detect topic locale and translate topic job" do
+      SiteSetting.experimental_content_localization = true
+      topic = post.topic
+      revisor = PostRevisor.new(post, topic)
+      revisor.revise!(
+        post.user,
+        { title: "A whole new hole" },
+        { validate_post: false, bypass_bump: false },
+      )
+      revisor.post_process_post
+
+      expect_job_enqueued(job: :detect_translate_topic, args: { topic_id: topic.id })
+    end
+
+    it "does not enqueue if setting disabled" do
+      SiteSetting.experimental_content_localization = false
+
+      expect(
+        job_enqueued?(job: :detect_translate_topic, args: { topic_id: post.topic_id }),
+      ).to eq false
+    end
+  end
 end
diff --git a/spec/services/topic_locale_detector_spec.rb b/spec/services/topic_locale_detector_spec.rb
new file mode 100644
index 00000000..2dc868de
--- /dev/null
+++ b/spec/services/topic_locale_detector_spec.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+describe DiscourseTranslator::TopicLocaleDetector do
+  describe ".detect_locale" do
+    fab!(:topic) { Fabricate(:topic, title: "this is a cat topic", locale: nil) }
+
+    let(:translator) { mock }
+
+    before { DiscourseTranslator::Provider::TranslatorProvider.stubs(:get).returns(translator) }
+
+    it "returns nil if topic is blank" do
+      expect(described_class.detect_locale(nil)).to eq(nil)
+    end
+
+    it "calls detect! on the provider with the topic" do
+      translator.expects(:detect!).with(topic).returns("zh")
+      expect(described_class.detect_locale(topic)).to eq("zh_CN")
+    end
+
+    it "updates the topic locale with the detected locale" do
+      translator.stubs(:detect!).with(topic).returns("zh")
+      expect { described_class.detect_locale(topic) }.to change { topic.reload.locale }.from(
+        nil,
+      ).to("zh_CN")
+    end
+  end
+end
diff --git a/spec/services/topic_translator_spec.rb b/spec/services/topic_translator_spec.rb
new file mode 100644
index 00000000..3bae3e37
--- /dev/null
+++ b/spec/services/topic_translator_spec.rb
@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+describe DiscourseTranslator::TopicTranslator do
+  describe ".translate" do
+    fab!(:topic) { Fabricate(:topic, title: "this is a cat topic :)") }
+    let(:translator) { mock }
+    let(:translated_title) { "これは猫の話題です :)" }
+    let(:fancy_title) { "これは猫の話題です :slight_smile:" }
+    let(:target_locale) { "ja" }
+
+    before do
+      DiscourseTranslator::Provider::TranslatorProvider.stubs(:get).returns(translator)
+      translator.stubs(:translate_topic!).with(topic, :ja).returns(translated_title)
+    end
+
+    it "returns nil if topic is blank" do
+      expect(described_class.translate(nil, "ja")).to eq(nil)
+    end
+
+    it "returns nil if target_locale is blank" do
+      expect(described_class.translate(topic, nil)).to eq(nil)
+      expect(described_class.translate(topic, "")).to eq(nil)
+    end
+
+    it "returns nil if target_locale is same as topic locale" do
+      topic.locale = "en"
+
+      expect(described_class.translate(topic, "en")).to eq(nil)
+    end
+
+    it "translates with topic and locale" do
+      translator.expects(:translate_topic!).with(topic, :ja).returns(translated_title)
+
+      described_class.translate(topic, "ja")
+    end
+
+    it "normalizes dashes to underscores and symbol type for locale" do
+      translator.expects(:translate_topic!).with(topic, :zh_CN).returns("这是一个猫主题 :)")
+
+      described_class.translate(topic, "zh-CN")
+    end
+
+    it "finds or creates a TopicLocalization and sets its fields" do
+      expect {
+        res = described_class.translate(topic, target_locale)
+        expect(res).to be_a(TopicLocalization)
+        expect(res).to have_attributes(
+          topic_id: topic.id,
+          locale: target_locale,
+          title: translated_title,
+          fancy_title: fancy_title,
+          localizer_user_id: Discourse.system_user.id,
+        )
+      }.to change { TopicLocalization.count }.by(1)
+    end
+
+    it "updates an existing TopicLocalization if present" do
+      localization =
+        Fabricate(
+          :topic_localization,
+          topic:,
+          locale: "ja",
+          title: "old title",
+          fancy_title: "old_fancy_title",
+        )
+      expect {
+        expect(described_class.translate(topic, "ja")).to have_attributes(
+          id: localization.id,
+          title: translated_title,
+          fancy_title: fancy_title,
+        )
+        expect(localization.reload).to have_attributes(
+          title: translated_title,
+          fancy_title: fancy_title,
+        )
+      }.to_not change { TopicLocalization.count }
+    end
+  end
+end