diff --git a/backend/spec/requests/tag_description_wiki_write_spec.rb b/backend/spec/requests/tag_description_wiki_write_spec.rb
index 6d83347..0b86adb 100644
--- a/backend/spec/requests/tag_description_wiki_write_spec.rb
+++ b/backend/spec/requests/tag_description_wiki_write_spec.rb
@@ -70,27 +70,12 @@ RSpec.describe 'Tag description Wiki dual writes', type: :request do
           tag_name:, body: 'before', created_by_user: user)
     end
     let!(:first_revision) { page.current_revision }
-    let!(:current_revision) do
-      # Repeated bodies create revisions, but no extra WikiVersion snapshot.
-      Wiki::Commit.content!(page:, body: 'before', created_user: user,
-                            base_revision_id: first_revision.id)
-    end
+
     let!(:description) do
-      TagDescription.create!(
-          id: page.id, tag:, language_code: 'ja', body: 'before', version_no: 2,
-          created_by_user_id: user.id, updated_by_user_id: user.id)
+      TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
     end
 
-    before do
-      [first_revision, current_revision].each_with_index do |revision, index|
-        TagDescriptionVersion.create!(
-            id: revision.id, tag_id: tag.id, language_code: 'ja', version_no: index + 1,
-            body: 'before', event_type: index.zero? ? 'create' : 'update',
-            created_by_user_id: user.id, created_at: revision.created_at)
-      end
-    end
-
-    def update_description body: 'after', title: tag_name.name, base: current_revision.id
+    def update_description body: 'after', title: tag_name.name, base: first_revision.id
       put "/wiki/#{ page.id }",
           params: { title:, body:, message: 'edit', base_revision_id: base },
           headers: headers
@@ -98,7 +83,7 @@ RSpec.describe 'Tag description Wiki dual writes', type: :request do
 
     it 'increments the independent description sequence and shares revision identity' do
       expect(page.reload.version_no).to eq(1)
-      expect(description.version_no).to eq(2)
+      expect(description.version_no).to eq(1)
       expect { update_description }
           .to change(WikiRevision, :count).by(1)
           .and change(WikiVersion, :count).by(1)
@@ -107,56 +92,116 @@ RSpec.describe 'Tag description Wiki dual writes', type: :request do
 
       revision = page.reload.current_revision
       version = TagDescriptionVersion.find(revision.id)
-      expect(description.reload).to have_attributes(body: 'after', version_no: 3)
+      expect(description.reload).to have_attributes(body: 'after', version_no: 2)
       expect(version).to have_attributes(
-          body: 'after', version_no: 3, event_type: 'update', created_by_user_id: user.id)
+          body: 'after', version_no: 2, event_type: 'update', created_by_user_id: user.id)
       expect(page).to have_attributes(body: 'after', version_no: 2)
       expect(revision.body).to eq(version.body)
       expect(page.wiki_versions.order(:version_no).last.body).to eq(version.body)
     end
 
-    it 'mirrors the Wiki revision for a title-only update despite identical bodies' do
-      expect { update_description(body: 'before', title: 'description_renamed') }
-          .to change(WikiRevision, :count).by(1)
-          .and change(TagDescriptionVersion, :count).by(1)
+    it 'does not add body history for a title-only update' do
+      revision_count = WikiRevision.count
+      wiki_version_count = WikiVersion.count
+      description_version_count = TagDescriptionVersion.count
+      wiki_version_no = page.reload.version_no
+      description_version_no = description.version_no
+      current_revision_id = page.current_revision.id
+      page_state = page.attributes
+      description_state = description.attributes
+
+      update_description(body: 'before', title: 'description_renamed')
+
       expect(response).to have_http_status(:ok)
       expect(tag_name.reload.name).to eq('description_renamed')
-      expect(description.reload).to have_attributes(body: 'before', version_no: 3)
-
-      revision = page.reload.current_revision
-      version = TagDescriptionVersion.find(revision.id)
-      expect(revision.body).to eq('before')
-      expect(version).to have_attributes(
-          tag_id: tag.id, language_code: 'ja', body: 'before', version_no: 3,
-          event_type: 'update', created_by_user_id: user.id)
-      expect(TagDescriptionVersion.where(tag_id: tag.id, language_code: 'ja').order(:id).ids)
-          .to eq(page.wiki_revisions.order(:id).ids)
+      expect(WikiRevision.count).to eq(revision_count)
+      expect(WikiVersion.count).to eq(wiki_version_count)
+      expect(TagDescriptionVersion.count).to eq(description_version_count)
+      expect(page.reload).to have_attributes(body: 'before', version_no: wiki_version_no)
+      expect(page.current_revision.id).to eq(current_revision_id)
+      expect(page.reload.attributes).to eq(page_state)
+      expect(description.reload).to have_attributes(
+          body: 'before', version_no: description_version_no)
+      expect(description.reload.attributes).to eq(description_state)
     end
 
-    it 'does not add a description version for a TagName rename through tags' do
-      expect do
-        patch "/tags/#{ tag.id }", params: { name: 'description_tag_renamed' }, headers: headers
-      end.not_to change(TagDescriptionVersion, :count)
+    it 'does not add body history for a TagName rename through tags' do
+      revision_count = WikiRevision.count
+      wiki_version_count = WikiVersion.count
+      description_version_count = TagDescriptionVersion.count
+      page_version_no = page.reload.version_no
+      current_revision_id = page.current_revision.id
+
+      patch "/tags/#{ tag.id }",
+            params: { name: 'description_tag_renamed' },
+            headers:
+
       expect(response).to have_http_status(:ok)
       expect(tag_name.reload.name).to eq('description_tag_renamed')
-      expect(description.reload).to have_attributes(body: 'before', version_no: 2)
+      expect(WikiRevision.count).to eq(revision_count)
+      expect(WikiVersion.count).to eq(wiki_version_count)
+      expect(TagDescriptionVersion.count).to eq(description_version_count)
+      expect(page.reload.version_no).to eq(page_version_no)
+      expect(page.current_revision.id).to eq(current_revision_id)
+      expect(description.reload).to have_attributes(
+          body: 'before', version_no: 1)
     end
 
     it 'keeps both systems and the title unchanged on a stale revision conflict' do
+      update_description(body: 'current body', base: first_revision.id)
+      expect(response).to have_http_status(:ok)
+
+      stale_revision_id = first_revision.id
       before_state = stored_state
-      update_description(title: 'conflicting_rename', base: first_revision.id)
+
+      update_description(
+          body: 'conflicting body',
+          title: 'conflicting_rename',
+          base: stale_revision_id)
+
       expect(response).to have_http_status(:conflict)
       expect(stored_state).to eq(before_state)
+      expect(tag_name.reload.name).not_to eq('conflicting_rename')
     end
 
     [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion].each do |model|
       it "rolls back both systems when #{ model.name } persistence fails" do
         before_state = stored_state
         aggregate_failures do
-          fail_save(model) { update_description(title: 'rollback_rename') }
+          fail_save(model) do
+            update_description(body: 'rollback body', title: 'rollback_rename')
+          end
           expect(stored_state).to eq(before_state)
         end
       end
     end
+
+    [['identical body', 'before'],
+     ['normalised-equivalent body', "before\n\n"]].each do |label, body|
+      it "does not write histories for #{ label }" do
+        before_state = stored_state
+        page_state = page.reload.attributes
+        description_state = description.reload.attributes
+        current_revision_id = page.current_revision.id
+        wiki_lines = WikiLine.order(:id).map(&:attributes)
+        revision_lines = WikiRevisionLine.order(:id).map(&:attributes)
+        page_version_no = page.version_no
+        description_version_no = description.version_no
+
+        update_description(body:)
+
+        expect(response).to have_http_status(:ok)
+        expect(WikiRevision.count).to eq(before_state[1].length)
+        expect(WikiVersion.count).to eq(before_state[2].length)
+        expect(TagDescriptionVersion.count).to eq(before_state[4].length)
+        expect(page.reload.version_no).to eq(page_version_no)
+        expect(description.reload.version_no).to eq(description_version_no)
+        expect(page.current_revision.id).to eq(current_revision_id)
+        expect(page.reload.attributes).to eq(page_state)
+        expect(description.reload.attributes).to eq(description_state)
+        expect(WikiLine.order(:id).map(&:attributes)).to eq(wiki_lines)
+        expect(WikiRevisionLine.order(:id).map(&:attributes)).to eq(revision_lines)
+      end
+    end
   end
 end
diff --git a/backend/spec/requests/tag_descriptions_spec.rb b/backend/spec/requests/tag_descriptions_spec.rb
index 104ef56..88d1a83 100644
--- a/backend/spec/requests/tag_descriptions_spec.rb
+++ b/backend/spec/requests/tag_descriptions_spec.rb
@@ -264,38 +264,49 @@ RSpec.describe 'Tag description native API', type: :request do
       tag
       Wiki::Commit.create_content!(tag_name:, body: 'before', created_by_user: author)
     end
-    let!(:second_revision) do
-      Wiki::Commit.content!(page:, body: 'before', created_user: author)
-    end
     let!(:description) do
       TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
     end
 
-    ['after', 'before'].each do |body|
-      it "appends matching revisions for body '#{ body }'" do
-        history = TagDescriptionVersion.where(tag_id: tag.id).order(:version_no).map(&:attributes)
-        expect(page.reload.version_no).to eq(1)
-        expect(description.version_no).to eq(2)
-        expect { native_write(:put, body:) }
-            .to change(WikiRevision, :count).by(1)
-            .and change(TagDescriptionVersion, :count).by(1)
-        expect(response).to have_http_status(:ok)
-        expect(description.reload).to have_attributes(
-            body:, version_no: 3, created_by_user_id: author.id, updated_by_user_id: editor.id)
-        expect(page.reload.body).to eq(body)
-        revision = page.current_revision
-        version = TagDescriptionVersion.find(revision.id)
-        expect(version).to have_attributes(
-            tag_id: tag.id, language_code: 'ja', version_no: 3, event_type: 'update',
-            body:, created_by_user_id: editor.id)
-        expect(revision.body).to eq(body)
-        expect(page.wiki_versions.order(:version_no).last.body).to eq(body)
-        expect(TagDescriptionVersion.where(id: history.pluck('id')).order(:version_no)
-            .map(&:attributes)).to eq(history)
+    it 'writes matching histories when the body changes' do
+      expect(page.reload.version_no).to eq(1)
+      expect(description.version_no).to eq(1)
+      expect { native_write(:put, body: 'after') }
+          .to change(WikiRevision, :count).by(1)
+          .and change(WikiVersion, :count).by(1)
+          .and change(TagDescriptionVersion, :count).by(1)
+      expect(response).to have_http_status(:ok)
+      expect(description.reload).to have_attributes(
+          body: 'after', version_no: 2,
+          created_by_user_id: author.id, updated_by_user_id: editor.id)
+      expect(page.reload).to have_attributes(body: 'after', version_no: 2)
+
+      revision = page.current_revision
+      version = TagDescriptionVersion.find(revision.id)
+      expect(version).to have_attributes(
+          tag_id: tag.id, language_code: 'ja', version_no: 2, event_type: 'update',
+          body: 'after', created_by_user_id: editor.id)
+      expect(revision.body).to eq(version.body)
+      expect(page.wiki_versions.order(:version_no).last.body).to eq(version.body)
+      get "/wiki/#{ description.id }"
+      expect(response).to have_http_status(:ok)
+      expect(json).to include('body' => 'after', 'revision_id' => version.id)
+    end
+
+    ['before', "before\n\n"].each do |body|
+      it 'does not write histories when the normalised body is unchanged' do
+        before_state = stored_state
+        page_state = page.reload.attributes
+        description_state = description.reload.attributes
+        current_revision_id = page.current_revision.id
+
+        native_write(:put, body:)
 
-        get "/wiki/#{ description.id }"
         expect(response).to have_http_status(:ok)
-        expect(json).to include('body' => body, 'revision_id' => version.id)
+        expect(stored_state).to eq(before_state)
+        expect(page.reload.attributes).to eq(page_state)
+        expect(description.reload.attributes).to eq(description_state)
+        expect(page.current_revision.id).to eq(current_revision_id)
       end
     end