From aef9280a78c29ae79d589382e895768cd3ff00bb Mon Sep 17 00:00:00 2001
From: Stanislav Lashmanov <slashmanov@gitlab.com>
Date: Wed, 3 Sep 2025 18:13:59 +0400
Subject: [PATCH 1/5] Remove rapid_diffs_on_compare_show feature flag

Changelog: added
---
 .../projects/compare_controller.rb            |  3 +-
 .../beta/rapid_diffs_on_compare_show.yml      |  9 ---
 .../projects/compare_controller_spec.rb       |  4 --
 spec/features/projects/compare_spec.rb        | 72 -------------------
 spec/features/projects/view_on_env_spec.rb    | 34 ---------
 5 files changed, 1 insertion(+), 121 deletions(-)
 delete mode 100644 config/feature_flags/beta/rapid_diffs_on_compare_show.yml

diff --git a/app/controllers/projects/compare_controller.rb b/app/controllers/projects/compare_controller.rb
index 3c2c8e4570dce5..d397166be74252 100644
--- a/app/controllers/projects/compare_controller.rb
+++ b/app/controllers/projects/compare_controller.rb
@@ -238,8 +238,7 @@ def rapid_diffs_force_disabled?
   end
 
   def rapid_diffs_enabled?
-    ::Feature.enabled?(:rapid_diffs_on_compare_show, current_user, type: :beta) &&
-      !rapid_diffs_force_disabled? &&
+    !rapid_diffs_force_disabled? &&
       params.permit(:format)[:format].blank?
   end
 end
diff --git a/config/feature_flags/beta/rapid_diffs_on_compare_show.yml b/config/feature_flags/beta/rapid_diffs_on_compare_show.yml
deleted file mode 100644
index 034f741fcf1da0..00000000000000
--- a/config/feature_flags/beta/rapid_diffs_on_compare_show.yml
+++ /dev/null
@@ -1,9 +0,0 @@
----
-name: rapid_diffs_on_compare_show
-feature_issue_url: https://gitlab.com/groups/gitlab-org/-/epics/11559
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/187955
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/539580
-milestone: '18.0'
-group: group::code review
-type: beta
-default_enabled: true
diff --git a/spec/controllers/projects/compare_controller_spec.rb b/spec/controllers/projects/compare_controller_spec.rb
index 447eae785a5d21..024b79a9eda7e5 100644
--- a/spec/controllers/projects/compare_controller_spec.rb
+++ b/spec/controllers/projects/compare_controller_spec.rb
@@ -76,10 +76,6 @@
     let(:straight) { nil }
     let(:page) { nil }
 
-    before do
-      stub_feature_flags(rapid_diffs_on_compare_show: false)
-    end
-
     context 'when the refs exist in the same project' do
       context 'when we set the white space param' do
         let(:from_project_id) { nil }
diff --git a/spec/features/projects/compare_spec.rb b/spec/features/projects/compare_spec.rb
index 6ac2fd388003c1..bd134ccdfe710d 100644
--- a/spec/features/projects/compare_spec.rb
+++ b/spec/features/projects/compare_spec.rb
@@ -93,78 +93,6 @@
       expect(find(".js-compare-from-dropdown .gl-new-dropdown-contents")).to have_selector('li.gl-new-dropdown-item', count: 1)
     end
 
-    context 'with legacy diffs' do
-      before do
-        stub_feature_flags(rapid_diffs_on_compare_show: false)
-      end
-
-      it 'renders additions info when click unfold diff' do
-        visit project_compare_index_path(project)
-
-        select_using_dropdown('from', RepoHelpers.sample_commit.parent_id, commit: true)
-        select_using_dropdown('to', RepoHelpers.sample_commit.id, commit: true)
-
-        click_button 'Compare'
-        expect(page).to have_content 'Commits on Source 1'
-        expect(page).to have_content "Showing 2 changed files"
-
-        diff = first('.js-unfold')
-        diff.click
-        wait_for_requests
-
-        page.within diff.query_scope do
-          expect(first('.new_line').text).not_to have_content "..."
-        end
-      end
-
-      context 'when commit has overflow', :js do
-        it 'displays warning' do
-          visit project_compare_index_path(project, from: "feature", to: "master")
-
-          allow(Commit).to receive(:max_diff_options).and_return(max_files: 3)
-          allow_next_instance_of(DiffHelper) do |instance|
-            allow(instance).to receive(:render_overflow_warning?).and_return(true)
-          end
-
-          click_button('Compare')
-
-          within_testid('too-many-changes-alert') do
-            expect(page).to have_text("Some changes are not shown. For a faster browsing experience, only 3 of 3+ files are shown.")
-            expect(page).not_to have_link("Plain diff")
-            expect(page).not_to have_link("Patches")
-          end
-        end
-      end
-
-      context "pagination" do
-        before do
-          stub_const("Projects::CompareController::COMMIT_DIFFS_PER_PAGE", 1)
-        end
-
-        it "shows an adjusted count for changed files on this page" do
-          visit project_compare_index_path(project, from: "feature", to: "master")
-
-          click_button('Compare')
-
-          expect(page).to have_content("Showing 1 changed file")
-        end
-
-        it "shows commits list only on the first page" do
-          visit project_compare_index_path(project, from: "feature", to: "master")
-          click_button('Compare')
-
-          expect(page).to have_content 'Commits on Source 29'
-
-          # go to the second page
-          within(".files .gl-pagination") do
-            click_on("2")
-          end
-
-          expect(page).not_to have_content 'Commits on Source 29'
-        end
-      end
-    end
-
     context 'when displayed with rapid_diffs' do
       let(:from) { RepoHelpers.sample_commit.parent_id }
       let(:to) { RepoHelpers.sample_commit.id }
diff --git a/spec/features/projects/view_on_env_spec.rb b/spec/features/projects/view_on_env_spec.rb
index a790a64ee8c5e8..9352328fe2c32f 100644
--- a/spec/features/projects/view_on_env_spec.rb
+++ b/spec/features/projects/view_on_env_spec.rb
@@ -48,40 +48,6 @@
       let(:environment) { create(:environment, project: project, name: 'review/feature', external_url: 'http://feature.review.example.com') }
       let!(:deployment) { create(:deployment, :success, environment: environment, ref: branch_name, sha: sha) }
 
-      context 'with legacy diffs' do
-        before do
-          stub_feature_flags(rapid_diffs_on_compare_show: false)
-        end
-
-        context 'when visiting a comparison for the branch' do
-          before do
-            sign_in(user)
-
-            visit project_compare_path(project, from: 'master', to: branch_name)
-
-            wait_for_requests
-          end
-
-          it 'has a "View on env" button' do
-            expect(page).to have_link('View on feature.review.example.com', href: 'http://feature.review.example.com/ruby/feature')
-          end
-        end
-
-        context 'when visiting a comparison for the commit' do
-          before do
-            sign_in(user)
-
-            visit project_compare_path(project, from: 'master', to: sha)
-
-            wait_for_requests
-          end
-
-          it 'has a "View on env" button' do
-            expect(page).to have_link('View on feature.review.example.com', href: 'http://feature.review.example.com/ruby/feature')
-          end
-        end
-      end
-
       context 'when visiting a blob on the branch' do
         before do
           sign_in(user)
-- 
GitLab


From 881e160825ff946a7f72f86f5638037d10960769 Mon Sep 17 00:00:00 2001
From: Stanislav Lashmanov <slashmanov@gitlab.com>
Date: Wed, 3 Sep 2025 18:36:54 +0400
Subject: [PATCH 2/5] Remove legacy code

---
 .../projects/compare/rapid_diffs/index.js     |  7 ----
 .../pages/projects/compare/show/index.js      | 12 ++----
 .../projects/compare_controller.rb            | 37 +++++-------------
 .../projects/compare/rapid_diffs.html.haml    | 35 -----------------
 app/views/projects/compare/show.html.haml     | 38 +++++++++----------
 .../projects/compare_controller_spec.rb       |  4 +-
 6 files changed, 33 insertions(+), 100 deletions(-)
 delete mode 100644 app/assets/javascripts/pages/projects/compare/rapid_diffs/index.js
 delete mode 100644 app/views/projects/compare/rapid_diffs.html.haml

diff --git a/app/assets/javascripts/pages/projects/compare/rapid_diffs/index.js b/app/assets/javascripts/pages/projects/compare/rapid_diffs/index.js
deleted file mode 100644
index dc0b9e8d22727e..00000000000000
--- a/app/assets/javascripts/pages/projects/compare/rapid_diffs/index.js
+++ /dev/null
@@ -1,7 +0,0 @@
-import initCompareSelector from '~/projects/compare';
-import { createRapidDiffsApp } from '~/rapid_diffs';
-
-initCompareSelector();
-
-const app = createRapidDiffsApp();
-app.init();
diff --git a/app/assets/javascripts/pages/projects/compare/show/index.js b/app/assets/javascripts/pages/projects/compare/show/index.js
index 328b5596e1a9fc..dc0b9e8d22727e 100644
--- a/app/assets/javascripts/pages/projects/compare/show/index.js
+++ b/app/assets/javascripts/pages/projects/compare/show/index.js
@@ -1,13 +1,7 @@
-import Diff from '~/diff';
-import GpgBadges from '~/gpg_badges';
-import { initDiffStatsDropdown } from '~/init_diff_stats_dropdown';
 import initCompareSelector from '~/projects/compare';
-import syntaxHighlight from '~/syntax_highlight';
+import { createRapidDiffsApp } from '~/rapid_diffs';
 
 initCompareSelector();
 
-new Diff(); // eslint-disable-line no-new
-initDiffStatsDropdown();
-GpgBadges.fetch();
-
-syntaxHighlight([document.querySelector('.files')]);
+const app = createRapidDiffsApp();
+app.init();
diff --git a/app/controllers/projects/compare_controller.rb b/app/controllers/projects/compare_controller.rb
index d397166be74252..cc80c98f64dcfd 100644
--- a/app/controllers/projects/compare_controller.rb
+++ b/app/controllers/projects/compare_controller.rb
@@ -13,7 +13,7 @@ class Projects::CompareController < Projects::ApplicationController
   before_action :require_non_empty_project
   before_action :authorize_read_code!
   # Defining ivars
-  before_action :define_diffs, only: [:show, :diff_for_path]
+  before_action :define_diffs, only: [:diff_for_path]
   before_action :define_environment, only: [:show]
   before_action :define_diff_notes_disabled, only: [:show, :diff_for_path]
   before_action :define_commits, only: [:show, :diff_for_path, :signatures]
@@ -33,29 +33,24 @@ def index
   end
 
   def show
-    apply_diff_view_cookie!
-
-    if rapid_diffs_enabled?
-      @js_action_name = 'rapid_diffs'
-      @rapid_diffs_presenter = ::RapidDiffs::ComparePresenter.new(
-        compare,
-        diff_view,
-        diff_options,
-        compare_params
-      )
-      return render action: :rapid_diffs
-    end
-
     respond_to do |format|
       format.html do
-        render locals: { pagination_params: params.permit(:page) }
+        apply_diff_view_cookie!
+        @rapid_diffs_presenter = ::RapidDiffs::ComparePresenter.new(
+          compare,
+          diff_view,
+          diff_options,
+          compare_params
+        )
       end
 
       format.patch do
+        define_diffs
         compare ? send_git_patch(source_project.repository, compare.diff_refs) : render_404
       end
 
       format.diff do
+        define_diffs
         compare ? send_git_diff(source_project.repository, compare.diff_refs) : render_404
       end
     end
@@ -191,8 +186,6 @@ def define_commits
   end
 
   def define_diffs
-    return if rapid_diffs_enabled?
-
     @diffs = compare.present? ? compare.diffs(diff_options) : []
   end
 
@@ -231,14 +224,4 @@ def compare_params
   def diffs_resource(options = {})
     compare&.diffs(diff_options.merge(options))
   end
-
-  def rapid_diffs_force_disabled?
-    ::Feature.enabled?(:rapid_diffs_debug, current_user, type: :ops) &&
-      params.permit(:rapid_diffs_disabled)[:rapid_diffs_disabled] == 'true'
-  end
-
-  def rapid_diffs_enabled?
-    !rapid_diffs_force_disabled? &&
-      params.permit(:format)[:format].blank?
-  end
 end
diff --git a/app/views/projects/compare/rapid_diffs.html.haml b/app/views/projects/compare/rapid_diffs.html.haml
deleted file mode 100644
index b1589dfdeb8309..00000000000000
--- a/app/views/projects/compare/rapid_diffs.html.haml
+++ /dev/null
@@ -1,35 +0,0 @@
-- @no_container = true
-- container_class = fluid_layout ? '' : 'container-limited'
-- add_to_breadcrumbs s_("CompareRevisions|Compare revisions"), project_compare_index_path(@project)
-- page_title "#{params[:from]} to #{params[:to]}"
--# Only show commit list in the first page
-- hide_commit_list = params[:page].present? && params[:page] != '1'
-- add_page_specific_style 'page_bundles/merge_requests'
-- add_page_specific_style 'page_bundles/compare_rapid_diffs'
-
-.container-fluid{ class: [container_class] }
-  .gl-border-b-0.gl-mb-0.gl-pt-4
-    .js-signature-container{ data: { 'signatures-path' => signatures_namespace_project_compare_index_path } }
-      #js-compare-selector{ data: project_compare_selector_data(@project, @merge_request, params) }
-
-- if @commits.present?
-  .container-fluid{ class: [container_class] }
-    = render "projects/commits/commit_list" unless hide_commit_list
-  .container-fluid
-    = render ::RapidDiffs::AppComponent.new(@rapid_diffs_presenter)
-- else
-  .container-fluid
-    = render Pajamas::CardComponent.new(card_options: { class: "gl-bg-subtle" }) do |c|
-      - c.with_body do
-        = render Pajamas::EmptyStateComponent.new(svg_path: 'illustrations/empty-state/empty-commit-md.svg',
-          title: s_("CompareRevisions|There isn't anything to compare")) do |c|
-
-          - c.with_description do
-            - if params[:to] == params[:from]
-              - source_branch = capture do
-                %span.ref-name= params[:from]
-              - target_branch = capture do
-                %span.ref-name= params[:to]
-              = (s_("CompareRevisions|%{source_branch} and %{target_branch} are the same.") % { source_branch: source_branch, target_branch: target_branch }).html_safe
-            - else
-              = _("To get a valid comparison, select two different branches.")
diff --git a/app/views/projects/compare/show.html.haml b/app/views/projects/compare/show.html.haml
index 62e77067d5c0ca..b1589dfdeb8309 100644
--- a/app/views/projects/compare/show.html.haml
+++ b/app/views/projects/compare/show.html.haml
@@ -2,36 +2,34 @@
 - container_class = fluid_layout ? '' : 'container-limited'
 - add_to_breadcrumbs s_("CompareRevisions|Compare revisions"), project_compare_index_path(@project)
 - page_title "#{params[:from]} to #{params[:to]}"
-- has_diff = @commits.present? || @diffs.present? && @diffs.diff_files.present?
 -# Only show commit list in the first page
 - hide_commit_list = params[:page].present? && params[:page] != '1'
+- add_page_specific_style 'page_bundles/merge_requests'
+- add_page_specific_style 'page_bundles/compare_rapid_diffs'
 
 .container-fluid{ class: [container_class] }
   .gl-border-b-0.gl-mb-0.gl-pt-4
     .js-signature-container{ data: { 'signatures-path' => signatures_namespace_project_compare_index_path } }
       #js-compare-selector{ data: project_compare_selector_data(@project, @merge_request, params) }
 
-- if has_diff
+- if @commits.present?
   .container-fluid{ class: [container_class] }
     = render "projects/commits/commit_list" unless hide_commit_list
   .container-fluid
-    = render "projects/diffs/diffs",
-      diffs: @diffs,
-      environment: @environment,
-      diff_page_context: "is-compare",
-      page: pagination_params[:page],
-      paginate_diffs: true,
-      paginate_diffs_per_page: Projects::CompareController::COMMIT_DIFFS_PER_PAGE
+    = render ::RapidDiffs::AppComponent.new(@rapid_diffs_presenter)
 - else
   .container-fluid
-    = render Pajamas::EmptyStateComponent.new(svg_path: 'illustrations/empty-state/empty-commit-md.svg',
-      title: s_("CompareRevisions|There isn't anything to compare")) do |c|
-      - c.with_description do
-        - if params[:to] == params[:from]
-          - source_branch = capture do
-            %span.ref-name= params[:from]
-          - target_branch = capture do
-            %span.ref-name= params[:to]
-          = (s_("CompareRevisions|%{source_branch} and %{target_branch} are the same.") % { source_branch: source_branch, target_branch: target_branch }).html_safe
-        - else
-          = _("To get a valid comparison, select two different branches.")
+    = render Pajamas::CardComponent.new(card_options: { class: "gl-bg-subtle" }) do |c|
+      - c.with_body do
+        = render Pajamas::EmptyStateComponent.new(svg_path: 'illustrations/empty-state/empty-commit-md.svg',
+          title: s_("CompareRevisions|There isn't anything to compare")) do |c|
+
+          - c.with_description do
+            - if params[:to] == params[:from]
+              - source_branch = capture do
+                %span.ref-name= params[:from]
+              - target_branch = capture do
+                %span.ref-name= params[:to]
+              = (s_("CompareRevisions|%{source_branch} and %{target_branch} are the same.") % { source_branch: source_branch, target_branch: target_branch }).html_safe
+            - else
+              = _("To get a valid comparison, select two different branches.")
diff --git a/spec/controllers/projects/compare_controller_spec.rb b/spec/controllers/projects/compare_controller_spec.rb
index 024b79a9eda7e5..641a69ec00b0c1 100644
--- a/spec/controllers/projects/compare_controller_spec.rb
+++ b/spec/controllers/projects/compare_controller_spec.rb
@@ -877,10 +877,10 @@
       }
     end
 
-    it 'renders rapid_diffs template' do
+    it 'renders show template' do
       send_request
 
-      expect(response).to render_template(:rapid_diffs)
+      expect(response).to render_template(:show)
     end
 
     describe 'Get #diff_files_metadata' do
-- 
GitLab


From 25c4c364d7f942265d052730d56347c2c5e6ab28 Mon Sep 17 00:00:00 2001
From: Stanislav Lashmanov <slashmanov@gitlab.com>
Date: Fri, 5 Sep 2025 16:30:30 +0400
Subject: [PATCH 3/5] Fix the spec, update outdated and missing code

---
 .../pages/projects/compare/show/index.js      |  2 +
 .../projects/compare_controller.rb            |  6 +-
 .../projects/compare_controller_spec.rb       | 78 ++++---------------
 3 files changed, 17 insertions(+), 69 deletions(-)

diff --git a/app/assets/javascripts/pages/projects/compare/show/index.js b/app/assets/javascripts/pages/projects/compare/show/index.js
index dc0b9e8d22727e..89bb533f28cf50 100644
--- a/app/assets/javascripts/pages/projects/compare/show/index.js
+++ b/app/assets/javascripts/pages/projects/compare/show/index.js
@@ -1,7 +1,9 @@
 import initCompareSelector from '~/projects/compare';
+import GpgBadges from '~/gpg_badges';
 import { createRapidDiffsApp } from '~/rapid_diffs';
 
 initCompareSelector();
+GpgBadges.fetch();
 
 const app = createRapidDiffsApp();
 app.init();
diff --git a/app/controllers/projects/compare_controller.rb b/app/controllers/projects/compare_controller.rb
index cc80c98f64dcfd..83c79bce0bce65 100644
--- a/app/controllers/projects/compare_controller.rb
+++ b/app/controllers/projects/compare_controller.rb
@@ -14,7 +14,6 @@ class Projects::CompareController < Projects::ApplicationController
   before_action :authorize_read_code!
   # Defining ivars
   before_action :define_diffs, only: [:diff_for_path]
-  before_action :define_environment, only: [:show]
   before_action :define_diff_notes_disabled, only: [:show, :diff_for_path]
   before_action :define_commits, only: [:show, :diff_for_path, :signatures]
   before_action :merge_request, only: [:index, :show]
@@ -24,10 +23,6 @@ class Projects::CompareController < Projects::ApplicationController
   feature_category :source_code_management
   urgency :low, [:show, :create, :signatures]
 
-  # Diffs may be pretty chunky, the less is better in this endpoint.
-  # Pagination design guides: https://design.gitlab.com/components/pagination/#behavior
-  COMMIT_DIFFS_PER_PAGE = 20
-
   def index
     compare_params
   end
@@ -189,6 +184,7 @@ def define_diffs
     @diffs = compare.present? ? compare.diffs(diff_options) : []
   end
 
+  # TODO: support 'view on environment' in Rapid Diffs
   def define_environment
     if compare
       environment_params = if source_project.repository.branch_exists?(head_ref)
diff --git a/spec/controllers/projects/compare_controller_spec.rb b/spec/controllers/projects/compare_controller_spec.rb
index 641a69ec00b0c1..08e1b5e25dfeb1 100644
--- a/spec/controllers/projects/compare_controller_spec.rb
+++ b/spec/controllers/projects/compare_controller_spec.rb
@@ -77,40 +77,15 @@
     let(:page) { nil }
 
     context 'when the refs exist in the same project' do
-      context 'when we set the white space param' do
-        let(:from_project_id) { nil }
-        let(:from_ref) { '08f22f25' }
-        let(:to_ref) { '66eceea0' }
-        let(:whitespace) { 1 }
-
-        it 'shows some diffs with ignore whitespace change option' do
-          allow(controller.current_user).to receive(:show_whitespace_in_diffs).and_return(false)
-
-          show_request
-
-          expect(response).to be_successful
-          diff_file = assigns(:diffs).diff_files.first
-          expect(diff_file).not_to be_nil
-          expect(assigns(:commits).length).to be >= 1
-          # without whitespace option, there are more than 2 diff_splits
-          diff_splits = diff_file.diff.diff.split("\n")
-          expect(diff_splits.length).to be <= 2
-        end
-      end
-
-      context 'when we do not set the white space param' do
-        let(:from_project_id) { nil }
-        let(:from_ref) { 'improve%2Fawesome' }
-        let(:to_ref) { 'feature' }
-        let(:whitespace) { nil }
+      let(:from_project_id) { nil }
+      let(:from_ref) { 'improve%2Fawesome' }
+      let(:to_ref) { 'feature' }
 
-        it 'sets the diffs and commits ivars' do
-          show_request
+      it 'sets the commits ivar' do
+        show_request
 
-          expect(response).to be_successful
-          expect(assigns(:diffs).diff_files.first).not_to be_nil
-          expect(assigns(:commits).length).to be >= 1
-        end
+        expect(response).to be_successful
+        expect(assigns(:commits).length).to be >= 1
       end
     end
 
@@ -169,11 +144,10 @@
       let(:to_ref) { 'feature' }
       let(:whitespace) { nil }
 
-      it 'shows the diff' do
+      it 'shows commits' do
         show_request
 
         expect(response).to be_successful
-        expect(assigns(:diffs).diff_files.first).not_to be_nil
         expect(assigns(:commits).length).to be >= 1
       end
     end
@@ -194,8 +168,6 @@
 
           expect(response).to be_successful
           expect(assigns(:commits).length).to be >= 2
-          expect(assigns(:diffs).raw_diff_files.size).to be >= 2
-          expect(assigns(:diffs).diff_files.first).to be_present
         end
       end
 
@@ -205,12 +177,11 @@
 
         let(:straight) { "true" }
 
-        it 'the commits are empty, but the removed lines are visible as diffs' do
+        it 'the commits are empty' do
           show_request
 
           expect(response).to be_successful
           expect(assigns(:commits).length).to eq 0
-          expect(assigns(:diffs).diff_files.size).to be >= 4
         end
       end
 
@@ -220,12 +191,11 @@
 
         let(:straight) { "false" }
 
-        it 'the additional commits are not visible in diffs and commits' do
+        it 'the additional commits are not visible' do
           show_request
 
           expect(response).to be_successful
           expect(assigns(:commits).length).to eq 0
-          expect(assigns(:diffs).diff_files.size).to eq 0
         end
       end
     end
@@ -240,7 +210,6 @@
         show_request
 
         expect(response).to be_successful
-        expect(assigns(:diffs)).to be_empty
         expect(assigns(:commits)).to be_empty
       end
     end
@@ -263,14 +232,13 @@
         }
       end
 
-      it 'does not show the diff' do
+      it 'does not show commits' do
         allow(controller).to receive(:source_project).and_return(project)
         expect(project).to receive(:default_merge_request_target).and_return(private_fork)
 
         show_request
 
         expect(response).to be_successful
-        expect(assigns(:diffs)).to be_empty
         expect(assigns(:commits)).to be_empty
       end
     end
@@ -280,11 +248,10 @@
       let(:from_ref) { 'non-existent-source-ref' }
       let(:to_ref) { 'feature' }
 
-      it 'sets empty diff and commit ivars' do
+      it 'sets empty commit ivar' do
         show_request
 
         expect(response).to be_successful
-        expect(assigns(:diffs)).to eq([])
         expect(assigns(:commits)).to eq([])
       end
     end
@@ -294,11 +261,10 @@
       let(:from_ref) { 'improve%2Fawesome' }
       let(:to_ref) { 'non-existent-target-ref' }
 
-      it 'sets empty diff and commit ivars' do
+      it 'sets empty commit ivar' do
         show_request
 
         expect(response).to be_successful
-        expect(assigns(:diffs)).to eq([])
         expect(assigns(:commits)).to eq([])
       end
     end
@@ -426,32 +392,16 @@
       let(:page) { 1 }
 
       shared_examples 'valid compare page' do
-        it 'shows the diff' do
+        it 'shows commits' do
           show_request
 
           expect(response).to be_successful
-          expect(assigns(:diffs).diff_files.first).to be_present
           expect(assigns(:commits).length).to be >= 1
         end
       end
 
       it_behaves_like 'valid compare page'
 
-      it 'only loads blobs in the current page' do
-        stub_const('Projects::CompareController::COMMIT_DIFFS_PER_PAGE', 1)
-
-        expect_next_instance_of(Repository) do |repository|
-          # This comparison contains 4 changed files but we expect only the blobs for the first one to be loaded
-          expect(repository).to receive(:blobs_at).with(
-            contain_exactly([from_ref, '.gitmodules'], [to_ref, '.gitmodules']), anything
-          ).and_call_original
-        end
-
-        show_request
-
-        expect(response).to be_successful
-      end
-
       context 'when from_ref is HEAD ref' do
         let(:from_ref) { 'HEAD' }
         let(:to_ref) { 'feature' } # Need to change to_ref too so there's something to compare with HEAD
-- 
GitLab


From 78be162d864cb9b17aac63ac8f2e1ffbecc11ffb Mon Sep 17 00:00:00 2001
From: Stanislav Lashmanov <slashmanov@gitlab.com>
Date: Fri, 5 Sep 2025 16:48:03 +0400
Subject: [PATCH 4/5] Put diff blobs behind a debug feature flag

---
 app/controllers/concerns/rapid_diffs/streaming_resource.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/app/controllers/concerns/rapid_diffs/streaming_resource.rb b/app/controllers/concerns/rapid_diffs/streaming_resource.rb
index 9018e2970c0d8a..b7337f8d08aad8 100644
--- a/app/controllers/concerns/rapid_diffs/streaming_resource.rb
+++ b/app/controllers/concerns/rapid_diffs/streaming_resource.rb
@@ -56,7 +56,8 @@ def stream_diff_files(options, view_context)
       return unless resource
 
       # NOTE: This is a temporary flag to test out the new diff_blobs
-      if !!ActiveModel::Type::Boolean.new.cast(params.permit(:diff_blobs)[:diff_blobs])
+      use_new_gitaly_rpc = ActiveModel::Type::Boolean.new.cast(params.permit(:diff_blobs)[:diff_blobs])
+      if use_new_gitaly_rpc && Feature.enabled?(:rapid_diffs_debug, current_user)
         stream_diff_blobs(options, view_context)
       else
         stream_diff_collection(options, view_context)
-- 
GitLab


From ae8916aa9748cbf8e5e5ba6b36075d186a668e62 Mon Sep 17 00:00:00 2001
From: Stanislav Lashmanov <slashmanov@gitlab.com>
Date: Mon, 8 Sep 2025 17:21:41 +0400
Subject: [PATCH 5/5] Apply 1 suggestion(s) to 1 file(s)

Co-authored-by: Hordur Freyr Yngvason <hfyngvason@gitlab.com>
---
 app/controllers/projects/compare_controller.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/app/controllers/projects/compare_controller.rb b/app/controllers/projects/compare_controller.rb
index 83c79bce0bce65..faab511027e7b9 100644
--- a/app/controllers/projects/compare_controller.rb
+++ b/app/controllers/projects/compare_controller.rb
@@ -185,6 +185,7 @@ def define_diffs
   end
 
   # TODO: support 'view on environment' in Rapid Diffs
+  # See https://gitlab.com/gitlab-org/gitlab/-/issues/554718
   def define_environment
     if compare
       environment_params = if source_project.repository.branch_exists?(head_ref)
-- 
GitLab