Remove dead paginate entry point and clarify resolved-anchor recording

The Paginator.paginate class method bypassed the instance, discarding the
resolved_anchor state the controller reads after .call; it had no callers, so
drop it and keep the single new(...).call entry point. Extract the activity
anchor side effect into record_resolved_anchor so the intent is explicit at the
call site, and pin the server contract with a request spec asserting an
unresolvable activity anchor omits the resolved-comment value.

app/services/work_packages/activities_tab/paginator.rb

@@ -62,10 +62,6 @@ class WorkPackages::ActivitiesTab::Paginator
   include Pagy::Method
   include WorkPackages::ActivitiesTab::JournalSortingInquirable
 
-  def self.paginate(work_package, params = {})
-    new(work_package, params).call
-  end
-
   attr_reader :work_package, :params, :filter, :resolved_anchor
 
   def initialize(work_package, params = {})
@@ -163,10 +159,7 @@ class WorkPackages::ActivitiesTab::Paginator
     activity_at, anchor_id = locate_anchor(anchor_type, target_record_id)
     return nil unless activity_at && anchor_id
 
-    # A comment anchor already matches the DOM's data-anchor-comment-id. An
-    # activity anchor has no rendered counterpart, so hand the comment id it
-    # resolved to back to the client to scroll to instead.
-    @resolved_anchor = anchor_id if anchor_type.activity?
+    record_resolved_anchor(anchor_type, anchor_id)
 
     rows_ahead = scope
       .where("(journals.created_at, journals.id) > (?, ?)", activity_at, anchor_id)
@@ -175,6 +168,13 @@ class WorkPackages::ActivitiesTab::Paginator
     (rows_ahead / limit) + 1
   end
 
+  # A comment anchor already matches the DOM's data-anchor-comment-id. An activity
+  # anchor has no rendered counterpart, so hand the comment id it resolved to back
+  # to the client to scroll to instead.
+  def record_resolved_anchor(anchor_type, anchor_id)
+    @resolved_anchor = anchor_id if anchor_type.activity?
+  end
+
   def locate_anchor(anchor_type, target_record_id)
     if anchor_type.comment?
       visible_journals.where(id: target_record_id).pick(:created_at, :id)
@@ -190,9 +190,9 @@ class WorkPackages::ActivitiesTab::Paginator
       .pick(:created_at, :id)
   end
 
-  # Eager-loads and the sequence version are applied to the page slice here, not
-  # to activities_scope, so the count query stays off them. Changeset journals
-  # map back to Changeset records; work package journals go through the wrapper.
+  # Eager-loads are applied to the page slice here, not to activities_scope, so
+  # the count query stays off them. Changeset journals map back to Changeset
+  # records; work package journals go through the wrapper.
   def load_activities(page_relation)
     journals = page_journals(page_relation)
     changesets = load_changesets(journals.select { changeset?(it) }.map(&:journable_id))

spec/requests/work_packages/activities_tab_spec.rb

@@ -73,5 +73,12 @@ RSpec.describe "Work package activities tab",
       expect(response).to have_http_status(:ok)
       expect(response.body).not_to include(resolved_value_attribute)
     end
+
+    it "omits the resolved-comment value for an unresolvable activity anchor" do
+      get work_package_activities_path(work_package), params: { anchor: "activity-999999" }
+
+      expect(response).to have_http_status(:ok)
+      expect(response.body).not_to include(resolved_value_attribute)
+    end
   end
 end