Skip the shuffle when the position doesn't actually change

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## [Unreleased]
 
 - Fix the healer not locking scopes without a `belongs_to` association (or with a nil one).
+- Don't write anything when an assigned position doesn't change. `updated_at` is no longer bumped and `saved_change_to_position?` is false in that case.
 
 ## [0.4.7] - 2025-08-09
 

lib/positioning/mechanisms.rb

@@ -29,6 +29,13 @@ def update_position
       clear_position if positioning_scope_changed? && !position_changed?
 
       solidify_position
+
+      # Assigning the position a record already has (e.g. a form resubmitting it) moves nothing
+      if !positioning_scope_changed? && position == position_was
+        @positioned.clear_attribute_changes [@column]
+        return
+      end
+
       move_out_of_the_way
 
       if positioning_scope_changed?

test/test_positioning.rb

@@ -805,6 +805,24 @@ def test_that_updating_an_item_does_not_change_its_position
     assert_equal [1, 2, 3], [@first_item, @second_item, @third_item].map(&:position)
   end
 
+  def test_that_assigning_the_current_position_does_not_write_anything
+    [2, {after: @first_item}, {before: @third_item}].each do |position|
+      queries = []
+      callback = ->(*, payload) { queries << payload[:sql] }
+
+      ActiveSupport::Notifications.subscribed(callback, "sql.active_record") do
+        @second_item.update position: position
+      end
+
+      assert_empty queries.grep(/\AUPDATE/i)
+      refute @second_item.saved_change_to_position?
+    end
+
+    reload_models
+
+    assert_equal [1, 2, 3], [@first_item, @second_item, @third_item].map(&:position)
+  end
+
   def test_that_prior_item_is_found
     assert_nil @first_item.prior_position
     assert_equal @first_item, @second_item.prior_position