fix: clean up reporter diff artifacts (diff, base.diff, heatmap) on Snap#delete!

Snap#delete! only removed .png and .base.png but left .diff.png,
.base.diff.png, and .heatmap.diff.png orphaned. Also Reporters::Default
#clean_tmp_files missed heatmap cleanup. Each test run leaked ~30 files
into tmp/ that accumulated indefinitely across runs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pftg

lib/capybara/screenshot/diff/reporters/default.rb

@@ -33,6 +33,7 @@ def generate
       def clean_tmp_files
         annotated_base_image_path.unlink if annotated_base_image_path.exist?
         annotated_image_path.unlink if annotated_image_path.exist?
+        heatmap_diff_path.unlink if heatmap_diff_path.exist?
       end
 
       def build_error_for_different_dimensions

lib/capybara_screenshot_diff/snap.rb

@@ -16,6 +16,7 @@ def initialize(full_name, format, manager: SnapManager.instance)
     def delete!
       path.delete if path.exist?
       base_path.delete if base_path.exist?
+      cleanup_diff_artifacts!
       cleanup_attempts!
     end
 
@@ -51,5 +52,15 @@ def cleanup_attempts!
     def find_attempts_paths
       Dir[@manager.abs_path_for("**/#{full_name}.attempt_[0-9][0-9].#{format}")]
     end
+
+    private
+
+    def cleanup_diff_artifacts!
+      [
+        path.sub_ext(".diff.#{format}"),
+        path.sub_ext(".heatmap.diff.#{format}"),
+        base_path.sub_ext(".diff.#{format}")
+      ].each { |f| f.delete if f.exist? }
+    end
   end
 end

test/unit/reporters/default_test.rb

@@ -30,6 +30,22 @@ class Reporters::DefaultTest < ActiveSupport::TestCase
       assert_same_images "a-and-b.heatmap.diff.png", reporter.heatmap_diff_path
     end
 
+    test "#clean_tmp_files removes heatmap diff along with other diff artifacts" do
+      skip "VIPS not present. Skipping VIPS driver tests." unless defined?(Vips)
+      driver = Drivers::VipsDriver.new
+      comparison = build_comparison_for(driver, "a.png", "b.png")
+      reporter = Reporters::Default.new(driver.find_difference_region(comparison))
+      reporter.generate
+
+      assert_predicate reporter.heatmap_diff_path, :exist?
+
+      reporter.clean_tmp_files
+
+      assert_not reporter.annotated_image_path.exist?, "diff should be cleaned"
+      assert_not reporter.annotated_base_image_path.exist?, "base diff should be cleaned"
+      assert_not reporter.heatmap_diff_path.exist?, "heatmap diff should be cleaned"
+    end
+
     private
 
     def build_comparison_for(driver, *images)

test/unit/snap_manager_test.rb

@@ -60,5 +60,24 @@ class SnapManagerTest < ActiveSupport::TestCase
       assert_includes snap.base_path.to_s, "test_image.base.png"
       assert_includes snap.next_attempt_path!.to_s, "test_image.attempt_00.png"
     end
+
+    test "#cleanup! removes diff artifacts created by reporters" do
+      snap = @manager.snapshot("test_image")
+      source = fixture_image_path_from("a")
+      @manager.provision_snap_with(snap, source)
+      @manager.provision_snap_with(snap, source, version: :base)
+
+      # Simulate reporter artifacts
+      diff_path = snap.path.sub_ext(".diff.png")
+      base_diff_path = snap.path.sub_ext(".base.diff.png")
+      heatmap_path = snap.path.sub_ext(".heatmap.diff.png")
+      [diff_path, base_diff_path, heatmap_path].each { |p| FileUtils.cp(source, p) }
+
+      @manager.cleanup!
+
+      assert_not diff_path.exist?, "diff artifact should be cleaned up"
+      assert_not base_diff_path.exist?, "base diff artifact should be cleaned up"
+      assert_not heatmap_path.exist?, "heatmap diff artifact should be cleaned up"
+    end
   end
 end