fix(diff): track upstream revision for reviewed diffs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

pkg/menus/diff_menu.go

@@ -160,12 +160,12 @@ func getLastSeenHash(ctx context.Context, cmdBuilder exe.ICmdBuilder, dir string
 	return gitEmptyTree, nil
 }
 
-// Update the AUR_SEEN ref to HEAD. We use this ref to determine which diff were
-// reviewed by the user.
+// Update the AUR_SEEN ref to the upstream HEAD. We use this ref to determine
+// which upstream diff was reviewed by the user, excluding local commits.
 func gitUpdateSeenRef(ctx context.Context, cmdBuilder exe.ICmdBuilder, dir string) error {
 	_, stderr, err := cmdBuilder.Capture(
 		cmdBuilder.BuildGitCmd(ctx,
-			dir, "update-ref", gitDiffRefName, "HEAD"))
+			dir, "update-ref", gitDiffRefName, "HEAD@{upstream}"))
 	if err != nil {
 		return fmt.Errorf("%s %w", stderr, err)
 	}

pkg/menus/menus_ops_test.go

@@ -88,6 +88,22 @@ func TestShowPkgbuildDiffHelpers(t *testing.T) {
 	require.Equal(t, "deadbeef", ref)
 }
 
+func TestGitUpdateSeenRefTracksUpstream(t *testing.T) {
+	t.Parallel()
+
+	var gotArgs []string
+	builder := &fakeMenusCmdBuilder{
+		captureFn: func(cmd *exec.Cmd) (string, string, error) {
+			gotArgs = cmd.Args
+
+			return "", "", nil
+		},
+	}
+
+	require.NoError(t, gitUpdateSeenRef(context.Background(), builder, "/tmp"))
+	require.Equal(t, []string{"git", "update-ref", gitDiffRefName, "HEAD@{upstream}"}, gotArgs)
+}
+
 type fakeMenusCmdBuilder struct {
 	captureFn  func(*exec.Cmd) (string, string, error)
 	captureCnt int