feat(pulls): support branch-validated stack reordering

Assisted-by: Codet:GPT-5-Codex

modules/task/pull_stack.go

@@ -120,6 +120,19 @@ func AddPullStackEntry(ctx stdctx.Context, login *config.Login, owner, repo stri
 	return &s, nil
 }
 
+// ReorderPullStack records the order of PR branches that are already linked.
+func ReorderPullStack(ctx stdctx.Context, login *config.Login, owner, repo string, id int64, pullIndices []int64) (*stack.Stack, error) {
+	var s stack.Stack
+	err := postStackJSON(ctx, login, fmt.Sprintf("/repos/%s/%s/stacks/%d/reorder", owner, repo, id),
+		struct {
+			PullIndices []int64 `json:"pull_indices"`
+		}{PullIndices: pullIndices}, http.StatusOK, &s)
+	if err != nil {
+		return nil, err
+	}
+	return &s, nil
+}
+
 // RestackPullStack queues a restack starting at the stack's base branch.
 func RestackPullStack(ctx stdctx.Context, login *config.Login, owner, repo string, id int64) error {
 	client := api.NewClient(login)

modules/task/pull_stack_test.go

@@ -134,6 +134,24 @@ func TestAddPullStackEntry(t *testing.T) {
 	assert.Equal(t, int64(5), stack.ID)
 }
 
+func TestReorderPullStack(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, http.MethodPost, r.Method)
+		assert.Equal(t, "/api/v1/repos/owner/repo/stacks/5/reorder", r.URL.Path)
+		body, err := io.ReadAll(r.Body)
+		require.NoError(t, err)
+		assert.JSONEq(t, `{"pull_indices":[2,3]}`, string(body))
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"id":5,"repo_id":2,"owner_id":3,"title":"feat: base","base_branch":"main","state":"open","auto_restack":true,"entries":[]}`))
+	}))
+	defer server.Close()
+	result, err := ReorderPullStack(t.Context(), &config.Login{
+		Name: "test", URL: server.URL, Token: "secret-token",
+	}, "owner", "repo", 5, []int64{2, 3})
+	require.NoError(t, err)
+	assert.Equal(t, int64(5), result.ID)
+}
+
 func TestRestackPullStack(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		assert.Equal(t, http.MethodPost, r.Method)