feat(pulls): support branch-validated stack reordering

Assisted-by: Codet:GPT-5-Codex

cmd/pulls/stack/reorder.go

@@ -0,0 +1,53 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package stack
+
+import (
+	stdctx "context"
+	"fmt"
+
+	"gitea.dev/tea/cmd/flags"
+	"gitea.dev/tea/modules/context"
+	"gitea.dev/tea/modules/task"
+	"gitea.dev/tea/modules/utils"
+
+	"github.com/urfave/cli/v3"
+)
+
+// CmdStackReorder stores a validated, already-linked PR branch order.
+var CmdStackReorder = cli.Command{
+	Name: "reorder", Usage: "Reorder PRs after their branches have been rebased",
+	ArgsUsage: "<stack id> <pull index> <pull index> [more pull indices]",
+	Flags:     flags.AllDefaultFlags, Action: RunStackReorder,
+}
+
+func RunStackReorder(requestCtx stdctx.Context, cmd *cli.Command) error {
+	if cmd.Args().Len() < 3 {
+		return fmt.Errorf("stack id and at least two pull numbers are required")
+	}
+	stackID, err := utils.ArgToIndex(cmd.Args().Get(0))
+	if err != nil {
+		return err
+	}
+	indices := make([]int64, 0, cmd.Args().Len()-1)
+	for i := 1; i < cmd.Args().Len(); i++ {
+		index, err := utils.ArgToIndex(cmd.Args().Get(i))
+		if err != nil {
+			return err
+		}
+		indices = append(indices, index)
+	}
+	ctx, err := context.InitCommand(cmd)
+	if err != nil {
+		return err
+	}
+	if err := ctx.Ensure(context.CtxRequirement{RemoteRepo: true}); err != nil {
+		return err
+	}
+	if _, err := task.ReorderPullStack(requestCtx, ctx.Login, ctx.Owner, ctx.Repo, stackID, indices); err != nil {
+		return err
+	}
+	fmt.Fprintf(ctx.Writer, "reordered stack #%d\n", stackID)
+	return nil
+}

cmd/pulls/stack/reorder_test.go

@@ -0,0 +1,17 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package stack
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStackReorderRequiresCompleteOrder(t *testing.T) {
+	cmd := CmdStackReorder
+	err := cmd.Run(context.Background(), []string{"reorder", "5", "2"})
+	assert.ErrorContains(t, err, "at least two pull numbers")
+}