resize_window kitten: Go RC escape-code helper

kittens/resize_window/rc.go

@@ -0,0 +1,28 @@
+// License: GPLv3 Copyright: 2026, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package resize_window
+
+import (
+	"encoding/json"
+
+	"github.com/kovidgoyal/kitty/tools/cmd/at"
+	"github.com/kovidgoyal/kitty/tools/utils"
+)
+
+type resize_payload struct {
+	Increment int    `json:"increment"`
+	Axis      string `json:"axis"`
+	Self      bool   `json:"self"`
+}
+
+func resize_command_escape_code(increment int, axis string) (string, error) {
+	rc := utils.RemoteControlCmd{
+		Cmd: "resize-window", Version: at.ProtocolVersion,
+		Payload: resize_payload{Increment: increment, Axis: axis, Self: true},
+	}
+	data, err := json.Marshal(rc)
+	if err != nil {
+		return "", err
+	}
+	return "\x1bP@kitty-cmd" + string(data) + "\x1b\\", nil
+}

kittens/resize_window/rc_test.go

@@ -0,0 +1,38 @@
+// License: GPLv3 Copyright: 2026, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package resize_window
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+func TestResizeCommandEscapeCode(t *testing.T) {
+	ec, err := resize_command_escape_code(-4, "vertical")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.HasPrefix(ec, "\x1bP@kitty-cmd") || !strings.HasSuffix(ec, "\x1b\\") {
+		t.Fatalf("bad framing: %q", ec)
+	}
+	var cmd struct {
+		Cmd     string `json:"cmd"`
+		Version [3]int `json:"version"`
+		Payload struct {
+			Increment int    `json:"increment"`
+			Axis      string `json:"axis"`
+			Self      bool   `json:"self"`
+		} `json:"payload"`
+	}
+	body := strings.TrimSuffix(strings.TrimPrefix(ec, "\x1bP@kitty-cmd"), "\x1b\\")
+	if err := json.Unmarshal([]byte(body), &cmd); err != nil {
+		t.Fatal(err)
+	}
+	if cmd.Cmd != "resize-window" || cmd.Payload.Increment != -4 || cmd.Payload.Axis != "vertical" || !cmd.Payload.Self {
+		t.Fatalf("bad command: %+v", cmd)
+	}
+	if cmd.Version == [3]int{} {
+		t.Fatal("version not set")
+	}
+}