package main

import (
	"github.com/alecthomas/kong"
)

type CmdCLI struct {
	InnerFlag string `kong:"env=INNER_FLAG"`
}

type TestCLI struct {
	TopFlag string `kong:"env=TOP_FLAG"`

	Cmd CmdCLI `kong:"cmd,envprefix=CMD_"`
}

type WrapCLI struct {
	TestCLI `kong:"envprefix=APP_"`
}

func main() {
	kcli := WrapCLI{}

	kctx := kong.Parse(&kcli,
		kong.UsageOnError(),
	)
	err := kctx.Run()
	kctx.FatalIfErrorf(err)
}

Usage: example cmd [flags]

Flags:
  -h, --help                 Show context-sensitive help.
      --top-flag=STRING      ($APP_TOP_FLAG)

      --inner-flag=STRING    ($INNER_FLAG)