ios – Apply shadow only outside of a SwifUI transparent button?

I have a SwiftUI button with a transparent background, a rounded border, and a shadow.

The issue is that because the button is transparent, the shadow is visible both outside and inside the rounded rectangle. I would like the shadow to appear only outside the button, without bleeding into the transparent interior.

Here is a minimal example:

import SwiftUI

#Preview("StackOverflow Transparent Button Shadow") {
    let cornerRadius: CGFloat = 15

    Button {} label: {
        Text("Transparent button")
            .font(.system(size: 14, weight: .semibold))
            .foregroundStyle(.black)
            .padding(.horizontal, 16)
            .padding(.vertical, 8)
            .frame(height: 40, alignment: .center)
    }
    .background(.white)
    .clipShape(RoundedRectangle(cornerRadius: cornerRadius))
    .overlay {
        RoundedRectangle(cornerRadius: cornerRadius)
            .stroke(.red, lineWidth: 1)
            .shadow(
                color: .blue,
                radius: 2,
                x: 0,
                y: 0
            )
    }
    .padding(48)
    .background(Color.white)
}

This produces a glow around the border, but the shadow is also rendered inside the transparent area of the button.

What I want is:

• keep the button background transparent
• keep the rounded border visible
• apply the shadow/glow only outside the rounded rectangle
• avoid any shadow appearing inside the button

Is there a recommended SwiftUI way to mask or clip the shadow so that it only renders outside the shape?