macOS 15+: ScreenCaptureKit ignores setContentProtection / NSWindow.sharingType

[columbusux]

Background

On macOS 15.x and later, Apple introduced changes to the window compositing and screen capture system. As a result, traditional methods for preventing window capture (including win.setContentProtection(true) in Electron or setting NSWindow.sharingType = .none in native apps) no longer work against the new ScreenCaptureKit framework.

Technical Details

• Window Compositing in macOS 15+
  All NSWindow contents are fully composited into a single framebuffer before being sent to the display.
  ScreenCaptureKit captures this framebuffer, meaning any visible window content is recorded regardless of flags or levels.

• NSWindow.sharingType
  On macOS ≤14, setting sharingType = .none could block capture.
  On macOS 15+, Apple confirms via developer forums that this flag is ignored by ScreenCaptureKit.

• Legacy techniques
  Hacks like CGShieldingWindowLevel or overlay windows are ineffective since the compositor merges all visible content.

• Implication for Tauri
  Even if Tauri sets NSWindow.sharingType = .none or similar protection flags, the window is still captured by ScreenCaptureKit on macOS 15+.
  This matches behavior reported in Electron:

  🔗 Electron Issue #48258 – ScreenCaptureKit and setContentProtection

[Related tauri issue]
(#10213)

Summary

• On macOS 15+, ScreenCaptureKit captures all visible content.
• setContentProtection / sharingType = .none only block legacy CoreGraphics APIs, not ScreenCaptureKit.
• This is a deliberate change by Apple and currently has no known workaround.

References

• Apple Developer Forum: ScreenCaptureKit
• Electron Issue #48258