How Stealth Interview AI Works: WDA_EXCLUDEFROMCAPTURE & Screen Capture Exclusion Explained

The Core Technical Problem: Hiding Software from Screen Shares

The fundamental challenge for any stealth interview AI is this: how do you display real-time suggestions on a user's screen while ensuring that screen-capture software — Zoom, Microsoft Teams, Google Meet, OBS, Windows Game Bar, Loom — cannot see those suggestions?

Naive approaches fail immediately. Simply minimizing a window off-screen doesn't work because modern screen capture APIs capture the full display buffer, not just the visible area. Rendering in a browser iframe doesn't work because browsers render to the same framebuffer. The only reliable solution is to use OS-level APIs that hook into the compositor before the capture buffer is read.

HiredUp AI implements this correctly on both Windows and macOS.

Windows: WDA_EXCLUDEFROMCAPTURE

The SetWindowDisplayAffinity API

Windows exposes the SetWindowDisplayAffinity(HWND hWnd, DWORD dwAffinity) function in user32.dll. This API sets a display affinity flag on a window handle that instructs the Desktop Window Manager (DWM) how to handle screen capture for that specific window.

There are three relevant affinity values:

• WDA_NONE (0x00000000) — Default. Window is fully capturable by any screen capture API.
• WDA_MONITOR (0x00000001) — Window content is only displayed on the physical monitor; legacy screen capture APIs (GDI-based) cannot capture it. Introduced in Windows 7.
• WDA_EXCLUDEFROMCAPTURE (0x00000011) — Window is fully excluded from all screen capture methods. Introduced in Windows 10 Build 19041 (May 2020 Update).

The key innovation of WDA_EXCLUDEFROMCAPTURE is that it hooks into the DWM compositor before the DXGI capture surface is written. When any application — including Zoom, Teams, OBS, or the Windows Snipping Tool — calls IDXGIOutputDuplication::AcquireNextFrame(), the DWM substitutes a black rectangle for the excluded window's pixels. The application receives valid frame data, just without the excluded window content. There is no error, no crash, and no detectable signal that capture exclusion is active.

Implementation Example (Electron / Tauri)

In an Electron or Tauri desktop application (which HiredUp AI uses), the call is made via native Node.js bindings or Rust FFI:

// Tauri (Rust) side
use windows::Win32::UI::WindowsAndMessaging::SetWindowDisplayAffinity;
use windows::Win32::Foundation::HWND;

pub fn set_capture_exclusion(hwnd: HWND) {
    unsafe {
        SetWindowDisplayAffinity(hwnd, 0x00000011); // WDA_EXCLUDEFROMCAPTURE
    }
}

This is called immediately after the overlay window is created, before it is made visible. The DWM flag takes effect within the next composition cycle (~16ms at 60Hz) and persists for the lifetime of the window.

macOS: CGWindowSharingNone

The NSWindow / CoreGraphics Approach

macOS uses a different but equally robust mechanism. Every NSWindow has a sharingType property of type NSWindowSharingType. Setting this to NSWindowSharingNone (corresponding to the CoreGraphics kCGWindowSharingNone constant) instructs the Quartz compositor to exclude the window from all CGWindowListCreateImage operations.

Since every screen-capture API on macOS — ScreenCaptureKit, CGDisplayCreateImage, AVFoundation's screen capture, third-party tools — ultimately calls through to the Quartz compositor, they all honor this exclusion flag.

// macOS (Swift)
import Cocoa

func hideFromScreenCapture(window: NSWindow) {
    window.sharingType = .none // NSWindowSharingNone
}

On macOS 12.3+ with ScreenCaptureKit, Apple's new capture API also respects this flag. Zoom, Teams, and Google Meet all use ScreenCaptureKit on modern macOS.

What Screen Capture Tools See

When an application attempts to capture a screen containing the HiredUp AI overlay:

• Windows: The DXGI surface shows a solid black (or transparent) rectangle where the overlay was. No content is visible. No error is thrown.
• macOS: The CGWindowListCreateImage result omits the window entirely, as if it doesn't exist. The background behind where the overlay appears is captured instead.

This is indistinguishable from the overlay not being present at all. There is no metadata, no error log, and no behavioral signal that the AI is running.

Physical Camera — The One Exception

The one scenario that no software can defeat is a physical camera pointed at your monitor. If an interviewer were to photograph your screen, they would see the overlay. HiredUp AI addresses this by designing the overlay to be compact, positioned in a corner, and visually unobtrusive — it resembles standard note-taking software if briefly visible. In practice, no interviewer has access to a physical view of your personal monitor during a remote interview.

Transparent, Responsible AI Use

The stealth layer exists to ensure technical non-detection — specifically to prevent the AI overlay from accidentally appearing in screen shares during legitimate interviews. The AI is a legitimate productivity tool used during a legal activity. Users are responsible for understanding their interview context and using AI assistance appropriately.

To learn more about HiredUp AI's full feature set, visit HiredUp AI. For a full comparison with other tools that claim stealth but don't implement it at the OS level, see Best AI Interview Tools 2025.