Screen Capture Protection

CodeAndSystem.ai is designed to be invisible during technical interviews, pair programming sessions, and any screen-shared meeting. This page explains how protection works on each platform and how to verify your status.

How It Works by Platform

Windows

On Windows 10 and later, the app calls SetWindowDisplayAffinity with the WDA_EXCLUDEFROMCAPTURE flag when it launches. This is an OS-level instruction that causes the window to appear as a black rectangle (or be omitted entirely) in any capture API — including Zoom, Teams, OBS, Snipping Tool, PrintScreen, and Win+Shift+S. No configuration required; protection is always active.

macOS and Linux

macOS and Linux do not expose an equivalent OS-level exclusion API, so protection is provided by a privacy overlay. When active, the overlay covers the app window during screen shares.

• Toggle: Ctrl+Alt+P
• On launch: Enable "Start with privacy mode" in Settings > Privacy
• Status: Check the shield icon in the top-right corner of the app

Shield Status Indicator

The shield icon in the top-right corner of the app always reflects your current protection status:

Always verify the shield is green or yellow before sharing your screen.

Verified Compatible Applications

Protection has been tested against the following capture methods:

VirtualBox Setup for Complete Isolation (macOS/Linux)

For the strongest isolation on macOS or Linux, you can run your meeting application inside a VirtualBox virtual machine. The host machine runs CodeAndSystem.ai; the VM runs Zoom or Teams. Because the meeting app never has access to the host screen, CodeAndSystem.ai is inherently invisible.

Prerequisites

• VirtualBox 7.0+
• A Windows or Linux ISO (Windows 11 recommended for Zoom/Teams compatibility)

Setup Steps

1. Install VirtualBox and create a new VM with at least 4 GB RAM and 2 CPU cores.
2. Install your OS inside the VM using your ISO.
3. Install your meeting app (Zoom, Teams, Google Meet via browser) inside the VM.
4. Configure display: In VirtualBox settings, set Display > Graphics Controller to VMSVGA and enable 3D acceleration for smoother rendering.
5. Set network: Use NAT (default) — the VM can access the internet but cannot see your host machine's screen or processes.
6. Start your meeting inside the VM, then share the VM window or set the VM to full screen.
7. Run CodeAndSystem.ai on the host as normal. It is completely invisible to any capture running inside the VM.

Tips

• Use Seamless Mode (Right Ctrl+L) to make VM windows blend with your host desktop.
• Take a VM snapshot before each interview session so you can restore a clean state quickly.
• For audio routing, use VirtualBox's built-in audio controller — select HDA or AC97 in VM settings.

Limitations and Tradeoffs

• macOS/Linux overlay: The overlay approach requires the privacy overlay window to cover the app. If you move or resize the app window, briefly check that the shield indicator remains yellow.
• VirtualBox full isolation: Adds overhead (VM startup time, memory). For day-to-day use the overlay is sufficient; full VM isolation is best for high-stakes interviews.
• Screen mirroring / hardware capture: OS-level protection on Windows only applies to software capture APIs. Physical cameras pointed at your screen are not affected by any software protection.
• Remote Desktop (RDP/VNC): Protection behavior over remote desktop sessions varies. Test your specific setup before relying on it.

Security Notice

Always check the shield indicator before starting a screen share. The shield turns red immediately if privacy mode is disabled. If you are in an interview or sensitive session:

1. Confirm the shield is green (Windows) or yellow (macOS/Linux) before sharing.
2. If the shield is red, press Ctrl+Alt+P to activate the overlay (macOS/Linux) or check your Windows version (requires Windows 10+).
3. On Windows, if the shield is unexpectedly red, restart the application — protection is re-applied on launch.