Wayland ext-transient-output protocol proposed for VNC and remote desktop software

Wayland developer Simon Ser has submitted a merge request for ext-transient-output, a protocol extension designed to help remoting software like VNC servers operate in Wayland environments. The protocol allows privileged clients to create independent virtual outputs that are automatically removed when the client disconnects, complementing the existing ext-transient-seat protocol which handles dynamic input device creation.

The virtual outputs created through ext-transient-output are not tied to physical hardware and can be captured via ext-image-copy-capture for transmission to remote clients. An experimental implementation already exists for the wlroots compositor library, suggesting relatively rapid potential adoption among wlroots-based compositors.

Protocol design and compositor integration

• Virtual output lifecycle: Transient outputs are created by privileged clients and automatically destroyed when the client destroys the object, preventing resource leaks in compositors.
• Hardware independence: The wl_output global generated by this protocol carries no binding to a particular physical display device, decoupling remote sessions from local monitor configurations.
• Complementary to ext-transient-seat: Together with the existing seat protocol for dynamic keyboard/pointer creation, this completes the core infrastructure needed for full remote desktop functionality without legacy X11 dependencies.
• Capture pipeline: Virtual outputs integrate with ext_output_image_capture_source_manager_v1 (ext-image-copy-capture) to provide frame buffers for encoding and network transmission.
• wlroots implementation: An experimental draft merge request against wlroots exists, indicating the protocol is being validated against a widely-used compositor library that underpins Sway, Hyprland, and other desktop environments.

Why it matters

This protocol addresses a longstanding gap in Wayland's remote desktop story, where VNC and similar tools have historically faced friction due to the display server's tighter security model and lack of implicit screen scraping. For Linux distributions shipping Wayland-by-default desktops and for administrators managing headless or remotely-accessed workstations, ext-transient-output provides a standardized path that avoids XWayland fallbacks or compositor-specific hacks. If merged and adopted across major compositors, it would strengthen Wayland's viability in server and remote-work scenarios where X11 has remained entrenched.