windows-reactor exposes no raw key-down/up or pointer-position/wheel events (only keyboard
accelerators + pointer button-state), so the WinUI 3 stream page captures input below XAML via
WH_KEYBOARD_LL / WH_MOUSE_LL, installed on the UI thread when the stream page mounts and removed
on unmount (held keys/buttons flushed). The SwapChainPanel fills the window, so the pointer maps
through the client rect (Contain-fit into the negotiated mode); keys carry the native Windows VK
directly (the wire contract — no table needed). While captured, events inside the video area are
swallowed so Alt+Tab/Win reach the host; Ctrl+Alt+Shift+Q toggles capture; clicks on the title
bar (outside the client rect) pass through. Mouse buttons (L/M/R/X1/X2), vertical + horizontal
wheel, and absolute motion all forwarded. Build + clippy + fmt green on x86_64-pc-windows-msvc.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
