Module runloop 

The shared render/event loop that drives a live App. Both the compiled cn run runtime (run::start_runtime) and the interpreted cn debug path (in the editor crate) pump the same loop; the only difference is the per-tick hook the debug path threads through to run its DebugHook. Keeping the platform event-pump and window-activation glue in one place means it is not duplicated per entry point.

On macOS the world loop must pump the Cocoa run loop on the main thread each tick so AppKit (GLFW window creation, Metal pipeline compilation, event dispatch) can process its callbacks and Metal drawable presentation fires. On all other platforms a tight Rust loop is used, which is what the Vulkan / DirectX renderers expect.

Functions

install_ctrlc_handler

Install the process CTRL+C handler that cancels the app’s shutdown token, so the render loop exits cleanly. Panics if a handler is already installed; only one entry point installs it per process.

run_loop

Drive the world loop to completion. Each iteration: exit if the shutdown token is cancelled; on macOS, when pump_events is set (a window is present), drain the pending AppKit/CoreFoundation events so the window stays responsive and Metal drawable callbacks fire; run the per-tick on_tick hook; then step the world, stopping on Stop/Done. on_tick is where the interpreted debug path ticks its DebugHook; the runtime passes a no-op.