Constant DEFAULT_DEBOUNCE_WINDOW 

pub const DEFAULT_DEBOUNCE_WINDOW: Duration;

Default debounce window. Matches Helix’s diff debounce (50ms); short enough that the visual lag is imperceptible during sustained typing, long enough that a burst of 5–10 keystrokes collapses to a single recompute. Overridable via DiffSubsystem::with_debounce_window for tests and host configuration.