Struct SystemEnv 

pub struct SystemEnv {
    pub appearance: Appearance,
    pub accent: Option<Color>,
    pub motion: MotionPref,
    pub locale: Option<Locale>,
    pub assistive: Assistive,
}

The user’s OS settings, as the host reports them. Not window facts and not display facts: things the person chose once, in a settings app, that a view is expected to honour. The core acts on two of them in one way: appearance and accent derive the theme, so the stock widgets and a <text> with no colour follow the OS — and nothing else moves. Reduced motion does not shorten an animation and a dark appearance repaints none of the app’s own colours: the view decides, because only it knows which of its colours is the background and which of its animations carries meaning.

Each field defaults to “the host cannot tell”, which is what a headless core reports and what any driver reports for a fact its platform gives it no way to ask. The kui-native runner asks the OS for all four on macOS and Windows (the appearance through winit, the rest in its system_env); elsewhere it answers what it can and leaves the rest unknown. The fifth, Assistive, is not a setting but a fact of the same shape — the user chose to run a screen reader — and comes from the accessibility bridge rather than a settings query.

Fields

appearance: Appearance

Light or dark, when the host can tell.

accent: Option<Color>

The OS accent/highlight colour, None when the host can’t tell.

motion: MotionPref

Whether the user asked for reduced motion.

locale: Option<Locale>

The UI language as a BCP-47 tag, None when the host can’t tell.

assistive: Assistive

Whether assistive technology has asked for the access tree.

Implementations

impl SystemEnv

pub fn over(self, base: SystemEnv) -> SystemEnv

self laid over base: every field self knows wins, every field it left at “cannot tell” is base’s. The merge behind a launcher’s pinned reading (kui_native::Launcher::system, Node’s runWindowed(.., {system}), the context a C host hands kui_run_with): the app’s partial over what the OS answered, applied every frame where the runner writes the real reading — so a pinned motion survives the write, and a real change to the accent still arrives, because that field was left unknown here and base is the OS’s.

Unknown means not pinned, which is why there is no separate override type: the four “cannot tell” readings are the defaults, so SystemEnv { motion: MotionPref::Reduced, ..Default::default() } is the whole of “as if this user asked for less motion”. What it cannot say is “pin this to unknown” — a window on a platform that answers has no test that needs it.

Trait Implementations

impl Clone for SystemEnv

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for SystemEnv

impl Debug for SystemEnv

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SystemEnv

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for SystemEnv

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for SystemEnv