Context

Context is a standard host object schema, not ordinary script-owned state. Hosts register it when scripts need deterministic time fields, event emission, or logging. Scripts receive a call-scoped HostRef; they never hold a real Rust mutable reference.

Fields

The standard context schema exposes now: i64 and tick: i64. These values come from the host and match the deterministic time model.

fn main(ctx: Context) {
    let stamp = ctx.now + ctx.tick;
    return stamp;
}

Field reads still go through HostAccess, so host read permissions and stale host reference checks apply.

Events And Logs

ctx.emit(event, payload?) records an event emission patch for the host safe point. ctx.log(level, message, payload?) records a log patch. Both are host methods with event effects.

fn main(ctx: Context, player: Player) {
    let stamp = ctx.now + ctx.tick;
    ctx.emit("player.level_checked", stamp);
    ctx.log("info", "player.level_checked", stamp);
    return stamp;
}

The payload parameter is optional and can be any script value that the host adapter accepts.

Capability Boundary

The host must register the context schema and grant the relevant host read, host call, and event capabilities. Denied context calls are runtime diagnostics, not Result::Err, because no event was accepted by the host boundary.

Context is intentionally domain-neutral. Game-specific event names, payload shapes, and host types come from the embedding application.