Function attach_back_handler 

pub fn attach_back_handler<State: 'static>(
    controller: NavigatorController<State>,
) -> BackHandler<State>

Android back-press ⇄ navigator auto-wiring: attach_back_handler/BackHandler pop a NavigatorController on a platform back press and keep frust-reactive‘s handles_back flag in sync with the stack depth, so a shell knows whether a root-level back should fall through to the platform (activity finish). Mirrors RouterDeepLinks’s shape and, like it, is the ONLY place in the facade that sees both frust-widgets’ NavigatorController and frust-reactive’s back-press source together — see BackHandler’s doc for the consume/dedupe and timing contracts. Call BackHandler::track from every Component::build. Android back-press ⇄ navigator auto-wiring: attach_back_handler/BackHandler pop a NavigatorController on a platform back press and keep frust-reactive‘s handles_back flag in sync with the stack depth, so a shell knows whether a root-level back should fall through to the platform (activity finish). Mirrors RouterDeepLinks’s shape and, like it, is the ONLY place in the facade that sees both frust-widgets’ NavigatorController and frust-reactive’s back-press source together — see BackHandler’s doc for the consume/dedupe and timing contracts. Call BackHandler::track from every Component::build. Android back-press ⇄ navigator auto-wiring: attach_back_handler/BackHandler pop a NavigatorController on a platform back press and keep frust-reactive‘s handles_back flag in sync with the stack depth, so a shell knows whether a root-level back should fall through to the platform (activity finish). Mirrors RouterDeepLinks’s shape and, like it, is the ONLY place in the facade that sees both frust-widgets’ NavigatorController and frust-reactive’s back-press source together — see BackHandler’s doc for the consume/dedupe and timing contracts. Call BackHandler::track from every Component::build. Convenience constructor equivalent to BackHandler::new — see its docs and RouterDeepLinks/router_with_deep_links for the mirrored API shape.

Note that back handling is automatic for any app using frust::navigator; this explicit surface is only needed when an app wants a handle it drives directly (e.g. Huddle).

use frust::{
    AnyView, BackHandler, Component, NavigatorController, any, attach_back_handler,
    navigator, text,
};

#[derive(Default)]
struct App;

struct AppState {
    back: BackHandler<AppState>,
}

impl Component for App {
    type State = AppState;

    fn init(&self) -> AppState {
        let nav: NavigatorController<AppState> = NavigatorController::new();
        AppState {
            back: attach_back_handler(nav),
        }
    }

    fn build(&self, state: &mut AppState) -> AnyView<AppState> {
        // Called every rebuild: consumes a new back press (via `request_back`)
        // and keeps the framework's handles-back interest in sync. The
        // `frust::navigator` call auto-wires the SAME controller — one press
        // still pops exactly once (shared consumption source).
        state.back.track();
        let controller = state.back.controller();
        any(navigator(controller, || any(text("home"))))
    }
}

frust::app!(App);