Bevy Idle clicker (thin router)

Genre router. Domain work lives in the Bevy skills below.

When to use

Load this for currencies that tick while the app runs.

ECS shape

• Components hold the genre's per-entity flags as plain data. This file does not name new engine types.
• Resources hold run-wide counters (score, wave index, seed) via bevy-data-resources.
• Systems read those components on Update or the fixed timestep from bevy-master. Order them with .chain() when a later system must see the result.
• Schedule: gameplay mode changes go through bevy-state-machines. Do not invent a genre plugin.

Routing

• bevy-economy-system - Currencies.
• bevy-ui-layout - Click target.
• bevy-input-handling - Click.
• bevy-save-load - Offline progress.

Examples

[dependencies]
bevy = "0.20"
serde = { version = "1", features = ["derive"] }

The wallet is one resource. Generators add coins on Update from Time::delta_secs.

#[derive(Resource)]
struct Wallet {
    coins: f64,
    per_second: f64,
}

fn tick_income(time: Res<Time>, mut wallet: ResMut<Wallet>) {
    wallet.coins += wallet.per_second * f64::from(time.delta_secs());
}

fn click(
    mouse: Res<ButtonInput<MouseButton>>,
    mut wallet: ResMut<Wallet>,
) {
    if mouse.just_pressed(MouseButton::Left) {
        wallet.coins += 1.0;
    }
}

fn install_income(app: &mut App) {
    app.insert_resource(Wallet {
        coins: 0.0,
        per_second: 2.5,
    })
    .add_systems(Update, (tick_income, click).chain());
}

Each building is an entity. One system writes the wallet so the generators cannot race each other.

#[derive(Component)]
struct Generator {
    rate: f64,
    owned: u32,
}

#[derive(Resource)]
struct Wallet {
    coins: f64,
    per_second: f64,
}

fn generators_to_wallet(
    gens: Query<&Generator>,
    mut wallet: ResMut<Wallet>,
    time: Res<Time>,
) {
    let mut rate = 0.0;
    for building in &gens {
        rate += building.rate * f64::from(building.owned);
    }
    wallet.per_second = rate;
    wallet.coins += rate * f64::from(time.delta_secs());
}

tick_income and generators_to_wallet both write Wallet. Run only one of them, or .chain() them if a later system must see the sum.

Offline progress stores a unix second, then banks elapsed time the next time the resource is inserted.

use serde::{Deserialize, Serialize};
use std::time::{SystemTime, UNIX_EPOCH};

#[derive(Resource, Clone, Serialize, Deserialize)]
struct IdleClock {
    last_unix: u64,
    per_second: f64,
    banked: f64,
}

fn bank_offline(mut clock: ResMut<IdleClock>) {
    let now = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .map(|d| d.as_secs())
        .unwrap_or(clock.last_unix);
    let elapsed = now.saturating_sub(clock.last_unix).min(8 * 60 * 60);
    clock.banked += clock.per_second * elapsed as f64;
    clock.last_unix = now;
}

#[derive(Resource)]
struct Wallet {
    coins: f64,
}

fn claim(mut clock: ResMut<IdleClock>, mut wallet: ResMut<Wallet>) {
    wallet.coins += clock.banked;
    clock.banked = 0.0;
}

bank_offline and claim both mutate IdleClock, so chain them. Persistence of the struct belongs on bevy-save-load.

Scope

• Currencies, the click, and the layout route to the skills in Routing.
• Cap offline time in the resource (the example caps at eight hours) so a bad clock cannot mint unbounded coins.

Expert Knowledge Delta

Target: Bevy 0.20+.

Core ECS types: Component, Resource, Query, Commands, Startup, Update, Fixed / FixedMain (bevy::time), .chain(), Plugin, DefaultPlugins, MinimalPlugins. Messages and observers are an ownership slot. See bevy-events-messaging for their APIs. Systems run in parallel unless .chain() orders the ones that conflict.

Who owns state

Borrow rule: two systems that both mutably query the same component must be ordered (.chain()) or split so only one writes. Unrelated systems stay parallel. That is the ECS page rule, not a guess at a system-set API.

Decision

Load references/ecs-ownership.md for the ownership table.

NEVER

• Do not pin /0.20.0/ in docs URLs. WHY: links stay on latest; the 0.20 target is stated once in prose.

• Do not mutably query the same component from two unordered systems. WHY: the schedule runs systems in parallel unless .chain() orders them.

• Do not invent a physics, navigation, networking, or XR crate here. WHY: this skill only names documented Bevy crates and modules.

• Do not let tick_income and generators_to_wallet both add Wallet.coins unless they are .chain()ed or only one is installed. WHY: unordered systems run in parallel and one income write is dropped.

• Do not leave offline elapsed uncapped. WHY: a clock jump mints unbounded coins into the wallet resource.

• No invented genre APIs. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.

• Do not pick a physics or net crate here. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.

Reference

The library pin on bevy-master stays 0.20.0. Official pages stay on the unversioned latest branch.

Official Documentation

• Assets - Official asset catalog. No third-party crate was selected.
• Examples - Example tree on the latest branch.
• ECS - Component, systems, Query, Startup, Update, and .chain().
• Plugins - Plugin, DefaultPlugins, MinimalPlugins, and add_plugins.

Related Skills

Prerequisites

• bevy-master - ECS ownership and schedules.
• bevy-ecs-composition - Spawn and query shape.

Complements

• godot-genre-idle-clicker - Idle clicker on the Godot engine, same depth.
• bevy-economy-system - Currencies.
• bevy-ui-layout - Click target.
• bevy-input-handling - Click.
• bevy-save-load - Offline progress.

Downstream / consumers

• None. This router does not own a second implementation.

Master

• bevy-master - Bevy router.