Bevy Party (thin router)

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

When to use

Load this for local minigame swaps and shared scores.

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. This file registers only seat scores and the minigame swap.

Routing

• bevy-state-machines - Minigame mode.
• bevy-input-handling - Local devices. Gamepad exists.
• bevy-game-loop-time-trial - When a minigame is timed.

Scope

Local seats, the shared board, and the current minigame are plain data. Mode machines, devices, and timed rounds stay in the skills linked above.

[dependencies]
bevy = "0.20"

#[derive(Component)]
struct LocalSeat {
    index: u8,
    score: i32,
}

#[derive(Resource)]
struct PartyBoard {
    active: u8,
    round: u32,
    award_pending: bool,
}

fn award(mut board: ResMut<PartyBoard>, mut seats: Query<&mut LocalSeat>) {
    if !board.award_pending {
        return;
    }
    board.award_pending = false;
    for mut seat in &mut seats {
        if seat.index == board.active {
            seat.score += 1;
        }
    }
}

pub struct ScorePlugin;

impl Plugin for ScorePlugin {
    fn build(&self, app: &mut App) {
        app.insert_resource(PartyBoard {
            active: 0,
            round: 1,
            award_pending: true,
        })
        .add_systems(Update, award);
    }
}

#[derive(Resource)]
struct PartyBoard {
    active: u8,
    round: u32,
    award_pending: bool,
}

#[derive(Clone, Copy, PartialEq, Eq)]
enum Minigame {
    Hub,
    Race,
    Score,
}

#[derive(Resource)]
struct CurrentMinigame(Minigame);

fn open_race(keys: Res<ButtonInput<KeyCode>>, mut current: ResMut<CurrentMinigame>) {
    if keys.just_pressed(KeyCode::Digit1) && current.0 == Minigame::Hub {
        current.0 = Minigame::Race;
    }
}

fn advance_round(
    keys: Res<ButtonInput<KeyCode>>,
    mut current: ResMut<CurrentMinigame>,
    mut board: ResMut<PartyBoard>,
) {
    if keys.just_pressed(KeyCode::Digit2) && current.0 == Minigame::Score {
        board.round += 1;
        board.active = board.active.wrapping_add(1) % 4;
        board.award_pending = true;
        current.0 = Minigame::Hub;
    }
}

pub struct MinigamePlugin;

impl Plugin for MinigamePlugin {
    fn build(&self, app: &mut App) {
        app.insert_resource(CurrentMinigame(Minigame::Hub))
            .add_systems(Update, (open_race, advance_round).chain());
    }
}

#[derive(Component)]
struct LocalSeat {
    index: u8,
    score: i32,
}

fn join_seat(keys: Res<ButtonInput<KeyCode>>, mut commands: Commands, seats: Query<&LocalSeat>) {
    if keys.just_pressed(KeyCode::KeyJ) {
        let index = seats.iter().count() as u8;
        if index < 4 {
            commands.spawn(LocalSeat { index, score: 0 });
        }
    }
}

pub struct JoinPlugin;

impl Plugin for JoinPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(Update, join_seat);
    }
}

fn main() {
    App::new()
        .add_plugins(MinimalPlugins)
        .add_plugins(JoinPlugin)
        .run();
}

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 add to a seat score every frame. WHY: the board flag awards once, then clears, so the active seat does not climb for free.

• 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 site.

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

• bevy-state-machines - Minigame mode.
• bevy-input-handling - Local devices. Gamepad exists.
• bevy-game-loop-time-trial - When a minigame is timed.

Downstream / consumers

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

Master

• bevy-master - Bevy router.