Bevy Genre Educational Agent Skill

Bevy Educational (thin router)

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

When to use

Load this for prompts, answers, and progress flags.

ECS shape

• Components hold a prompt and each choice as plain data.
• Resources hold how many answers were graded and how many were correct.
• Systems select a choice, then grade it. .chain() keeps the grade after the selection.
• Schedule: gameplay mode changes go through bevy-state-machines.

[package]
name = "educational"
version = "0.1.0"
edition = "2021"

[dependencies]
bevy = "0.20"

One prompt, two choices, one progress resource.

#[derive(Component)]
struct Prompt {
    text: String,
}

#[derive(Component)]
struct Choice {
    label: String,
    correct: bool,
    picked: bool,
    graded: bool,
}

#[derive(Resource, Default)]
struct LessonProgress {
    answered: u32,
    correct: u32,
}

fn spawn_lesson(mut commands: Commands) {
    commands.spawn(Prompt {
        text: "Which way is north?".to_string(),
    });
    commands.spawn(Choice {
        label: "Up".to_string(),
        correct: true,
        picked: false,
        graded: false,
    });
    commands.spawn(Choice {
        label: "Down".to_string(),
        correct: false,
        picked: false,
        graded: false,
    });
    commands.init_resource::<LessonProgress>();
}

fn pick_first(mut choices: Query<&mut Choice>) {
    for mut choice in &mut choices {
        if choice.correct && !choice.graded && !choice.picked {
            choice.picked = true;
            break;
        }
    }
}

fn grade(mut progress: ResMut<LessonProgress>, mut choices: Query<&mut Choice>) {
    for mut choice in &mut choices {
        if choice.picked && !choice.graded {
            progress.answered = progress.answered.saturating_add(1);
            if choice.correct {
                progress.correct = progress.correct.saturating_add(1);
            }
            choice.graded = true;
            choice.picked = false;
        }
    }
}

pub struct LessonPlugin;

impl Plugin for LessonPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(Startup, spawn_lesson)
            .add_systems(Update, (pick_first, grade).chain());
    }
}

pick_first and grade both write Choice, so they stay chained.

A readout only reads progress.

#[derive(Resource, Default)]
struct LessonProgress {
    answered: u32,
    correct: u32,
}

fn show_score(progress: Res<LessonProgress>) {
    let _answered = progress.answered;
    let _correct = progress.correct;
}

pub struct ScorePlugin;

impl Plugin for ScorePlugin {
    fn build(&self, app: &mut App) {
        app.init_resource::<LessonProgress>()
            .add_systems(Update, show_score);
    }
}

Lesson data

| Need | Bevy idiom |

| --- | --- |

| Prompts and choices | Entities plus the domain skills linked below |

| Lesson totals | A Resource |

| One-shot loop notices | bevy-events-messaging |

Routing

• bevy-ui-text - Prompts.
• bevy-ui-layout - Choices.
• bevy-save-load - Progress saves.
• bevy-state-machines - Lesson mode.

Scope

• Prompts, choices, and the progress resource are gameplay data you define. UI text and layout stay on the linked UI skills.

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

| Piece | Owner | Who may mutate | Schedule |

| --- | --- | --- | --- |

| Data on one entity | Component | One system via Query | Update or FixedMain |

| One value for the whole app | Resource | One system | Startup to insert, then the schedule that reads it |

| Spawn | Commands | The spawning system | Startup for the initial world; later schedules for runtime spawn |

| Order that must not race | .chain() | The chained systems only | Same schedule |

| Plugin boundary | Plugin | build registers systems and resources | Before the app runs |

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

| If you need | Do this | Do not |

| --- | --- | --- |

| Per-entity data | Component + Query | One struct that stores every entity's fields |

| App-wide config or clock | Resource | Copy the value onto every entity |

| Stable simulation step | FixedMain and the Fixed clock | Tie simulation to raw frame Update |

| Startup spawn | Commands in Startup | Spawn from a render system |

| Cross-system notice that is not shared state | Message or observer slot in bevy-events-messaging | A new event type invented in this file |

| An API outside the documented set | Read the linked Bevy pages | A made-up crate or API |

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.

• No scene-tree types in Bevy code. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
• 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 links stay on the unversioned learn pages.

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-ui-text - Prompts.
• bevy-ui-layout - Choices.
• bevy-save-load - Progress saves.
• bevy-state-machines - Lesson mode.

Downstream / consumers

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

Master

• bevy-master - Bevy router.