bevy-events-messaging

사용 방법

설치 명령을 복사하고 자신의 에이전트 환경에 설치하기 전에 소스 패키지를 확인하세요.
필요한 도구, 인증 정보, 지원 환경은 원본 문서에서 확인하세요.
입력과 원하는 산출물을 설명하고 출처와 결과를 대조하세요.

npx skills add https://github.com/thedivergentai/game-design-agentic-skills --skill bevy-events-messaging

시작 전 확인

설치에는 모델 구독, API 한도, 파일 접근 권한이 포함되지 않습니다.
별점 수와 설치 수는 활동 지표이며 독립적인 품질·보안 검증이 아닙니다.

원본 Skill 문서

원본 저장소의 제목, 예시, 코드, 표, 링크, 이미지를 유지해 표시합니다.

Bevy events and messaging

When to use

Load this when one system should notice that something happened without storing that fact on every entity. Pick the mechanism from the pages below. Do not invent a third channel.

ECS shape

Messages (pull). bevy::ecs::message 0.20.0 defines the Message trait as a buffered message for pull-based handling. MessageWriter writes. MessageReader reads and tracks what it already saw. Messages holds what occurred within the last two Messages::update calls. message_update_system calls Messages::update on registered messages. signal_message_update_system signals that update after FixedUpdate systems. Check the App docs for message registration helpers before writing a method name.
Events (push). The Event trait page: derive Event, add an observer, trigger. The sample uses World::trigger and world.add_observer with On<Speak>. Commands::trigger is also named. Observers run immediately inside the trigger call. Event::Trigger defaults to GlobalTrigger for derived events.
Observers. bevy::ecs::observer: an Observer is a component that holds a system. On is the system parameter that processes the event. EntityEvent is the page's pointer for events that target one entity. Check that trait page for method names before writing them.
State transitions. bevy::state documents StateTransitionEvent<S> when state S changes. That type lives with states. See bevy-state-machines.

Coming from Godot

Godot idea	Bevy idiom
Something happened; readers poll later	A `Message` plus `MessageWriter` / `MessageReader`
Something happened; listeners run now	An `Event` plus an `Observer` (`On<...>`) and `trigger`
Notice on one entity	`EntityEvent`. Check the trait page for methods before writing them.
Global signal singleton	Not this. Use a message type or a global event

Scope

Check the App docs for methods that register a message type before writing them.
Check the observer module for EntityEvent methods, entity-targeted trigger helpers, and observer run-condition helpers beyond the module index names.
Check the message docs for ordering between message_update_system and gameplay systems beyond the FixedUpdate signal function name.

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`	A Godot node script
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	Check the official docs first	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 Godot signal types or a signal bus autoload. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
No invented message-registration or trigger methods. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
No third-party crates. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.

Reference

docs.rs links use the unversioned latest permalink. The library pin on bevy-master stays 0.20.0.

Official Documentation

Migration guides - Unversioned hop index.
bevy crate - Unversioned API index.
bevy::ecs::message - Message, MessageWriter, MessageReader, Messages, message_update_system.
Event - Event, On, World::trigger, Commands::trigger, add_observer.
bevy::ecs::observer - Observer and On.
Examples - Example tree on the latest branch.