bevy-fluent

Bevy 0.19 — Localization (es-fluent)

When to use this skill

• Adding Fluent-based i18n to a Bevy app (es-fluent-manager-bevy = "0.19.2").
• Defining typed UI messages with #[derive(EsFluent)] and #[derive(BevyFluentText)].
• Wrapping a UI text entity with FluentText<T> for automatic locale-driven refresh.
• Switching locales at runtime via LocaleChangeEvent.
• Reading the current locale from RequestedLanguageId.

Canonical pattern — 5-file minimum shape

Cargo.toml:

[dependencies]
bevy                   = "0.19"
es-fluent              = { version = "0.18.1", features = ["derive"] }
es-fluent-manager-bevy = { version = "0.19.2", features = ["macros"] }
unic-langid            = "0.9"

i18n.toml (crate root, read at compile time):

fallback_language = "en"
assets_dir = "assets/locales"

src/i18n.rs:

es_fluent_manager_bevy::define_i18n_module!();

src/lib.rs — message types must live here (see Gotchas):

use bevy::prelude::*;
use es_fluent::EsFluent;
use es_fluent_manager_bevy::{
    BevyFluentText, FluentText, I18nPlugin, LocaleChangeEvent, RequestedLanguageId,
};
use unic_langid::langid;

pub mod i18n;

#[derive(BevyFluentText, Clone, EsFluent)]
#[fluent(namespace = "ui")]
pub enum UiMessage { StartGame, Settings, QuitGame }

pub fn build_i18n_plugin() -> I18nPlugin {
    I18nPlugin::with_language(langid!("en"))
}

pub fn setup_ui(mut commands: Commands) {
    commands.spawn(Camera2d);
    // FluentText<T> writes translations into a sibling Text component.
    commands.spawn((FluentText::new(UiMessage::StartGame), Text::new("")));
}

pub fn switch_locale_on_keypress(
    keys: Res<ButtonInput<KeyCode>>,
    requested: Res<RequestedLanguageId>,
    mut locale_events: MessageWriter<LocaleChangeEvent>,
) {
    if keys.just_pressed(KeyCode::KeyL) {
        let next = if requested.0.to_string() == "en" { langid!("fr") } else { langid!("en") };
        locale_events.write(LocaleChangeEvent(next));
    }
}