feat(locale): add Fluent translations

Default to the platform language with persisted overrides across native and web builds.

Refs #630

src/app/mod.rs

@@ -855,6 +855,8 @@ pub(super) struct OpenCADStudio {
     save_dialog_for_unsaved: bool,
     /// User preference for the first save of a new/unsaved drawing.
     default_save_format: String,
+    /// Persisted interface language selection.
+    language: crate::i18n::Language,
 
     // ── DimStyle Dialog ───────────────────────────────────────────────────
     /// Name of the style currently shown in the dialog.
@@ -1602,6 +1604,8 @@ pub enum Message {
     OptionsThemeChanged(String),
     /// Edit one of Custom theme's six base colours as #RRGGBB.
     OptionsThemeColorChanged(usize, String),
+    /// Switch the interface language and redraw localized views.
+    LanguageChanged(crate::i18n::Language),
     ClearScene,
     SetWireframe(bool),
     /// Set the active tab's render mode (one of acadrust's seven visual
@@ -2648,6 +2652,10 @@ impl OpenCADStudio {
     }
 
     fn new() -> Self {
+        let config = config::AppConfig::load();
+        if let Err(error) = crate::i18n::set_language(config.settings.language) {
+            eprintln!("Unable to apply saved UI language: {error}");
+        }
         // Boot with only the Welcome/Start tab. The user creates drawings
         // explicitly (File → New); we never auto-spawn Drawing1.
         let start_tab = DocumentTab::new_start();
@@ -2827,6 +2835,7 @@ impl OpenCADStudio {
             save_dialog_filename: "drawing.dwg".to_string(),
             save_dialog_for_unsaved: false,
             default_save_format: crate::io::DEFAULT_SAVE_FORMAT.to_string(),
+            language: crate::i18n::Language::default(),
             // Plot style
             active_plot_style: crate::io::plot_style::PlotStyleTable::load_named(
                 crate::io::plot_style::DEFAULT_PLOT_STYLE,
@@ -2997,7 +3006,7 @@ impl OpenCADStudio {
         // so preferences, recents, status-bar layout, ribbon density and print
         // options survive across sessions (issue #68). `last_saved_config` is
         // seeded below so the first change — not the boot — triggers a write.
-        app.apply_config(config::AppConfig::load());
+        app.apply_config(config);
         // Load command aliases from ocad.pgp (writes the shipped default file
         // on first launch). The hide-set keeps aliases out of autocomplete while
         // their target command still shows.

src/app/settings.rs

@@ -151,6 +151,9 @@ pub struct UserSettings {
     /// (#188).
     pub bg_color: Option<[u8; 3]>,
     pub paper_bg_color: Option<[u8; 3]>,
+    /// Interface language preference. `System` negotiates against the
+    /// platform locale on every launch.
+    pub language: crate::i18n::Language,
 }
 
 impl Default for UserSettings {
@@ -177,6 +180,7 @@ impl Default for UserSettings {
             pick_drag_rect: false,
             bg_color: None,
             paper_bg_color: None,
+            language: crate::i18n::Language::default(),
         }
     }
 }

src/app/update/file.rs

@@ -288,6 +288,7 @@ impl OpenCADStudio {
             pick_drag_rect: self.pick_drag_rect,
             bg_color: self.default_bg_color.map(f4_to_u3),
             paper_bg_color: self.default_paper_bg_color.map(f4_to_u3),
+            language: self.language,
         }
     }
 
@@ -317,6 +318,9 @@ impl OpenCADStudio {
         self.pick_drag_rect = s.pick_drag_rect;
         self.default_bg_color = s.bg_color.map(u3_to_f4);
         self.default_paper_bg_color = s.paper_bg_color.map(u3_to_f4);
+        if crate::i18n::set_language(s.language).is_ok() {
+            self.language = s.language;
+        }
         // Push the restored background onto every drawing tab that exists now
         // (the start tab and any initial drawing). Tabs created later pick it
         // up via `apply_bg_default` at their construction site.

src/app/update/mod.rs

@@ -4323,6 +4323,22 @@ impl OpenCADStudio {
                 Task::none()
             }
 
+            Message::LanguageChanged(language) => {
+                if self.language == language {
+                    return Task::none();
+                }
+                match crate::i18n::set_language(language) {
+                    Ok(()) => {
+                        self.language = language;
+                        self.persist_settings_if_changed();
+                    }
+                    Err(error) => self
+                        .command_line
+                        .push_error(&format!("Unable to change UI language: {error}")),
+                }
+                Task::none()
+            }
+
             Message::AboutOpen => {
                 self.active_modal = Some(super::ModalKind::About);
                 Task::none()

src/app/view/mod.rs

@@ -2318,7 +2318,7 @@ fn start_page_content<'a>(
     let headline = text("Open CAD Studio").size(40).style(start_primary_style);
 
     // Plain outlined button (Open / New / Help / Contribute).
-    let outline_btn = |label: &'static str, msg: Message| {
+    let outline_btn = |label: String, msg: Message| {
         button(text(label).size(14))
             .on_press(msg)
             .padding([10, 22])
@@ -2346,7 +2346,7 @@ fn start_page_content<'a>(
         button(
             row![
                 crate::ui::icons::themed_danger_text(crate::ui::icons::HEART, 14.0),
-                text("Donate").size(14),
+                text(crate::tr!("start-donate")).size(14),
             ]
             .spacing(5)
             .align_y(iced::Center),
@@ -2360,8 +2360,8 @@ fn start_page_content<'a>(
     };
 
     let primary_row = WrapFlow::new(vec![
-        outline_btn("New Drawing", Message::TabNew).into(),
-        outline_btn("Open File…", Message::OpenFile).into(),
+        outline_btn(crate::tr!("start-new-drawing"), Message::TabNew).into(),
+        outline_btn(crate::tr!("start-open-file"), Message::OpenFile).into(),
         donate_btn.into(),
     ])
     .spacing_x(12.0)
@@ -2371,16 +2371,16 @@ fn start_page_content<'a>(
     #[cfg_attr(target_arch = "wasm32", allow(unused_mut))]
     let mut secondary_items: Vec<Element<'a, Message>> = vec![
         outline_btn(
-            "Send Feedback",
+            crate::tr!("start-send-feedback"),
             Message::RibbonToolClick {
                 tool_id: "REPORT".to_string(),
                 event: crate::modules::ModuleEvent::Command("REPORT".to_string()),
             },
         )
         .into(),
-        outline_btn("Options", Message::OptionsOpen).into(),
+        outline_btn(crate::tr!("action-options"), Message::OptionsOpen).into(),
     ];
-    secondary_items.push(outline_btn("Plugins", Message::PluginManagerOpen).into());
+    secondary_items.push(outline_btn(crate::tr!("action-plugins"), Message::PluginManagerOpen).into());
     // The web build is already in the browser, so only the desktop offers a
     // link to the web version.
     #[cfg(not(target_arch = "wasm32"))]
@@ -2403,7 +2403,7 @@ fn start_page_content<'a>(
         .report_natural_width(action_width_out.clone());
 
     let sponsors = column![
-        text("Sponsors").size(15),
+        text(crate::tr!("start-sponsors")).size(15),
         mouse_area(
             container(
                 iced::widget::svg(iced::widget::svg::Handle::from_memory(include_bytes!(
@@ -2505,7 +2505,7 @@ fn start_page_content<'a>(
         // whole thumbnail remains visible when that width changes.
         let thumb_h =
             (panel_w - VIDEO_PANEL_PADDING * 2.0 - VIDEO_SCROLL_GUTTER) * 9.0 / 16.0;
-        let mut list = column![text("Tutorials").size(15)]
+        let mut list = column![text(crate::tr!("start-tutorials")).size(15)]
             .spacing(10)
             .width(Fill)
             // Keep the scrollbar off the thumbnails.
@@ -2545,14 +2545,14 @@ fn start_page_content<'a>(
         }
         if videos.is_empty() {
             let note = if videos_loading {
-                "Loading videos…"
+                crate::tr!("start-loading-videos")
             } else {
-                "Videos load from the internet."
+                crate::tr!("start-videos-online")
             };
             list = list.push(text(note).size(12).style(start_muted_style));
         }
         let playlist_btn = mouse_area(
-            container(text("Open playlist on YouTube").size(12))
+            container(text(crate::tr!("start-open-playlist")).size(12))
             .padding([6, 10])
             .width(Fill)
             .center_x(Fill)
@@ -2605,7 +2605,7 @@ fn start_page_content<'a>(
     // web builds read the CI-generated snapshot. Both sources mark pinned
     // discussions and sort them before the rest of the list.
     let discussions_panel: Element<'a, Message> = {
-        let mut list = column![text("Discussions").size(15)]
+        let mut list = column![text(crate::tr!("start-discussions")).size(15)]
             .spacing(8)
             .width(Fill);
         for discussion in discussions {
@@ -2618,7 +2618,7 @@ fn start_page_content<'a>(
             .align_y(iced::Center);
             if discussion.pinned {
                 meta = meta.push(
-                    text("Pinned")
+                    text(crate::tr!("start-pinned"))
                         .size(10)
                         .style(start_primary_style),
                 );
@@ -2661,14 +2661,14 @@ fn start_page_content<'a>(
         }
         if discussions.is_empty() {
             let note = if discussions_loading {
-                "Loading discussions…"
+                crate::tr!("start-loading-discussions")
             } else {
-                "Discussions load from GitHub."
+                crate::tr!("start-discussions-online")
             };
             list = list.push(text(note).size(12).style(start_muted_style));
         }
         let open_btn = mouse_area(
-            container(text("Open Discussions on GitHub").size(12))
+            container(text(crate::tr!("start-open-discussions")).size(12))
                 .padding([6, 10])
                 .width(Fill)
                 .center_x(Fill)
@@ -2725,7 +2725,7 @@ fn start_page_content<'a>(
     // shows, so the rail always invites support.
     let supporters: Element<'a, Message> = {
         let mut list = column![
-            text("Supporters").size(15),
+            text(crate::tr!("start-supporters")).size(15),
             Space::new().height(iced::Length::Fixed(12.0)),
         ]
         .spacing(6)
@@ -2746,7 +2746,7 @@ fn start_page_content<'a>(
             container(
                 iced::widget::row![
                     crate::ui::icons::themed_danger_text(crate::ui::icons::HEART, 13.0),
-                    text("Support on Patreon").size(12),
+                    text(crate::tr!("start-support-on-patreon")).size(12),
                 ]
                 .spacing(6)
                 .align_y(iced::Center),
@@ -2831,7 +2831,7 @@ fn start_page_content<'a>(
             .height(Fill)
             .into(),
         StartLayout::Compact => {
-            let tab_btn = |label: &'static str, section: super::StartSection| {
+            let tab_btn = |label: String, section: super::StartSection| {
                 let is_active = active == section;
                 button(text(label).size(14))
                     .on_press(Message::StartSectionSelect(section))
@@ -2864,11 +2864,11 @@ fn start_page_content<'a>(
                     })
             };
             let tab_bar = Row::with_children(vec![
-                tab_btn("Recent Files", super::StartSection::Recent).into(),
-                tab_btn("Videos", super::StartSection::Videos).into(),
-                tab_btn("Welcome", super::StartSection::Welcome).into(),
-                tab_btn("Discussions", super::StartSection::Discussions).into(),
-                tab_btn("Supporters", super::StartSection::Supporters).into(),
+                tab_btn(crate::tr!("start-recent-files"), super::StartSection::Recent).into(),
+                tab_btn(crate::tr!("start-videos"), super::StartSection::Videos).into(),
+                tab_btn(crate::tr!("start-welcome"), super::StartSection::Welcome).into(),
+                tab_btn(crate::tr!("start-discussions"), super::StartSection::Discussions).into(),
+                tab_btn(crate::tr!("start-supporters"), super::StartSection::Supporters).into(),
             ])
             .spacing(6.0)
             .align_y(iced::Center)
@@ -2944,11 +2944,11 @@ pub(super) fn recent_files_panel<'a>(
 ) -> Element<'a, Message> {
     // Title mirrors the Supporters rail: size 15 in the bright text colour,
     // followed by a 12px gap before the content.
-    let title = text("Recent Documents").size(15);
+    let title = text(crate::tr!("start-recent-documents")).size(15);
 
     let body: Element<'a, Message> = if recents.is_empty() {
         container(
-            text("Files you open will show up here.")
+            text(crate::tr!("start-no-recent-files"))
                 .size(12)
                 .style(start_muted_style)
         )
@@ -2976,7 +2976,7 @@ pub(super) fn recent_files_panel<'a>(
             // directory line.
             #[cfg(target_arch = "wasm32")]
             let dir = if dir.is_empty() {
-                "Browser storage".to_string()
+                crate::tr!("start-browser-storage")
             } else {
                 dir
             };
@@ -3087,7 +3087,7 @@ pub(super) fn recent_files_panel<'a>(
         .padding([2, 6])
         .width(iced::Length::Fixed(46.0));
     let limit_row = row![
-        text("Keep recent files").size(11).style(start_muted_style).width(Fill),
+        text(crate::tr!("start-keep-recent-files")).size(11).style(start_muted_style).width(Fill),
         button(crate::ui::icons::themed(crate::ui::icons::MINUS, 11.0))
             .on_press(Message::SetRecentLimit(shown.saturating_sub(STEP)))
             .padding([3, 6])

src/app/view/modal.rs

@@ -5,41 +5,41 @@ use iced::{Background, Element, Fill, Fit, Theme};
 impl OpenCADStudio {
     /// Title shown in the active modal's title bar. Keep in sync with the
     /// [`Self::modal_content`] dispatch.
-    pub(super) fn modal_title(&self) -> &'static str {
+    pub(super) fn modal_title(&self) -> String {
         use super::super::ModalKind as K;
         match self.active_modal {
-            Some(K::About) => "About",
-            Some(K::Shortcuts) => "Keyboard Shortcuts",
-            Some(K::Aliases) => "Command Aliases",
-            Some(K::Options) => "Options",
-            Some(K::FindReplace) => "Find and Replace",
-            Some(K::PluginManager) => "Plugin Manager",
-            Some(K::UpdateNotice) => "Update Available",
-            Some(K::Layers) => "Layer Manager",
-            Some(K::LayerStateManager) => "Layer State Manager",
-            Some(K::LayerStateEditor) => "Edit Layer State",
-            Some(K::Plot) => "Plot",
-            Some(K::LayoutManager) => "Layout Manager",
-            Some(K::ScaleManager) => "Scale Manager",
-            Some(K::AnnoObjectScale) => "Annotation Object Scale",
-            Some(K::Plotstyle) => "Plot Style Editor",
-            Some(K::TextStyle) => "Text Style Manager",
-            Some(K::MlStyle) => "Multiline Style Manager",
-            Some(K::TableStyle) => "Table Style Manager",
-            Some(K::MLeaderStyle) => "Multileader Style Manager",
-            Some(K::DimStyle) => "Dimension Style Manager",
-            Some(K::AssocPrompt) => "Default Application",
-            Some(K::AecDropWarning) => "Save Warning",
+            Some(K::About) => crate::tr!("modal-about"),
+            Some(K::Shortcuts) => crate::tr!("modal-keyboard-shortcuts"),
+            Some(K::Aliases) => crate::tr!("modal-command-aliases"),
+            Some(K::Options) => crate::tr!("action-options"),
+            Some(K::FindReplace) => crate::tr!("modal-find-replace"),
+            Some(K::PluginManager) => crate::tr!("modal-plugin-manager"),
+            Some(K::UpdateNotice) => crate::tr!("modal-update-available"),
+            Some(K::Layers) => crate::tr!("modal-layer-manager"),
+            Some(K::LayerStateManager) => crate::tr!("modal-layer-state-manager"),
+            Some(K::LayerStateEditor) => crate::tr!("modal-edit-layer-state"),
+            Some(K::Plot) => crate::tr!("modal-plot"),
+            Some(K::LayoutManager) => crate::tr!("modal-layout-manager"),
+            Some(K::ScaleManager) => crate::tr!("modal-scale-manager"),
+            Some(K::AnnoObjectScale) => crate::tr!("modal-annotation-object-scale"),
+            Some(K::Plotstyle) => crate::tr!("modal-plot-style-editor"),
+            Some(K::TextStyle) => crate::tr!("modal-text-style-manager"),
+            Some(K::MlStyle) => crate::tr!("modal-multiline-style-manager"),
+            Some(K::TableStyle) => crate::tr!("modal-table-style-manager"),
+            Some(K::MLeaderStyle) => crate::tr!("modal-multileader-style-manager"),
+            Some(K::DimStyle) => crate::tr!("modal-dimension-style-manager"),
+            Some(K::AssocPrompt) => crate::tr!("modal-default-application"),
+            Some(K::AecDropWarning) => crate::tr!("modal-save-warning"),
             #[cfg(not(target_arch = "wasm32"))]
-            Some(K::FileInUse) => "Unable to Save Drawing",
+            Some(K::FileInUse) => crate::tr!("modal-unable-save"),
             #[cfg(not(target_arch = "wasm32"))]
-            Some(K::ExternalChange) => "Drawing Changed on Disk",
-            Some(K::LayerDeleteWarning) => "Delete Layer",
-            Some(K::Unsaved) => "Unsaved Changes",
-            Some(K::PointStyle) => "Point Style",
-            Some(K::AttributeEditor) => "Attribute Editor",
-            Some(K::SaveDialog) => "Save Drawing As",
-            None => "",
+            Some(K::ExternalChange) => crate::tr!("modal-drawing-changed"),
+            Some(K::LayerDeleteWarning) => crate::tr!("modal-delete-layer"),
+            Some(K::Unsaved) => crate::tr!("modal-unsaved-changes"),
+            Some(K::PointStyle) => crate::tr!("modal-point-style"),
+            Some(K::AttributeEditor) => crate::tr!("modal-attribute-editor"),
+            Some(K::SaveDialog) => crate::tr!("modal-save-drawing-as"),
+            None => String::new(),
         }
     }
 
@@ -90,6 +90,7 @@ impl OpenCADStudio {
                         &self.default_save_format,
                         &self.ui_theme,
                         &self.theme_color_inputs,
+                        self.language,
                         flow,
                     )
                 },

src/i18n.rs

@@ -0,0 +1,153 @@
+//! Application language selection and embedded Fluent resources.
+
+use i18n_embed::fluent::{fluent_language_loader, FluentLanguageLoader};
+use i18n_embed::LanguageLoader;
+#[cfg(not(target_arch = "wasm32"))]
+use i18n_embed::DesktopLanguageRequester;
+#[cfg(target_arch = "wasm32")]
+use i18n_embed::WebLanguageRequester;
+use rust_embed::RustEmbed;
+use serde::{Deserialize, Serialize};
+use std::sync::OnceLock;
+
+#[derive(RustEmbed)]
+#[folder = "locales/"]
+struct Localizations;
+
+/// User-selectable UI language. `System` keeps following the platform's
+/// preferred locale while explicit choices remain stable across restarts.
+#[derive(Clone, Copy, Debug, Default, Eq, PartialEq, Serialize, Deserialize)]
+pub enum Language {
+    #[default]
+    #[serde(rename = "system")]
+    System,
+    #[serde(rename = "en-US")]
+    EnUs,
+    #[serde(rename = "tr-TR")]
+    TrTr,
+    #[serde(rename = "nl-NL")]
+    NlNl,
+    #[serde(rename = "fr-FR")]
+    FrFr,
+    #[serde(rename = "de-DE")]
+    DeDe,
+    #[serde(rename = "hi-IN")]
+    HiIn,
+    #[serde(rename = "ru-RU")]
+    RuRu,
+    #[serde(rename = "zh-CN")]
+    ZhCn,
+}
+
+impl Language {
+    pub const ALL: [Language; 9] = [
+        Language::System,
+        Language::EnUs,
+        Language::TrTr,
+        Language::NlNl,
+        Language::FrFr,
+        Language::DeDe,
+        Language::HiIn,
+        Language::RuRu,
+        Language::ZhCn,
+    ];
+
+    fn requested(self) -> Vec<i18n_embed::unic_langid::LanguageIdentifier> {
+        match self {
+            Language::System => system_languages(),
+            Language::EnUs => vec!["en-US".parse().expect("valid locale")],
+            Language::TrTr => vec!["tr-TR".parse().expect("valid locale")],
+            Language::NlNl => vec!["nl-NL".parse().expect("valid locale")],
+            Language::FrFr => vec!["fr-FR".parse().expect("valid locale")],
+            Language::DeDe => vec!["de-DE".parse().expect("valid locale")],
+            Language::HiIn => vec!["hi-IN".parse().expect("valid locale")],
+            Language::RuRu => vec!["ru-RU".parse().expect("valid locale")],
+            Language::ZhCn => vec!["zh-CN".parse().expect("valid locale")],
+        }
+    }
+}
+
+impl std::fmt::Display for Language {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let label = match self {
+            Language::System => crate::tr!("language-system"),
+            Language::EnUs => crate::tr!("language-english"),
+            Language::TrTr => crate::tr!("language-turkish"),
+            Language::NlNl => crate::tr!("language-dutch"),
+            Language::FrFr => crate::tr!("language-french"),
+            Language::DeDe => crate::tr!("language-german"),
+            Language::HiIn => crate::tr!("language-hindi"),
+            Language::RuRu => crate::tr!("language-russian"),
+            Language::ZhCn => crate::tr!("language-chinese-simplified"),
+        };
+        f.write_str(&label)
+    }
+}
+
+fn system_languages() -> Vec<i18n_embed::unic_langid::LanguageIdentifier> {
+    #[cfg(target_arch = "wasm32")]
+    let requested = WebLanguageRequester::requested_languages();
+    #[cfg(not(target_arch = "wasm32"))]
+    let requested = DesktopLanguageRequester::requested_languages();
+    requested
+}
+
+fn load_language(
+    loader: &FluentLanguageLoader,
+    language: Language,
+) -> Result<(), i18n_embed::I18nEmbedError> {
+    let mut requested = language.requested();
+    if requested.is_empty() {
+        requested.push(loader.fallback_language().clone());
+    }
+    i18n_embed::select(loader, &Localizations, &requested).map(|_| ())
+}
+
+pub fn loader() -> &'static FluentLanguageLoader {
+    static LOADER: OnceLock<FluentLanguageLoader> = OnceLock::new();
+    LOADER.get_or_init(|| {
+        let loader = fluent_language_loader!();
+        if let Err(error) = load_language(&loader, Language::System) {
+            eprintln!("Unable to load system UI language: {error}");
+            loader
+                .load_languages(&Localizations, &[loader.fallback_language().clone()])
+                .expect("fallback UI language must be embedded");
+        }
+        loader
+    })
+}
+
+/// Apply a user preference process-wide. The loader swaps resources atomically,
+/// so the next Iced view pass immediately receives the new language.
+pub fn set_language(language: Language) -> Result<(), i18n_embed::I18nEmbedError> {
+    load_language(loader(), language)
+}
+
+/// Built-in ribbon modules have stable ids; plug-ins keep their supplied title
+/// until they provide their own localization bundle.
+pub fn ribbon_module_title(id: &str, fallback: &str) -> String {
+    match id {
+        "draw" => crate::tr!("ribbon-tab-draw"),
+        "annotate" => crate::tr!("ribbon-tab-annotate"),
+        "insert" => crate::tr!("ribbon-tab-insert"),
+        "model" => crate::tr!("ribbon-tab-model"),
+        "layout" => crate::tr!("ribbon-tab-layout"),
+        "manage" => crate::tr!("ribbon-tab-manage"),
+        "view" => crate::tr!("ribbon-tab-view"),
+        _ => fallback.to_string(),
+    }
+}
+
+#[macro_export]
+macro_rules! tr {
+    ($message_id:literal $(,)?) => {
+        i18n_embed_fl::fl!($crate::i18n::loader(), $message_id)
+    };
+    ($message_id:literal, $($name:ident = $value:expr),+ $(,)?) => {
+        i18n_embed_fl::fl!(
+            $crate::i18n::loader(),
+            $message_id,
+            $($name = $value),+
+        )
+    };
+}

src/lib.rs

@@ -6,6 +6,7 @@ pub mod config;
 pub mod cli;
 pub mod command;
 pub mod entities;
+pub mod i18n;
 pub mod io;
 #[cfg(not(target_arch = "wasm32"))]
 pub(crate) mod network;

src/main.rs

@@ -10,6 +10,7 @@ mod config;
 mod cli;
 mod command;
 mod entities;
+mod i18n;
 mod io;
 #[cfg(not(target_arch = "wasm32"))]
 mod network;

src/modules/draw/modify/copy.rs

@@ -61,23 +61,27 @@ impl CadCommand for CopyCommand {
 
     fn prompt(&self) -> String {
         if self.awaiting_count {
-            return "COPY  Enter number of items to array:".to_string();
+            return crate::tr!("command-copy-array-count");
         }
         match &self.step {
-            Step::Base => format!(
-                "COPY  Specify base point  [{} objects]:",
-                self.handles.len()
+            Step::Base => crate::tr!(
+                "command-copy-base",
+                count = (self.handles.len() as i64),
             ),
             Step::Placing(base) => {
                 if let Some(n) = self.array_count {
-                    format!(
-                        "COPY  Specify second point for {n}-item array  [base {:.3},{:.3}]:",
-                        base.x, base.y
+                    crate::tr!(
+                        "command-copy-array-target",
+                        count = (n as i64),
+                        x = format!("{:.3}", base.x),
+                        y = format!("{:.3}", base.y),
                     )
                 } else {
-                    format!(
-                        "COPY  Specify destination  [{} copies so far | Array | Enter=done | base {:.3},{:.3}]:",
-                        self.count, base.x, base.y
+                    crate::tr!(
+                        "command-copy-target",
+                        count = (self.count as i64),
+                        x = format!("{:.3}", base.x),
+                        y = format!("{:.3}", base.y),
                     )
                 }
             }

src/modules/draw/modify/translate.rs

@@ -53,13 +53,14 @@ impl CadCommand for MoveCommand {
 
     fn prompt(&self) -> String {
         match &self.step {
-            Step::Base => format!(
-                "MOVE  Specify base point  [{} objects]:",
-                self.handles.len()
+            Step::Base => crate::tr!(
+                "command-move-base",
+                count = (self.handles.len() as i64),
             ),
-            Step::Target(base) => format!(
-                "MOVE  Specify destination  [base {:.3},{:.3}]:",
-                base.x, base.y
+            Step::Target(base) => crate::tr!(
+                "command-move-target",
+                x = format!("{:.3}", base.x),
+                y = format!("{:.3}", base.y),
             ),
         }
     }

src/ui/command_line.rs

@@ -111,8 +111,8 @@ pub enum EntryKind {
 impl CommandLine {
     pub fn new() -> Self {
         let mut cl = Self::default();
-        cl.push_info("Open CAD Studio ready.");
-        cl.push_info("Type a command or use the ribbon. Open OBJ: INSERT tab.");
+        cl.push_info(&crate::tr!("command-line-ready"));
+        cl.push_info(&crate::tr!("command-line-hint"));
         cl
     }
 
@@ -430,7 +430,7 @@ impl CommandLine {
                 }
             });
         let prompt = container(
-            text("Command:").size(11).style(|theme: &Theme| iced::widget::text::Style {
+            text(crate::tr!("command-line-label")).size(11).style(|theme: &Theme| iced::widget::text::Style {
                 color: Some(theme.palette().success.base.color),
             }),
         )
@@ -467,10 +467,7 @@ impl CommandLine {
                 ..Default::default()
             }
         });
-        let literal_tip = container(
-            text("Literal spaces: Space stays in the line instead of running the command (same as typing a leading '>'). Stays on until toggled off.")
-                .size(11),
-        )
+        let literal_tip = container(text(crate::tr!("command-line-literal-spaces")).size(11))
         .padding([3, 6])
         .style(container::bordered_box);
         let literal_btn = tooltip(literal_btn, literal_tip, tooltip::Position::Top).gap(4);

src/ui/modal.rs

@@ -253,7 +253,7 @@ pub fn backdrop<'a>(
 /// title bar; pass `Vector::ZERO` to keep it centred.
 pub fn modal<'a>(
     base: impl Into<Element<'a, Message>>,
-    title: &'a str,
+    title: impl iced::widget::text::IntoFragment<'a>,
     content: impl Into<Element<'a, Message>>,
     on_close: Message,
     offset: Vector,

src/ui/ribbon/mod.rs

@@ -422,7 +422,7 @@ impl Ribbon {
                 let is_active = i == self.active;
                 let is_contextual = module.id() == "layout";
                 let btn = container(
-                    button(text(module.title()).size(12))
+                    button(text(crate::i18n::ribbon_module_title(module.id(), module.title())).size(12))
                         .on_press(Message::RibbonSelectTab(i))
                         .style(move |theme: &Theme, status| {
                             let palette = theme.palette();

src/ui/window/options.rs

@@ -9,6 +9,7 @@ pub fn view_window<'a>(
     default_save_format: &'a str,
     ui_theme: &'a UiThemeConfig,
     theme_color_inputs: &'a [String; 6],
+    language: crate::i18n::Language,
     sizing: crate::ui::modal::ModalSizing,
 ) -> Element<'a, Message> {
     let selected_format = crate::io::SAVE_FORMAT_OPTIONS
@@ -25,12 +26,12 @@ pub fn view_window<'a>(
 
     let palette = ui_theme.palette.to_iced();
     let colors = [
-        ("Background", palette.background),
-        ("Text", palette.text),
-        ("Primary", palette.primary),
-        ("Success", palette.success),
-        ("Warning", palette.warning),
-        ("Danger", palette.danger),
+        (crate::tr!("options-color-background"), palette.background),
+        (crate::tr!("options-color-text"), palette.text),
+        (crate::tr!("options-color-primary"), palette.primary),
+        (crate::tr!("options-color-success"), palette.success),
+        (crate::tr!("options-color-warning"), palette.warning),
+        (crate::tr!("options-color-danger"), palette.danger),
     ];
 
     let mut color_controls = column![].spacing(8);
@@ -60,16 +61,31 @@ pub fn view_window<'a>(
         );
     }
 
-    let close = button(text("Close").size(12))
+    let close = button(text(crate::tr!("action-close")).size(12))
         .on_press(Message::CloseModal)
         .padding([6, 18])
         .style(button::secondary);
 
     let content = column![
-        text("Open and Save").size(15),
+        text(crate::tr!("options-language-section")).size(15),
         Space::new().height(10),
         row![
-            text("Default save format:").size(12).width(150),
+            text(crate::tr!("options-language-label")).size(12).width(150),
+            iced::widget::pick_list(
+                Some(language),
+                crate::i18n::Language::ALL,
+                |value| value.to_string(),
+            )
+            .on_select(Message::LanguageChanged)
+            .width(sizing.width),
+        ]
+        .spacing(12)
+        .align_y(iced::Center),
+        Space::new().height(22),
+        text(crate::tr!("options-open-save-section")).size(15),
+        Space::new().height(10),
+        row![
+            text(crate::tr!("options-default-save-format-label")).size(12).width(150),
             iced::widget::pick_list(
                 selected_format,
                 crate::io::SAVE_FORMAT_OPTIONS,
@@ -81,16 +97,14 @@ pub fn view_window<'a>(
         .spacing(12)
         .align_y(iced::Center),
         Space::new().height(8),
-        text(
-            "Used for the first save of a new drawing. Existing drawings keep their file type and version."
-        )
+        text(crate::tr!("options-default-save-format-help"))
         .size(11)
         .width(sizing.width),
         Space::new().height(22),
-        text("Theme").size(15),
+        text(crate::tr!("options-theme-section")).size(15),
         Space::new().height(10),
         row![
-            text("Iced theme:").size(12).width(150),
+            text(crate::tr!("options-theme-label")).size(12).width(150),
             iced::widget::pick_list(
                 selected_theme,
                 theme_options,
@@ -102,9 +116,7 @@ pub fn view_window<'a>(
         .spacing(12)
         .align_y(iced::Center),
         Space::new().height(8),
-        text(
-            "Changing a base colour switches to Custom. Iced generates every component shade from these six colours."
-        )
+        text(crate::tr!("options-theme-help"))
         .size(11)
         .width(sizing.width),
         Space::new().height(12),