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,
                     )
                 },