German interface language (de)

Add the German catalog: every menu string, every `tl!` literal, the plural
forms and the status and error messages (3,818 rows), written from the meaning
of the English labels in the vocabulary German-speaking users of vector
illustration software know (Zeichenfläche, Farbfelder, Kontur, Fläche, Pfad,
Ankerpunkt, Ebene, Verlauf, Deckkraft). Conventions are in the header of
`de.tsv`.

- Register `de` ("Deutsch") in `i18n::LANGUAGES` as a complete language; every
  `de-*` locale (`de-DE`, `de-AT`, `de-CH` …) resolves to it.
- Tests: German joins the menu-label, menu-string, `tl!`-literal and message
  coverage checks; `german_reads_as_german` pins the core vocabulary, the
  plurals, a nested message, the joined "…format" style names and the theme
  context ("Erscheinungsbild" vs the Appearance panel's "Aussehen"); ä ö Ä Ö ß
  are checked in the bundled UI fonts. The "unsupported locale" cases use
  Dutch now that German is supported.
- README, ROADMAP and docs/development.md list German.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -213,7 +213,7 @@ doesn't write Affinity files. Current `.af` validation includes 33 pinned files,
 and every-board SVG/PDF/PSD export, with fixes for Affinity 3 artboards, source-backed JPEGs and text runs.
 [Scope and limits](crates/affinity/README.md); [source audit and remaining gaps](docs/affinity-validation.md).
 The interface
-speaks English, Japanese, Traditional and Simplified Chinese, Spanish, French, Italian, Russian and Ukrainian (and Czech and Brazilian Portuguese in the menus).
+speaks English, German, Japanese, Traditional and Simplified Chinese, Spanish, French, Italian, Russian and Ukrainian (and Czech and Brazilian Portuguese in the menus).
 The scores are
 self-assessed, so the [honest assessment](ROADMAP.md#honest-assessment-2026-10-05) explains how far to trust them.
 

crates/ui-egui/src/dialogs/missing_fonts.rs

@@ -733,7 +733,7 @@ mod tests {
         let fr = crate::i18n::Lang::from_code("fr").unwrap();
         let shown = crate::i18n::message(fr, "2 font file(s) are now in /Fonts; 1 couldn't be added: a.otf: larger than 256 MB");
         assert!(shown.contains("se trouvent maintenant dans /Fonts") && shown.contains("a.otf") && shown.contains("plus de 256 Mo"), "{shown}");
-        for code in ["es", "fr", "it", "ru"] {
+        for code in ["de", "es", "fr", "it", "ru"] {
             let lang = crate::i18n::Lang::from_code(code).unwrap();
             for s in [
                 "every search thread stopped on an internal error (please report this bug)",

crates/ui-egui/src/i18n/mod.rs

@@ -82,13 +82,23 @@ fn plural_east_slavic(n: u64) -> usize {
 }
 
 /// The registry. English first: it is the fallback and the source language.
-pub static LANGUAGES: [LangInfo; 11] = [
+pub static LANGUAGES: [LangInfo; 12] = [
     LangInfo { code: "en", name: "English", source: "", plural: plural_one_other, complete_menus: false, catalog: OnceLock::new() },
     // Japanese: the whole interface (every menu string and `tl!` literal) and the status and error
     // messages, keeping the product, workspace and perspective preset names in English (`MENU_KEEP_AS_IS`).
     LangInfo { code: "ja", name: "日本語", source: include_str!("ja.tsv"), plural: plural_none, complete_menus: true, catalog: OnceLock::new() },
     // Czech: every menu label (`menu_catalogs_translate_every_menu_label`); panels and dialogs not yet.
     LangInfo { code: "cs", name: "Čeština", source: include_str!("cs.tsv"), plural: plural_czech, complete_menus: false, catalog: OnceLock::new() },
+    // German: the whole interface and the status and error messages, keeping the same names in
+    // English as Spanish; every `de-*` locale (`de-DE`, `de-AT`, `de-CH`, `de-LU` …) resolves here.
+    LangInfo {
+        code: "de",
+        name: "Deutsch",
+        source: include_str!("de.tsv"),
+        plural: plural_one_other,
+        complete_menus: true,
+        catalog: OnceLock::new(),
+    },
     // Spanish: the whole interface in neutral, international Spanish, keeping the same names in
     // English as Japanese; every `es-*` locale (`es-ES`, `es-MX`, `es-AR`, `es-419` …) resolves here.
     LangInfo {

crates/ui-egui/src/i18n/tests.rs

@@ -8,7 +8,11 @@ fn tags_map_to_languages() {
     assert_eq!(lang_from_tag("en_US.UTF-8"), Some(Lang::EN));
     assert_eq!(lang_from_tag("C"), Some(Lang::EN));
     assert_eq!(lang_from_tag("POSIX"), Some(Lang::EN));
-    assert_eq!(lang_from_tag("de_DE"), None);
+    assert_eq!(lang_from_tag("nl_NL"), None);
+    // German: Germany, Austria, Switzerland and the rest share the one catalog.
+    for tag in ["de", "de_DE.UTF-8", "de-AT", "de_CH", "de-LU", "de_DE.UTF-8@euro"] {
+        assert_eq!(lang_from_tag(tag), Some(de()), "{tag}");
+    }
     assert_eq!(lang_from_tag("ja_JP.UTF-8"), Lang::from_code("ja"));
     assert_eq!(lang_from_tag("ja"), Lang::from_code("ja"));
     // Spanish: every region (and Latin America as a whole) resolves to the one catalog.
@@ -51,7 +55,8 @@ fn candidates_walk_from_specific_to_general() {
 #[test]
 fn os_language_lists_are_parsed() {
     assert_eq!(first_supported("(\n    \"zh-Hant-TW\",\n    \"en-US\"\n)\n"), Some(ZH()));
-    assert_eq!(first_supported("(\n    \"de-DE\",\n    \"en-US\"\n)\n"), Some(Lang::EN));
+    assert_eq!(first_supported("(\n    \"nl-NL\",\n    \"en-US\"\n)\n"), Some(Lang::EN));
+    assert_eq!(first_supported("(\n    \"de-DE\",\n    \"en-US\"\n)\n"), Some(de()));
     assert_eq!(first_supported("(\n    \"fr-FR\",\n    \"en-US\"\n)\n"), Lang::from_code("fr"));
     assert_eq!(first_supported("("), None);
     // Windows: `reg query HKCU\Control Panel\International /v LocaleName`.
@@ -435,9 +440,9 @@ fn cs() -> Lang {
 }
 
 /// Languages whose catalogs leave [`MENU_KEEP_AS_IS`] in English.
-const KEEPS_MENU_NAMES: [&str; 8] = ["cs", "es", "fr", "it", "ja", "pt-br", "ru", "uk"];
+const KEEPS_MENU_NAMES: [&str; 9] = ["cs", "de", "es", "fr", "it", "ja", "pt-br", "ru", "uk"];
 
-/// Menu labels the menu-complete catalogs (Czech, Spanish, Italian, Japanese, Brazilian Portuguese) show as they are: the product name, a format name, the built-in workspace
+/// Menu labels the menu-complete catalogs (Czech, German, Spanish, Italian, Japanese, Brazilian Portuguese) show as they are: the product name, a format name, the built-in workspace
 /// names and the perspective grid presets (names, shown untranslated wherever else they appear).
 /// Each language's own name in the Language menu is left alone too.
 const MENU_KEEP_AS_IS: &[&str] = &[
@@ -527,7 +532,7 @@ fn toggled_labels() -> Vec<String> {
     labels
 }
 
-/// Czech, Spanish, Italian, Japanese and Brazilian Portuguese cover every menu label, the Show/Hide pairs
+/// Czech, German, Spanish, Italian, Japanese and Brazilian Portuguese cover every menu label, the Show/Hide pairs
 /// and the canvas context menu included (panels and dialogs not yet).
 #[test]
 fn menu_catalogs_translate_every_menu_label() {
@@ -565,9 +570,14 @@ fn menu_catalogs_translate_every_menu_label() {
     }
     assert_eq!(tr(Lang::from_code("pt-br").expect("pt-br"), "File"), "Arquivo");
     assert_eq!(tr(es(), "File"), "Archivo");
+    assert_eq!(tr(de(), "File"), "Datei");
     assert_eq!(tr(it(), "Edit"), "Modifica");
 }
 
+fn de() -> Lang {
+    Lang::from_code("de").expect("de registered")
+}
+
 fn es() -> Lang {
     Lang::from_code("es").expect("es registered")
 }
@@ -609,6 +619,36 @@ fn spanish_reads_as_spanish() {
     assert_eq!(trn(es(), 3, "{n} Layer", "{n} Layers"), "3 capas");
 }
 
+/// German uses the vector-illustration vocabulary its users know, has two plural forms like
+/// English (zero takes the plural), translates the reason inside a message too, and tells the
+/// interface theme ("Erscheinungsbild") from the Appearance panel ("Aussehen").
+#[test]
+fn german_reads_as_german() {
+    for (en, want) in [
+        ("Artboard Tool", "Zeichenflächen-Werkzeug"),
+        ("Swatches", "Farbfelder"),
+        ("Pathfinder", "Pathfinder"),
+        ("Stroke", "Kontur"),
+        ("Fill", "Fläche"),
+        ("Direct Selection Tool", "Direktauswahl-Werkzeug"),
+        ("Save As…", "Speichern unter…"),
+        ("Undo", "Rückgängig"),
+    ] {
+        assert_eq!(tr(de(), en), want);
+    }
+    assert_eq!(trn(de(), 1, "{n} Layer", "{n} Layers"), "1 Ebene");
+    assert_eq!(trn(de(), 0, "{n} Layer", "{n} Layers"), "0 Ebenen");
+    assert_eq!(trn(de(), 3, "{n} Layer", "{n} Layers"), "3 Ebenen");
+    assert_eq!(tr_ctx(de(), "axis", "Both"), "Beide");
+    assert_eq!(tr(de(), "Appearance"), "Aussehen");
+    assert_eq!(tr_ctx(de(), "theme", "Appearance"), "Erscheinungsbild");
+    let nested = "command `object.group` is not available right now: nothing selected";
+    assert_eq!(message(de(), nested), "der Befehl `object.group` ist derzeit nicht verfügbar: nichts ausgewählt");
+    // Text styles are "…format" in German: the kind is joined to it ("Neues Zeichenformat erstellen").
+    assert_eq!(fmt(tr(de(), "Create New {kind} Style"), &[("kind", tr(de(), "Character"))]), "Neues Zeichenformat erstellen");
+    assert_eq!(fmt(tr(de(), "Show {kind} Brushes"), &[("kind", tr(de(), "Calligraphic"))]), "Kalligrafiepinsel einblenden");
+}
+
 /// French uses the vector-illustration vocabulary its users know, puts zero in the singular (« 0
 /// calque »), and reads the same in the menus and in the panels.
 #[test]
@@ -769,7 +809,7 @@ fn russian_plurals_have_three_forms() {
     assert_eq!(forms, [2, 0, 1, 1, 2, 2, 0, 1, 2, 2, 0]);
 }
 
-/// Czech, Spanish, French and Italian letters (and the punctuation their text uses) come from each family's own first font, not
+/// Czech, German, Spanish, French and Italian letters (and the punctuation their text uses) come from each family's own first font, not
 /// from a fallback further down the stack. (`has_glyph` can't tell: it counts characters of the
 /// face that draws missing glyphs, the first one, as missing.)
 #[test]
@@ -784,7 +824,7 @@ fn latin_script_glyphs_are_available_without_system_fonts() {
             let first = first.unwrap();
             let mut font = fonts.fonts.font(&family);
             let chars = font.characters();
-            for ch in "áčďéěíňóřšťúůýžÁČĎÉĚÍŇÓŘŠŤÚŮÝŽ„“‚‘…–ñÑüÜ¿¡”àèìòùÀÈÌÒÙ«»’âêîôûçëïÿœæÂÊÎÔÛÇËÏŒÆ\u{a0}".chars()
+            for ch in "áčďéěíňóřšťúůýžÁČĎÉĚÍŇÓŘŠŤÚŮÝŽ„“‚‘…–ñÑüÜ¿¡”àèìòùÀÈÌÒÙ«»’âêîôûçëïÿœæÂÊÎÔÛÇËÏŒÆäöÄÖß\u{a0}".chars()
             {
                 assert!(chars.get(&ch).is_some_and(|fonts| fonts.contains(&first)), "{first} ({family:?}) has no {ch}");
             }
@@ -884,7 +924,7 @@ fn complete_languages_translate_every_message() {
 }
 
 /// Languages whose catalogs cover every status and error message.
-const COMPLETE_MESSAGES: &[&str] = &["es", "fr", "it", "ja", "ru", "uk"];
+const COMPLETE_MESSAGES: &[&str] = &["de", "es", "fr", "it", "ja", "ru", "uk"];
 
 /// Crates whose error and status messages reach the status bar.
 const MESSAGE_CRATES: &[&str] = &["ui-egui", "engine", "doc", "format", "svg", "pdf", "eps", "text", "plugins", "metafile", "cad", "trace"];

docs/development.md

@@ -166,7 +166,8 @@ always use the English ids and labels, so agents and scripts never see translate
 Languages shipped: English (`en`, the source), Traditional Chinese (`zh-hant`, complete, in the vocabulary used
 in Taiwan; `zh-TW`, `zh-HK`, `zh-MO` and `zh-Hant-*` locales all resolve to it), Simplified Chinese (`zh-hans`,
 complete, in the vocabulary used in mainland China; `zh-CN`, `zh-SG`, `zh-Hans-*` and a bare `zh` resolve to it,
-so the two scripts never mix), Japanese (`ja`, complete), Spanish (`es`, complete, in neutral
+so the two scripts never mix), Japanese (`ja`, complete), German (`de`, complete; `de-DE`, `de-AT`, `de-CH` and every
+other `de-*` locale resolve to it), Spanish (`es`, complete, in neutral
 international Spanish; every `es-*` locale such as `es-ES`, `es-MX`, `es-AR` or `es-419` resolves to it), French (`fr`,
 complete; `fr-FR`, `fr-BE`, `fr-CA`, `fr-CH` and every other `fr-*` locale resolve to it), Italian (`it`,
 complete; `it-IT`, `it-CH` and every other `it-*` locale resolve to it), Russian (`ru`, complete; every `ru-*`