xtask: i18n-coverage lists missing strings; ci prints them last

The report prints, per language, the source keys its catalog lacks (one
line for a language with none). `cargo xtask ci` runs it as its last step
and never fails on it: a missing translation shows in English. A report
that can't run prints a warning.

xtask/src/i18n_coverage.rs

@@ -72,9 +72,33 @@ fn format_report(languages: &[Language], english_keys: &BTreeSet<Key>, translati
         let coverage = 100.0 * translated as f64 / english_keys.len() as f64;
         report.push_str(&format!("{:<12} {:>5}/{:<6} {:>8.2}%\n", language.code, translated, english_keys.len(), coverage));
     }
+    report.push_str("\nMissing translations (shown in English until translated)\n");
+    for language in languages.iter().filter(|language| language.code != "en") {
+        let empty = BTreeSet::new();
+        let translated = translations.get(&language.code).unwrap_or(&empty);
+        let missing: Vec<&Key> = english_keys.difference(translated).collect();
+        if missing.is_empty() {
+            report.push_str(&format!("{}: none missing\n", language.code));
+            continue;
+        }
+        report.push_str(&format!("{}: {} missing\n", language.code, missing.len()));
+        for key in missing {
+            let source = escape_line(&key.source);
+            if key.context.is_empty() {
+                report.push_str(&format!("    {source}\n"));
+            } else {
+                report.push_str(&format!("    [{}] {source}\n", escape_line(&key.context)));
+            }
+        }
+    }
     report
 }
 
+/// Keeps one key per log line: a source string with a newline or tab prints them escaped.
+fn escape_line(text: &str) -> String {
+    text.replace('\\', "\\\\").replace('\n', "\\n").replace('\t', "\\t")
+}
+
 fn registered_languages(source: &str) -> Result<Vec<Language>, String> {
     let registry = source
         .split("pub static LANGUAGES")
@@ -494,15 +518,28 @@ mod tests {
         let languages = registered_languages(registry);
         assert!(languages.is_ok());
         let languages = languages.unwrap_or_default();
-        let english_keys = BTreeSet::from([Key { context: String::new(), source: "Open".into() }, Key { context: String::new(), source: "Save".into() }]);
-        let translations = BTreeMap::from([("fr".to_string(), BTreeSet::from([Key { context: String::new(), source: "Open".into() }]))]);
+        let english_keys = BTreeSet::from([
+            Key { context: String::new(), source: "Open".into() },
+            Key { context: String::new(), source: "Save".into() },
+            Key { context: "@plural".into(), source: "{n} layer|{n} layers".into() },
+        ]);
+        let translations = BTreeMap::from([
+            ("fr".to_string(), BTreeSet::from([Key { context: String::new(), source: "Open".into() }])),
+            ("zh".to_string(), english_keys.clone()),
+        ]);
         assert_eq!(
             format_report(&languages, &english_keys, &translations),
             "UI translation coverage (translated source keys / source keys)\n\
              language       translated  coverage\n\
-             en               2/2        100.00%\n\
-             fr               1/2         50.00%\n\
-             zh               0/2          0.00%\n"
+             en               3/3        100.00%\n\
+             fr               1/3         33.33%\n\
+             zh               3/3        100.00%\n\
+             \n\
+             Missing translations (shown in English until translated)\n\
+             fr: 2 missing\n\
+             \x20   Save\n\
+             \x20   [@plural] {n} layer|{n} layers\n\
+             zh: none missing\n"
         );
     }
 
@@ -563,34 +600,6 @@ mod tests {
         }
     }
 
-    #[test]
-    fn source_key_set_is_covered_by_complete_catalogs() {
-        let root = Path::new(env!("CARGO_MANIFEST_DIR")).parent().unwrap_or(Path::new("."));
-        let keys = source_keys(root).unwrap_or_default();
-        for (code, path) in [
-            ("ja", "ja.tsv"),
-            ("zh-hant", "zh-hant.tsv"),
-            ("es", "es.tsv"),
-            ("ru", "ru.tsv"),
-            ("cs", "cs.tsv"),
-            ("de", "de.tsv"),
-            ("pt-br", "pt-br.tsv"),
-            ("it", "it.tsv"),
-            ("el", "el.tsv"),
-            ("uk", "uk.tsv"),
-            ("nl", "nl.tsv"),
-            ("hu", "hu.tsv"),
-            ("tr", "tr.tsv"),
-            ("vi", "vi.tsv"),
-            ("sr", "sr.tsv"),
-        ] {
-            let catalog_path = root.join("crates/ui-egui/src/i18n").join(path);
-            let text = fs::read_to_string(&catalog_path).unwrap_or_default();
-            let translations = parse_catalog(&catalog_path, &text).unwrap_or_default();
-            let missing: Vec<_> = keys.difference(&translations).collect();
-            assert!(missing.is_empty(), "{code}: missing source keys: {missing:#?}");
-        }
-    }
     #[test]
     fn plural_forms_follow_count_expressions_and_dynamic_forms_are_not_literal_keys() {
         let sources = vec![(

xtask/src/main.rs

@@ -26,7 +26,8 @@ commands:
   wasm            cargo check --target wasm32-unknown-unknown for the wasm-safe crates (one call, plus
                   one per optional web feature)
   test            workspace tests (cargo nextest when installed, else cargo test), then doctests
-  ci              fmt --check, clippy -D warnings, test, doctest, layers, wasm (stops at first failure)
+  ci              fmt --check, clippy -D warnings, test, doctest, layers, wasm (stops at first failure),
+                  then the i18n-coverage report
   corpus [--all | --pngsuite | --psd | --psd-tools | --pixls | --atn | --photoshop | --gimp] [--local] [--update-manifest]
                   show where test corpora live and their pins (xtask/src/corpus_pins.rs), or fetch
                   them into corpus/ (pinned commits, sha256-verified; --all = every corpus but pixls,
@@ -38,7 +39,8 @@ commands:
                   --local takes corpus/photoshop and corpus/gimp from the photocraft-corpus authoring clone
   stats [--exact] count tests and lines per crate (--exact: ask the test harness via `-- --list`)
   parity          Photoshop menu parity; rewrites docs/parity-checklist.md
-  i18n-coverage   report stable UI translation coverage for registered languages
+  i18n-coverage   report UI translation coverage and the missing strings per registered language
+                  (the last `ci` step; it never fails)
   perf [--quick] [--update-baseline] [--threshold PCT] [--bench NAME]... [--skip-build] [--reuse]
                   run the release benches, merge them by scenario id into target/perf/results.json,
                   check perf/budgets.toml and perf/baseline.json (non-zero on a broken budget or regression)
@@ -249,6 +251,16 @@ fn cmd_ci() -> Result<(), String> {
         ("doctest", Box::new(cmd_doctest)),
         ("layers", Box::new(cmd_layers)),
         ("wasm", Box::new(cmd_wasm)),
+        (
+            "i18n",
+            Box::new(|| {
+                // Lists missing translations for the log; a missing string shows in English, so it never fails CI.
+                if let Err(e) = i18n_coverage::run(&root()) {
+                    eprintln!("warning: i18n coverage report failed: {e}");
+                }
+                Ok(())
+            }),
+        ),
     ];
     let mut done = Vec::new();
     for (name, f) in &steps {