[client] Warn on missing translations and check placeholders (#8090)

client/ui/i18n/check-translations.mjs

@@ -1,13 +1,20 @@
 #!/usr/bin/env node
-// Validates that every shipped translation bundle carries exactly the same set
-// of keys as the English source of truth. English (en) defines the keys; every
-// other locale declared in _index.json must match it 1:1:
+// Validates every shipped translation bundle against the English source of
+// truth. English (en) defines the keys; for every other locale declared in
+// _index.json:
 //
-//   - no missing keys — a missing key silently falls back to English at runtime
-//     (see i18n bundle fallback), so the gap never surfaces to users or CI
-//     without this check;
-//   - no orphaned keys — keys left behind after an English key is renamed or
-//     removed are dead weight and a sign the locale is drifting.
+//   - missing keys are reported as a warning, not a failure — a missing key
+//     falls back to English at runtime (see i18n bundle fallback), and Crowdin
+//     exports only translated strings (skip_untranslated_strings in
+//     crowdin.yml), so a locale is routinely behind English until translators
+//     catch up;
+//   - orphaned keys fail — keys left behind after an English key is renamed or
+//     removed are dead weight and a sign the locale is drifting;
+//   - empty messages fail — a present key with an empty, whitespace-only or
+//     missing message renders blank instead of falling back to English;
+//   - placeholder mismatches fail — a translation must use exactly the
+//     {placeholders} of its English string, otherwise a value silently never
+//     renders (or a literal "{name}" leaks into the UI).
 //
 // Pure Node, no dependencies, so it runs without installing the frontend
 // toolchain.
@@ -23,17 +30,40 @@ const SOURCE = "en";
 const localesDir = join(dirname(fileURLToPath(import.meta.url)), "locales");
 const isCI = Boolean(process.env.GITHUB_ACTIONS);
 
+// Matches the i18next interpolation configured in the frontend
+// (prefix "{", suffix "}") and the Go bundle's applyPlaceholders.
+const PLACEHOLDER = /\{([^{}\s]+)\}/g;
+
 function readJSON(path) {
     return JSON.parse(readFileSync(path, "utf8"));
 }
 
-function keysOf(langCode) {
-    return Object.keys(readJSON(join(localesDir, langCode, "common.json")));
+function messagesOf(langCode) {
+    const entries = readJSON(join(localesDir, langCode, "common.json"));
+    const messages = new Map();
+    for (const [key, entry] of Object.entries(entries)) {
+        // null marks an unusable entry (missing or non-string message).
+        messages.set(key, typeof entry?.message === "string" ? entry.message : null);
+    }
+    return messages;
 }
 
-// Emit a GitHub Actions annotation so failures render inline on the PR diff.
-function annotate(file, message) {
-    if (isCI) console.log(`::error file=${file}::${message}`);
+function placeholdersOf(message) {
+    // Code-point order: placeholder names are identifiers, not prose.
+    return [...new Set([...message.matchAll(PLACEHOLDER)].map((m) => m[1]))].sort((a, b) => {
+        if (a < b) return -1;
+        if (a > b) return 1;
+        return 0;
+    });
+}
+
+function formatPlaceholders(names) {
+    return names.length ? names.map((n) => `{${n}}`).join(", ") : "none";
+}
+
+// Emit a GitHub Actions annotation so findings render inline on the PR diff.
+function annotate(level, file, message) {
+    if (isCI) console.log(`::${level} file=${file}::${message}`);
 }
 
 const index = readJSON(join(localesDir, "_index.json"));
@@ -44,8 +74,13 @@ if (!declared.includes(SOURCE)) {
     process.exit(1);
 }
 
-const sourceKeys = keysOf(SOURCE);
-const sourceSet = new Set(sourceKeys);
+const source = messagesOf(SOURCE);
+const sourceKeys = [...source.keys()];
+const emptySource = sourceKeys.filter((k) => !source.get(k)?.trim());
+if (emptySource.length) {
+    console.error(`FATAL: ${SOURCE}/common.json has empty or missing messages: ${emptySource.join(", ")}`);
+    process.exit(1);
+}
 console.log(`Source of truth: ${SOURCE}/common.json — ${sourceKeys.length} keys\n`);
 
 let failed = false;
@@ -54,40 +89,67 @@ for (const code of declared) {
     if (code === SOURCE) continue;
     const file = `client/ui/i18n/locales/${code}/common.json`;
 
-    let keys;
+    let messages;
     try {
-        keys = keysOf(code);
+        messages = messagesOf(code);
     } catch (e) {
         failed = true;
         const msg = `bundle is declared in _index.json but common.json is missing or invalid (${e.message})`;
         console.error(`✗ ${code}: ${msg}`);
-        annotate("client/ui/i18n/locales/_index.json", `${code}: ${msg}`);
+        annotate("error", "client/ui/i18n/locales/_index.json", `${code}: ${msg}`);
         continue;
     }
 
-    const set = new Set(keys);
-    const missing = sourceKeys.filter((k) => !set.has(k));
-    const extra = keys.filter((k) => !sourceSet.has(k));
-
-    if (missing.length === 0 && extra.length === 0) {
-        console.log(`✓ ${code}: ${keys.length} keys`);
-        continue;
+    const missing = sourceKeys.filter((k) => !messages.has(k));
+    const extra = [...messages.keys()].filter((k) => !source.has(k));
+    const empty = [];
+    const badPlaceholders = [];
+    for (const [key, message] of messages) {
+        if (!source.has(key)) continue;
+        if (!message?.trim()) {
+            empty.push(key);
+            continue;
+        }
+        const want = placeholdersOf(source.get(key));
+        const got = placeholdersOf(message);
+        if (want.length !== got.length || want.some((name, i) => name !== got[i])) {
+            badPlaceholders.push(`${key} (expected ${formatPlaceholders(want)}, got ${formatPlaceholders(got)})`);
+        }
     }
 
-    failed = true;
-    console.error(`✗ ${code}: ${keys.length} keys (expected ${sourceKeys.length})`);
+    const translated = sourceKeys.length - missing.length - empty.length;
+    const coverage = Math.floor((translated / sourceKeys.length) * 100);
+    const hasErrors = extra.length > 0 || empty.length > 0 || badPlaceholders.length > 0;
+    let mark = "✓";
+    if (hasErrors) mark = "✗";
+    else if (missing.length) mark = "⚠";
+    const log = hasErrors ? console.error : console.log;
+    log(`${mark} ${code}: ${translated}/${sourceKeys.length} keys translated (${coverage}%)`);
+
     if (missing.length) {
-        console.error(`    missing ${missing.length}: ${missing.join(", ")}`);
-        annotate(file, `Missing ${missing.length} key(s) present in ${SOURCE}: ${missing.join(", ")}`);
+        console.warn(`    missing ${missing.length} (falls back to English): ${missing.join(", ")}`);
+        annotate("warning", file, `Missing ${missing.length} key(s) present in ${SOURCE}, shown in English: ${missing.join(", ")}`);
     }
     if (extra.length) {
+        failed = true;
         console.error(`    extra ${extra.length}: ${extra.join(", ")}`);
-        annotate(file, `Has ${extra.length} key(s) not present in ${SOURCE}: ${extra.join(", ")}`);
+        annotate("error", file, `Has ${extra.length} key(s) not present in ${SOURCE}: ${extra.join(", ")}`);
+    }
+    if (empty.length) {
+        failed = true;
+        console.error(`    empty message ${empty.length} (renders blank): ${empty.join(", ")}`);
+        annotate("error", file, `Empty or missing message in ${empty.length} key(s), renders blank: ${empty.join(", ")}`);
+    }
+    if (badPlaceholders.length) {
+        failed = true;
+        console.error(`    placeholder mismatch ${badPlaceholders.length}: ${badPlaceholders.join("; ")}`);
+        annotate("error", file, `Placeholders differ from ${SOURCE} in ${badPlaceholders.length} key(s): ${badPlaceholders.join("; ")}`);
     }
 }
 
-// Locale directories present on disk but not declared in _index.json are never
-// loaded by the app — surface them so dead translation files don't rot silently.
+// Locale directories present on disk but not declared in _index.json are not
+// offered in the language picker — surface them so dead translation files don't
+// rot silently.
 const onDisk = readdirSync(localesDir, { withFileTypes: true })
     .filter((e) => e.isDirectory())
     .map((e) => e.name);
@@ -98,7 +160,7 @@ if (undeclared.length) {
 
 console.log();
 if (failed) {
-    console.error("Translation check FAILED — every locale must match the English key set.");
+    console.error("Translation check FAILED — fix orphaned keys, empty messages and placeholder mismatches above.");
     process.exit(1);
 }
-console.log("Translation check passed — all locales match the English key set.");
+console.log("Translation check passed — no orphaned keys, empty messages or placeholder mismatches.");