ci(i18n): add unused & missing translation-key check to Quality Gate

Dependency-free Bun script (bun run i18n:check, added to the linting matrix):
flags keys referenced in code but missing from en.json, and keys in en.json
referenced nowhere. Handles dynamic t(\prefix.\\) and keys stored as string
constants (exact delimited-literal match). Source-only: only en.json is
checked/edited; Crowdin syncs the other locales. Planned-feature keys are
allow-listed in scripts/i18n-keys.config.json.

.github/workflows/linting.yml

@@ -97,6 +97,7 @@ jobs:
           - "check"
           - "format"
           - "typecheck"
+          - "i18n:check"
 
     steps:
       - name: "📥 Checkout PR code"

package.json

@@ -22,6 +22,8 @@
     "lint": "biome check --write --unsafe --max-diagnostics 1000",
     "format": "biome format --write .",
     "doctor": "expo-doctor",
+    "i18n:check": "bun scripts/check-i18n-keys.mjs",
+    "i18n:fix-unused": "bun scripts/check-i18n-keys.mjs --fix-unused",
     "test": "bun run typecheck && bun run lint && bun run format && bun run doctor",
     "postinstall": "patch-package"
   },

scripts/check-i18n-keys.mjs

@@ -0,0 +1,261 @@
+#!/usr/bin/env bun
+/**
+ * i18n key checker for Streamyfin.
+ *
+ * Detects:
+ *   - MISSING keys: a static `t("a.b.c")` / `i18nKey="a.b.c"` referenced in the code
+ *     that does not exist in the source locale (translations/en.json). These are bugs —
+ *     the app renders the raw key. Always fails CI.
+ *   - UNUSED (dead) keys: a key in the source locale that is referenced nowhere in the
+ *     code, neither statically nor via a detected dynamic prefix (`t(`a.b.${x}`)`).
+ *     These are dead weight that also clutter every locale on Crowdin.
+ *
+ * Dynamic usage is handled conservatively:
+ *   - `t(`prefix.${x}`)`  -> every key starting with `prefix.` is considered used.
+ *   - `t(`${x}`)`         -> fully dynamic, reported for manual review, never used to
+ *                            whitelist keys (in Streamyfin these are user-defined section
+ *                            titles, not translation keys).
+ *   - Edge cases the static scan cannot see can be allow-listed in the config file.
+ *
+ * Usage:
+ *   bun scripts/check-i18n-keys.mjs                # report + exit 1 on missing OR unused
+ *   bun scripts/check-i18n-keys.mjs --unused=warn  # exit 1 only on missing; unused = warning
+ *   bun scripts/check-i18n-keys.mjs --unused=off   # ignore unused entirely
+ *   bun scripts/check-i18n-keys.mjs --json         # machine-readable output
+ *   bun scripts/check-i18n-keys.mjs --fix-unused   # remove dead keys from en.json (Crowdin syncs the rest)
+ */
+
+import {
+  existsSync,
+  readdirSync,
+  readFileSync,
+  statSync,
+  writeFileSync,
+} from "node:fs";
+import { extname, join, relative } from "node:path";
+
+const ROOT = process.cwd();
+const args = process.argv.slice(2);
+const flag = (name, def) => {
+  const a = args.find((x) => x === `--${name}` || x.startsWith(`--${name}=`));
+  if (!a) return def;
+  const [, v] = a.split("=");
+  return v === undefined ? true : v;
+};
+const UNUSED_MODE = String(flag("unused", "error")); // error | warn | off
+const JSON_OUT = !!flag("json", false);
+const FIX_UNUSED = !!flag("fix-unused", false);
+
+// ---- config ----
+const CONFIG_PATH = join(ROOT, "scripts", "i18n-keys.config.json");
+const DEFAULT_CONFIG = {
+  localesDir: "translations",
+  sourceLocale: "en",
+  // Scan the whole repo by default so keys referenced outside the obvious dirs
+  // (e.g. packages/, key constants in utils/atoms) are not wrongly flagged as dead.
+  srcDirs: ["."],
+  srcExtensions: [".ts", ".tsx", ".js", ".jsx", ".mjs", ".cjs"],
+  excludeDirs: [
+    "node_modules",
+    "ios",
+    "android",
+    ".expo",
+    ".git",
+    "dist",
+    "build",
+    "translations",
+    "scripts",
+  ],
+  // Keys (or glob-ish prefixes ending with .* or *) known to be used dynamically / externally.
+  ignoreUnused: [],
+};
+const config = existsSync(CONFIG_PATH)
+  ? { ...DEFAULT_CONFIG, ...JSON.parse(readFileSync(CONFIG_PATH, "utf8")) }
+  : DEFAULT_CONFIG;
+
+// ---- helpers ----
+const flatten = (obj, prefix = "", out = {}) => {
+  for (const [k, v] of Object.entries(obj)) {
+    const key = prefix ? `${prefix}.${k}` : k;
+    if (v && typeof v === "object" && !Array.isArray(v)) flatten(v, key, out);
+    else out[key] = v;
+  }
+  return out;
+};
+
+const globMatch = (key, pattern) => {
+  if (pattern.endsWith(".*"))
+    return key === pattern.slice(0, -2) || key.startsWith(pattern.slice(0, -1));
+  if (pattern.endsWith("*")) return key.startsWith(pattern.slice(0, -1));
+  return key === pattern;
+};
+
+const walk = (dir, files = []) => {
+  let entries;
+  try {
+    entries = readdirSync(dir);
+  } catch {
+    return files;
+  }
+  for (const name of entries) {
+    const full = join(dir, name);
+    let st;
+    try {
+      st = statSync(full);
+    } catch {
+      continue;
+    }
+    if (st.isDirectory()) {
+      if (config.excludeDirs.includes(name)) continue;
+      walk(full, files);
+    } else if (config.srcExtensions.includes(extname(name))) {
+      files.push(full);
+    }
+  }
+  return files;
+};
+
+// ---- load source keys ----
+const sourcePath = join(ROOT, config.localesDir, `${config.sourceLocale}.json`);
+const sourceKeys = Object.keys(
+  flatten(JSON.parse(readFileSync(sourcePath, "utf8"))),
+);
+const sourceKeySet = new Set(sourceKeys);
+
+// ---- scan code ----
+const STATIC_RE = /\bt\(\s*(['"])((?:\\.|(?!\1).)+?)\1/g; // t("a.b") / t('a.b')
+const TPL_STATIC_RE = /\bt\(\s*`([^`$]+)`/g; // t(`a.b`) no interpolation
+const TPL_DYN_RE = /\bt\(\s*`([^`$]*)\$\{/g; // t(`a.b.${x}`) -> prefix "a.b."
+const I18NKEY_RE = /\bi18nKey\s*=\s*(?:\{\s*)?(['"])((?:\\.|(?!\1).)+?)\1/g; // <Trans i18nKey="a.b">
+const KEY_SHAPE = /^[A-Za-z0-9_]+(\.[A-Za-z0-9_]+)+$/; // dotted key, e.g. home.x.y
+
+const usedStatic = new Set(); // keys passed to t(...) / i18nKey — used for MISSING detection
+const dynamicPrefixes = new Set();
+const fullyDynamic = []; // { file, line }
+let codeBlob = ""; // all source text — searched for delimited key literals
+
+const files = config.srcDirs.flatMap((d) =>
+  walk(join(ROOT, d === "." ? "" : d) || ROOT),
+);
+for (const file of files) {
+  const text = readFileSync(file, "utf8");
+  codeBlob += `\n${text}`;
+  for (const m of text.matchAll(STATIC_RE)) usedStatic.add(m[2]);
+  for (const m of text.matchAll(TPL_STATIC_RE)) usedStatic.add(m[1]);
+  for (const m of text.matchAll(I18NKEY_RE)) usedStatic.add(m[2]);
+  for (const m of text.matchAll(TPL_DYN_RE)) {
+    const prefix = m[1];
+    if (prefix?.includes(".")) dynamicPrefixes.add(prefix);
+    else {
+      const idx = text.slice(0, m.index).split("\n").length;
+      fullyDynamic.push({ file: relative(ROOT, file), line: idx });
+    }
+  }
+}
+
+const prefixList = [...dynamicPrefixes];
+// A key counts as used if its EXACT delimited literal ("k" / 'k' / `k`) appears anywhere in
+// the code (covers t("k"), <Trans i18nKey>, and keys stored as bare string constants in
+// arrays/config then resolved via t(variable)), or it is reached via a dynamic prefix, or
+// explicitly allow-listed. Delimited search avoids substring false-matches (e.g. a.b vs a.b_c).
+const literalUsed = (key) =>
+  codeBlob.includes(`"${key}"`) ||
+  codeBlob.includes(`'${key}'`) ||
+  codeBlob.includes(`\`${key}\``);
+const isUsed = (key) =>
+  literalUsed(key) ||
+  prefixList.some((p) => key.startsWith(p)) ||
+  config.ignoreUnused.some((g) => globMatch(key, g));
+
+// ---- compute ----
+const unused = sourceKeys.filter((k) => !isUsed(k)).sort();
+const missing = [...usedStatic]
+  .filter(
+    (k) =>
+      KEY_SHAPE.test(k) &&
+      !sourceKeySet.has(k) &&
+      !prefixList.some((p) => k.startsWith(p)),
+  )
+  .sort();
+
+// ---- optional fix: strip dead keys from all locale files ----
+const removeKey = (obj, parts) => {
+  const [head, ...rest] = parts;
+  if (!(head in obj)) return;
+  if (rest.length === 0) {
+    delete obj[head];
+    return;
+  }
+  removeKey(obj[head], rest);
+  if (
+    obj[head] &&
+    typeof obj[head] === "object" &&
+    Object.keys(obj[head]).length === 0
+  )
+    delete obj[head];
+};
+if (FIX_UNUSED && unused.length) {
+  // Only edit the SOURCE locale (en.json). Crowdin owns the target locales and removes
+  // the keys from them automatically on the next sync once they disappear from the source.
+  const data = JSON.parse(readFileSync(sourcePath, "utf8"));
+  for (const key of unused) removeKey(data, key.split("."));
+  writeFileSync(sourcePath, `${JSON.stringify(data, null, 2)}\n`);
+  console.log(
+    `🧹 Removed ${unused.length} dead key(s) from ${config.sourceLocale}.json (Crowdin will sync the other locales).`,
+  );
+}
+
+// ---- report ----
+if (JSON_OUT) {
+  console.log(
+    JSON.stringify(
+      {
+        sourceKeys: sourceKeys.length,
+        missing,
+        unused,
+        dynamicPrefixes: prefixList,
+        fullyDynamic,
+      },
+      null,
+      2,
+    ),
+  );
+} else {
+  console.log(
+    `🔑 i18n key check — source: ${relative(ROOT, sourcePath)} (${sourceKeys.length} keys), scanned ${files.length} files`,
+  );
+  if (prefixList.length)
+    console.log(
+      `   dynamic prefixes treated as used: ${prefixList.map((p) => `${p}*`).join(", ")}`,
+    );
+  if (fullyDynamic.length)
+    console.log(
+      `   ⚠️  ${fullyDynamic.length} fully-dynamic t(\`\${…}\`) call(s) (not key-based, manual review): ${fullyDynamic.map((d) => `${d.file}:${d.line}`).join(", ")}`,
+    );
+
+  if (missing.length) {
+    console.log(
+      `\n❌ MISSING keys (used in code, absent from ${config.sourceLocale}.json) — ${missing.length}:`,
+    );
+    for (const k of missing) console.log(`   - ${k}`);
+  } else console.log("\n✅ No missing keys.");
+
+  if (UNUSED_MODE !== "off") {
+    if (unused.length) {
+      console.log(
+        `\n${UNUSED_MODE === "error" ? "❌" : "⚠️ "} UNUSED keys (in ${config.sourceLocale}.json, referenced nowhere) — ${unused.length}:`,
+      );
+      for (const k of unused) console.log(`   - ${k}`);
+      console.log(
+        `\n   → remove with: bun scripts/check-i18n-keys.mjs --fix-unused`,
+      );
+      console.log(
+        `   → or allow-list a dynamic key in scripts/i18n-keys.config.json ("ignoreUnused").`,
+      );
+    } else console.log("\n✅ No unused keys.");
+  }
+}
+
+const fail =
+  missing.length > 0 || (UNUSED_MODE === "error" && unused.length > 0);
+process.exit(fail ? 1 : 0);

scripts/i18n-keys.config.json

@@ -0,0 +1,43 @@
+{
+  "localesDir": "translations",
+  "sourceLocale": "en",
+  "srcDirs": [
+    "app",
+    "components",
+    "hooks",
+    "providers",
+    "utils",
+    "modules",
+    "packages",
+    "constants"
+  ],
+  "srcExtensions": [".ts", ".tsx", ".js", ".jsx", ".mjs", ".cjs"],
+  "excludeDirs": [
+    "node_modules",
+    "ios",
+    "android",
+    ".expo",
+    ".git",
+    "dist",
+    "build",
+    "translations"
+  ],
+  "_ignoreUnusedNote": "Keys for planned features that are intentionally kept in en.json but not yet wired in code. They are exempt from the unused-key check until implemented. Remove an entry once its feature ships and uses the key.",
+  "ignoreUnused": [
+    "watchlists.add_to_watchlist",
+    "watchlists.remove_from_watchlist",
+    "watchlists.create_one_first",
+    "watchlists.no_compatible_watchlists",
+    "pin.confirm_pin",
+    "pin.pins_dont_match",
+    "player.search_subtitles",
+    "player.subtitle_search",
+    "player.subtitle_download_hint",
+    "player.subtitle_tracks",
+    "player.using_jellyfin_server",
+    "player.swipe_down_settings",
+    "player.stopPlayback",
+    "player.stopPlayingTitle",
+    "player.stopPlayingConfirm"
+  ]
+}