diff --git a/package.json b/package.json
index 692286f..02fa246 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,8 @@
     "screen:preview": "tsx scripts/preview.ts",
     "brand": "tsx scripts/brand.ts",
     "e2e": "playwright test",
-    "holidays:sync": "tsx scripts/sync-holidays.ts"
+    "holidays:sync": "tsx scripts/sync-holidays.ts",
+    "translate:test": "tsx scripts/test-translation.ts"
   },
   "dependencies": {
     "@fontsource-variable/inter": "^5.3.0",
diff --git a/scripts/test-translation.ts b/scripts/test-translation.ts
new file mode 100644
index 0000000..2e2c4a9
--- /dev/null
+++ b/scripts/test-translation.ts
@@ -0,0 +1,56 @@
+/**
+ * Round-trips a phrase through the translation service.
+ *
+ *   npm run translate:test  ["texte à traduire"]
+ *
+ * The settings page has the same button; this exists to check a deployment
+ * from the host, before anyone signs in, and to see the cache working.
+ */
+
+import 'dotenv/config';
+
+import { prisma } from '../lib/db';
+import { defaultProvider, translateToEnglish } from '../lib/translation/service';
+
+async function main(): Promise<void> {
+  const text = process.argv[2] ?? 'Fermeture exceptionnelle jeudi après-midi';
+  const provider = defaultProvider();
+
+  if (!provider) {
+    console.error('Service non configuré : renseignez TRANSLATION_API_URL et TRANSLATION_API_KEY.');
+    process.exitCode = 1;
+    return;
+  }
+
+  console.log(`Modèle   : ${provider.model}`);
+  console.log(`Français : ${text}`);
+
+  const started = Date.now();
+  const first = await translateToEnglish(text, provider);
+  const elapsed = Date.now() - started;
+
+  if (!first.ok) {
+    console.error(`Échec    : ${first.error}`);
+    process.exitCode = 1;
+    return;
+  }
+
+  console.log(`Anglais  : ${first.text}`);
+  console.log(`Durée    : ${elapsed} ms (cache : ${first.cached ? 'oui' : 'non'})`);
+
+  // Second pass proves the cache: it must not touch the network at all.
+  const again = Date.now();
+  const second = await translateToEnglish(text, provider);
+  console.log(
+    `2e appel : ${Date.now() - again} ms (cache : ${second.ok && second.cached ? 'oui' : 'non'})`,
+  );
+}
+
+main()
+  .catch((error: unknown) => {
+    console.error(error);
+    process.exitCode = 1;
+  })
+  .finally(() => {
+    void prisma.$disconnect();
+  });