fix(shell): stale tabs now know the gateway was updated

Recurring confusion all day: the SPA lives in an open tab until reload, so
after a gateway rebuild/update users kept seeing (and benchmarking with!) an
old interface — "where is the feature", "why are the test ids old". The meta
endpoint now carries the process start timestamp; the existing 20s health
poll compares it, and when the gateway has restarted the tab shows a fixed
banner: "The gateway was updated — this page is running an older interface"
with a one-click Reload. 2 strings in all 7 languages.

src/admin/mod.rs

@@ -600,8 +600,18 @@ async fn provider_models(
 }
 
 async fn meta(State(state): State<SharedState>) -> ApiResult {
+    // process start marker: open tabs poll this and offer a reload when the
+    // gateway (and thus the embedded SPA) has been restarted/updated
+    static STARTED: std::sync::OnceLock<u64> = std::sync::OnceLock::new();
+    let started = *STARTED.get_or_init(|| {
+        std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap_or_default()
+            .as_secs()
+    });
     ok(json!({
         "version": env!("CARGO_PKG_VERSION"),
+        "started": started,
         "update_available": state.gateway_update.lock().unwrap().clone(),
         "admin_open_public": state
             .admin_open_public

web/js/app.js

@@ -256,12 +256,30 @@ function showLogin() {
   mount(document.getElementById("app"), renderLogin(boot));
 }
 
+let staleNotified = false;
+async function checkUiFresh() {
+  // the SPA lives in the tab until reload; if the gateway restarted (dev
+  // rebuild, update, config restart) the embedded UI may have changed —
+  // tell the user instead of letting them stare at stale views
+  try {
+    const m = await api.meta();
+    if (appState.meta?.started && m.started && m.started !== appState.meta.started && !staleNotified) {
+      staleNotified = true;
+      const bar = h("div", { class: "callout warn", style: "position:fixed; left:50%; transform:translateX(-50%); bottom:18px; z-index:99; box-shadow:0 8px 24px rgba(0,0,0,.35)" },
+        h("span", {}, "🔄 " + t("shell.uiStale")), " ",
+        h("button", { class: "btn sm primary", onClick: () => location.reload() }, t("shell.reload")));
+      document.body.append(bar);
+    }
+  } catch {}
+}
+
 async function refreshHealth() {
   try {
     appState.health = await api.health();
   } catch {
     appState.health = null;
   }
+  checkUiFresh();
   // re-render topbar only if shell present
   const route = currentRoute();
   const main = document.querySelector(".main");

web/js/i18n/de.js

@@ -619,4 +619,6 @@ export default {
   "bm.degraded": "Router degradiert",
   "bm.routerDegraded": "Der Router hat nicht rechtzeitig geantwortet — die Anfrage nutzte die Fallback-Kette; die Klassifikation wird nicht gewertet.",
   "bm.cutByCap": "Budget ging fürs Denken drauf — keine Antwort mehr",
+  "shell.uiStale": "Das Gateway wurde aktualisiert — diese Seite zeigt eine ältere Oberfläche.",
+  "shell.reload": "Neu laden",
 };

web/js/i18n/en.js

@@ -612,4 +612,6 @@ export default {
   "bm.degraded": "router degraded",
   "bm.routerDegraded": "The router did not answer in time — the request used the fallback chain; classification is not judged.",
   "bm.cutByCap": "budget spent on reasoning — answer never came",
+  "shell.uiStale": "The gateway was updated — this page is running an older interface.",
+  "shell.reload": "Reload",
 };

web/js/i18n/es.js

@@ -619,4 +619,6 @@ export default {
   "bm.degraded": "router degradado",
   "bm.routerDegraded": "El router no respondió a tiempo — la petición usó la cadena de reserva; la clasificación no se cuenta.",
   "bm.cutByCap": "presupuesto gastado en razonar — sin respuesta final",
+  "shell.uiStale": "La pasarela se actualizó — esta página usa una interfaz antigua.",
+  "shell.reload": "Recargar",
 };

web/js/i18n/fr.js

@@ -619,4 +619,6 @@ export default {
   "bm.degraded": "routeur dégradé",
   "bm.routerDegraded": "Le routeur n'a pas répondu à temps — la requête a suivi la chaîne de secours ; la classification n'est pas comptée.",
   "bm.cutByCap": "budget épuisé en raisonnement — pas de réponse",
+  "shell.uiStale": "La passerelle a été mise à jour — cette page utilise une ancienne interface.",
+  "shell.reload": "Recharger",
 };

web/js/i18n/ru.js

@@ -611,4 +611,6 @@ export default {
   "bm.degraded": "роутер деградировал",
   "bm.routerDegraded": "Роутер не успел ответить — запрос ушёл по резервной цепочке; классификация не засчитывается.",
   "bm.cutByCap": "бюджет ушёл на размышления — ответ не успел",
+  "shell.uiStale": "Шлюз обновился — на этой странице старый интерфейс.",
+  "shell.reload": "Перезагрузить",
 };

web/js/i18n/tr.js

@@ -619,4 +619,6 @@ export default {
   "bm.degraded": "yönlendirici yedeğe düştü",
   "bm.routerDegraded": "Yönlendirici zamanında yanıt vermedi — istek yedek zincire gitti; sınıflandırma sayılmaz.",
   "bm.cutByCap": "bütçe düşünmeye gitti — yanıt gelemedi",
+  "shell.uiStale": "Ağ geçidi güncellendi — bu sayfa eski arayüzü çalıştırıyor.",
+  "shell.reload": "Yeniden yükle",
 };

web/js/i18n/zh.js

@@ -619,4 +619,6 @@ export default {
   "bm.degraded": "路由器降级",
   "bm.routerDegraded": "路由器未及时响应 — 请求走了备用链路；分类不计入统计。",
   "bm.cutByCap": "预算全用于思考——未能给出答案",
+  "shell.uiStale": "网关已更新 — 此页面运行的是旧界面。",
+  "shell.reload": "重新加载",
 };