feat(admin): render-engine kill switch (block renders + show message)

Lets an admin disable rendering when no render node is available — users can't
start new renders and see a localized "service unavailable until <date>" message.

- Admin → فارم رندر → موتور رندر (RenderEngineAdmin): on/off toggle + fa/en message
  + optional Jalali "until" date; saved as one `render_service` Website Setting
  (jsonb) via /v1/settings — no backend change, no migration.
- lib/render-service.ts: fetchRenderServiceStatus (fail-open) + renderServiceMessage
  (locale + appends the date).
- Enforcement: POST /api/render returns 503 {code:render_disabled, messages} when off;
  studio render page reads GET /api/render/service on mount → disables "شروع رندر"
  and shows the banner, and handles the 503 on click.
- i18n: appAdminLayout.renderEngine (fa+en, parity 1045/1045). tsc + next build clean.
  Verified: disabled setting → /api/render/service returns enabled:false.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/[locale]/admin/layout.tsx

@@ -64,6 +64,7 @@ export default async function AdminLayout({
     {
       title: "فارم رندر",
       items: [
+        { href: "/admin/render-engine", label: t("renderEngine") },
         { href: "/admin/nodes", label: t("nodes") },
         { href: "/admin/node-fonts", label: t("nodeFonts") },
         { href: "/admin/renders", label: t("renderQueue") },

src/app/[locale]/admin/render-engine/page.tsx

@@ -0,0 +1,7 @@
+"use client";
+
+import { RenderEngineAdmin } from "@/components/admin/RenderEngineAdmin";
+
+export default function Page() {
+  return <RenderEngineAdmin />;
+}

src/app/[locale]/studio/render/[projectId]/page.tsx

@@ -12,9 +12,12 @@ import {
   RefreshCw,
 } from "lucide-react";
 
+import { useLocale } from "next-intl";
+
 import { apiFetch } from "@/lib/api/fetch";
 import { RENDER_EXPORT_PRESETS, type RenderExportPreset } from "@/lib/render-presets";
 import type { RenderSettings } from "@/lib/render-schemas";
+import { renderServiceMessage, type RenderServiceStatus } from "@/lib/render-service";
 import { cn } from "@/lib/utils";
 
 type Phase = "config" | "submitting" | "polling" | "completed" | "failed";
@@ -57,6 +60,13 @@ export default function RenderPage() {
   const projectId = params.projectId;
   const presetKey = search.get("preset") as RenderExportPreset | null;
 
+  const locale = useLocale();
+  const [renderService, setRenderService] = useState<RenderServiceStatus | null>(null);
+  const serviceDisabled = renderService?.enabled === false;
+  const serviceMessage = renderService
+    ? renderServiceMessage(renderService, locale, "سرویس رندر در حال حاضر در دسترس نیست.")
+    : "";
+
   const [resolution, setResolution] = useState<RenderSettings["resolution"]>("1080p");
   const [fps, setFps] = useState<RenderSettings["fps"]>(30);
   const [phase, setPhase] = useState<Phase>("config");
@@ -80,6 +90,23 @@ export default function RenderPage() {
     setFps(cfg.settings.fps);
   }, [presetKey]);
 
+  // Render-engine kill switch: learn whether new renders are allowed.
+  useEffect(() => {
+    let cancelled = false;
+    (async () => {
+      try {
+        const res = await fetch("/api/render/service", { cache: "no-store" });
+        const data = (await res.json()) as RenderServiceStatus;
+        if (!cancelled) setRenderService(data);
+      } catch {
+        if (!cancelled) setRenderService({ enabled: true });
+      }
+    })();
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
   // On mount: resume this project's render if one is in flight, or flag a render
   // running on another project so we can block starting a new one.
   useEffect(() => {
@@ -170,7 +197,26 @@ export default function RenderPage() {
           settings: { resolution, format: "mp4" as const, fps },
         }),
       });
-      const data = (await res.json()) as { jobId?: string; error?: string; code?: string };
+      const data = (await res.json()) as {
+        jobId?: string;
+        error?: string;
+        code?: string;
+        messageFa?: string;
+        messageEn?: string;
+        untilDate?: string;
+      };
+      if (data.code === "render_disabled") {
+        const status: RenderServiceStatus = {
+          enabled: false,
+          messageFa: data.messageFa,
+          messageEn: data.messageEn,
+          untilDate: data.untilDate,
+        };
+        setRenderService(status);
+        setPhase("config");
+        setErrorMessage(renderServiceMessage(status, locale, data.error ?? "سرویس رندر در حال حاضر در دسترس نیست."));
+        return;
+      }
       if (res.status === 409 || data.code === "active_render_limit") {
         setPhase("config");
         setErrorMessage(
@@ -191,7 +237,7 @@ export default function RenderPage() {
       setPhase("failed");
       setErrorMessage("Could not reach the render service.");
     }
-  }, [projectId, resolution, fps]);
+  }, [projectId, resolution, fps, locale]);
 
   const backToStudio = `/studio/video/${projectId}`;
   const isBusy = phase === "submitting" || phase === "polling";
@@ -313,7 +359,12 @@ export default function RenderPage() {
         ) : (
           // Config
           <div className="w-full max-w-md space-y-5">
-            {errorMessage && (
+            {serviceDisabled && (
+              <div className="rounded-lg border border-amber-900/50 bg-amber-950/40 px-4 py-3 text-sm text-amber-200">
+                {serviceMessage}
+              </div>
+            )}
+            {errorMessage && !serviceDisabled && (
               <p className="rounded-lg border border-amber-900/50 bg-amber-950/40 px-3 py-2 text-sm text-amber-300">
                 {errorMessage}
               </p>
@@ -372,7 +423,7 @@ export default function RenderPage() {
             <button
               type="button"
               onClick={startRender}
-              disabled={!!blockingJobId}
+              disabled={!!blockingJobId || serviceDisabled}
               className="w-full rounded-lg bg-primary-600 px-4 py-3 text-sm font-semibold text-white hover:bg-primary-700 disabled:cursor-not-allowed disabled:opacity-50"
             >
               شروع رندر

src/app/api/render/route.ts

@@ -3,6 +3,7 @@ import { NextResponse } from "next/server";
 import { getAccessToken } from "@/lib/auth/session";
 import { createRenderJob } from "@/lib/render-jobs";
 import { renderRequestSchema } from "@/lib/render-schemas";
+import { fetchRenderServiceStatus } from "@/lib/render-service";
 
 export const runtime = "nodejs";
 
@@ -12,6 +13,21 @@ export async function POST(request: Request) {
     return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
   }
 
+  // Render-engine kill switch (admin-controlled). Block new renders when disabled.
+  const service = await fetchRenderServiceStatus();
+  if (!service.enabled) {
+    return NextResponse.json(
+      {
+        error: service.messageEn || service.messageFa || "Render service is currently unavailable.",
+        code: "render_disabled",
+        messageFa: service.messageFa,
+        messageEn: service.messageEn,
+        untilDate: service.untilDate,
+      },
+      { status: 503 },
+    );
+  }
+
   let body: unknown;
   try {
     body = await request.json();

src/app/api/render/service/route.ts

@@ -0,0 +1,14 @@
+import { NextResponse } from "next/server";
+
+import { fetchRenderServiceStatus } from "@/lib/render-service";
+
+export const runtime = "nodejs";
+
+/** Public read of the render-engine kill switch, so the studio can disable the
+ *  "start render" button and show the unavailable message before the user clicks. */
+export async function GET() {
+  const status = await fetchRenderServiceStatus();
+  return NextResponse.json(status, {
+    headers: { "Cache-Control": "no-store" },
+  });
+}