feat(multiplayer): replace polling with server-sent events and redis pub/sub

app/api/rooms/[code]/route.ts

@@ -4,6 +4,7 @@
 import { NextRequest } from "next/server";
 import type { Room, Player } from "../route";
 import { prisma } from "../../../../lib/prisma";
+import { redis, roomChannel } from "../../../../lib/redis";
 
 function dbToRoom(row: {
   code: string;
@@ -498,4 +499,6 @@ async function saveRoom(room: Room) {
       roundStart: room.roundStart !== null ? BigInt(room.roundStart) : null,
     },
   });
+  // Notifie tous les clients SSE abonnés à cette room
+  await redis.publish(roomChannel(room.code), JSON.stringify(room));
 }

app/api/rooms/[code]/stream/route.ts

@@ -0,0 +1,68 @@
+// GET /api/rooms/[code]/stream — SSE : pousse l'état de la room en temps réel
+// Le client s'abonne une seule fois ; chaque saveRoom publie sur Redis et notifie ici.
+
+import { NextRequest } from "next/server";
+import { createSubscriber, roomChannel } from "../../../../../lib/redis";
+
+export const dynamic = "force-dynamic";
+
+export async function GET(
+  _req: NextRequest,
+  { params }: { params: Promise<{ code: string }> },
+) {
+  const { code } = await params;
+  const channel = roomChannel(code.toUpperCase());
+
+  const sub = createSubscriber();
+
+  const stream = new ReadableStream({
+    start(controller) {
+      const encode = (data: string) =>
+        new TextEncoder().encode(`data: ${data}\n\n`);
+
+      // Ping toutes les 25s pour garder la connexion alive (proxys/Coolify)
+      const keepAlive = setInterval(() => {
+        try {
+          controller.enqueue(new TextEncoder().encode(": ping\n\n"));
+        } catch {
+          clearInterval(keepAlive);
+        }
+      }, 25_000);
+
+      sub.subscribe(channel, (err) => {
+        if (err) {
+          controller.close();
+          clearInterval(keepAlive);
+          sub.disconnect();
+        }
+      });
+
+      sub.on("message", (_chan: string, message: string) => {
+        try {
+          controller.enqueue(encode(message));
+        } catch {
+          // Client déconnecté
+        }
+      });
+
+      sub.on("error", () => {
+        clearInterval(keepAlive);
+        try { controller.close(); } catch { /* déjà fermé */ }
+        sub.disconnect();
+      });
+    },
+    cancel() {
+      sub.unsubscribe(channel);
+      sub.disconnect();
+    },
+  });
+
+  return new Response(stream, {
+    headers: {
+      "Content-Type": "text/event-stream",
+      "Cache-Control": "no-cache, no-transform",
+      Connection: "keep-alive",
+      "X-Accel-Buffering": "no", // désactive le buffering nginx/Coolify
+    },
+  });
+}