Configure board deployment and backend proxy

server/.dockerignore

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+node_modules
+.DS_Store

server/Dockerfile

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+FROM node:22-alpine
+WORKDIR /app
+
+COPY package.json package-lock.json ./
+RUN npm ci --omit=dev && npm cache clean --force
+COPY realtime-server.mjs ./
+
+USER node
+EXPOSE 8787
+HEALTHCHECK --interval=15s --timeout=3s --start-period=5s --retries=3 \
+  CMD wget -qO- http://127.0.0.1:8787/healthz | grep -q '"status":"ok"'
+
+CMD ["node", "realtime-server.mjs"]

server/package-lock.json

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+{
+  "name": "wc-board-realtime",
+  "version": "0.1.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "wc-board-realtime",
+      "version": "0.1.0",
+      "dependencies": {
+        "ws": "^8.18.3"
+      }
+    },
+    "node_modules/ws": {
+      "version": "8.21.3",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-8.21.3.tgz",
+      "integrity": "sha512-201TZ/kPWxoPr/OKWjquZR1SWKXcvxdH+e1xrx89b3YbmzLMFCLfnaG1HFIgWzJOEWZ7MvpK++odZufgYR50Rw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=10.0.0"
+      },
+      "peerDependencies": {
+        "bufferutil": "^4.0.1",
+        "utf-8-validate": ">=5.0.2"
+      },
+      "peerDependenciesMeta": {
+        "bufferutil": {
+          "optional": true
+        },
+        "utf-8-validate": {
+          "optional": true
+        }
+      }
+    }
+  }
+}

server/package.json

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+{
+  "name": "wc-board-realtime",
+  "private": true,
+  "version": "0.1.0",
+  "type": "module",
+  "scripts": {
+    "dev": "node realtime-server.mjs",
+    "start": "node realtime-server.mjs",
+    "test": "node --test"
+  },
+  "dependencies": {
+    "ws": "^8.18.3"
+  }
+}

server/realtime-server.mjs

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+import { createServer } from 'node:http';
+import { pathToFileURL } from 'node:url';
+import { WebSocketServer } from 'ws';
+
+function isFocusEvent(value) {
+  return (
+    typeof value === 'object' &&
+    value !== null &&
+    value.type === 'FOCUS_NAME' &&
+    typeof value.cloudId === 'string' &&
+    typeof value.name === 'string' &&
+    typeof value.messageId === 'string' &&
+    typeof value.sentAt === 'number' &&
+    (value.targetIndex === undefined ||
+      (typeof value.targetIndex === 'number' &&
+        Number.isInteger(value.targetIndex) &&
+        value.targetIndex >= 0))
+  );
+}
+
+export function createRealtimeServer(port = Number(process.env.REALTIME_PORT || 8787)) {
+  const server = createServer((request, response) => {
+    if (request.url === '/healthz') {
+      response.writeHead(200, { 'content-type': 'application/json' });
+      response.end(JSON.stringify({ status: 'ok' }));
+      return;
+    }
+
+    response.writeHead(404, { 'content-type': 'text/plain' });
+    response.end('Not found');
+  });
+  const realtime = new WebSocketServer({
+    server,
+    maxPayload: 16 * 1024,
+  });
+  const heartbeat = setInterval(() => {
+    for (const socket of realtime.clients) {
+      if (socket.isAlive === false) {
+        socket.terminate();
+        continue;
+      }
+
+      socket.isAlive = false;
+      socket.ping();
+    }
+  }, 30_000);
+
+  heartbeat.unref();
+
+  realtime.on('connection', (socket) => {
+    socket.isAlive = true;
+    socket.on('pong', () => {
+      socket.isAlive = true;
+    });
+
+    socket.on('message', (data) => {
+      let value;
+
+      try {
+        value = JSON.parse(data.toString());
+      } catch {
+        return;
+      }
+
+      if (!isFocusEvent(value)) {
+        return;
+      }
+
+      const message = JSON.stringify(value);
+
+      for (const client of realtime.clients) {
+        if (client !== socket && client.readyState === client.OPEN) {
+          client.send(message);
+        }
+      }
+    });
+  });
+
+  realtime.on('close', () => {
+    clearInterval(heartbeat);
+  });
+
+  return server;
+}
+
+if (import.meta.url === pathToFileURL(process.argv[1] || '').href) {
+  const port = Number(process.env.REALTIME_PORT || 8787);
+  createRealtimeServer(port).listen(port, () => {
+    console.log(`Realtime WebSocket server listening on port ${port}`);
+  });
+}

server/realtime-server.test.mjs

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+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { createRealtimeServer } from './realtime-server.mjs';
+import WebSocket from 'ws';
+
+test('broadcasts focus events to other connected clients', async () => {
+  const server = createRealtimeServer(0);
+  await new Promise((resolve) => server.listen(resolve));
+  const { port } = server.address();
+
+  try {
+    const screen = new WebSocket(`ws://127.0.0.1:${port}`);
+    const controller = new WebSocket(`ws://127.0.0.1:${port}`);
+
+    await Promise.all([
+      new Promise((resolve) => screen.once('open', resolve)),
+      new Promise((resolve) => controller.once('open', resolve)),
+    ]);
+
+    const received = new Promise((resolve) => {
+      screen.once('message', (data) => resolve(JSON.parse(data)));
+    });
+
+    controller.send(JSON.stringify({
+      type: 'FOCUS_NAME',
+      cloudId: 'demo',
+      name: 'Sophia',
+      messageId: 'focus-1',
+      sentAt: 1,
+    }));
+
+    assert.deepEqual(await received, {
+      type: 'FOCUS_NAME',
+      cloudId: 'demo',
+      name: 'Sophia',
+      messageId: 'focus-1',
+      sentAt: 1,
+    });
+
+    screen.close();
+    controller.close();
+  } finally {
+    await new Promise((resolve) => server.close(resolve));
+  }
+});