feat(signaling): add deployable signaling server for Fly.io

Standalone y-webrtc compatible signaling server for WebRTC peer
discovery and device pairing. Configured for Fly.io with auto-sleep.

Author: pheuberger

signaling-server/Dockerfile

@@ -0,0 +1,12 @@
+FROM node:20-slim
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm install --omit=dev
+
+COPY server.js ./
+
+EXPOSE 8080
+
+CMD ["node", "server.js"]

signaling-server/fly.toml

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+# fly.toml app configuration file generated for hypermark-signaling on 2026-01-24T10:45:55+02:00
+#
+# See https://fly.io/docs/reference/configuration/ for information about how to use this file.
+#
+
+app = 'hypermark-signaling'
+primary_region = 'sjc'
+
+[build]
+
+[env]
+  PORT = '8080'
+
+[http_service]
+  internal_port = 8080
+  force_https = true
+  auto_stop_machines = 'stop'
+  auto_start_machines = true
+  min_machines_running = 0
+
+[[vm]]
+  memory = '256mb'
+  cpu_kind = 'shared'
+  cpus = 1
+  memory_mb = 256

signaling-server/package.json

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+{
+  "name": "hypermark-signaling",
+  "version": "1.0.0",
+  "description": "WebRTC signaling server for Hypermark",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "start": "node server.js"
+  },
+  "dependencies": {
+    "ws": "^8.18.0"
+  },
+  "engines": {
+    "node": ">=18"
+  }
+}

signaling-server/server.js

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+/**
+ * y-webrtc compatible signaling server
+ * Handles pub/sub for WebRTC peer discovery and pairing
+ */
+
+import { WebSocketServer } from 'ws'
+
+const PORT = process.env.PORT || 4444
+const PING_INTERVAL = 30000
+
+const wss = new WebSocketServer({ port: PORT })
+
+// topic -> Set<WebSocket>
+const topics = new Map()
+
+function send(ws, message) {
+  if (ws.readyState === ws.OPEN) {
+    ws.send(JSON.stringify(message))
+  }
+}
+
+function subscribe(ws, topicList) {
+  for (const topic of topicList) {
+    if (!topics.has(topic)) {
+      topics.set(topic, new Set())
+    }
+    topics.get(topic).add(ws)
+
+    if (!ws.topics) ws.topics = new Set()
+    ws.topics.add(topic)
+  }
+}
+
+function unsubscribe(ws, topicList) {
+  for (const topic of topicList) {
+    if (topics.has(topic)) {
+      topics.get(topic).delete(ws)
+      if (topics.get(topic).size === 0) {
+        topics.delete(topic)
+      }
+    }
+    if (ws.topics) {
+      ws.topics.delete(topic)
+    }
+  }
+}
+
+function publish(ws, topic, data) {
+  if (!topics.has(topic)) return
+
+  const message = JSON.stringify({ topic, data })
+
+  for (const client of topics.get(topic)) {
+    // Don't send back to sender
+    if (client !== ws && client.readyState === client.OPEN) {
+      client.send(message)
+    }
+  }
+}
+
+function cleanup(ws) {
+  if (ws.topics) {
+    unsubscribe(ws, Array.from(ws.topics))
+  }
+}
+
+wss.on('connection', (ws) => {
+  ws.isAlive = true
+
+  ws.on('pong', () => {
+    ws.isAlive = true
+  })
+
+  ws.on('message', (data) => {
+    try {
+      const message = JSON.parse(data.toString())
+
+      switch (message.type) {
+        case 'subscribe':
+          subscribe(ws, message.topics || [])
+          break
+        case 'unsubscribe':
+          unsubscribe(ws, message.topics || [])
+          break
+        case 'publish':
+          publish(ws, message.topic, message.data)
+          break
+        case 'ping':
+          send(ws, { type: 'pong' })
+          break
+      }
+    } catch (err) {
+      console.error('Failed to parse message:', err)
+    }
+  })
+
+  ws.on('close', () => {
+    cleanup(ws)
+  })
+
+  ws.on('error', (err) => {
+    console.error('WebSocket error:', err)
+    cleanup(ws)
+  })
+})
+
+// Heartbeat to detect dead connections
+const interval = setInterval(() => {
+  wss.clients.forEach((ws) => {
+    if (ws.isAlive === false) {
+      cleanup(ws)
+      return ws.terminate()
+    }
+    ws.isAlive = false
+    ws.ping()
+  })
+}, PING_INTERVAL)
+
+wss.on('close', () => {
+  clearInterval(interval)
+})
+
+console.log(`Signaling server running on port ${PORT}`)