refactor: simplify HQ architecture with active health checking

- Remove heartbeat mechanism from HQClient - now just registers and forgets
- Update RemoteRegistry to actively check remote health via GET /api/sessions
- Remove /api/remotes/:remoteId/heartbeat endpoint as it's no longer needed
- Pass password to RemoteRegistry for authenticated health checks
- Remote servers no longer need to maintain connection to HQ after registration
- HQ checks remote health every 15 seconds with 5 second timeout

This simplifies the architecture - remotes just tell HQ they exist, and HQ
is responsible for monitoring their health status.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

web/src/hq-client.ts

@@ -5,26 +5,18 @@ export class HQClient {
   private readonly hqUrl: string;
   private readonly remoteId: string;
   private readonly remoteName: string;
-  private token: string;
-  private heartbeatInterval: NodeJS.Timeout | null = null;
+  private readonly token: string;
+  private readonly password: string;
   private registrationRetryTimeout: NodeJS.Timeout | null = null;
 
   constructor(hqUrl: string, password: string) {
     this.hqUrl = hqUrl;
     this.remoteId = uuidv4();
     this.remoteName = `${os.hostname()}-${process.pid}`;
-    this.token = this.generateToken();
-
-    // Store password for future use
+    this.token = uuidv4();
     this.password = password;
   }
 
-  private password: string;
-
-  private generateToken(): string {
-    return uuidv4();
-  }
-
   async register(): Promise<void> {
     try {
       const response = await fetch(`${this.hqUrl}/api/remotes/register`, {
@@ -46,7 +38,8 @@ export class HQClient {
       }
 
       console.log(`Successfully registered with HQ at ${this.hqUrl}`);
-      this.startHeartbeat();
+      console.log(`Remote ID: ${this.remoteId}`);
+      console.log(`Token: ${this.token}`);
     } catch (error) {
       console.error('Failed to register with HQ:', error);
       // Retry registration after 5 seconds
@@ -54,70 +47,7 @@ export class HQClient {
     }
   }
 
-  private async sendHeartbeat(): Promise<void> {
-    try {
-      // Get session count from the session manager
-      const sessionCount = await this.getSessionCount();
-
-      const response = await fetch(`${this.hqUrl}/api/remotes/${this.remoteId}/heartbeat`, {
-        method: 'POST',
-        headers: {
-          'Content-Type': 'application/json',
-          Authorization: `Bearer ${this.token}`,
-        },
-        body: JSON.stringify({
-          sessionCount,
-        }),
-      });
-
-      if (!response.ok) {
-        console.error('Heartbeat failed:', response.statusText);
-        // Re-register if heartbeat fails
-        this.stopHeartbeat();
-        await this.register();
-      }
-    } catch (error) {
-      console.error('Failed to send heartbeat:', error);
-    }
-  }
-
-  private startHeartbeat(): void {
-    // Send heartbeat every 15 seconds
-    this.heartbeatInterval = setInterval(() => {
-      this.sendHeartbeat();
-    }, 15000);
-
-    // Send first heartbeat immediately
-    this.sendHeartbeat();
-  }
-
-  private stopHeartbeat(): void {
-    if (this.heartbeatInterval) {
-      clearInterval(this.heartbeatInterval);
-      this.heartbeatInterval = null;
-    }
-  }
-
-  private async getSessionCount(): Promise<number> {
-    try {
-      const response = await fetch(`http://localhost:${process.env.PORT || 4020}/api/sessions`, {
-        headers: {
-          Authorization: `Basic ${Buffer.from(`user:${this.password}`).toString('base64')}`,
-        },
-      });
-
-      if (response.ok) {
-        const sessions = await response.json();
-        return Array.isArray(sessions) ? sessions.length : 0;
-      }
-    } catch {
-      // Ignore errors
-    }
-    return 0;
-  }
-
   destroy(): void {
-    this.stopHeartbeat();
     if (this.registrationRetryTimeout) {
       clearTimeout(this.registrationRetryTimeout);
     }

web/src/remote-registry.ts

@@ -11,11 +11,14 @@ export interface RemoteServer {
 
 export class RemoteRegistry {
   private remotes: Map<string, RemoteServer> = new Map();
-  private heartbeatInterval: NodeJS.Timeout | null = null;
-  private readonly HEARTBEAT_TIMEOUT = 30000; // 30 seconds
+  private healthCheckInterval: NodeJS.Timeout | null = null;
+  private readonly HEALTH_CHECK_INTERVAL = 15000; // Check every 15 seconds
+  private readonly HEALTH_CHECK_TIMEOUT = 5000; // 5 second timeout per check
+  private password: string | null;
 
-  constructor() {
-    this.startHeartbeatChecker();
+  constructor(password: string | null = null) {
+    this.password = password;
+    this.startHealthChecker();
   }
 
   register(remote: Omit<RemoteServer, 'registeredAt' | 'lastHeartbeat' | 'status'>): RemoteServer {
@@ -30,6 +33,9 @@ export class RemoteRegistry {
     this.remotes.set(remote.id, registeredRemote);
     console.log(`Remote registered: ${remote.name} (${remote.id}) from ${remote.url}`);
 
+    // Immediately check health of new remote
+    this.checkRemoteHealth(registeredRemote);
+
     return registeredRemote;
   }
 
@@ -42,17 +48,6 @@ export class RemoteRegistry {
     return false;
   }
 
-  updateHeartbeat(remoteId: string, sessionCount: number): boolean {
-    const remote = this.remotes.get(remoteId);
-    if (remote) {
-      remote.lastHeartbeat = new Date();
-      remote.sessionCount = sessionCount;
-      remote.status = 'online';
-      return true;
-    }
-    return false;
-  }
-
   getRemote(remoteId: string): RemoteServer | undefined {
     return this.remotes.get(remoteId);
   }
@@ -69,24 +64,60 @@ export class RemoteRegistry {
     return this.getAllRemotes().filter((r) => r.status === 'online');
   }
 
-  private startHeartbeatChecker() {
-    this.heartbeatInterval = setInterval(() => {
-      const now = Date.now();
+  private async checkRemoteHealth(remote: RemoteServer): Promise<void> {
+    try {
+      const controller = new AbortController();
+      const timeoutId = setTimeout(() => controller.abort(), this.HEALTH_CHECK_TIMEOUT);
 
-      for (const remote of this.remotes.values()) {
-        const timeSinceLastHeartbeat = now - remote.lastHeartbeat.getTime();
-
-        if (timeSinceLastHeartbeat > this.HEARTBEAT_TIMEOUT && remote.status === 'online') {
-          remote.status = 'offline';
-          console.log(`Remote went offline: ${remote.name} (${remote.id})`);
-        }
+      const headers: Record<string, string> = {};
+      if (this.password) {
+        headers['Authorization'] =
+          `Basic ${Buffer.from(`user:${this.password}`).toString('base64')}`;
       }
-    }, 10000); // Check every 10 seconds
+
+      const response = await fetch(`${remote.url}/api/sessions`, {
+        headers,
+        signal: controller.signal,
+      });
+
+      clearTimeout(timeoutId);
+
+      if (response.ok) {
+        const sessions = await response.json();
+        remote.lastHeartbeat = new Date();
+        remote.sessionCount = Array.isArray(sessions) ? sessions.length : 0;
+
+        if (remote.status !== 'online') {
+          remote.status = 'online';
+          console.log(`Remote came online: ${remote.name} (${remote.id})`);
+        }
+      } else {
+        throw new Error(`HTTP ${response.status}`);
+      }
+    } catch (error) {
+      if (remote.status !== 'offline') {
+        remote.status = 'offline';
+        console.log(`Remote went offline: ${remote.name} (${remote.id}) - ${error}`);
+      }
+    }
+  }
+
+  private startHealthChecker() {
+    this.healthCheckInterval = setInterval(() => {
+      // Check all remotes in parallel
+      const healthChecks = Array.from(this.remotes.values()).map((remote) =>
+        this.checkRemoteHealth(remote)
+      );
+
+      Promise.all(healthChecks).catch((err) => {
+        console.error('Error in health checks:', err);
+      });
+    }, this.HEALTH_CHECK_INTERVAL);
   }
 
   destroy() {
-    if (this.heartbeatInterval) {
-      clearInterval(this.heartbeatInterval);
+    if (this.healthCheckInterval) {
+      clearInterval(this.healthCheckInterval);
     }
   }
 }

web/src/server.ts

@@ -114,7 +114,7 @@ let remoteRegistry: RemoteRegistry | null = null;
 let hqClient: HQClient | null = null;
 
 if (isHQMode) {
-  remoteRegistry = new RemoteRegistry();
+  remoteRegistry = new RemoteRegistry(basicAuthPassword);
   console.log(`${GREEN}Running in HQ mode${RESET}`);
 }
 
@@ -448,40 +448,6 @@ app.post('/api/remotes/register', (req, res) => {
   res.json({ success: true, remote: { id: remote.id, name: remote.name } });
 });
 
-// Heartbeat from remote server
-app.post('/api/remotes/:remoteId/heartbeat', (req, res) => {
-  if (!isHQMode || !remoteRegistry) {
-    return res.status(404).json({ error: 'HQ mode not enabled' });
-  }
-
-  const { remoteId } = req.params;
-  const { sessionCount } = req.body;
-  const authHeader = req.headers.authorization;
-
-  // Verify token
-  const remote = remoteRegistry.getRemote(remoteId);
-  if (!remote) {
-    return res.status(404).json({ error: 'Remote not found' });
-  }
-
-  if (!authHeader || !authHeader.startsWith('Bearer ')) {
-    return res.status(401).json({ error: 'Missing authorization' });
-  }
-
-  const token = authHeader.slice(7);
-  if (token !== remote.token) {
-    return res.status(401).json({ error: 'Invalid token' });
-  }
-
-  const success = remoteRegistry.updateHeartbeat(remoteId, sessionCount || 0);
-
-  if (success) {
-    res.json({ success: true });
-  } else {
-    res.status(404).json({ error: 'Remote not found' });
-  }
-});
-
 // Unregister remote
 app.delete('/api/remotes/:remoteId', (req, res) => {
   if (!isHQMode || !remoteRegistry) {