Add host connection status check endpoint and UI indicator

- Implement handle_connection_status API to test host port reachability
- Display Host:Up/Down status in the UI

src/static/webssh.css

@@ -134,6 +134,16 @@ body {
   color: #9ca3af;
 }
 
+.host-status {
+  margin-top: 4px;
+  font-size: 11px;
+  font-weight: 500;
+}
+
+.host-status.up { color: #34d399; }
+.host-status.down { color: #f87171; }
+.host-status.checking { color: #fbbf24; }
+
 .connection-status {
   display: inline-block;
   width: 8px;

src/static/webssh.js

@@ -10,6 +10,7 @@ let maxUploadSize = localStorage.getItem('maxUploadSize') ? parseInt(localStorag
 let apiBaseUrl = window.location.origin;
 let backendWsPort = null;
 let backendWsHost = null;
+let hostStatusTimer = null;
 
 // Use the frontend proxy so the browser does not need direct access to the backend port.
 function getWsUrl() {
@@ -41,6 +42,8 @@ async function loadSavedConnections() {
         if (!conn.terminalBuffer) conn.terminalBuffer = [];
       });
       renderConnectionList();
+      refreshHostStatuses();
+      startHostStatusPolling();
       if (connections.length > 0) {
         term.writeln(`[Loaded ${connections.length} connections from server]`);
       }
@@ -454,6 +457,9 @@ function renderConnectionList() {
         <span class="connection-status ${conn.connected ? 'connected' : 'disconnected'}"></span>
         ${conn.username}@${conn.host}:${conn.port}
       </div>
+      <div class="host-status ${conn.hostStatus === true ? 'up' : conn.hostStatus === false ? 'down' : 'checking'}">
+        Host: ${conn.hostStatus === true ? 'Up' : conn.hostStatus === false ? 'Down' : 'Checking...'}
+      </div>
       <div class="connection-actions" onclick="event.stopPropagation()">
         ${conn.connected 
           ? `<button class="btn-small btn-disconnect" onclick="disconnectConnection('${conn.id}')">Disconnect</button>`
@@ -467,6 +473,40 @@ function renderConnectionList() {
   });
 }
 
+async function refreshHostStatuses() {
+  if (!authToken || connections.length === 0) return;
+
+  connections.forEach(conn => { conn.hostStatus = null; });
+  renderConnectionList();
+
+  try {
+    const response = await fetch(`${apiBaseUrl}/api/connections/status`, {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        'Authorization': `Bearer ${authToken}`
+      },
+      body: JSON.stringify({ ids: connections.map(conn => conn.id) })
+    });
+    if (!response.ok) return;
+
+    const data = await response.json();
+    connections.forEach(conn => {
+      if (Object.prototype.hasOwnProperty.call(data.statuses || {}, conn.id)) {
+        conn.hostStatus = data.statuses[conn.id];
+      }
+    });
+    renderConnectionList();
+  } catch (e) {
+    console.warn('Failed to refresh host statuses:', e);
+  }
+}
+
+function startHostStatusPolling() {
+  if (hostStatusTimer) clearInterval(hostStatusTimer);
+  hostStatusTimer = setInterval(refreshHostStatuses, 30000);
+}
+
 function selectConnection(id) {
   currentConnectionId = id;
   const conn = getCurrentConnection();

src/webssh_backend/http_api.py

@@ -5,7 +5,9 @@ import hashlib
 import io
 import json
 import os
+import socket
 import stat
+from concurrent.futures import ThreadPoolExecutor
 from datetime import datetime, timedelta, timezone
 from http.server import BaseHTTPRequestHandler
 from typing import Optional
@@ -44,6 +46,8 @@ class LoginHandler(BaseHTTPRequestHandler):
             self.handle_verify()
         elif parsed.path == '/api/connections':
             self.handle_save_connection()
+        elif parsed.path == '/api/connections/status':
+            self.handle_connection_status()
         elif parsed.path == '/api/config':
             self.handle_config()
         elif parsed.path == '/api/sftp/list':
@@ -197,6 +201,44 @@ class LoginHandler(BaseHTTPRequestHandler):
             logger.error(f"Get connections error: {e}")
             self.send_json_response(500, {'error': 'Internal error'})
 
+    def handle_connection_status(self):
+        """Check whether the configured host ports are reachable."""
+        username = self._get_username_from_token()
+        if not username:
+            self.send_json_response(401, {'error': 'Authentication required'})
+            return
+
+        try:
+            content_length = int(self.headers.get('Content-Length', 0))
+            body = self.rfile.read(content_length).decode('utf-8')
+            requested_ids = json.loads(body).get('ids', [])
+            if not isinstance(requested_ids, list):
+                self.send_json_response(400, {'error': 'Connection IDs must be a list'})
+                return
+
+            connections = creds_manager.get_connections(username)
+            requested_ids = set(requested_ids)
+            targets = [conn for conn in connections if conn['id'] in requested_ids]
+
+            def check_host(conn):
+                try:
+                    with socket.create_connection(
+                        (conn['host'], int(conn.get('port', 22))), timeout=2
+                    ):
+                        return conn['id'], True
+                except (OSError, ValueError, TypeError):
+                    return conn['id'], False
+
+            with ThreadPoolExecutor(max_workers=10) as executor:
+                statuses = dict(executor.map(check_host, targets))
+
+            self.send_json_response(200, {'statuses': statuses})
+        except (json.JSONDecodeError, TypeError, ValueError):
+            self.send_json_response(400, {'error': 'Invalid request'})
+        except Exception as e:
+            logger.error(f"Connection status error: {e}")
+            self.send_json_response(500, {'error': 'Internal error'})
+
     def handle_config(self):
         """Get configuration including max upload size."""
         username = self._get_username_from_token()