Merge branch 'worktree-agent-aae48b78656e5a4e0' into arch-review-remediation

# Conflicts:
#	src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Repositories/SiteExternalSystemRepository.cs

src/ZB.MOM.WW.ScadaBridge.CLI/ManagementHttpClient.cs

@@ -9,13 +9,53 @@ public class ManagementHttpClient : IDisposable
     private readonly HttpClient _httpClient;
 
     /// <summary>
-    /// Initializes a new instance of the <see cref="ManagementHttpClient"/> class.
+    /// WP2.6e (arch-review misc — CLI HttpClient timeout): default overall
+    /// <see cref="HttpClient.Timeout"/> for the shared client construction (30 s). This
+    /// bounds a hung/black-holed connection — before this, the public constructor left
+    /// <see cref="HttpClient.Timeout"/> at its framework default (100 s), silently longer
+    /// than most CLI callers' own per-request <c>TimeSpan timeout</c> argument
+    /// (<see cref="SendCommandAsync"/>/<see cref="SendGetAsync"/>/<see cref="SendPostAsync"/>
+    /// already bound each call via their own <see cref="CancellationTokenSource"/>, but a
+    /// connection attempt that never completes at all — no response headers, ever — is
+    /// bounded by <see cref="HttpClient.Timeout"/> instead, since that governs the whole
+    /// request/response including connect). Config-overridable via the
+    /// <c>SCADABRIDGE_HTTP_TIMEOUT_SECONDS</c> environment variable, consistent with how
+    /// every other CLI setting is overridden (see <see cref="CliConfig"/>) — kept
+    /// self-contained here (no <see cref="CliConfig"/>/command-file plumbing) since CLI
+    /// commands are owned by a separate work package this phase.
+    /// </summary>
+    public static readonly TimeSpan DefaultTimeout = TimeSpan.FromSeconds(30);
+
+    /// <summary>Test seam (WP2.6e) — the effective <see cref="HttpClient.Timeout"/> this instance was constructed with.</summary>
+    internal TimeSpan EffectiveTimeout { get; }
+
+    /// <summary>
+    /// Resolves the effective default timeout: the <c>SCADABRIDGE_HTTP_TIMEOUT_SECONDS</c>
+    /// environment variable when set to a positive integer, otherwise <see cref="DefaultTimeout"/>.
+    /// </summary>
+    private static TimeSpan ResolveDefaultTimeout()
+    {
+        var env = Environment.GetEnvironmentVariable("SCADABRIDGE_HTTP_TIMEOUT_SECONDS");
+        if (!string.IsNullOrWhiteSpace(env)
+            && int.TryParse(env, out var seconds)
+            && seconds > 0)
+        {
+            return TimeSpan.FromSeconds(seconds);
+        }
+
+        return DefaultTimeout;
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ManagementHttpClient"/> class, with
+    /// <see cref="HttpClient.Timeout"/> set to <see cref="ResolveDefaultTimeout"/>
+    /// (30 s, or the <c>SCADABRIDGE_HTTP_TIMEOUT_SECONDS</c> override).
     /// </summary>
     /// <param name="baseUrl">The base URL for the management API.</param>
     /// <param name="username">The username for HTTP Basic authentication.</param>
     /// <param name="password">The password for HTTP Basic authentication.</param>
     public ManagementHttpClient(string baseUrl, string username, string password)
-        : this(new HttpClient(), baseUrl, username, password)
+        : this(new HttpClient { Timeout = ResolveDefaultTimeout() }, baseUrl, username, password)
     {
     }
 
@@ -31,6 +71,9 @@ public class ManagementHttpClient : IDisposable
     internal ManagementHttpClient(HttpClient httpClient, string baseUrl, string username, string password)
     {
         _httpClient = httpClient;
+        // Test seam (WP2.6e): exposes the constructed HttpClient's effective Timeout
+        // without requiring reflection.
+        EffectiveTimeout = httpClient.Timeout;
         _httpClient.BaseAddress = new Uri(baseUrl.TrimEnd('/') + "/");
         var credentials = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{username}:{password}"));
         _httpClient.DefaultRequestHeaders.Authorization =