Stufe 2 (#764): Huelle ClawdDotNet.Shell mit eingebettetem Chromium

Avalonia 11.3.17 + CefGlue.Next 152 in eigenem Ordner shell/. Startet den
Manager (ManagerStarter, nach Core gezogen), holt ueber den lokalen Socket
einen Einmal-Link und zeigt die WebUI angemeldet; Taskleistensymbol mit
Zustand. ClawdDotNet ohne Schalter startet die Huelle, sonst den Browser.
publish.py baut sie mit (--no-shell zum Weglassen), unter Linux mit den
Chromium-Ressourcen neben libcef.so. --selftest fuer die Pruefung ohne Blick.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ClawdDotNet.Core/Instances/ManagerStarter.cs

@@ -0,0 +1,165 @@
+using System.Diagnostics;
+using System.Net.Sockets;
+using System.Text.Json;
+using ClawdDotNet.Core.Storage;
+
+namespace ClawdDotNet.Core.Instances;
+
+/// <summary>
+/// #764: Finds the running instance manager, or starts it — for the two programs a person starts
+/// by hand: <c>ClawdDotNet</c> without a switch and the shell (<c>ClawdDotNet.Shell</c>).
+///
+/// <para><b>Never a second manager.</b> If the manager answers, it is left alone. If it runs as a
+/// systemd service on this machine, the service is started — starting the program next to it
+/// would put two managers on the same instances. Only otherwise is the manager program started
+/// directly.</para>
+/// </summary>
+public static class ManagerStarter
+{
+    public const int DefaultPort = 7000;
+    public const string ServiceUnit = "clawddotnet-manager.service";
+    private static readonly TimeSpan StartWait = TimeSpan.FromSeconds(30);
+
+    /// <summary>Where <c>manager.json</c> lives — and next to it the manager's local socket.</summary>
+    public static string ConfigDirectory => AppPaths.ConfigDirectory;
+
+    /// <summary>
+    /// Makes sure the manager answers. Returns the port, or the reason it does not answer.
+    /// </summary>
+    /// <param name="searchFrom">Folder of the calling program; the manager is looked for there and one level up.</param>
+    public static async Task<(int Port, string? Problem)> EnsureRunningAsync(string searchFrom)
+    {
+        var port = Port(ConfigDirectory);
+        if (Answers(port))
+            return (port, null);
+
+        if (Start(searchFrom) is { } problem)
+            return (port, problem);
+
+        var until = DateTime.UtcNow + StartWait;
+        while (!Answers(port) && DateTime.UtcNow < until)
+            await Task.Delay(500).ConfigureAwait(false);
+
+        return Answers(port)
+            ? (port, null)
+            : (port, $"The instance manager did not answer on port {port} within {StartWait.TotalSeconds:0} s. "
+                     + "Its log is under Logs/Manager in the data directory.");
+    }
+
+    public static bool Answers(int port)
+    {
+        try
+        {
+            using var client = new TcpClient();
+            return client.ConnectAsync("127.0.0.1", port).Wait(TimeSpan.FromSeconds(1)) && client.Connected;
+        }
+        catch (Exception)
+        {
+            return false;
+        }
+    }
+
+    /// <summary>
+    /// The port from <c>manager.json</c>; the default on any doubt. Read as one field, not as the
+    /// manager's settings type, which the callers do not know.
+    /// </summary>
+    public static int Port(string configDirectory)
+    {
+        try
+        {
+            var file = Path.Combine(configDirectory, "manager.json");
+            if (!File.Exists(file)) return DefaultPort;
+
+            using var doc = JsonDocument.Parse(File.ReadAllText(file));
+            return doc.RootElement.TryGetProperty("webUiPort", out var port)
+                   && port.ValueKind == JsonValueKind.Number
+                   && port.TryGetInt32(out var value)
+                   && value is > 0 and < 65536
+                ? value
+                : DefaultPort;
+        }
+        catch (Exception)
+        {
+            return DefaultPort;
+        }
+    }
+
+    /// <returns>Why the manager could not be started, or <c>null</c>.</returns>
+    private static string? Start(string searchFrom)
+    {
+        if (OperatingSystem.IsLinux() && Systemctl("cat", ServiceUnit) == 0)
+        {
+            return Systemctl("start", ServiceUnit) == 0
+                ? null
+                : $"systemctl --user start {ServiceUnit} failed; see journalctl --user -u {ServiceUnit}.";
+        }
+
+        if (FindExecutable(searchFrom) is not { } manager)
+            return "The instance manager (ClawdDotNet.Instanzmanager) was not found next to this program.";
+
+        try
+        {
+            // On Windows with its own console window: that is where the manager shows the access
+            // token on first start. Elsewhere a plain child that outlives the caller.
+            Process.Start(new ProcessStartInfo(manager)
+            {
+                UseShellExecute = OperatingSystem.IsWindows(),
+                WorkingDirectory = Path.GetDirectoryName(manager)!
+            });
+            return null;
+        }
+        catch (Exception ex)
+        {
+            return $"The instance manager could not be started: {ex.Message}";
+        }
+    }
+
+    private static int Systemctl(string verb, string unit)
+    {
+        try
+        {
+            var start = new ProcessStartInfo("systemctl") { RedirectStandardOutput = true, RedirectStandardError = true };
+            start.ArgumentList.Add("--user");
+            start.ArgumentList.Add(verb);
+            start.ArgumentList.Add(unit);
+            using var p = Process.Start(start)!;
+            p.StandardOutput.ReadToEnd();
+            p.StandardError.ReadToEnd();
+            p.WaitForExit(30_000);
+            return p.HasExited ? p.ExitCode : -1;
+        }
+        catch (Exception)
+        {
+            return -1; // no systemd here
+        }
+    }
+
+    /// <summary>
+    /// Next to the caller, one level up (the shell lives in <c>shell/</c>), or in the build folders
+    /// of a development checkout.
+    ///
+    /// <para>Built from segments, not as a string: a path with backslashes is one file name on
+    /// Linux, and the search never found anything there (moved here from the old
+    /// <c>App.axaml.cs</c>).</para>
+    /// </summary>
+    public static string? FindExecutable(string searchFrom)
+    {
+        var name = OperatingSystem.IsWindows() ? "ClawdDotNet.Instanzmanager.exe" : "ClawdDotNet.Instanzmanager";
+
+        string[][] candidates =
+        [
+            [],
+            [".."],
+            ["..", "..", "..", "..", "ClawdDotNet.ManagerApp", "bin", "Debug", "net10.0"],
+            ["..", "..", "..", "..", "..", "src", "ClawdDotNet.ManagerApp", "bin", "Debug", "net10.0"]
+        ];
+
+        foreach (var segments in candidates)
+        {
+            var path = Path.GetFullPath(Path.Combine([searchFrom, .. segments, name]));
+            if (File.Exists(path)) return path;
+        }
+
+        return null;
+    }
+}