feat(console): add Core.Headless flag and guard the exit-pause prompt

Projects/Server/Console/HeadlessConsoleInputException.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace Server;
+
+/// <summary>
+/// Thrown when interactive console input is required but the server is running
+/// headless (stdin is not a TTY). Rides the fatal-shutdown path.
+/// </summary>
+public sealed class HeadlessConsoleInputException : Exception
+{
+    public HeadlessConsoleInputException(string context)
+        : base(
+            $"Interactive console input required but the server is headless (stdin is not a TTY). " +
+            $"Pre-supply the required configuration/save data. Prompt: {context}."
+        )
+    {
+    }
+}

Projects/Server/Main.cs

@@ -147,6 +147,8 @@ public static class Core
 
     public static bool Closing => ClosingTokenSource.IsCancellationRequested;
 
+    public static bool Headless { get; private set; }
+
     public static int GlobalUpdateRange { get; set; } = 18;
 
     public static int GlobalMaxUpdateRange { get; set; } = 24;
@@ -258,7 +260,7 @@ public static class Core
                 // ignored
             }
 
-            if (!close)
+            if (!close && !Core.Headless)
             {
                 Console.WriteLine("This exception is fatal, press return to exit");
                 ConsoleInputHandler.ReadLine();
@@ -407,6 +409,12 @@ public static class Core
 
         Console.CancelKeyPress += Console_CancelKeyPressed;
 
+        Headless = Console.IsInputRedirected;
+        if (Headless)
+        {
+            logger.Information("Headless mode detected (stdin is not a TTY); interactive console input is disabled.");
+        }
+
         // LibDeflate is not thread safe, so we need to create a new instance for each thread
         var standard = Deflate.Standard;
         AppDomain.CurrentDomain.ProcessExit += (_, _) => standard.Dispose();