Bound captured ServiceControl stderr

src/Particular.PlatformSample/AppLauncher.cs

@@ -17,7 +17,7 @@ sealed class AppLauncher(bool showPlatformToolConsoleOutput) : IAsyncDisposable
         readonly Stack<Func<ValueTask>> cleanupActions = new();
         readonly List<PlatformTool> platformTools = [];
 
-        public sealed record PlatformTool(string Name, Process Process, StringBuilder ErrorOutput);
+        public sealed record PlatformTool(string Name, Process Process, BoundedOutput ErrorOutput);
 
         public void StopProcesses()
         {
@@ -215,7 +215,7 @@ void StartProcess(string name, string assemblyPath, Dictionary<string, string> e
             }
 
             var process = Process.Start(startInfo);
-            var tool = new PlatformTool(name, process, new StringBuilder());
+            var tool = new PlatformTool(name, process, new BoundedOutput());
 
             // without this in certain occasions the start takes waaaaay longer!
             if (hideConsoleOutput)

src/Particular.PlatformSample/BoundedOutput.cs

@@ -0,0 +1,46 @@
+namespace Particular
+{
+    using System;
+    using System.Text;
+
+    sealed class BoundedOutput
+    {
+        const int MaximumLength = 8192;
+        readonly StringBuilder output = new(MaximumLength);
+
+        public void AppendLine(string line)
+        {
+            lock (output)
+            {
+                Append(line.AsSpan());
+                Append(Environment.NewLine.AsSpan());
+            }
+        }
+
+        void Append(ReadOnlySpan<char> text)
+        {
+            if (text.Length >= MaximumLength)
+            {
+                output.Clear();
+                output.Append(text[^MaximumLength..]);
+                return;
+            }
+
+            var excess = output.Length + text.Length - MaximumLength;
+            if (excess > 0)
+            {
+                output.Remove(0, excess);
+            }
+
+            output.Append(text);
+        }
+
+        public override string ToString()
+        {
+            lock (output)
+            {
+                return output.ToString();
+            }
+        }
+    }
+}