Add a error/recap summary at the end of the build

src/MSBuild.UnitTests/Snapshots/TerminalLogger_Tests.PrintDetailedBuildSummary_FailedWithErrorAndWarning.Linux.verified.txt

@@ -0,0 +1,12 @@
+]9;4;3;\  project failed with 1 error(s) and 1 warning(s) (0.2s)
+    directory/file(1,2,3,4): warning AA0000: Warning!
+    directory/file(1,2,3,4): error AA0000: Error!
+[?25l
+[?25h
+Build summary:
+  project
+    directory/file(1,2,3,4): warning AA0000: Warning!
+    directory/file(1,2,3,4): error AA0000: Error!
+
+Build failed with 1 error(s) and 1 warning(s) in 5.0s
+]9;4;0;\

src/MSBuild.UnitTests/Snapshots/TerminalLogger_Tests.PrintDetailedBuildSummary_FailedWithErrorAndWarning.OSX.verified.txt

@@ -0,0 +1,12 @@
+  project failed with 1 error(s) and 1 warning(s) (0.2s)
+    directory/file(1,2,3,4): warning AA0000: Warning!
+    directory/file(1,2,3,4): error AA0000: Error!
+[?25l
+[?25h
+Build summary:
+  project
+    directory/file(1,2,3,4): warning AA0000: Warning!
+    directory/file(1,2,3,4): error AA0000: Error!
+
+Build failed with 1 error(s) and 1 warning(s) in 5.0s
+

src/MSBuild.UnitTests/Snapshots/TerminalLogger_Tests.PrintDetailedBuildSummary_FailedWithErrorAndWarning.Windows.verified.txt

@@ -0,0 +1,12 @@
+]9;4;3;\  project failed with 1 error(s) and 1 warning(s) (0.2s)
+    directory/file(1,2,3,4): warning AA0000: Warning!
+    directory/file(1,2,3,4): error AA0000: Error!
+[?25l
+[?25h
+Build summary:
+  project
+    directory/file(1,2,3,4): warning AA0000: Warning!
+    directory/file(1,2,3,4): error AA0000: Error!
+
+Build failed with 1 error(s) and 1 warning(s) in 5.0s
+]9;4;0;\

src/MSBuild.UnitTests/TerminalLogger_Tests.cs

@@ -414,6 +414,26 @@ public Task PrintBuildSummary_FailedWithErrors()
             return Verify(_outputWriter.ToString(), _settings).UniqueForOSPlatform();
         }
 
+        [Fact]
+        public Task PrintDetailedBuildSummary_FailedWithErrorAndWarning()
+        {
+            string? originalParameters = _terminallogger.Parameters;
+            _terminallogger.Parameters = "SUMMARY";
+            _terminallogger.ParseParameters();
+
+            InvokeLoggerCallbacksForSimpleProject(succeeded: false, () =>
+            {
+                WarningRaised?.Invoke(_eventSender, MakeWarningEventArgs("Warning!"));
+                ErrorRaised?.Invoke(_eventSender, MakeErrorEventArgs("Error!"));
+            });
+
+            // Restore original parameters
+            _terminallogger.Parameters = originalParameters;
+            _terminallogger.ParseParameters();
+
+            return Verify(_outputWriter.ToString(), _settings).UniqueForOSPlatform();
+        }
+
         [Fact]
         public Task PrintBuildSummary_FailedWithErrorsAndWarnings()
         {

src/MSBuild/Resources/Strings.resx

@@ -1661,6 +1661,12 @@
       's' should reflect the localized abbreviation for seconds
     </comment>
   </data>
+  <data name="BuildSummary" xml:space="preserve">
+    <value>Build summary:</value>
+    <comment>
+      A header used by Terminal Logger to introduce the build summary.
+    </comment>
+  </data>
   <data name="BuildResult_FailedWithErrors" xml:space="preserve">
     <value>failed with {0} error(s)</value>
     <comment>

src/MSBuild/TerminalLogger/Project.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 
 namespace Microsoft.Build.Logging.TerminalLogger;
 
@@ -16,8 +17,9 @@ internal sealed class Project
     /// Initialized a new <see cref="Project"/> with the given <paramref name="targetFramework"/>.
     /// </summary>
     /// <param name="targetFramework">The target framework of the project or null if not multi-targeting.</param>
-    public Project(string? targetFramework, StopwatchAbstraction? stopwatch)
+    public Project(string projectFile, string? targetFramework, StopwatchAbstraction? stopwatch)
     {
+        File = projectFile;
         TargetFramework = targetFramework;
 
         if (stopwatch is not null)
@@ -31,6 +33,8 @@ public Project(string? targetFramework, StopwatchAbstraction? stopwatch)
         }
     }
 
+    public string File { get; }
+
     /// <summary>
     /// A stopwatch to time the build of the project.
     /// </summary>
@@ -69,4 +73,17 @@ public void AddBuildMessage(MessageSeverity severity, string message)
         BuildMessages ??= new List<BuildMessage>();
         BuildMessages.Add(new BuildMessage(severity, message));
     }
+
+    /// <summary>
+    /// Filters the build messages to only include errors and warnings.
+    /// </summary>
+    /// <returns>A sequence of error and warning build messages.</returns>
+    public IEnumerable<BuildMessage> GetBuildErrorAndWarningMessages()
+    {
+        return BuildMessages is null ?
+            Enumerable.Empty<BuildMessage>() :
+            BuildMessages.Where(message =>
+                message.Severity == MessageSeverity.Error ||
+                message.Severity == MessageSeverity.Warning);
+    }
 }