Rebuilt how AI Studio knows what a model can do (#960)

app/Build/Tools/CommandRunner.cs

@@ -0,0 +1,62 @@
+using System.ComponentModel;
+using System.Diagnostics;
+
+namespace Build.Tools;
+
+/// <summary>
+/// Runs one external tool and lets it write straight to the terminal.
+/// </summary>
+/// <remarks>
+/// The output is deliberately not captured. A gate which swallows the output of a failing test run
+/// and then prints "failed" leaves the person who has to fix it with nothing to go on, while the
+/// tools it runs already say everything worth saying -- which test, which line, which lint.
+/// </remarks>
+public static class CommandRunner
+{
+    /// <summary>
+    /// What a tool which could not be started at all reports.
+    /// </summary>
+    /// <remarks>
+    /// Anything but zero counts as a failure, so the exact number matters only in that it is not
+    /// one a tool would plausibly return itself.
+    /// </remarks>
+    public const int COULD_NOT_START = 127;
+
+    /// <summary>
+    /// Runs a tool and waits for it.
+    /// </summary>
+    /// <param name="workingDirectory">Where the tool should run.</param>
+    /// <param name="fileName">The tool, as it is called on the PATH.</param>
+    /// <param name="arguments">What to pass it.</param>
+    /// <returns>The exit code of the tool, or COULD_NOT_START when it never ran.</returns>
+    public static async Task<int> RunAsync(string workingDirectory, string fileName, string arguments)
+    {
+        Console.WriteLine($"- Running '{fileName} {arguments}' in '{workingDirectory}' ...");
+        var startInfo = new ProcessStartInfo
+        {
+            FileName = fileName,
+            Arguments = arguments,
+            WorkingDirectory = workingDirectory,
+            UseShellExecute = false,
+        };
+
+        try
+        {
+            using var process = Process.Start(startInfo);
+            if (process is null)
+            {
+                Console.WriteLine($"- Error: '{fileName}' did not start, and the system did not say why.");
+                return COULD_NOT_START;
+            }
+
+            await process.WaitForExitAsync();
+            return process.ExitCode;
+        }
+        catch (Win32Exception exception)
+        {
+            Console.WriteLine($"- Error: '{fileName}' could not be started: {exception.Message}");
+            Console.WriteLine($"   Is '{fileName}' installed and on the PATH?");
+            return COULD_NOT_START;
+        }
+    }
+}

app/Build/Tools/Environment.cs

@@ -34,6 +34,28 @@ public static class Environment
         return Path.GetFullPath(directory);
     }
     
+    public static string GetTestsDirectory()
+    {
+        var currentDirectory = Directory.GetCurrentDirectory();
+        var directory = Path.Combine(currentDirectory, "..", "Tests");
+        return Path.GetFullPath(directory);
+    }
+
+    /// <summary>
+    /// The root of the git repository, which is what a path in a report is written relative to.
+    /// </summary>
+    /// <remarks>
+    /// GitHub resolves the file of an annotation against the checkout, not against wherever a tool
+    /// happened to run. An absolute path of somebody's machine would therefore land the annotation
+    /// nowhere, without saying so.
+    /// </remarks>
+    public static string GetRepositoryDirectory()
+    {
+        var currentDirectory = Directory.GetCurrentDirectory();
+        var directory = Path.Combine(currentDirectory, "..", "..");
+        return Path.GetFullPath(directory);
+    }
+
     public static string GetRustRuntimeDirectory()
     {
         var currentDirectory = Directory.GetCurrentDirectory();