Added support for organization-approved assistant plugins (#821)

app/SharedTools/AssistantPluginHash.cs

@@ -0,0 +1,40 @@
+using System.Security.Cryptography;
+using System.Text;
+
+namespace SharedTools;
+
+/// <summary>
+/// Computes the canonical assistant-plugin hash across all Lua files in a plugin directory.
+/// </summary>
+public static class AssistantPluginHash
+{
+    public static string Compute(string pluginDirectory)
+    {
+        if (string.IsNullOrWhiteSpace(pluginDirectory) || !Directory.Exists(pluginDirectory))
+            return string.Empty;
+
+        var luaFiles = Directory.EnumerateFiles(pluginDirectory, "*.lua", SearchOption.AllDirectories)
+            .OrderBy(path => path, StringComparer.Ordinal)
+            .ToList();
+        if (luaFiles.Count == 0)
+            return string.Empty;
+
+        using var stream = new MemoryStream();
+        using var writer = new BinaryWriter(stream, Encoding.UTF8, leaveOpen: true);
+
+        foreach (var filePath in luaFiles)
+        {
+            var relativePath = Path.GetRelativePath(pluginDirectory, filePath).Replace('\\', '/');
+            var pathBytes = Encoding.UTF8.GetBytes(relativePath);
+            var contentBytes = File.ReadAllBytes(filePath);
+
+            writer.Write(pathBytes.Length);
+            writer.Write(pathBytes);
+            writer.Write(contentBytes.Length);
+            writer.Write(contentBytes);
+        }
+
+        writer.Flush();
+        return Convert.ToHexString(SHA256.HashData(stream.ToArray()));
+    }
+}