Add ITool + ToolRegistry + GetCurrentTimeTool

backend.tests/ToolRegistryTests.cs

@@ -0,0 +1,29 @@
+using backend.Tools;
+using FluentAssertions;
+using Xunit;
+
+namespace backend.tests;
+
+public class ToolRegistryTests
+{
+    private readonly ITool[] _all = new ITool[]
+    {
+        new GetCurrentTimeTool(),
+    };
+
+    [Fact]
+    public void Get_returns_tool_by_exact_name()
+    {
+        var reg = new ToolRegistry(_all);
+        reg.Get("get_current_time").Should().NotBeNull();
+        reg.Get("does_not_exist").Should().BeNull();
+    }
+
+    [Fact]
+    public void Filter_returns_only_enabled_tools_preserving_order()
+    {
+        var reg = new ToolRegistry(_all);
+        var enabled = new HashSet<string> { "get_current_time", "ghost" };
+        reg.EnabledFor(enabled).Select(t => t.Name).Should().Equal("get_current_time");
+    }
+}