feat(a2a-client): read remote agents from agents.json on every call

tests/Volcanic.AgenticCore.Extensions.Tests/A2A/AgentsFileTests.cs

@@ -0,0 +1,59 @@
+using Volcanic.AgenticCore.Extensions.A2A;
+
+namespace Volcanic.AgenticCore.Extensions.Tests.A2A;
+
+public sealed class AgentsFileTests : IDisposable
+{
+    private readonly string _ws = Path.Combine(Path.GetTempPath(), "a2a-agents", Guid.NewGuid().ToString("N"));
+
+    private void Write(string json)
+    {
+        Directory.CreateDirectory(Path.GetDirectoryName(AgentsFile.PathFor(_ws))!);
+        File.WriteAllText(AgentsFile.PathFor(_ws), json);
+    }
+
+    [Fact]
+    public void Missing_NoAgentsNoError()
+    {
+        var r = AgentsFile.Read(_ws);
+        Assert.Empty(r.Agents);
+        Assert.Null(r.Error);
+    }
+
+    [Fact]
+    public void Agents_MalformedFile_ReportsFile()
+    {
+        Write("{ nope");
+        var r = AgentsFile.Read(_ws);
+        Assert.Empty(r.Agents);
+        Assert.Contains("agents.json", r.Error);
+    }
+
+    [Fact]
+    public void Read_ValidatesEntries_AndNeverEchoesKeys()
+    {
+        Write("""
+            [ { "name": "travel-bot", "url": "https://travel.example/", "key": "secret-1", "description": "Trips" },
+              { "name": "Bad Name", "url": "https://x.example/", "key": "secret-2" },
+              { "name": "no-url" },
+              { "name": "ftp", "url": "ftp://x.example/" },
+              { "name": "travel-bot", "url": "https://dup.example/" } ]
+            """);
+        var r = AgentsFile.Read(_ws);
+        var agent = Assert.Single(r.Agents);
+        Assert.Equal(new RemoteAgentEntry("travel-bot", "https://travel.example/", "secret-1", "Trips"), agent);
+        Assert.Equal(4, r.Problems.Count);
+        Assert.DoesNotContain(r.Problems, p => p.Contains("secret"));
+    }
+
+    [Fact]
+    public void Agents_FileEdited_AppliesToNextCall()
+    {
+        Write("""[ { "name": "a", "url": "https://a.example/" } ]""");
+        Assert.NotNull(AgentsFile.Find(_ws, "a"));
+        Write("[]");
+        Assert.Null(AgentsFile.Find(_ws, "a"));
+    }
+
+    public void Dispose() { try { Directory.Delete(_ws, true); } catch (IOException) { } }
+}