From ebbe23c639eb939aa7b6e5fcb5fa9ff8972ca77a Mon Sep 17 00:00:00 2001
From: Assistant builder <meelstorm@gmail.com>
Date: Thu, 11 Jun 2026 21:21:13 +0000
Subject: [PATCH] Add EndSessionTool (no params, returns ok; relay closes on
 this tool name)

---
 backend.tests/EndSessionToolTests.cs | 35 ++++++++++++++++++++++++++++
 backend/Tools/EndSessionTool.cs      | 20 ++++++++++++++++
 2 files changed, 55 insertions(+)
 create mode 100644 backend.tests/EndSessionToolTests.cs
 create mode 100644 backend/Tools/EndSessionTool.cs

diff --git a/backend.tests/EndSessionToolTests.cs b/backend.tests/EndSessionToolTests.cs
new file mode 100644
index 0000000..531537e
--- /dev/null
+++ b/backend.tests/EndSessionToolTests.cs
@@ -0,0 +1,35 @@
+using System.Text.Json;
+using backend.Tools;
+using FluentAssertions;
+using Xunit;
+
+namespace backend.tests;
+
+public class EndSessionToolTests
+{
+    [Fact]
+    public async Task Returns_ok_true()
+    {
+        var tool = new EndSessionTool();
+        var ctx = new DeviceContext(Guid.NewGuid(), Guid.NewGuid(), new NoopChannel());
+
+        var res = await tool.ExecuteAsync(
+            new ToolInvocation("call_1", JsonDocument.Parse("{}").RootElement), ctx, default);
+
+        res.Output.GetProperty("ok").GetBoolean().Should().BeTrue();
+    }
+
+    [Fact]
+    public void Name_and_runs_during_response_match_spec()
+    {
+        var tool = new EndSessionTool();
+        tool.Name.Should().Be("end_session");
+        tool.RunsDuringResponse.Should().BeFalse();
+    }
+
+    private class NoopChannel : IDeviceChannel
+    {
+        public Task<JsonElement> CallPiToolAsync(string n, JsonElement a, CancellationToken ct)
+            => throw new NotSupportedException();
+    }
+}
diff --git a/backend/Tools/EndSessionTool.cs b/backend/Tools/EndSessionTool.cs
new file mode 100644
index 0000000..39d4f7f
--- /dev/null
+++ b/backend/Tools/EndSessionTool.cs
@@ -0,0 +1,20 @@
+using System.Text.Json;
+
+namespace backend.Tools;
+
+public class EndSessionTool : ITool
+{
+    public string Name => "end_session";
+    public string Description =>
+        "Call this when the user has said goodbye or otherwise indicates the conversation is over.";
+    public bool RunsDuringResponse => false;
+
+    public JsonElement ParameterSchema { get; } =
+        JsonDocument.Parse("""{"type":"object","properties":{},"required":[]}""").RootElement;
+
+    public Task<ToolResult> ExecuteAsync(ToolInvocation invocation, DeviceContext device, CancellationToken ct)
+    {
+        var output = JsonDocument.Parse("""{"ok":true}""").RootElement;
+        return Task.FromResult(new ToolResult(output));
+    }
+}