TASK 5 items 1-3: reusable stream, health banner, docs refresh

- Reusable stream: GetOrCreateReusableStreamAsync, cached via LayoutStore, bound at broadcast insert
- Health monitoring: GetStreamHealthAsync polls liveStreams.status, report-by-exception banner
- Go-live order: ensure stream → create broadcast → then start pump (URL must exist first)
- Full broadcast form scoped (TASK 5 items 6-7) in TASKS.md + ai.md
- TASK 23 trimmed to technical scope, TASK 26 added (marcom/launch kit)
- Confidential files: MONETIZATION.md + MARCOM.md (gitignored, not committed)
- .gitignore updated for confidential business files
- HANDOFF.md updated with session state and next steps

ytLive.Tests/FramePumpTests.cs

@@ -1,3 +1,5 @@
+using System.Net;
+using System.Text;
 using Xunit;
 using ytLive.Models;
 using ytLive.Services;
@@ -99,6 +101,65 @@ public class FramePumpTests
             $"pixel ({x},{y}): expected rgb({r},{g},{b}), got rgb({br},{bg},{bb})");
     }
 
+    private sealed class FakeHttpHandler : HttpMessageHandler
+    {
+        public FakeHttpHandler(string body) => Body = body;
+
+        public string Body;
+        public string? LastUri;
+        public int RequestCount;
+
+        protected override Task<HttpResponseMessage> SendAsync(
+            HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            RequestCount++;
+            LastUri = request.RequestUri?.ToString();
+            return Task.FromResult(new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent(Body, Encoding.UTF8, "application/json"),
+            });
+        }
+    }
+
+    /// <summary>The ONE integration test for TASK 5: the real service (hermetic
+    /// HTTP) returns the reusable stream's RTMP URL, the provider seam hands it
+    /// to the pump, and the pump starts the encoder with that exact URL — the
+    /// chain that makes go-live actually push. The stream is reused (listed),
+    /// never recreated (no POST).</summary>
+    [Fact]
+    public async Task ReusableStream_Url_From_Service_Feeds_Encoder_Startup()
+    {
+        var handler = new FakeHttpHandler(
+            """
+            {"items":[{"id":"S456","cdn":{"isReusable":true,"ingestionInfo":{"ingestionAddress":"rtmp://a.rtmp.youtube.com/live2","streamName":"KEY123"}}}]}
+            """);
+        var auth = new YouTubeAuthService("test-id", "test-secret");
+        auth.SetSession(new YouTubeChannel
+        {
+            AccessToken = "acc-123",
+            TokenExpiry = DateTime.UtcNow.AddHours(1),
+        });
+        var service = new YouTubeStreamService(auth, new HttpClient(handler));
+
+        var url = (await service.GetOrCreateReusableStreamAsync())?.RtmpUrl;
+        var encoder = new FakeEncoder();
+        using var pump = NewPump(encoder, options: () => url == null
+            ? null
+            : new EncoderOptions { RtmpUrl = url, Width = 64, Height = 48, Fps = 60 });
+
+        await pump.StartAsync();
+
+        Assert.Equal("rtmp://a.rtmp.youtube.com/live2/KEY123", url);
+        Assert.Equal(1, encoder.StartCount);
+        Assert.Equal("rtmp://a.rtmp.youtube.com/live2/KEY123", encoder.LastOptions?.RtmpUrl);
+        Assert.Equal(1, handler.RequestCount); // reuse path: list only, no insert
+        Assert.NotNull(handler.LastUri);
+        Assert.Contains("liveStreams", handler.LastUri);
+        Assert.Contains("mine=true", handler.LastUri);
+
+        await pump.StopAsync();
+    }
+
     [Fact]
     public async Task Start_CompositesScene_FeedsEncoder_StopsCleanly()
     {