ISOs armed with Zoom capture off are loud now (T3.7 / #470)

native-shell/CoreVideoPro.MediaCore.Tests/IsoCapturePreflightTests.cs

@@ -0,0 +1,45 @@
+using CoreVideoPro.MediaCore.Services;
+using Xunit;
+
+namespace CoreVideoPro.MediaCore.Tests;
+
+// #470 / T3.7. Live 2026-09-10: 7 Zoom ISOs armed with Engine off recorded
+// nothing, reported nothing, and the operator lost the head of every stream.
+public class IsoCapturePreflightTests
+{
+    [Fact]
+    public void ArmedZoomIsosWithCaptureOffAreLoud()
+    {
+        var warning = IsoCapturePreflight.Describe(isoEnabled: true, zoomIsoSourceCount: 7, rawMediaActive: false);
+        Assert.NotNull(warning);
+        Assert.Contains("7 Zoom ISO sources", warning);
+        // It must say what to do, not just that something is wrong.
+        Assert.Contains("Turn Engine on", warning);
+    }
+
+    [Fact]
+    public void OneSourceReadsAsOneSource()
+    {
+        var warning = IsoCapturePreflight.Describe(true, 1, false);
+        Assert.NotNull(warning);
+        Assert.Contains("1 Zoom ISO source ", warning);
+    }
+
+    [Theory]
+    [InlineData(true, 3, true)]    // capture on: nothing to say
+    [InlineData(false, 3, false)]  // ISOs off: the switch is off, not a fault
+    [InlineData(true, 0, false)]   // no Zoom ISO sources selected
+    public void NothingToSayStaysSilent(bool isoEnabled, int count, bool rawMediaActive)
+    {
+        Assert.Null(IsoCapturePreflight.Describe(isoEnabled, count, rawMediaActive));
+    }
+
+    // UNKNOWN is not a problem. Before the first snapshot we cannot tell
+    // capture-off from not-yet-reported, and warning on an unobserved state is
+    // how an indicator gets trained into background noise.
+    [Fact]
+    public void AnUnobservedCaptureStateIsNotAWarning()
+    {
+        Assert.Null(IsoCapturePreflight.Describe(isoEnabled: true, zoomIsoSourceCount: 7, rawMediaActive: null));
+    }
+}

native-shell/CoreVideoPro.MediaCore/Services/IsoCapturePreflight.cs

@@ -0,0 +1,47 @@
+namespace CoreVideoPro.MediaCore.Services;
+
+/// <summary>
+/// #470 / T3.7. ISO streams armed while Zoom capture is OFF write nothing, and
+/// said nothing.
+///
+/// Seen live 2026-09-10: recording started with ISOs enabled and 7 Zoom guests
+/// selected while Engine was off. Program recorded normally; all 7 ISO streams
+/// sat at framesWritten 0 with no file, recording.warning null and no per-stream
+/// warning. Turning Engine on mid-recording opened the writers lazily at the
+/// first frame, so the operator silently lost the head of every ISO.
+///
+/// It cannot be caught downstream: an ISO writer opens lazily at its first
+/// frame, so a source that never produces one has no stream to carry a warning.
+/// The only place that knows is the arming decision itself.
+///
+/// Breaks ISO-1's "Loud, never silent" (a video-only-broken ISO must be as loud
+/// as #286 made a video-only program).
+/// </summary>
+public static class IsoCapturePreflight
+{
+    /// <param name="isoEnabled">The "Program + ISOs" switch.</param>
+    /// <param name="zoomIsoSourceCount">Selected ISO sources that come from Zoom.</param>
+    /// <param name="rawMediaActive">The ENGINE-reported capture state (null when
+    /// no snapshot has arrived yet), not the button we last pressed.</param>
+    /// <returns>An operator-facing warning, or null when there is nothing to say.</returns>
+    public static string? Describe(bool isoEnabled, int zoomIsoSourceCount, bool? rawMediaActive)
+    {
+        if (!isoEnabled || zoomIsoSourceCount <= 0)
+        {
+            return null;
+        }
+
+        // UNKNOWN is not a problem. Before the first snapshot arrives we cannot
+        // tell capture-off from not-yet-reported, and warning on a state we have
+        // not observed is how an indicator gets ignored.
+        if (rawMediaActive is not false)
+        {
+            return null;
+        }
+
+        var sources = zoomIsoSourceCount == 1 ? "1 Zoom ISO source" : $"{zoomIsoSourceCount} Zoom ISO sources";
+        return $"{sources} will record NOTHING while Zoom capture is off. " +
+               "Turn Engine on before recording — an ISO writer opens at its first frame, " +
+               "so turning it on later loses everything before that point.";
+    }
+}

native-shell/CoreVideoPro.WinUI/ViewModels/StudioViewModel.cs

@@ -233,6 +233,19 @@
     {
         get
         {
+            // #470 / T3.7 FIRST, because it is the case with no stream to warn
+            // on: an ISO writer opens lazily at its first frame, so sources that
+            // never produce one leave nothing behind to carry a warning. Armed
+            // with capture off, all 7 ISOs recorded nothing and said nothing.
+            var capture = IsoCapturePreflight.Describe(
+                IsoRecordingEnabled,
+                BuildIsoSourceTargets().SourceIds.Count(id => id.StartsWith("zoom:", StringComparison.Ordinal)),
+                Settings.RawMediaActive);
+            if (capture is not null)
+            {
+                return capture;
+            }
+
             var streams = _bridge.LastSnapshot?.Recording?.Streams;
             if (streams is null)
             {
@@ -3592,7 +3605,7 @@
         }
     }
 
     partial void OnActiveSceneIdChanged(string oldValue, string value)
     {
         if (!_scenes.Any(scene => string.Equals(scene.Id, value, StringComparison.Ordinal)))
         {