fix(panel): Galahad II LCD brightness fix

src/Panel/Streams/IStreamedPanelTransport.cs

@@ -32,17 +32,21 @@ public interface IStreamedPanelDiscovery
 /// <summary>
 /// Transport that may be able to dim its panel. Implementing it is not the capability test -
 /// whether the attached model has a backlight command is, and an implementation that finds
-/// it does not ignores the binding.
+/// it does not ignore the binding.
 /// </summary>
 public interface IBrightnessPanelTransport
 {
     /// <summary>
     /// Supplies the panel record's backlight percent, or null when the record has none and
     /// the panel keeps whatever it powered up with. Polled while frames flow: unlike
     /// orientation this is a device command rather than a frame filter, so the transport
-    /// writes only when the polled value changes.
+    /// writes only when the polled value changes. A caller may also force an immediate apply
+    /// after a settings edit, even when no frames are currently flowing.
     /// </summary>
     void BindBrightness(Func<int?> source);
+
+    /// <summary>Applies the currently bound backlight value immediately.</summary>
+    void ApplyBrightness();
 }
 
 /// <summary>

src/Panel/Streams/JpegPanelStreamTransport.cs

@@ -34,6 +34,7 @@ public sealed class JpegPanelStreamTransport : IStreamedPanelTransport, IOrienta
     private int _brightnessApplied = -1;
     private long _brightnessNextReadMs;
     private bool _brightnessFaultLogged;
+    private readonly object _brightnessLock = new();
 
     private readonly byte[] _turned;
 
@@ -63,17 +64,26 @@ public void BindBrightness(Func<int?> source)
         _brightnessNextReadMs = 0;
     }
 
-    /// <summary>Runs on the frame path, the only thread that owns this transport.</summary>
-    private void ApplyBrightness()
+    /// <summary>Applies a changed backlight from either the frame or settings path.</summary>
+    public void ApplyBrightness()
+    {
+        lock (_brightnessLock)
+        {
+            _brightnessNextReadMs = 0;
+            TryApplyBrightnessLocked();
+        }
+    }
+
+    private bool TryApplyBrightnessLocked()
     {
         if (_brightness is null)
         {
-            return;
+            return false;
         }
         long nowMs = Environment.TickCount64;
         if (nowMs < _brightnessNextReadMs)
         {
-            return;
+            return false;
         }
         _brightnessNextReadMs = nowMs + BrightnessTtlMs;
         int? wanted;
@@ -85,18 +95,20 @@ private void ApplyBrightness()
                 _brightnessFaultLogged = true;
                 ServiceLog.Warn($"[{_hub.Model.HandlerId}] backlight source threw: {ex.GetType().Name}: {ex.Message}");
             }
-            return;
+            return false;
         }
         // No record value means the panel keeps what it powered up with.
         if (wanted is not int percent || percent == _brightnessApplied)
         {
-            return;
+            return true;
         }
         if (_hub.SetBrightness(percent))
         {
             _brightnessApplied = percent;
             ServiceLog.Info($"[{_hub.Model.HandlerId}] backlight {percent}%");
+            return true;
         }
+        return false;
     }
 
     public string Serial { get; }
@@ -136,7 +148,7 @@ public void Write(ReadOnlySpan<byte> payload)
 
     private void PushFrame()
     {
-        ApplyBrightness();
+        lock (_brightnessLock) { TryApplyBrightnessLocked(); }
         ReadOnlySpan<byte> jpeg;
         try
         {

src/Panel/Streams/StreamedPanelCoordinator.cs

@@ -194,6 +194,21 @@ public HashSet<string> LivePanelDeviceIds()
         return ids;
     }
 
+    /// <summary>Applies a persisted panel backlight change without waiting for a frame.</summary>
+    public void ApplyBrightness(string panelDeviceId)
+    {
+        lock (_lock)
+        {
+            foreach (var ds in _bySerial.Values)
+            {
+                if (ds.Session.Closed || !string.Equals(ds.Session.PanelDeviceId, panelDeviceId, StringComparison.Ordinal))
+                    continue;
+                (ds.Transport as IBrightnessPanelTransport)?.ApplyBrightness();
+                return;
+            }
+        }
+    }
+
     /// <summary>Suppresses assignments while a focus mode asks for rendering to stop; the overlay closes its render hosts on the empty list and rebuilds them when it returns.</summary>
     public void SetRenderingPaused(bool paused)
     {

src/Peripherals/JpegPanels/LianLiAioHandshake.cs

@@ -37,6 +37,12 @@ public sealed class LianLiAioHandshake : IJpegPanelHandshake, IJpegPanelBrightne
     private const byte ModeLocalUi = 0x00;
     private const byte ModeApplication = 0x01;
 
+    /// <summary>
+    /// Family-wide LcdSetting mode used for brightness-only control packets (reference
+    /// driver: not Galahad-specific, HydroShift takes it too).
+    /// </summary>
+    internal const byte LcdSettingMode = 0x04;
+
     /// <summary>Backlight a panel runs at until the user sets one.</summary>
     public const byte DefaultBrightness = 100;
 
@@ -116,7 +122,7 @@ public bool BeforeFrame(IHidDevice device, int reportLength, long nowMs)
     public bool ApplyBrightness(IHidDevice device, int reportLength)
     {
         var report = Buffer(reportLength);
-        if (!SendLcdControl(device, report, ModeApplication, _brightness))
+        if (!SendLcdControl(device, report, LcdSettingMode, _brightness))
         {
             return false;
         }

src/Routes/PanelRoutes.cs

@@ -321,7 +321,7 @@ public static void MapPanelEndpoints(this WebApplication app)
             return Results.Json(record, AppJsonContext.Default.PanelDeviceRecord);
         }).AllowPanel();
 
-        app.MapPost("/panel/devices/{id}", (string id, PanelDevicePatch body, HttpContext ctx, PanelDeviceRegistry registry, MultiplexHub hub, TokenService tokens) =>
+        app.MapPost("/panel/devices/{id}", (string id, PanelDevicePatch body, HttpContext ctx, PanelDeviceRegistry registry, MultiplexHub hub, TokenService tokens, Nexus.Service.Panel.Streams.StreamedPanelCoordinator streams) =>
         {
             // A panel session may rearrange or remove the deck keys it has, but
             // authoring a key that opens a file, sends a key chord, types text or
@@ -341,6 +341,8 @@ public static void MapPanelEndpoints(this WebApplication app)
             // for the active-profile flush of OTHER fields; we don't need the
             // explicit dirty pulse here, and keeping it implied PanelDevices
             // was profile-scoped, which is the bug this change fixes.
+            if (body.LcdBrightness.HasValue)
+                streams.ApplyBrightness(updated.Id);
             BroadcastDeviceChanged(hub, id);
             return Results.Json(updated, AppJsonContext.Default.PanelDeviceRecord);
         }).AllowPanel();

tests/Nexus.Service.Tests/JpegPanels/JpegPanelHubTests.cs

@@ -140,7 +140,7 @@ private static JpegPanelModel Dimmable() =>
         JpegPanelModel.GalahadIiLcd with { Handshake = new LianLiAioHandshake("test-lcd", 24) };
 
     [Fact]
-    public void SetBrightness_reaches_an_attached_panel_in_application_mode()
+    public void SetBrightness_reaches_an_attached_panel_in_lcd_setting_mode()
     {
         using var hub = new JpegPanelHub(Dimmable());
         var device = new RecordingHidDevice();
@@ -151,7 +151,7 @@ public void SetBrightness_reaches_an_attached_panel_in_application_mode()
 
         var control = Assert.Single(device.Writes);
         Assert.Equal(0x0C, control[1]);
-        Assert.Equal(0x01, control[11]);
+        Assert.Equal(LianLiAioHandshake.LcdSettingMode, control[11]);
         Assert.Equal(35, control[12]);
     }
 

tests/Nexus.Service.Tests/JpegPanels/LianLiAioHandshakeTests.cs

@@ -54,7 +54,29 @@ public void The_control_packet_matches_the_reference_driver_byte_for_byte()
     }
 
     [Fact]
-    public void A_brightness_change_rides_application_mode_so_the_glass_stays_claimed()
+    public void Galahad_brightness_packet_uses_the_hardware_verified_settings_mode()
+    {
+        var handshake = new LianLiAioHandshake("lianli-galahad2-lcd", 24);
+        var device = new ScriptedHidDevice();
+
+        Assert.True(handshake.OnAttach(device, ReportLength));
+        device.Writes.Clear();
+        handshake.SetBrightness(35);
+        Assert.True(handshake.ApplyBrightness(device, ReportLength));
+
+        var control = Assert.Single(device.Writes);
+        Assert.Equal(
+            new byte[]
+            {
+                0x02, 0x0C, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x08,
+                0x04, 35, 0x00, 0x00, 0x00, 0x00, 0x00, 24,
+            },
+            control[..19]);
+        Assert.All(control[19..], b => Assert.Equal(0, b));
+    }
+
+    [Fact]
+    public void A_brightness_change_uses_the_family_wide_settings_mode()
     {
         var handshake = new LianLiAioHandshake("lianli-hydroshift-lcd", 24);
         var device = new ScriptedHidDevice();
@@ -66,8 +88,10 @@ public void A_brightness_change_rides_application_mode_so_the_glass_stays_claime
 
         var control = Assert.Single(device.Writes);
         Assert.Equal(0x0C, control[1]);
-        // Application, not the settings mode: the other documented mode hands the glass back.
-        Assert.Equal(new byte[] { 0x01, 35, 0x00, 0x00, 0x00, 0x00, 0x00, 24 }, control[11..19]);
+        // LcdSetting (0x04), the reference driver's brightness-only mode for the whole
+        // family - not application mode, which OnAttach uses to take the glass in the
+        // first place.
+        Assert.Equal(new byte[] { 0x04, 35, 0x00, 0x00, 0x00, 0x00, 0x00, 24 }, control[11..19]);
     }
 
     [Fact]

tests/Nexus.Service.Tests/Panel/Streams/StreamedPanelCoordinatorTests.cs

@@ -4,6 +4,7 @@
 using System.Linq;
 using Microsoft.AspNetCore.Http;
 using Nexus.Service.Devices;
+using Nexus.Service.Models.Panel;
 using Nexus.Service.Panel;
 using Nexus.Service.Panel.Streams;
 using Nexus.Service.Persistence;
@@ -88,17 +89,46 @@ public void Write(ReadOnlySpan<byte> annexBAccessUnit) { }
         public void Dispose() { IsOpen = false; }
     }
 
+    private sealed class FakeBrightnessTransport : IStreamedPanelTransport, IBrightnessPanelTransport
+    {
+        public bool IsOpen { get; private set; }
+        public string Serial { get; }
+        public int ApplyCalls { get; private set; }
+        public int? LastApplied { get; private set; }
+        private Func<int?>? _source;
+
+        public FakeBrightnessTransport(string serial) { Serial = serial; }
+        public void Open() => IsOpen = true;
+        public void StartPlayer() { }
+        public void Write(ReadOnlySpan<byte> annexBAccessUnit) { }
+        public void Dispose() => IsOpen = false;
+        public void BindBrightness(Func<int?> source) => _source = source;
+        public void ApplyBrightness()
+        {
+            ApplyCalls++;
+            LastApplied = _source?.Invoke();
+        }
+    }
+
     private sealed class FakeDiscovery : IStreamedPanelDiscovery
     {
         public string HandlerId => "fake-panel";
         public List<StreamedPanelDeviceInfo> Devices { get; } = new();
         public List<FakeTransport> Transports { get; } = new();
+        public List<FakeBrightnessTransport> BrightnessTransports { get; } = new();
+        public bool UseBrightnessTransport { get; set; }
         public bool FailOpen { get; set; }
 
         public IReadOnlyList<StreamedPanelDeviceInfo> Discover() => Devices.ToList();
 
         public IStreamedPanelTransport CreateTransport(StreamedPanelDeviceInfo info)
         {
+            if (UseBrightnessTransport)
+            {
+                var brightness = new FakeBrightnessTransport(info.Serial);
+                BrightnessTransports.Add(brightness);
+                return brightness;
+            }
             var t = new FakeTransport(info.Serial) { FailOpen = FailOpen };
             Transports.Add(t);
             return t;
@@ -238,4 +268,21 @@ public void Unknown_session_id_does_not_bind()
         var coordinator = Coordinator();
         Assert.Null(coordinator.TryBindIngest("nope", new DefaultHttpContext()));
     }
+
+    [Fact]
+    public void Brightness_change_can_apply_without_an_incoming_frame()
+    {
+        _discovery.UseBrightnessTransport = true;
+        _discovery.Devices.Add(Device());
+        var coordinator = Coordinator();
+        coordinator.TickOnce();
+        var assignment = Assert.Single(coordinator.GetAssignments().Assignments);
+
+        _registry.Patch(assignment.PanelDeviceId, new PanelDevicePatch { LcdBrightness = 35 });
+
+        coordinator.ApplyBrightness(assignment.PanelDeviceId);
+        var transport = Assert.Single(_discovery.BrightnessTransports);
+        Assert.Equal(1, transport.ApplyCalls);
+        Assert.Equal(35, transport.LastApplied);
+    }
 }