acdream/tests/AcDream.App.Tests/UI/Layout/ChatLayoutConformanceTests.cs

using System.Numerics;
using AcDream.App.Rendering;
using AcDream.App.Rendering.Gpu;
using AcDream.App.Tests.Rendering.Gpu;
using AcDream.App.UI;
using AcDream.App.UI.Layout;
using AcDream.Core.Chat;
using AcDream.UI.Abstractions;
using AcDream.UI.Abstractions.Panels.Chat;

namespace AcDream.App.Tests.UI.Layout;

/// <summary>
/// Dat-free conformance tests for the committed chat_2100006f.json golden fixture —
/// retail's ACTUAL main chat window (LayoutDesc <c>0x2100006F</c>, window root
/// <c>0x10000600</c>, authored 410x100; Campaign CH slice CH6a). Verifies that
/// LayoutImporter.ImportInfos correctly resolves the BaseElement / BaseLayoutId
/// inheritance chain.
/// </summary>
public class ChatLayoutConformanceTests
{
    private static (uint, int, int) NoTex(uint _) => (0, 0, 0);

    private static ElementInfo? Find(ElementInfo n, uint id)
    {
        if (n.Id == id) return n;
        foreach (var c in n.Children)
        {
            var f = Find(c, id);
            if (f is not null) return f;
        }
        return null;
    }

    [Fact]
    public void ChatFixture_ResolvesKnownElements()
    {
        var root = FixtureLoader.LoadChatInfos();
        Assert.NotNull(Find(root, 0x10000011u)); // transcript
        Assert.NotNull(Find(root, 0x10000016u)); // input
        Assert.NotNull(Find(root, 0x10000012u)); // scrollbar track
        Assert.NotNull(Find(root, 0x10000014u)); // channel menu
        Assert.NotNull(Find(root, 0x10000019u)); // send button
        Assert.NotNull(Find(root, 0x1000046Fu)); // max/min button
    }

    [Fact]
    public void ChatFixture_ResolvedTypes_MatchRetailRegistry()
    {
        var root = FixtureLoader.LoadChatInfos();
        Assert.Equal(6u,  Find(root, 0x10000014u)!.Type);  // Menu
        Assert.Equal(11u, Find(root, 0x10000012u)!.Type);  // Scrollbar
        Assert.Equal(1u,  Find(root, 0x10000019u)!.Type);  // Button (Send)
        Assert.Equal(1u,  Find(root, 0x1000046Fu)!.Type);  // Button (Max/Min)
        Assert.Equal(12u, Find(root, 0x10000011u)!.Type);  // Text/style-prototype (transcript)
        Assert.Equal(12u, Find(root, 0x10000016u)!.Type);  // Text/style-prototype (input)
    }

    [Theory]
    [InlineData(0x10000522u)]
    [InlineData(0x10000523u)]
    [InlineData(0x10000524u)]
    [InlineData(0x10000525u)]
    public void ChatFixture_ChatWindowIndicatorButtons_ImportFromTheAuthoredTree(uint indicatorId)
    {
        // gmMainChatUI::RecvNotice_SetPanelVisibility @0x004CCD80 writes these
        // four state-mirror buttons for floating chat windows 1-4. CH6a imports
        // them generically (visible, inert) and leaves wiring their live/pressed
        // state to CH6b's floating-window slice.
        var root = FixtureLoader.LoadChatInfos();
        Assert.NotNull(Find(root, indicatorId));
    }

    [Theory]
    [InlineData(0x10000522u)]
    [InlineData(0x10000523u)]
    [InlineData(0x10000524u)]
    [InlineData(0x10000525u)]
    public void MountedChatWindow_IndicatorButtons_BindAloneLeavesClickUnwiredButSelfFlipSuppressed(
        uint indicatorId)
    {
        // Bind() alone (no BindIndicatorClicks call) leaves OnClick unwired —
        // the click half is a separate opt-in step RetailUiRuntime performs
        // once its own ToggleFloatingChatWindow method is available (round 4,
        // 2026-08-10 — see ChatWindowController.SetIndicatorOpen's doc for the
        // full retail mechanism reconciliation). This test only proves the
        // Bind-alone state; MountedChatWindow_IndicatorButtons_ClickTogglesWindow
        // below exercises the full click round trip through BindIndicatorClicks.
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos, layout, new ChatVM(new ChatLog()), () => NullCommandBus.Instance, new ChatWindowState(), null, null, NoTex);
        Assert.NotNull(controller);

        UiElement? indicator = layout.FindElement(indicatorId);
        Assert.NotNull(indicator);
        Assert.True(indicator!.Visible);
        var button = Assert.IsType<UiButton>(indicator);
        Assert.Null(button.OnClick);
        Assert.Null(button.OnClickAt);

        // CH6a/b REJECT-review SHOULD-FIX 3: OnClick==null is the wrong level
        // to prove "self-flip suppressed" — the fixture's own 0x0B
        // (ToggleBehavior) = true means a plain press/release would still
        // flip UiButton's internal Selected mirror even with no OnClick
        // bound. SuppressSelfToggle (set by ChatWindowController.Bind) is
        // the actual guard, and it stays true even after round 4 wires a
        // real click handler — see SetIndicatorOpen's doc for why the blind
        // self-flip must stay suppressed regardless.
        Assert.True(button.SuppressSelfToggle);
        bool before = button.Selected;
        button.OnEvent(new UiEvent(0, button, UiEventType.MouseDown, Data1: 2, Data2: 2));
        button.OnEvent(new UiEvent(0, button, UiEventType.MouseUp, Data1: 2, Data2: 2));
        Assert.Equal(before, button.Selected);
    }

    [Theory]
    [InlineData(0x10000522u, 1)]
    [InlineData(0x10000523u, 2)]
    [InlineData(0x10000524u, 3)]
    [InlineData(0x10000525u, 4)]
    public void MountedChatWindow_IndicatorButtons_ClickTogglesWindow_ThroughBindIndicatorClicks(
        uint indicatorId, int expectedWindowId)
    {
        // Round 4 (2026-08-10): clicking an indicator now toggles its floating
        // chat window through the SAME chokepoint the Alt+1..4 keybinds use
        // (user-directed retail behavior — see SetIndicatorOpen's doc for the
        // full mechanism reconciliation: the generic UIElement_Button
        // action-dispatch system is real and armed on the button side, but
        // the shipped floating-window fixture authors no matching listener
        // registration, so this wiring cannot be proven purely from the DAT).
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos, layout, new ChatVM(new ChatLog()), () => NullCommandBus.Instance, new ChatWindowState(), null, null, NoTex);
        Assert.NotNull(controller);

        var toggled = new List<int>();
        controller!.BindIndicatorClicks(windowId =>
        {
            toggled.Add(windowId);
            return true;
        });

        UiElement? indicator = layout.FindElement(indicatorId);
        var button = Assert.IsType<UiButton>(indicator);
        Assert.NotNull(button.OnClick);

        button.OnEvent(new UiEvent(0, button, UiEventType.MouseDown, Data1: 2, Data2: 2));
        button.OnEvent(new UiEvent(0, button, UiEventType.MouseUp, Data1: 2, Data2: 2));
        button.OnEvent(new UiEvent(0, button, UiEventType.Click, Data1: 2, Data2: 2));

        Assert.Equal(new[] { expectedWindowId }, toggled);
    }

    [Fact]
    public void MountedChatWindow_IndicatorButtons_ClickRoundTrip_KeepsMirrorConsistent()
    {
        // The full round trip: click -> BindIndicatorClicks' delegate calls the
        // real toggle -> the caller (standing in for RetailUiRuntime's
        // WindowVisibilityChanged plumbing) calls SetIndicatorOpen with the
        // window's NEW state -> Selected matches that new state, not a blind
        // self-flip. SuppressSelfToggle staying true is what makes this
        // authoritative-writer invariant hold even though the button now has
        // a real OnClick.
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos, layout, new ChatVM(new ChatLog()), () => NullCommandBus.Instance, new ChatWindowState(), null, null, NoTex);
        Assert.NotNull(controller);

        bool windowOpen = false;
        controller!.BindIndicatorClicks(windowId =>
        {
            windowOpen = !windowOpen;
            controller.SetIndicatorOpen(windowId, windowOpen);
            return true;
        });

        var button = Assert.IsType<UiButton>(layout.FindElement(0x10000522u));
        Assert.False(button.Selected);

        button.OnEvent(new UiEvent(0, button, UiEventType.MouseDown, Data1: 2, Data2: 2));
        button.OnEvent(new UiEvent(0, button, UiEventType.MouseUp, Data1: 2, Data2: 2));
        button.OnEvent(new UiEvent(0, button, UiEventType.Click, Data1: 2, Data2: 2));
        Assert.True(button.Selected);

        button.OnEvent(new UiEvent(0, button, UiEventType.MouseDown, Data1: 2, Data2: 2));
        button.OnEvent(new UiEvent(0, button, UiEventType.MouseUp, Data1: 2, Data2: 2));
        button.OnEvent(new UiEvent(0, button, UiEventType.Click, Data1: 2, Data2: 2));
        Assert.False(button.Selected);
    }

    [Theory]
    [InlineData(0x10000693u)]
    [InlineData(0x10000694u)]
    [InlineData(0x10000695u)]
    [InlineData(0x10000696u)]
    [InlineData(0x10000697u)]
    [InlineData(0x10000698u)]
    [InlineData(0x10000699u)]
    [InlineData(0x1000069Au)]
    public void MountedChatWindow_LockedTwinBorderArt_DefaultsHidden(uint lockedTwinId)
    {
        // Register row AP-185: CH6a shows only the live (unlocked) grip/dragbar
        // border-art set by default, matching UiRoot.UiLocked's own false
        // default and avoiding a double-rendered border.
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos, layout, new ChatVM(new ChatLog()), () => NullCommandBus.Instance, new ChatWindowState(), null, null, NoTex);
        Assert.NotNull(controller);

        UiElement? twin = layout.FindElement(lockedTwinId);
        Assert.NotNull(twin);
        Assert.False(twin!.Visible);
    }

    [Fact]
    public void ChatFixture_BuildsSelectableTranscriptAndEditableInputInPlace()
    {
        var layout = FixtureLoader.LoadChat();

        var transcript = Assert.IsType<UiText>(layout.FindElement(0x10000011u));
        var input = Assert.IsType<UiField>(layout.FindElement(0x10000016u));

        Assert.True(transcript.Selectable);
        Assert.True(input.Selectable);
        Assert.True(input.OneLine);
        Assert.Equal(0x10000016u, input.DatElementId);
    }

    /// <summary>
    /// Campaign CH round 4 (<c>docs/research/2026-08-10-retail-ui-text-style.md</c>
    /// §2.5/§2.6): the chat transcript's base style (<c>0x10000372</c> in layout
    /// <c>0x2100003F</c>) authors NO property 0x21 (Outline) anywhere in its
    /// inheritance chain — regenerated straight from the real installed DAT
    /// (<c>ChatLayoutFixtureGenerator</c>), proving the property-0x21/0x22
    /// importer (<see cref="ElementReader.ApplyCanonicalLegacyProjection"/>)
    /// resolves this correctly end to end, not merely by a missing-field JSON
    /// default.
    /// </summary>
    [Fact]
    public void ChatFixture_TranscriptElementInfo_CarriesNoOutline()
    {
        var root = FixtureLoader.LoadChatInfos();
        var transcript = Find(root, 0x10000011u)!;

        Assert.False(transcript.Outline);
        Assert.Null(transcript.OutlineColor);
    }

    /// <summary>Same fact at the built-widget level — <c>DatWidgetFactory.BuildText</c>
    /// must not turn a false <c>ElementInfo.Outline</c> into a true <c>UiText.Outline</c>.</summary>
    [Fact]
    public void ChatFixture_TranscriptWidget_OutlineIsOff()
    {
        var layout = FixtureLoader.LoadChat();
        var transcript = Assert.IsType<UiText>(layout.FindElement(0x10000011u));

        Assert.False(transcript.Outline);
    }

    /// <summary>
    /// The transcript's default fill resolves to the authored
    /// <c>ARGB(255,204,204,204)</c> (style <c>0x10000372</c> property 0x1B) —
    /// Fix 5's target. Pins the value at the built-widget level, on the SAME
    /// regenerated fixture the outline test above uses.
    /// </summary>
    [Fact]
    public void ChatFixture_TranscriptWidget_DefaultColorIsAuthoredOffWhite()
    {
        var layout = FixtureLoader.LoadChat();
        var transcript = Assert.IsType<UiText>(layout.FindElement(0x10000011u));

        var expected = new System.Numerics.Vector4(204f / 255f, 204f / 255f, 204f / 255f, 1f);
        Assert.Equal(expected, transcript.DefaultColor);
    }

    [Fact]
    public void ChatFixture_ScrollbarImportsInheritedMediaRoles()
    {
        var layout = FixtureLoader.LoadChat();
        var scrollbar = Assert.IsType<UiScrollbar>(layout.FindElement(0x10000012u));

        Assert.Equal(0x06004C5Fu, scrollbar.TrackSprite);
        Assert.Equal(0x06004C60u, scrollbar.ThumbTopSprite);
        Assert.Equal(0x06004C63u, scrollbar.ThumbSprite);
        Assert.Equal(0x06004C66u, scrollbar.ThumbBotSprite);
        Assert.Equal(0x06004C69u, scrollbar.UpSprite);
        Assert.Equal(0x06004C6Cu, scrollbar.DownSprite);
    }

    [Fact]
    public void ChatFixture_WindowRootCarriesRetailHeightConstraints()
    {
        var root = FixtureLoader.LoadChatInfos();
        var window = Find(root, 0x10000600u)!;

        Assert.True(window.TryGetEffectiveInteger(0x3Eu, out int minHeight));
        Assert.True(window.TryGetEffectiveInteger(0x3Cu, out int maxHeight));
        Assert.Equal(100, minHeight);
        Assert.Equal(2000, maxHeight);
    }

    [Fact]
    public void ChatFixture_WindowRootCarriesRetailWidthConstraints()
    {
        var root = FixtureLoader.LoadChatInfos();
        var window = Find(root, 0x10000600u)!;

        Assert.True(window.TryGetEffectiveInteger(0x3Fu, out int minWidth));
        Assert.True(window.TryGetEffectiveInteger(0x3Du, out int maxWidth));
        Assert.Equal(300, minWidth);
        Assert.Equal(2000, maxWidth);
    }

    [Fact]
    public void ChatFixture_RootIsAuthored410x100_NoCropNeeded()
    {
        // Campaign CH slice CH6a: 0x2100006F's window root is already the exact
        // mounted extent — the 490px content-width crop that the wrong
        // 0x21000006 import needed no longer applies to anything.
        var root = FixtureLoader.LoadChatInfos();
        Assert.Equal(410f, root.Width);
        Assert.Equal(100f, root.Height);
    }

    [Fact]
    public void ChatFixture_DockedRoot_ReflowsContentAcrossMountedWidth()
    {
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos,
            layout,
            new ChatVM(new ChatLog()),
            () => NullCommandBus.Instance,
            new ChatWindowState(),
            null,
            null,
            NoTex);
        Assert.NotNull(controller);

        // No crop-then-rebase dance needed: the root's OWN authored extent
        // (410x100) already matches the design width children's imported
        // LayoutPolicy captured, so growing it directly exercises the same
        // raw-edge reflow the crop workaround needed a rebase step for.
        var root = controller!.Root;
        Assert.Equal(410f, root.Width);
        root.Width = 615;

        // Both panels are authored with a 5px margin to BOTH the left and right
        // window edges (X=5, right-edge width = 410-(5+400) = 5) — a stretch
        // grows the panel by the delta MINUS both margins: 615 - 5 - 5 = 605.
        var transcriptPanel = layout.FindElement(0x10000010u)!;
        var inputBar = layout.FindElement(0x10000013u)!;
        transcriptPanel.ApplyAnchor(root.Width, root.Height);
        inputBar.ApplyAnchor(root.Width, root.Height);

        Assert.Equal(605f, transcriptPanel.Width);
        Assert.Equal(605f, inputBar.Width);
    }

    [Fact]
    public void ChatFixture_ChannelCaptionWidth_SurvivesImportedLayoutPass()
    {
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos,
            layout,
            new ChatVM(new ChatLog()),
            () => NullCommandBus.Instance,
            new ChatWindowState(),
            null,
            null,
            NoTex);
        Assert.NotNull(controller);

        controller!.Menu.OnSelect!.Invoke(ChatChannelKind.General);
        float fittedWidth = controller.Menu.Width;
        controller.Menu.ApplyAnchor(controller.Menu.Parent!.Width, controller.Menu.Parent.Height);

        Assert.True(fittedWidth > 46f);
        Assert.Equal(fittedWidth, controller.Menu.Width);
        Assert.Equal(controller.Menu.Left + fittedWidth, controller.Input.Left);
    }

    [Fact]
    public void ChatMaximize_ResizesOuterFrameByHalfParent_AndRestores()
    {
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos,
            layout,
            new ChatVM(new ChatLog()),
            () => NullCommandBus.Instance,
            new ChatWindowState(),
            null,
            null,
            NoTex)!;
        var root = new UiRoot { Width = 800, Height = 600 };
        // Campaign CH slice CH6a: 0x2100006F's own border art IS the window
        // chrome — Chrome=Imported, no content-width crop, no MinWidth override
        // (the DAT's own 0x3D/0x3F=2000/300 govern). Frame == content, so the
        // maximize math below operates directly on the authored 410x100 extent
        // with the DAT's real minH=100/maxH=2000 (not the wrong layout's 360).
        RetailWindowHandle handle = RetailWindowFrame.Mount(
            root,
            controller.Root,
            NoTex,
            new RetailWindowFrame.Options
            {
                WindowName = WindowNames.Chat,
                Chrome = RetailWindowChrome.Imported,
                Left = 12f,
                Top = 390f,
                DatConstraintSource = controller.DatWindowInfo,
            });
        controller.AttachWindow(handle);
        var maxMin = Assert.IsType<UiButton>(layout.FindElement(0x1000046Fu));

        // frame.Height=100, parentHeight=600, expansion=300 → targetHeight =
        // clamp(min(400,600),100,2000) = 400. growUp because Top(390)+400>600.
        // targetTop = max(0, 390-(400-100)) = 90. Lower edge fixed at 490.
        maxMin.OnClick!();

        Assert.True(controller.IsMaximized);
        Assert.Equal(90f, handle.Top);
        Assert.Equal(400f, handle.Height);
        Assert.Equal(490f, handle.Top + handle.Height); // lower edge stays fixed while growing upward
        Assert.Equal(RetailUiStateIds.Maximized, maxMin.ActiveRetailStateId);

        maxMin.OnClick!();

        Assert.False(controller.IsMaximized);
        Assert.Equal(390f, handle.Top);
        Assert.Equal(100f, handle.Height);
        Assert.Equal(RetailUiStateIds.Minimized, maxMin.ActiveRetailStateId);
    }

    [Theory]
    [InlineData(0x1000069Bu, UiResizeGrip.Border.UpperLeft)]
    [InlineData(0x1000069Du, UiResizeGrip.Border.UpperRight)]
    [InlineData(0x1000069Fu, UiResizeGrip.Border.LowerLeft)]
    [InlineData(0x100006A1u, UiResizeGrip.Border.LowerRight)]
    public void MountedChatWindow_CornerGrip_ImportsWithCorrectBorderLocation(
        uint elementId, UiResizeGrip.Border expected)
    {
        // Campaign CH slice CH6a, user-gate round 2 item 6: pins that the 4
        // corner grips from 0x2100006F import with the RIGHT BorderLocation —
        // the prerequisite for the reported "no diagonal cursor" / "can't grow
        // in Y from the bottom-right corner" symptoms to be fixed at all.
        var layout = FixtureLoader.LoadChat();
        var grip = Assert.IsType<UiResizeGrip>(layout.FindElement(elementId));
        Assert.Equal(expected, grip.BorderLocation);
    }

    [Fact]
    public void MountedChatWindow_TopStrip_IsAMoveHandleNotAGrip()
    {
        // 0x1000069C (the plain top edge, between the two top corners) is a
        // Type-2 Dragbar in the real DAT, not a Resizebar — retail's main chat
        // window has no title bar, so the top strip moves the window while its
        // two corners (above) resize it.
        var layout = FixtureLoader.LoadChat();
        var topStrip = layout.FindElement(0x1000069Cu);
        Assert.NotNull(topStrip);
        Assert.IsNotType<UiResizeGrip>(topStrip);
        Assert.True(topStrip!.WindowMoveHandle);
    }

    [Theory]
    [InlineData(0x1000069Bu)]   // TL corner
    [InlineData(0x1000069Du)]   // TR corner
    [InlineData(0x1000069Eu)]   // left edge
    [InlineData(0x1000069Fu)]   // BL corner
    [InlineData(0x100006A0u)]   // bottom edge
    [InlineData(0x100006A1u)]   // BR corner
    [InlineData(0x100006A2u)]   // right edge
    public void MountedChatWindow_LiveGrip_ResolvesNonZeroSprite(uint elementId)
    {
        // CH6a/b REJECT-review BLOCKER 1: pre-fix, UiResizeGrip drew nothing —
        // it was constructed without its ElementInfo/resolve pair, so all seven
        // live Type-9 grips rendered NOTHING even though the fixture proves
        // every one of them carries real authored art (the 0x06006129 family).
        // This is the regression guard: every live grip must resolve a non-zero
        // DirectState sprite id, not just decode the right BorderLocation.
        var layout = FixtureLoader.LoadChat();
        var grip = Assert.IsType<UiResizeGrip>(layout.FindElement(elementId));
        Assert.NotEqual(0u, grip.SpriteFile);
    }

    private sealed class NullGpuFrameSource : ICurrentGpuFrameSource
    {
        public IGpuFrame? CurrentFrame => null;
    }

    [Theory]
    [InlineData(0x1000069Bu)]   // TL corner
    [InlineData(0x1000069Du)]   // TR corner
    [InlineData(0x1000069Eu)]   // left edge
    [InlineData(0x1000069Fu)]   // BL corner
    [InlineData(0x100006A0u)]   // bottom edge
    [InlineData(0x100006A1u)]   // BR corner
    [InlineData(0x100006A2u)]   // right edge
    public void MountedChatWindow_LiveGrip_ActuallyEmitsASpriteDraw_NotJustResolvesSpriteFile(uint elementId)
    {
        // CH6a/b re-review rider: MountedChatWindow_LiveGrip_ResolvesNonZeroSprite
        // (above) only proves the ElementInfo carries a non-zero DirectState
        // sprite id — it never calls OnDraw, so a media-less regression (a grip
        // constructed WITHOUT its resolve delegate, or one whose resolve always
        // returns a zero handle/dimension — exactly the CH6a/b BLOCKER 1 bug)
        // would still pass it. This drives the grip through a REAL
        // UiRenderContext over a REAL TextRenderer (backed by the in-memory
        // RecordingGpuDevice test double, no live GPU) and asserts the draw
        // call chain actually queued sprite geometry for that grip's texture.
        var infos = FixtureLoader.LoadChatInfos();
        // Distinct from FixtureLoader's own null-returning resolver: echoes the
        // sprite id as a nonzero fake texture handle with nonzero dimensions,
        // so UiResizeGrip.OnDraw's `tex == 0 || tw == 0 || th == 0` guard does
        // not short-circuit before reaching ctx.DrawSprite.
        var layout = LayoutImporter.Build(infos, id => (id, 8, 8), null);
        var grip = Assert.IsType<UiResizeGrip>(layout.FindElement(elementId));
        Assert.NotEqual(0u, grip.SpriteFile);
        Assert.True(grip.Visible);

        var device = new RecordingGpuDevice();
        var renderer = new TextRenderer(device, new NullGpuFrameSource(), "unused");
        renderer.Begin(new Vector2(800f, 600f));
        var ctx = new UiRenderContext(renderer, new Vector2(800f, 600f));

        grip.DrawSelfAndChildren(ctx);

        var seg = Assert.Single(
            renderer.DebugSpriteSegments,
            s => s.Texture == grip.SpriteFile);
        Assert.True(seg.VertexCount > 0);
    }

    [Fact]
    public void MountedChatWindow_BottomRightGrip_GrowsBothAxes_NotOnlyShrinks()
    {
        // The literal user-gate round 2 report: "the window cannot grow in the
        // Y axis when dragging from the bottom-right corner." Exercises the
        // FULL production path (ChatWindowController.Bind + RetailWindowFrame.Mount
        // with the real Chrome=Imported options and the real DAT min/max
        // constraints from 0x2100006F, minH=100/maxH=2000/minW=300/maxW=2000)
        // rather than just the pure ResizeRect math.
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos,
            layout,
            new ChatVM(new ChatLog()),
            () => NullCommandBus.Instance,
            new ChatWindowState(),
            null,
            null,
            NoTex)!;
        var root = new UiRoot { Width = 1600, Height = 1200 };
        RetailWindowHandle handle = RetailWindowFrame.Mount(
            root,
            controller.Root,
            NoTex,
            new RetailWindowFrame.Options
            {
                WindowName = WindowNames.Chat,
                Chrome = RetailWindowChrome.Imported,
                Left = 10f,
                Top = 440f,
                DatConstraintSource = controller.DatWindowInfo,
            });
        controller.AttachWindow(handle);

        var brGrip = Assert.IsType<UiResizeGrip>(layout.FindElement(0x100006A1u));
        Assert.Equal(UiResizeGrip.Border.LowerRight, brGrip.BorderLocation);

        var gs = brGrip.ScreenPosition;
        int pressX = (int)(gs.X + 2), pressY = (int)(gs.Y + 2);

        // Shrink first (this direction was never in question per the report).
        // Height is already AT the DAT's authored minimum (minH=100 == the
        // authored 100px height), so it clamps rather than shrinking further —
        // width has headroom (minW=300 < 410) and does shrink.
        root.OnMouseDown(UiMouseButton.Left, pressX, pressY);
        root.OnMouseMove(pressX - 20, pressY - 20);
        root.OnMouseUp(UiMouseButton.Left, pressX - 20, pressY - 20);
        Assert.Equal(390f, handle.Width);
        Assert.Equal(100f, handle.Height);

        // Now grow from the shrunken state — this is the reported-broken direction.
        var brGripAfterShrink = Assert.IsType<UiResizeGrip>(layout.FindElement(0x100006A1u));
        var gs2 = brGripAfterShrink.ScreenPosition;
        int pressX2 = (int)(gs2.X + 2), pressY2 = (int)(gs2.Y + 2);
        root.OnMouseDown(UiMouseButton.Left, pressX2, pressY2);
        root.OnMouseMove(pressX2 + 70, pressY2 + 70);
        root.OnMouseUp(UiMouseButton.Left, pressX2 + 70, pressY2 + 70);

        Assert.Equal(460f, handle.Width);
        Assert.Equal(170f, handle.Height);
    }

    [Fact]
    public void MountedChatScrollbar_ButtonsAndThumbDragDriveTranscriptModel()
    {
        var infos = FixtureLoader.LoadChatInfos();
        var layout = LayoutImporter.Build(infos, NoTex, null);
        var controller = ChatWindowController.Bind(
            infos,
            layout,
            new ChatVM(new ChatLog()),
            () => NullCommandBus.Instance,
            new ChatWindowState(),
            null,
            null,
            NoTex)!;
        var root = new UiRoot { Width = 800, Height = 600 };
        RetailWindowHandle handle = RetailWindowFrame.Mount(
            root,
            controller.Root,
            NoTex,
            new RetailWindowFrame.Options
            {
                WindowName = WindowNames.Chat,
                Chrome = RetailWindowChrome.Imported,
                Left = 10f,
                Top = 440f,
                DatConstraintSource = controller.DatWindowInfo,
            });
        controller.AttachWindow(handle);

        UiScrollbar bar = controller.Scrollbar;
        UiScrollable scroll = controller.Transcript.Scroll;
        scroll.LineHeight = 16;
        scroll.SetExtents(contentHeight: 400, viewHeight: 50, preserveEnd: true);
        Assert.Equal(350, scroll.ScrollY);

        var screen = bar.ScreenPosition;
        int centerX = (int)(screen.X + bar.Width / 2f);

        // Top/decrement button.
        int upY = (int)(screen.Y + 8f);
        root.OnMouseDown(UiMouseButton.Left, centerX, upY);
        root.OnMouseUp(UiMouseButton.Left, centerX, upY);
        Assert.Equal(334, scroll.ScrollY);

        // Re-layout must retain the position chosen through the scrollbar.
        scroll.SetExtents(contentHeight: 400, viewHeight: 50, preserveEnd: true);
        Assert.Equal(334, scroll.ScrollY);

        // Drag the thumb toward the top of the track.
        float trackTop = 16f;
        float trackLength = bar.Height - 32f;
        var (thumbY, thumbHeight) = UiScrollbar.ThumbRect(scroll, trackTop, trackLength);
        int dragStartY = (int)(screen.Y + thumbY + thumbHeight / 2f);
        int dragEndY = (int)(screen.Y + trackTop + thumbHeight / 2f);
        root.OnMouseDown(UiMouseButton.Left, centerX, dragStartY);
        root.OnMouseMove(centerX, dragEndY);
        root.OnMouseUp(UiMouseButton.Left, centerX, dragEndY);

        Assert.True(scroll.ScrollY < 334);
        int draggedPosition = scroll.ScrollY;
        scroll.SetExtents(contentHeight: 400, viewHeight: 50, preserveEnd: true);
        Assert.Equal(draggedPosition, scroll.ScrollY);
    }
}