feat(D.2b): Step-0 chrome sprites confirmed + direct-RenderSurface upload path

Step-0 prove-out result: retail UI chrome sprites are RenderSurface objects
(0x06xxxxxx) that must be decoded DIRECTLY, not via the Surface->SurfaceTexture
chain GetOrUpload uses for world materials (which produced 1x1 magenta/garbage).
Added TextureCache.GetOrUploadRenderSurface(id, out w, out h) — Portal/HighRes
TryGet<RenderSurface> -> DecodeRenderSurface(palette:null) -> upload, separately
cached. This is the path UI chrome + (later) dat fonts use.

Confirmed the universal floating-window bevel is an 8-piece border + center fill:
  center  0x06004CC2 (48x48)
  edges   0x060074BF/C1 (10x5 horiz)  0x060074C0/C2 (5x10 vert)
  corners 0x060074C3..C6 (5x5)
Recorded in RetailChromeSprites.cs (edge/corner->position mapping is a best
guess pending the LayoutDesc 0x21000040 parse; visually confirmed at panel
render). The memory-note ids were right; only the decode path was wrong.

Temporary prove-out harness (added to GameWindow.OnRender) removed. proveout*.log
gitignored.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitignore

@@ -30,6 +30,7 @@ references/*
 /.superpowers/
 launch.log
 launch-*.log
+proveout*.log
 launch.utf8.log
 n4-verify*.log
 

src/AcDream.App/Rendering/TextureCache.cs

@@ -31,6 +31,12 @@ public sealed unsafe class TextureCache : Wb.ITextureCachePerInstance, IDisposab
     private readonly Dictionary<(uint surfaceId, uint origTexOverride, ulong paletteHash), uint> _handlesByPalette = new();
     private uint _magentaHandle;
 
+    // Direct-RenderSurface caches for UI sprites: 0x06xxxxxx RenderSurface ids
+    // decoded directly (Portal/HighRes → DecodeRenderSurface), bypassing the
+    // Surface→SurfaceTexture chain that GetOrUpload uses for world materials.
+    private readonly Dictionary<uint, uint> _handlesByRenderSurfaceId = new();
+    private readonly Dictionary<uint, (int w, int h)> _rsSizeById = new();
+
     private readonly Wb.BindlessSupport? _bindless;
 
     // Bindless / Texture2DArray parallel caches. Keys mirror the legacy three
@@ -103,6 +109,43 @@ public sealed unsafe class TextureCache : Wb.ITextureCachePerInstance, IDisposab
         return h;
     }
 
+    /// <summary>
+    /// Upload a UI sprite by its RenderSurface DataId (0x06xxxxxx), decoded
+    /// DIRECTLY (Portal/HighRes → DecodeRenderSurface) rather than through the
+    /// Surface→SurfaceTexture chain that <see cref="GetOrUpload(uint)"/> uses
+    /// for world-geometry materials. This is the correct path for retail UI
+    /// chrome + font glyph sheets, which reference RenderSurface directly.
+    /// Palette is null for now (a paletted INDEX16/P8 UI sprite would return
+    /// Magenta — wire a UI palette when one is actually encountered). Returns a
+    /// 1x1 magenta handle on miss.
+    /// </summary>
+    public uint GetOrUploadRenderSurface(uint renderSurfaceId, out int width, out int height)
+    {
+        if (_handlesByRenderSurfaceId.TryGetValue(renderSurfaceId, out var existing)
+            && _rsSizeById.TryGetValue(renderSurfaceId, out var sz))
+        {
+            width = sz.w; height = sz.h;
+            return existing;
+        }
+
+        DecodedTexture decoded;
+        if (_dats.Portal.TryGet<RenderSurface>(renderSurfaceId, out var rs)
+            || _dats.HighRes.TryGet<RenderSurface>(renderSurfaceId, out rs))
+        {
+            decoded = SurfaceDecoder.DecodeRenderSurface(rs, palette: null);
+        }
+        else
+        {
+            decoded = DecodedTexture.Magenta;
+        }
+
+        uint h = UploadRgba8(decoded);
+        _handlesByRenderSurfaceId[renderSurfaceId] = h;
+        _rsSizeById[renderSurfaceId] = (decoded.Width, decoded.Height);
+        width = decoded.Width; height = decoded.Height;
+        return h;
+    }
+
     /// <summary>
     /// Alpha-channel histogram for one decoded texture. Used to diagnose
     /// "why are clouds not transparent" — if cloud textures come out with

src/AcDream.App/UI/RetailChromeSprites.cs

@@ -0,0 +1,48 @@
+namespace AcDream.App.UI;
+
+/// <summary>
+/// Retail window-chrome RenderSurface DataIds, CONFIRMED via the D.2b Step-0
+/// prove-out (2026-06-14). These are RenderSurface objects (0x06xxxxxx) decoded
+/// DIRECTLY (<see cref="Rendering.TextureCache.GetOrUploadRenderSurface"/>), NOT
+/// through the Surface→SurfaceTexture chain.
+///
+/// <para>
+/// The universal floating-window bevel is an <b>8-piece border</b> (4 corners
+/// 5×5 + 4 edges) drawn around a tiled center fill — it is NOT a single
+/// 9-slice texture. Decoded sizes are in the comments (from the prove-out).
+/// </para>
+///
+/// <para>
+/// The edge/corner → position mapping below is a reasonable guess pending the
+/// LayoutDesc 0x21000040 parse (sub-project 3) and is confirmed visually in the
+/// first vitals-panel render. If a corner's bevel highlight looks wrong, swap
+/// the four corner constants; if top/bottom or left/right look inverted, swap
+/// those edge pairs.
+/// </para>
+/// </summary>
+public static class RetailChromeSprites
+{
+    /// <summary>Tiled interior fill — the shared panel background (48×48).</summary>
+    public const uint CenterFill = 0x06004CC2;
+
+    /// <summary>Horizontal top edge (10×5, tiled across the top span).</summary>
+    public const uint TopEdge = 0x060074BF;
+    /// <summary>Horizontal bottom edge (10×5).</summary>
+    public const uint BottomEdge = 0x060074C1;
+    /// <summary>Vertical left edge (5×10).</summary>
+    public const uint LeftEdge = 0x060074C0;
+    /// <summary>Vertical right edge (5×10).</summary>
+    public const uint RightEdge = 0x060074C2;
+
+    /// <summary>Top-left corner (5×5).</summary>
+    public const uint CornerTL = 0x060074C3;
+    /// <summary>Top-right corner (5×5).</summary>
+    public const uint CornerTR = 0x060074C4;
+    /// <summary>Bottom-left corner (5×5).</summary>
+    public const uint CornerBL = 0x060074C5;
+    /// <summary>Bottom-right corner (5×5).</summary>
+    public const uint CornerBR = 0x060074C6;
+
+    /// <summary>Border thickness in pixels = the corner/edge sprite size (5px).</summary>
+    public const int Border = 5;
+}