Centralize shared card surface styling

World Manager for Minecraft/ContentUIShared.swift

@@ -1,6 +1,65 @@
 import AppKit
 import SwiftUI
 
+enum AppChrome {
+    static let sidebarRowCornerRadius: CGFloat = 10
+    static let placeholderCardCornerRadius: CGFloat = 16
+    static let panelCardCornerRadius: CGFloat = 18
+}
+
+enum AppCardStyle {
+    case primaryPanel
+    case secondaryPanel
+    case placeholder
+
+    fileprivate var cornerRadius: CGFloat {
+        switch self {
+        case .primaryPanel, .secondaryPanel:
+            return AppChrome.panelCardCornerRadius
+        case .placeholder:
+            return AppChrome.placeholderCardCornerRadius
+        }
+    }
+
+    fileprivate var fillStyle: AnyShapeStyle {
+        switch self {
+        case .primaryPanel:
+            return AnyShapeStyle(.regularMaterial)
+        case .secondaryPanel:
+            return AnyShapeStyle(.quaternary.opacity(0.32))
+        case .placeholder:
+            return AnyShapeStyle(.thinMaterial)
+        }
+    }
+}
+
+private struct AppCardSurfaceModifier: ViewModifier {
+    let style: AppCardStyle
+
+    func body(content: Content) -> some View {
+        content.background(
+            style.fillStyle,
+            in: RoundedRectangle(cornerRadius: style.cornerRadius, style: .continuous)
+        )
+    }
+}
+
+extension View {
+    func appCardSurface(_ style: AppCardStyle) -> some View {
+        modifier(AppCardSurfaceModifier(style: style))
+    }
+
+    func appSidebarRowSurface(isHighlighted: Bool) -> some View {
+        let fillStyle = isHighlighted
+            ? AnyShapeStyle(.secondary.opacity(0.08))
+            : AnyShapeStyle(Color.clear)
+        return background(
+            fillStyle,
+            in: RoundedRectangle(cornerRadius: AppChrome.sidebarRowCornerRadius, style: .continuous)
+        )
+    }
+}
+
 struct ToolbarShareButton: View {
     let systemImage: String
     let isEnabled: Bool

World Manager for Minecraft/ItemDetailColumnViews.swift

@@ -253,7 +253,7 @@ private struct SourceDetailView: View {
                 }
             }
             .padding(18)
-            .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 18, style: .continuous))
+            .appCardSurface(.primaryPanel)
         }
     }
 
@@ -609,7 +609,7 @@ private struct SourceDetailView: View {
                 }
             }
             .padding(18)
-            .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 18, style: .continuous))
+            .appCardSurface(.primaryPanel)
         }
     }
 }
@@ -1083,7 +1083,7 @@ struct ItemDetailView: View {
             }
             .frame(maxWidth: .infinity, alignment: .leading)
             .padding(18)
-            .background(.quaternary.opacity(0.32), in: RoundedRectangle(cornerRadius: 18, style: .continuous))
+            .appCardSurface(.secondaryPanel)
         }
     }
 

World Manager for Minecraft/SidebarColumnViews.swift

@@ -180,7 +180,7 @@ private struct SourceHeaderRow: View {
         }
         .padding(.horizontal, 10)
         .padding(.vertical, 8)
-        .background(backgroundStyle, in: RoundedRectangle(cornerRadius: 10, style: .continuous))
+        .appSidebarRowSurface(isHighlighted: isHovering && !isSelected)
         .contentShape(Rectangle())
         .onTapGesture(perform: onSelect)
         .onHover { isHovering = $0 }
@@ -229,15 +229,6 @@ private struct SourceHeaderRow: View {
     private var availabilityBadgeEmphasis: Bool {
         source.availability == .limited
     }
-
-    private var backgroundStyle: AnyShapeStyle {
-        if isHovering && !isSelected {
-            return AnyShapeStyle(.secondary.opacity(0.08))
-        }
-
-        return AnyShapeStyle(.clear)
-    }
-
     @ViewBuilder
     private var statusIndicator: some View {
         if source.isScanning {

World Manager for Minecraft/SourceAccess/ConnectedDevice/ConnectedDeviceSourcePickerView.swift

@@ -284,7 +284,7 @@ struct ConnectedDeviceSourcePickerView: View {
                 .foregroundStyle(.secondary)
         }
         .frame(maxWidth: .infinity, maxHeight: .infinity)
-        .background(.thinMaterial, in: RoundedRectangle(cornerRadius: 16, style: .continuous))
+        .appCardSurface(.placeholder)
     }
 
     private func emptyState(_ title: String) -> some View {
@@ -298,6 +298,6 @@ struct ConnectedDeviceSourcePickerView: View {
                 .multilineTextAlignment(.center)
         }
         .frame(maxWidth: .infinity, maxHeight: .infinity)
-        .background(.thinMaterial, in: RoundedRectangle(cornerRadius: 16, style: .continuous))
+        .appCardSurface(.placeholder)
     }
 }