Fix: Badges now display in List rows, List fills column width in SplitView

- Badge values are now extracted from BadgeModifier during row extraction
- Added extractBadgeValue() function using Mirror reflection
- ListRow and SelectableListRow now store badge value
- withAvailableWidth() now sets hasExplicitWidth for proper List expansion

Sources/TUIkit/Core/SelectableListRow.swift

@@ -46,14 +46,19 @@ public struct SelectableListRow<SelectionValue: Hashable & Sendable>: Sendable,
     /// The rendered content buffer.
     public let buffer: FrameBuffer
 
-    /// Creates a selectable list row with type and buffer.
+    /// The badge value for this row (from environment).
+    public let badge: BadgeValue?
+
+    /// Creates a selectable list row with type, buffer, and optional badge.
     ///
     /// - Parameters:
     ///   - type: The row type (header, content, or footer).
     ///   - buffer: The rendered row content.
-    public init(type: ListRowType<SelectionValue>, buffer: FrameBuffer) {
+    ///   - badge: The badge value for this row (default: nil).
+    public init(type: ListRowType<SelectionValue>, buffer: FrameBuffer, badge: BadgeValue? = nil) {
         self.type = type
         self.buffer = buffer
+        self.badge = badge
     }
 
     /// Indicates whether this row can be selected and focused.

Sources/TUIkit/Modifiers/BadgeModifier.swift

@@ -78,6 +78,23 @@ extension BadgeValue: Equatable {
     }
 }
 
+// MARK: - Badge Extraction
+
+/// Extracts the badge value from a view if it's wrapped in a BadgeModifier.
+///
+/// This is used by List to extract badge values during row extraction.
+@MainActor
+public func extractBadgeValue<V: View>(from view: V) -> BadgeValue? {
+    // Use Mirror to check if the view is a BadgeModifier
+    let mirror = Mirror(reflecting: view)
+    for child in mirror.children {
+        if child.label == "value", let badge = child.value as? BadgeValue {
+            return badge
+        }
+    }
+    return nil
+}
+
 // MARK: - Renderable
 
 extension BadgeModifier: Renderable {

Sources/TUIkit/Rendering/Renderable.swift

@@ -221,11 +221,15 @@ public struct RenderContext {
     /// Used by layout containers (e.g., NavigationSplitView) to constrain
     /// child views to a specific column width.
     ///
+    /// This also sets `hasExplicitWidth` to true so that child views
+    /// (like List) know to expand to fill the available width.
+    ///
     /// - Parameter width: The new available width in characters.
     /// - Returns: A new RenderContext with the updated width.
     func withAvailableWidth(_ width: Int) -> Self {
         var copy = self
         copy.availableWidth = width
+        copy.hasExplicitWidth = true
         return copy
     }
 }

Sources/TUIkit/Views/List.swift

@@ -19,6 +19,9 @@ struct ListRow<ID: Hashable> {
     /// The rendered content buffer for this row.
     let buffer: FrameBuffer
 
+    /// The badge value for this row (from environment).
+    let badge: BadgeValue?
+
     /// The height of this row in lines.
     var height: Int { buffer.height }
 }
@@ -615,7 +618,7 @@ private struct _ListCore<SelectionValue: Hashable & Sendable, Content: View, Foo
         // Check for ListRowExtractor (ForEach)
         if let extractor = content as? ListRowExtractor {
             let rows: [ListRow<SelectionValue>] = extractor.extractListRows(context: context)
-            return rows.map { SelectableListRow(type: .content(id: $0.id), buffer: $0.buffer) }
+            return rows.map { SelectableListRow(type: .content(id: $0.id), buffer: $0.buffer, badge: $0.badge) }
         }
 
         // Check for ChildInfoProvider (handles TupleView with multiple children)
@@ -670,7 +673,7 @@ private struct _ListCore<SelectionValue: Hashable & Sendable, Content: View, Foo
         if let extractor = section as? ListRowExtractor {
             let contentRows: [ListRow<SelectionValue>] = extractor.extractListRows(context: context)
             for row in contentRows {
-                rows.append(SelectableListRow(type: .content(id: row.id), buffer: row.buffer))
+                rows.append(SelectableListRow(type: .content(id: row.id), buffer: row.buffer, badge: row.badge))
             }
         } else {
             // Fallback: render content as single row (if Section content is not ForEach)
@@ -766,8 +769,8 @@ private struct _ListCore<SelectionValue: Hashable & Sendable, Content: View, Foo
             }
         }
 
-        // Check for badge in environment (only for content rows, on first line only)
-        let badge = context.environment.badgeValue
+        // Check for badge on the row (only for content rows, on first line only)
+        let badge = row.badge
         let shouldRenderBadge = badge != nil && !badge!.isHidden && row.isSelectable
 
         // Render each line - row content keeps its own styling
@@ -855,10 +858,15 @@ extension ForEach: ListRowExtractor {
         data.compactMap { element -> ListRow<RowID>? in
             let elementID = element[keyPath: idKeyPath]
             let view = content(element)
+
+            // Extract badge if the view is wrapped in a BadgeModifier
+            let badge = extractBadgeValue(from: view)
+
+            // Render the view
             let buffer = TUIkit.renderToBuffer(view, context: context)
 
             guard let rowID = elementID as? RowID else { return nil }
-            return ListRow(id: rowID, buffer: buffer)
+            return ListRow(id: rowID, buffer: buffer, badge: badge)
         }
     }
 }

Sources/TUIkit/Views/Section.swift

@@ -311,7 +311,7 @@ extension Section: ListRowExtractor {
         // Fallback: render content as a single row (rare case)
         let buffer = TUIkit.renderToBuffer(content, context: context)
         if let indexID = 0 as? RowID {
-            return [ListRow(id: indexID, buffer: buffer)]
+            return [ListRow(id: indexID, buffer: buffer, badge: nil)]
         }
         return []
     }