WIP: keep selected clip visible in shelf

sources/clipbored/views/ClipboardPanelView.swift

@@ -566,11 +566,32 @@ final class ClipboardPanelView: NSVisualEffectView, NSSearchFieldDelegate {
   }
 
   private func updateSelection() {
+    var selectedCard: ClipboardItemCardView?
     for (index, card) in cardViews.enumerated() {
-      card.setSelected(index == viewModel.selectedIndex)
+      let selected = index == viewModel.selectedIndex
+      card.setSelected(selected)
+      if selected {
+        selectedCard = card
       }
     }
 
+    if let selectedCard {
+      scrollCardIntoView(selectedCard)
+    }
+  }
+
+  private func scrollCardIntoView(_ card: NSView) {
+    guard scrollView.documentView === itemsStack else { return }
+    guard card.window != nil else { return }
+    scrollView.layoutSubtreeIfNeeded()
+    itemsStack.layoutSubtreeIfNeeded()
+
+    let frame = card.convert(card.bounds, to: itemsStack)
+    let paddedFrame = frame.insetBy(dx: -Metrics.cardSpacing, dy: 0)
+    itemsStack.scrollToVisible(paddedFrame)
+    scrollView.reflectScrolledClipView(scrollView.contentView)
+  }
+
   private func updateStatus(_ message: String) {
     let text: String
     if !message.isEmpty {
@@ -846,6 +867,18 @@ final class ClipboardPanelView: NSVisualEffectView, NSSearchFieldDelegate {
     cardViews.map(\.debugHeaderBadgeSymbol)
   }
 
+  var debugSelectedCardFrameInDocument: NSRect {
+    guard viewModel.selectedIndex >= 0, viewModel.selectedIndex < cardViews.count else {
+      return .zero
+    }
+    let card = cardViews[viewModel.selectedIndex]
+    return card.convert(card.bounds, to: itemsStack)
+  }
+
+  var debugCardRailVisibleRect: NSRect {
+    scrollView.contentView.bounds
+  }
+
   var debugFirstCardMenuTitles: [String] {
     cardViews.first?.debugMenuTitles ?? []
   }

tests/clipboredtests/ClipboardPanelViewTests.swift

@@ -243,6 +243,38 @@ final class ClipboardPanelViewTests: XCTestCase {
     XCTAssertTrue(fixture.view.debugCustomCollectionTitles.contains("Product References"))
   }
 
+  func testSelectionScrollsCardRailToKeepSelectedCardVisible() {
+    let fixture = makePanelFixture()
+    fixture.window.setFrame(NSRect(x: 0, y: 0, width: 620, height: 520), display: true)
+
+    for index in 0..<8 {
+      fixture.store.upsert(makeTextItem("Scrollable clipboard item \(index)", store: fixture.store))
+      drainMainQueue()
+    }
+    fixture.window.contentView?.layoutSubtreeIfNeeded()
+
+    fixture.viewModel.selectFirstItem()
+    drainMainQueue()
+    fixture.window.contentView?.layoutSubtreeIfNeeded()
+    XCTAssertLessThanOrEqual(fixture.view.debugCardRailVisibleRect.minX, 1)
+
+    fixture.viewModel.selectItem(at: fixture.viewModel.visibleItems.count - 1)
+    drainMainQueue()
+    fixture.window.contentView?.layoutSubtreeIfNeeded()
+
+    let visibleRect = fixture.view.debugCardRailVisibleRect
+    let selectedFrame = fixture.view.debugSelectedCardFrameInDocument
+    XCTAssertGreaterThan(visibleRect.minX, 0)
+    XCTAssertLessThanOrEqual(selectedFrame.minX, visibleRect.maxX)
+    XCTAssertGreaterThanOrEqual(visibleRect.maxX + 1, selectedFrame.maxX)
+
+    fixture.viewModel.selectItem(at: 0)
+    drainMainQueue()
+    fixture.window.contentView?.layoutSubtreeIfNeeded()
+
+    XCTAssertLessThanOrEqual(fixture.view.debugCardRailVisibleRect.minX, 1)
+  }
+
   func testFilteredEmptyStateNamesCurrentCollection() {
     let fixture = makePanelFixture()
     fixture.store.upsert(makeTextItem("Only text exists", store: fixture.store))