macOS: Command palette has no selection by default, selection wraps (#7175)

#7173

(1) The command palette no longer has any selection by default. If and
when we introduce most recently used commands, defaulting to that would
make sense. A selection only appears when the arrow keys are used or the
user starts typing.

(2) The selection with arrow keys now wraps, so if you press "down" on
the last option, it will wrap to the first option, and if you press "up"
on the first option, it will wrap to the last option. This matches both
VSCode and Zed.

macos/Sources/Features/Command Palette/CommandPalette.swift

@@ -21,8 +21,8 @@ struct CommandPaletteView: View {
     var backgroundColor: Color = Color(nsColor: .windowBackgroundColor)
     var options: [CommandOption]
     @State private var query = ""
-    @State private var selectedIndex: UInt = 0
-    @State private var hoveredOptionID: UUID? = nil
+    @State private var selectedIndex: UInt?
+    @State private var hoveredOptionID: UUID?
 
     // The options that we should show, taking into account any filtering from
     // the query.
@@ -35,7 +35,8 @@ struct CommandPaletteView: View {
     }
 
     var selectedOption: CommandOption? {
-        if selectedIndex < filteredOptions.count {
+        guard let selectedIndex else { return nil }
+        return if selectedIndex < filteredOptions.count {
             filteredOptions[Int(selectedIndex)]
         } else {
             filteredOptions.last
@@ -54,20 +55,38 @@ struct CommandPaletteView: View {
                     selectedOption?.action()
 
                 case .move(.up):
-                    if selectedIndex > 0 {
-                        selectedIndex -= 1
-                    }
+                    if filteredOptions.isEmpty { break }
+                    let current = selectedIndex ?? UInt(filteredOptions.count)
+                    selectedIndex = (current == 0)
+                        ? UInt(filteredOptions.count - 1)
+                        : current - 1
 
                 case .move(.down):
-                    if selectedIndex < filteredOptions.count - 1 {
-                        selectedIndex += 1
-                    }
+                    if filteredOptions.isEmpty { break }
+                    let current = selectedIndex ?? UInt.max
+                    selectedIndex = (current >= UInt(filteredOptions.count - 1))
+                        ? 0
+                        : current + 1
 
                 case .move(_):
                     // Unknown, ignore
                     break
                 }
             }
+            .onChange(of: query) { newValue in
+                // If the user types a query then we want to make sure the first
+                // value is selected. If the user clears the query and we were selecting
+                // the first, we unset any selection.
+                if !newValue.isEmpty {
+                    if selectedIndex == nil {
+                        selectedIndex = 0
+                    }
+                } else {
+                    if let selectedIndex, selectedIndex == 0 {
+                        self.selectedIndex = nil
+                    }
+                }
+            }
 
             Divider()
                 .padding(.bottom, 4)
@@ -148,7 +167,7 @@ fileprivate struct CommandPaletteQuery: View {
 
 fileprivate struct CommandTable: View {
     var options: [CommandOption]
-    @Binding var selectedIndex: UInt
+    @Binding var selectedIndex: UInt?
     @Binding var hoveredOptionID: UUID?
     var action: (CommandOption) -> Void
 
@@ -164,9 +183,15 @@ fileprivate struct CommandTable: View {
                         ForEach(Array(options.enumerated()), id: \.1.id) { index, option in
                             CommandRow(
                                 option: option,
-                                isSelected: selectedIndex == index ||
-                                    (selectedIndex >= options.count &&
-                                     index == options.count - 1),
+                                isSelected: {
+                                    if let selected = selectedIndex {
+                                        return selected == index ||
+                                            (selected >= options.count &&
+                                                index == options.count - 1)
+                                    } else {
+                                        return false
+                                    }
+                                }(),
                                 hoveredID: $hoveredOptionID
                             ) {
                                 action(option)
@@ -176,7 +201,8 @@ fileprivate struct CommandTable: View {
                 }
                 .frame(maxHeight: 200)
                 .onChange(of: selectedIndex) { _ in
-                    guard selectedIndex < options.count else { return }
+                    guard let selectedIndex,
+                          selectedIndex < options.count else { return }
                     proxy.scrollTo(
                         options[Int(selectedIndex)].id)
                 }