Address Copilot review feedback

- Fix pika://set/... URL parsing: pass arg1 (hex) not arg2 (nil) to handleSet
- Skip pushUndo() in recordHistory() when history is empty to avoid restoring
  an empty snapshot on first undo
- Guard against empty history in swap() to prevent index-out-of-range crash
- Remove stale isActivePair reference from ColorPair comment (active tracking
  is now by id, not hex equality)
- Fix history toggle hidden shortcut: ⌘Y → plain H to match storyboard/docs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: superhighfives

Pika/Services/ColorPair.swift

@@ -11,8 +11,8 @@ struct ColorPair: Codable, Identifiable, Equatable {
     var backgroundColor: NSColor { Self.colorFromHex(backgroundHex) }
 
     // Reconstructs the color in Defaults[.colorSpace] — the same space toHexString()
-    // reads from. This makes set() a no-op (colorSpace → colorSpace), so the stored
-    // hex round-trips exactly and isActivePair comparison always holds.
+    // reads from. This makes set() a no-op (colorSpace → colorSpace) so the stored
+    // hex round-trips exactly.
     private static func colorFromHex(_ hex: String) -> NSColor {
         let fallback = NSColor.black.usingColorSpace(Defaults[.colorSpace]) ?? .black
         let h = hex.replacingOccurrences(of: "#", with: "")

Pika/Services/Eyedroppers.swift

@@ -39,7 +39,7 @@ class Eyedroppers: ObservableObject {
             return
         }
 
-        pushUndo()
+        if !history.isEmpty { pushUndo() }
         let pair = ColorPair(id: UUID(), foregroundHex: fgHex, backgroundHex: bgHex, date: Date())
         var updated = [pair] + history
         if updated.count > ColorPair.maxHistory {
@@ -56,6 +56,7 @@ class Eyedroppers: ObservableObject {
         background.color = temp
 
         var history = Defaults[.colorHistory]
+        guard !history.isEmpty else { return }
         let index = activeIndex
         let entry = history[index]
         history[index] = ColorPair(

Pika/Services/URLSchemeHandler.swift

@@ -28,7 +28,7 @@ final class URLSchemeHandler: NSObject {
         case "pick":       handlePick(task: task)
         case "system":     handleSystem(task: task)
         case "copy":       handleCopy(task: task)
-        case "set":        handleSet(task: task, hex: arg2)
+        case "set":        handleSet(task: task, hex: arg1)
         case "history":    handleHistory(task: task)
         case "window":     handleWindow(task: task, arg1: arg1, arg2: arg2)
         case "appearance": handleAppearance(task: task)

Pika/Views/NavigationMenu.swift

@@ -70,7 +70,7 @@ struct NavigationMenu: View {
                         historyDrawerVisible.toggle()
                     }
                 })
-                .keyboardShortcut("y", modifiers: .command)
+                .keyboardShortcut("h", modifiers: [])
             }
             .opacity(0)
             .frame(width: 0, height: 0)