Fix 3 critical bugs: infinite recursion, stuck loading state, unstable IDs

- Rename waitForExistence() to waitForAppearance() in UI test helpers
  to fix infinite recursion caused by shadowing XCUIElement's built-in method
- Add else branch in fetchItemPrice() so watchlist items show "Parse Error"
  instead of staying stuck in loading state when JSON parsing fails
- Change AttackResult.id from computed property (generating new UUID on
  every access) to stored property assigned once at init, preventing
  SwiftUI re-render thrashing in ForEach

MacTorn/MacTorn/Models/TornModels.swift

@@ -373,7 +373,7 @@ struct AttackResult: Codable, Identifiable {
     let result: String?
     let respect: Double?
 
-    var id: String { code ?? UUID().uuidString }
+    let id: String
 
     enum CodingKeys: String, CodingKey {
         case code
@@ -386,6 +386,33 @@ struct AttackResult: Codable, Identifiable {
         case result, respect
     }
 
+    init(code: String?, timestampStarted: Int?, timestampEnded: Int?, attackerId: Int?, attackerName: String?, defenderId: Int?, defenderName: String?, result: String?, respect: Double?) {
+        self.code = code
+        self.timestampStarted = timestampStarted
+        self.timestampEnded = timestampEnded
+        self.attackerId = attackerId
+        self.attackerName = attackerName
+        self.defenderId = defenderId
+        self.defenderName = defenderName
+        self.result = result
+        self.respect = respect
+        self.id = code ?? UUID().uuidString
+    }
+
+    init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        code = try container.decodeIfPresent(String.self, forKey: .code)
+        timestampStarted = try container.decodeIfPresent(Int.self, forKey: .timestampStarted)
+        timestampEnded = try container.decodeIfPresent(Int.self, forKey: .timestampEnded)
+        attackerId = try container.decodeIfPresent(Int.self, forKey: .attackerId)
+        attackerName = try container.decodeIfPresent(String.self, forKey: .attackerName)
+        defenderId = try container.decodeIfPresent(Int.self, forKey: .defenderId)
+        defenderName = try container.decodeIfPresent(String.self, forKey: .defenderName)
+        result = try container.decodeIfPresent(String.self, forKey: .result)
+        respect = try container.decodeIfPresent(Double.self, forKey: .respect)
+        id = code ?? UUID().uuidString
+    }
+
     func opponentName(forUserId userId: Int) -> String {
         let name: String?
         if attackerId == userId {

MacTorn/MacTorn/ViewModels/AppState.swift

@@ -312,6 +312,9 @@ class AppState: ObservableObject {
                 } else {
                     await updateItemError(itemId: itemId, error: "No listings")
                 }
+            } else {
+                logger.error("Item \(itemId): failed to parse JSON response")
+                await updateItemError(itemId: itemId, error: "Parse Error")
             }
         } catch {
             logger.error("Item \(itemId) price fetch error: \(error.localizedDescription)")

MacTorn/MacTornUITests/MacTornUITests.swift

@@ -136,8 +136,8 @@ final class MacTornUITests: XCTestCase {
 // MARK: - UI Test Helpers
 
 extension XCUIElement {
-    /// Wait for element to exist with timeout
-    func waitForExistence(timeout: TimeInterval = 5) -> Bool {
+    /// Wait for element to appear within the given timeout
+    func waitForAppearance(timeout: TimeInterval = 5) -> Bool {
         return self.waitForExistence(timeout: timeout)
     }