fix(swift-host): Robust teardown with single source of truth

- Move isTearingDown to ToolCallInfo (observable state)
- Remove local @State that caused desync issues
- Add 5-second timeout to prevent stuck cards
- Guard against double-tap with early return
- Card observes model state via @ObservedObject

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ochafik

examples/basic-host-swift/Sources/BasicHostApp/ContentView.swift

@@ -183,7 +183,6 @@ struct ToolCallCard: View {
     let onRemove: () -> Void
 
     @State private var isInputExpanded = false
-    @State private var isTearingDown = false
 
     var body: some View {
         VStack(alignment: .leading, spacing: 8) {
@@ -200,7 +199,7 @@ struct ToolCallCard: View {
 
                 Spacer()
 
-                if isTearingDown {
+                if toolCallInfo.isTearingDown {
                     HStack(spacing: 4) {
                         ProgressView().scaleEffect(0.6)
                         Text("Closing...")
@@ -222,10 +221,7 @@ struct ToolCallCard: View {
                             .foregroundColor(.secondary)
                     }
 
-                    Button {
-                        isTearingDown = true
-                        onRemove()
-                    } label: {
+                    Button(action: onRemove) {
                         Image(systemName: "xmark")
                             .font(.caption)
                             .foregroundColor(.secondary)
@@ -290,8 +286,8 @@ struct ToolCallCard: View {
         .padding(10)
         .background(Color(UIColor.secondarySystemBackground))
         .cornerRadius(10)
-        .opacity(isTearingDown ? 0.5 : 1.0)
-        .animation(.easeInOut(duration: 0.2), value: isTearingDown)
+        .opacity(toolCallInfo.isTearingDown ? 0.5 : 1.0)
+        .animation(.easeInOut(duration: 0.2), value: toolCallInfo.isTearingDown)
     }
 
     private var stateColor: Color {

examples/basic-host-swift/Sources/BasicHostApp/McpHostViewModel.swift

@@ -288,6 +288,7 @@ class ToolCallInfo: ObservableObject, Identifiable {
     @Published var result: ToolResult?
     @Published var state: ExecutionState = .calling
     @Published var error: String?
+    @Published var isTearingDown = false
 
     init(
         serverName: String,
@@ -486,15 +487,32 @@ class ToolCallInfo: ObservableObject, Identifiable {
 
     /// Teardown the app bridge before removing the tool call
     func teardown() async {
+        // Prevent double-tap
+        guard !isTearingDown else { return }
+        isTearingDown = true
+
         if let bridge = appBridge {
             do {
-                _ = try await bridge.sendResourceTeardown()
+                // Use a timeout so we don't wait forever if app is unresponsive
+                try await withThrowingTaskGroup(of: Void.self) { group in
+                    group.addTask {
+                        _ = try await bridge.sendResourceTeardown()
+                    }
+                    group.addTask {
+                        try await Task.sleep(nanoseconds: 5_000_000_000) // 5 second timeout
+                        throw CancellationError()
+                    }
+                    // Wait for first to complete (either teardown or timeout)
+                    try await group.next()
+                    group.cancelAll()
+                }
             } catch {
-                print("[Host] Teardown failed: \(error)")
+                print("[Host] Teardown failed or timed out: \(error)")
             }
             await bridge.close()
         }
         appBridge = nil
+        // Note: isTearingDown stays true - the card will be removed from the list
     }
 }