feat(swift-host): Add toast notifications for teardown errors

- Add toastMessage property and showToast() method to ViewModel
- Add toast overlay at bottom of screen (auto-dismiss after 3s)
- Change teardown() to return optional error message
- Show toast when teardown fails or times out
- Add OSLog-based logging for debugging
- Improve logs.sh script for better log filtering

🤖 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

@@ -47,6 +47,20 @@ struct ContentView: View {
             }
             .navigationTitle("MCP Host")
             .navigationBarTitleDisplayMode(.inline)
+            .overlay(alignment: .bottom) {
+                if let toast = viewModel.toastMessage {
+                    Text(toast)
+                        .font(.footnote)
+                        .foregroundColor(.white)
+                        .padding(.horizontal, 16)
+                        .padding(.vertical, 10)
+                        .background(Color.red.opacity(0.9))
+                        .cornerRadius(8)
+                        .padding(.bottom, 80) // Above toolbar
+                        .transition(.move(edge: .bottom).combined(with: .opacity))
+                        .animation(.easeInOut, value: viewModel.toastMessage)
+                }
+            }
         }
     }
 

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

@@ -2,6 +2,9 @@ import Foundation
 import SwiftUI
 import MCP
 import McpApps
+import os.log
+
+private let logger = Logger(subsystem: "com.example.BasicHostSwift", category: "ToolCall")
 
 /// View model managing MCP server connection and tool execution.
 @MainActor
@@ -22,6 +25,15 @@ class McpHostViewModel: ObservableObject {
     }
     @Published var activeToolCalls: [ToolCallInfo] = []
     @Published var errorMessage: String?
+    @Published var toastMessage: String?
+
+    func showToast(_ message: String, duration: TimeInterval = 3.0) {
+        toastMessage = message
+        Task {
+            try? await Task.sleep(nanoseconds: UInt64(duration * 1_000_000_000))
+            await MainActor.run { self.toastMessage = nil }
+        }
+    }
 
     /// Known MCP servers (matches examples/servers.json)
     static let knownServers = [
@@ -240,7 +252,9 @@ class McpHostViewModel: ObservableObject {
     }
 
     func removeToolCall(_ toolCall: ToolCallInfo) async {
-        await toolCall.teardown()
+        if let error = await toolCall.teardown() {
+            showToast(error)
+        }
         activeToolCalls.removeAll { $0.id == toolCall.id }
     }
 }
@@ -465,8 +479,10 @@ class ToolCallInfo: ObservableObject, Identifiable {
             ]
         }
 
+        logger.info("Connecting bridge to transport...")
         try await bridge.connect(transport)
         self.appBridge = bridge
+        logger.info("AppBridge is now set and ready")
     }
 
     private func sendToolResult(_ result: ToolResult, to bridge: AppBridge) async throws {
@@ -486,33 +502,56 @@ class ToolCallInfo: ObservableObject, Identifiable {
     }
 
     /// Teardown the app bridge before removing the tool call
-    func teardown() async {
+    /// Returns an error message if teardown failed, nil on success
+    func teardown() async -> String? {
         // Prevent double-tap
-        guard !isTearingDown else { return }
+        guard !isTearingDown else {
+            logger.info("Teardown already in progress, skipping")
+            return nil
+        }
         isTearingDown = true
+        logger.info("Starting teardown, appBridge exists: \(self.appBridge != nil)")
+
+        var errorMessage: String?
 
         if let bridge = appBridge {
-            do {
-                // Use a timeout so we don't wait forever if app is unresponsive
-                try await withThrowingTaskGroup(of: Void.self) { group in
-                    group.addTask {
+            logger.info("Sending teardown request...")
+
+            // Race between teardown and timeout
+            await withTaskGroup(of: String?.self) { group in
+                group.addTask {
+                    do {
+                        logger.info("Calling bridge.sendResourceTeardown()...")
                         _ = try await bridge.sendResourceTeardown()
+                        logger.info("Teardown request completed successfully")
+                        return nil
+                    } catch {
+                        logger.error("Teardown request failed: \(String(describing: error)), type: \(type(of: error))")
+                        return "Teardown failed: app may not have saved data"
                     }
-                    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 or timed out: \(error)")
+                group.addTask {
+                    try? await Task.sleep(nanoseconds: 5_000_000_000) // 5 second timeout
+                    logger.warning("Teardown timeout reached after 5 seconds")
+                    return "Teardown timed out: app may not have saved data"
+                }
+                // Wait for first to complete
+                if let result = await group.next() {
+                    errorMessage = result
+                }
+                logger.info("Task group completed")
+                group.cancelAll()
             }
+
+            logger.info("Closing bridge...")
             await bridge.close()
+            logger.info("Bridge closed")
+        } else {
+            logger.warning("No bridge to teardown (appBridge is nil)")
         }
         appBridge = nil
-        // Note: isTearingDown stays true - the card will be removed from the list
+        logger.info("Teardown complete, will remove card from list")
+        return errorMessage
     }
 }
 

examples/basic-host-swift/scripts/logs.sh

@@ -9,10 +9,8 @@ echo "📋 Streaming logs from $BUNDLE_ID on '$SIMULATOR'..."
 echo "   Press Ctrl+C to stop"
 echo ""
 
-# Stream logs, filtering for our app
+# Stream logs, filtering for our app (both OSLog and print statements)
 xcrun simctl spawn "$SIMULATOR" log stream \
     --predicate "subsystem == '$BUNDLE_ID' OR process == 'BasicHostSwift'" \
-    --style compact 2>/dev/null || \
-xcrun simctl spawn "$SIMULATOR" log stream \
-    --predicate "process == 'BasicHostSwift'" \
+    --level debug \
     --style compact