fix(kotlin-host): add proper WebView lifecycle management

- Add DisposableEffect to handle WebView cleanup on composable disposal
- Add LifecycleEventObserver to pause/resume WebView on activity lifecycle changes
- Properly clean up WebView reference when composable is disposed
- Add update lambda to sync WebView state with lifecycle

This fixes the issue where WebView content was killed when going out of
view (e.g., scrolled off in LazyColumn) and failed to reload because
the lifecycle wasn't properly managed.

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

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

Author: ochafik

examples/basic-host-kotlin/src/main/kotlin/com/example/mcpappshost/MainActivity.kt

@@ -26,7 +26,10 @@ import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.text.font.FontFamily
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.LocalLifecycleOwner
 import androidx.compose.ui.viewinterop.AndroidView
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleEventObserver
 import androidx.lifecycle.viewmodel.compose.viewModel
 import kotlinx.serialization.json.jsonArray
 import kotlinx.serialization.json.jsonObject
@@ -334,6 +337,11 @@ fun ToolCallCard(
 
 /**
  * WebView composable that handles full MCP Apps protocol communication.
+ *
+ * Implements proper lifecycle management to handle:
+ * - Activity pause/resume (calls WebView.onPause/onResume)
+ * - Composable disposal (cleans up WebView references)
+ * - LazyColumn recycling (preserves WebView state via key)
  */
 @Composable
 fun McpAppWebView(
@@ -345,6 +353,7 @@ fun McpAppWebView(
     modifier: Modifier = Modifier
 ) {
     val context = LocalContext.current
+    val lifecycleOwner = LocalLifecycleOwner.current
     val coroutineScope = rememberCoroutineScope()
     val json = remember { kotlinx.serialization.json.Json { ignoreUnknownKeys = true } }
     var webViewRef by remember { mutableStateOf<WebView?>(null) }
@@ -353,6 +362,50 @@ fun McpAppWebView(
     var teardownCompleted by remember { mutableStateOf(false) }
     var currentHeight by remember { mutableIntStateOf(toolCall.preferredHeight) }
 
+    // Track whether the WebView is currently paused
+    var isPaused by remember { mutableStateOf(false) }
+
+    // Lifecycle observer to pause/resume WebView when activity lifecycle changes
+    DisposableEffect(lifecycleOwner) {
+        val observer = LifecycleEventObserver { _, event ->
+            when (event) {
+                Lifecycle.Event.ON_PAUSE -> {
+                    android.util.Log.d("McpAppWebView", "Lifecycle ON_PAUSE - pausing WebView")
+                    webViewRef?.onPause()
+                    isPaused = true
+                }
+                Lifecycle.Event.ON_RESUME -> {
+                    android.util.Log.d("McpAppWebView", "Lifecycle ON_RESUME - resuming WebView")
+                    if (isPaused) {
+                        webViewRef?.onResume()
+                        isPaused = false
+                    }
+                }
+                Lifecycle.Event.ON_DESTROY -> {
+                    android.util.Log.d("McpAppWebView", "Lifecycle ON_DESTROY - cleaning up WebView")
+                    webViewRef?.let { wv ->
+                        wv.stopLoading()
+                        wv.destroy()
+                    }
+                    webViewRef = null
+                }
+                else -> {}
+            }
+        }
+        lifecycleOwner.lifecycle.addObserver(observer)
+        onDispose {
+            android.util.Log.d("McpAppWebView", "DisposableEffect onDispose - cleaning up")
+            lifecycleOwner.lifecycle.removeObserver(observer)
+            // Clean up WebView when composable is disposed
+            webViewRef?.let { wv ->
+                wv.stopLoading()
+                // Don't destroy here - just clear the reference
+                // The WebView will be garbage collected or reused
+            }
+            webViewRef = null
+        }
+    }
+
     // Inject bridge script into HTML
     val injectedHtml = remember(toolCall.htmlContent) {
         injectBridgeScript(toolCall.htmlContent!!)
@@ -574,6 +627,19 @@ fun McpAppWebView(
                 loadDataWithBaseURL(null, injectedHtml, "text/html", "UTF-8", null)
             }
         },
+        update = { webView ->
+            // Update webViewRef if it changed (e.g., after recreation)
+            if (webViewRef != webView) {
+                android.util.Log.d("McpAppWebView", "WebView reference updated")
+                webViewRef = webView
+            }
+            // Sync paused state with current lifecycle
+            if (isPaused && lifecycleOwner.lifecycle.currentState.isAtLeast(Lifecycle.State.RESUMED)) {
+                android.util.Log.d("McpAppWebView", "Resuming WebView after lifecycle sync")
+                webView.onResume()
+                isPaused = false
+            }
+        },
         modifier = modifier
     )
 }