Addressing comments

Author: YoussefKeyrouz

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/models/DuckAiModelManager.kt

@@ -65,7 +65,7 @@ interface DuckAiModelManager {
 
     suspend fun selectReasoningMode(mode: ReasoningMode)
 
-    fun setChatScopedReasoningMode(mode: ReasoningMode?)
+    suspend fun setChatScopedReasoningMode(mode: ReasoningMode?)
 
     fun getSelectedModelId(): String?
 
@@ -216,8 +216,10 @@ class RealDuckAiModelManager @Inject constructor(
         }
     }
 
-    override fun setChatScopedReasoningMode(mode: ReasoningMode?) {
-        _modelState.value = _modelState.value.copy(chatScopedReasoningMode = mode)
+    override suspend fun setChatScopedReasoningMode(mode: ReasoningMode?) {
+        stateMutex.withLock {
+            _modelState.value = _modelState.value.copy(chatScopedReasoningMode = mode)
+        }
     }
 
     override fun getSelectedModelId(): String? = _modelState.value.selectedModelId

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/ui/NativeInputModeWidgetViewModel.kt

@@ -129,6 +129,11 @@ class NativeInputModeWidgetViewModel @Inject constructor(
     private val currentChat = MutableStateFlow<DuckAiChat?>(null)
     private var currentChatJob: Job? = null
 
+    // Defensive buffer for the (rare) case where setActiveChatId fires before configure has set
+    // activeTabId. Replayed inside configure / configureContextual when activeTabId becomes known.
+    private var pendingChatId: String? = null
+    private var hasPendingChatId = false
+
     private val commandChannel = Channel<Command>(capacity = 1, onBufferOverflow = DROP_OLDEST)
     val commands = commandChannel.receiveAsFlow()
 
@@ -157,8 +162,12 @@ class NativeInputModeWidgetViewModel @Inject constructor(
     }
 
     fun getSelectedModelId(): String? {
-        // Existing chat: send chat's stored model.
-        validChat()?.model?.let { return it }
+        // Existing chat: send the chat's stored model — but only if its model is still in the
+        // current list. If not (server stopped offering it, slug renamed, etc.) use global instead.
+        val chat = validChat()
+        if (chat != null && ReasoningResolver.forChat(chat, modelManager.modelState.value) != null) {
+            return chat.model
+        }
         // New chat with picker off: nothing to send.
         if (!_modelPickerEnabled.value) return null
         // New chat with picker on: send what the user picked.
@@ -273,15 +282,23 @@ class NativeInputModeWidgetViewModel @Inject constructor(
     }
 
     fun setActiveChatId(chatId: String?) {
-        val tabId = activeTabId.value ?: return
+        val tabId = activeTabId.value
+        if (tabId == null) {
+            // configure hasn't run yet — buffer until activeTabId is known, replayed in configure.
+            pendingChatId = chatId
+            hasPendingChatId = true
+            return
+        }
+        applyChatId(tabId, chatId)
+    }
+
+    private fun applyChatId(tabId: String, chatId: String?) {
         nativeInputStatePublisher.update(tabId) { it.copy(chatId = chatId) }
-        modelManager.setChatScopedReasoningMode(null)
         currentChatJob?.cancel()
         currentChat.value = null
-        if (chatId != null) {
-            currentChatJob = viewModelScope.launch {
-                currentChat.value = duckAiChatStore.getChatById(chatId)
-            }
+        currentChatJob = viewModelScope.launch {
+            modelManager.setChatScopedReasoningMode(null)
+            if (chatId != null) currentChat.value = duckAiChatStore.getChatById(chatId)
         }
     }
 
@@ -290,6 +307,16 @@ class NativeInputModeWidgetViewModel @Inject constructor(
         val context = if (isDuckAiMode) NativeInputState.InputContext.DUCK_AI else NativeInputState.InputContext.BROWSER
         val position = if (isBottom) NativeInputState.InputPosition.BOTTOM else NativeInputState.InputPosition.TOP
         widgetConfig.value = WidgetConfig(inputContext = context, inputPosition = position)
+        replayPendingChatId(tabId)
+    }
+
+    private fun replayPendingChatId(tabId: String) {
+        if (hasPendingChatId) {
+            val pending = pendingChatId
+            pendingChatId = null
+            hasPendingChatId = false
+            applyChatId(tabId, pending)
+        }
     }
 
     fun storePendingPrompt(
@@ -306,6 +333,7 @@ class NativeInputModeWidgetViewModel @Inject constructor(
     fun configureContextual(tabId: String) {
         activeTabId.value = tabId
         widgetConfig.update { it.copy(inputContext = NativeInputState.InputContext.DUCK_AI_CONTEXTUAL) }
+        replayPendingChatId(tabId)
     }
 
     fun cancelChatSuggestions() {

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/ui/nativeinput/views/ReasoningModePickerViewModel.kt

@@ -132,7 +132,7 @@ class ReasoningModePickerViewModel @Inject constructor(
         }
         if (match.isAccessible) {
             if (chatResolution != null) {
-                modelManager.setChatScopedReasoningMode(mode)
+                viewModelScope.launch { modelManager.setChatScopedReasoningMode(mode) }
             } else {
                 viewModelScope.launch { modelManager.selectReasoningMode(mode) }
             }

duckchat/duckchat-impl/src/test/kotlin/com/duckduckgo/duckchat/impl/ui/NativeInputModeWidgetViewModelTest.kt

@@ -558,6 +558,10 @@ class NativeInputModeWidgetViewModelTest {
     @Test
     fun whenChatIdSetThenGetSelectedModelIdReturnsChatsModel() = runTest {
         whenever(modelManager.getSelectedModelId()).thenReturn("global-model")
+        val modelStateFlow = MutableStateFlow(
+            ModelState(models = listOf(aiModel(id = "chat-model", supported = listOf(ReasoningEffort.NONE)))),
+        )
+        whenever(modelManager.modelState).thenReturn(modelStateFlow)
         whenever(duckAiChatStore.getChatById("chat-1")).thenReturn(
             DuckAiChat(chatId = "chat-1", title = "t", model = "chat-model", lastEdit = "now", pinned = false),
         )
@@ -569,11 +573,37 @@ class NativeInputModeWidgetViewModelTest {
         assertEquals("chat-model", viewModel.getSelectedModelId())
     }
 
+    @Test
+    fun whenChatModelNotInModelsListThenGetSelectedModelIdFallsBackToGlobal() = runTest {
+        // Chat references "missing-model" no longer offered server-side. Submission must fall back to
+        // global on both halves — chat-model + global-effort would be a mismatched pair.
+        whenever(modelManager.getSelectedModelId()).thenReturn("global-model")
+        val modelStateFlow = MutableStateFlow(
+            ModelState(
+                models = listOf(aiModel(id = "other-model", supported = listOf(ReasoningEffort.NONE))),
+            ),
+        )
+        whenever(modelManager.modelState).thenReturn(modelStateFlow)
+        whenever(duckAiChatStore.getChatById("chat-1")).thenReturn(
+            DuckAiChat(chatId = "chat-1", title = "t", model = "missing-model", lastEdit = "now", pinned = false),
+        )
+        val viewModel = createViewModel()
+        viewModel.configure(tabId = "tab-A", isDuckAiMode = true, isBottom = false)
+        viewModel.setActiveChatId("chat-1")
+        advanceUntilIdle()
+
+        assertEquals("global-model", viewModel.getSelectedModelId())
+    }
+
     @Test
     fun whenChatIdSetAndPickerDisabledThenGetSelectedModelIdStillReturnsChatsModel() = runTest {
         // Production binds modelPickerEnabled to `chatId == null`, so existing chats always have the
         // picker disabled. Submission must still carry the chat's stored model.
         whenever(modelManager.getSelectedModelId()).thenReturn("global-model")
+        val modelStateFlow = MutableStateFlow(
+            ModelState(models = listOf(aiModel(id = "chat-model", supported = listOf(ReasoningEffort.NONE)))),
+        )
+        whenever(modelManager.modelState).thenReturn(modelStateFlow)
         whenever(duckAiChatStore.getChatById("chat-1")).thenReturn(
             DuckAiChat(chatId = "chat-1", title = "t", model = "chat-model", lastEdit = "now", pinned = false),
         )
@@ -603,6 +633,15 @@ class NativeInputModeWidgetViewModelTest {
         // for chat-B is suspended. Submission must fall back to global rather than return chat-A's
         // model tagged to chat-B.
         whenever(modelManager.getSelectedModelId()).thenReturn("global-model")
+        val modelStateFlow = MutableStateFlow(
+            ModelState(
+                models = listOf(
+                    aiModel(id = "chat-A-model", supported = listOf(ReasoningEffort.NONE)),
+                    aiModel(id = "chat-B-model", supported = listOf(ReasoningEffort.NONE)),
+                ),
+            ),
+        )
+        whenever(modelManager.modelState).thenReturn(modelStateFlow)
         whenever(duckAiChatStore.getChatById("chat-A")).thenReturn(
             DuckAiChat(chatId = "chat-A", title = "t", model = "chat-A-model", lastEdit = "now", pinned = false),
         )
@@ -634,6 +673,10 @@ class NativeInputModeWidgetViewModelTest {
         // setActiveChatId nulls currentChat synchronously and launches the lookup. During the in-
         // flight window, submission must fall back to global rather than return chat-A's data.
         whenever(modelManager.getSelectedModelId()).thenReturn("global-model")
+        val modelStateFlow = MutableStateFlow(
+            ModelState(models = listOf(aiModel(id = "chat-A-model", supported = listOf(ReasoningEffort.NONE)))),
+        )
+        whenever(modelManager.modelState).thenReturn(modelStateFlow)
         whenever(duckAiChatStore.getChatById("chat-A")).thenReturn(
             DuckAiChat(chatId = "chat-A", title = "t", model = "chat-A-model", lastEdit = "now", pinned = false),
         )
@@ -1092,6 +1135,21 @@ class NativeInputModeWidgetViewModelTest {
         assertNull(nativeInputStateProvider.stateForTab(tabId).value.chatId)
     }
 
+    @Test
+    fun whenSetActiveChatIdBeforeConfigureThenChatIdIsBufferedAndPublishedOnConfigure() = runTest {
+        // Defensive: setActiveChatId fires before activeTabId is set. The pending value must be
+        // replayed once configure runs.
+        val freshViewModel = createViewModel()
+
+        freshViewModel.setActiveChatId("chat-123")
+        advanceUntilIdle()
+
+        freshViewModel.configure(tabId = "tab-A", isDuckAiMode = false, isBottom = false)
+        advanceUntilIdle()
+
+        assertEquals("chat-123", nativeInputStateProvider.stateForTab("tab-A").value.chatId)
+    }
+
     // endregion
 
     // region fireChatHistorySelectedPixel