fix: resolve new conversation message send bug

Two bugs were causing the first message in a new conversation to fail:

1. Session not found: sendMessage threw "No session found" because the
   session was only created in useEffect (which runs after sendMessage).
   Fix: Auto-open session in sendMessage if one doesn't exist, using
   the conversation's provider/model from Dexie.

2. Pending message cleared: useEffect that resets state on conversationId
   change also ran when creating a new conversation, clearing the
   pendingUserMessage we just set.
   Fix: Track isCreatingConversationRef and skip the reset when we're
   in the middle of creating a conversation.

https://claude.ai/code/session_01HqtD9R33oqfB14Gu1V5wHC

src/components/AIViewer.tsx

@@ -263,8 +263,20 @@ function ChatPanel({
   const messagesEndRef = useRef<HTMLDivElement>(null);
   const textareaRef = useRef<HTMLTextAreaElement>(null);
 
-  // Reset input when switching conversations
+  // Track if we're in the middle of creating a new conversation
+  // This prevents the reset useEffect from clearing pendingUserMessage
+  const isCreatingConversationRef = useRef(false);
+
+  // Reset input when switching conversations (but not when creating new one)
   useEffect(() => {
+    if (isCreatingConversationRef.current) {
+      // We just created this conversation - don't reset pendingUserMessage
+      isCreatingConversationRef.current = false;
+      textareaRef.current?.focus();
+      return;
+    }
+
+    // User switched to a different conversation - reset everything
     setInput("");
     setPendingUserMessage(null);
     textareaRef.current?.focus();
@@ -302,14 +314,17 @@ function ChatPanel({
           providerInstanceId,
           modelId,
         );
+        // Mark that we're creating - prevents useEffect from clearing pendingUserMessage
+        isCreatingConversationRef.current = true;
         onConversationCreated(activeConversationId);
       }
 
-      // Send via session manager (handles everything)
+      // Send via session manager (auto-opens session if needed)
       await sendMessage(activeConversationId, userContent);
     } catch (err) {
       console.error("Failed to send message:", err);
       setPendingUserMessage(null);
+      isCreatingConversationRef.current = false;
     }
   };
 

src/services/llm/session-manager.ts

@@ -258,23 +258,29 @@ class ChatSessionManager {
   /**
    * Send a message and stream the response.
    * This is the main entry point for chat interactions.
+   * Auto-opens a session if one doesn't exist.
    */
   async sendMessage(conversationId: string, content: string): Promise<void> {
-    const session = this.getSession(conversationId);
+    // Get conversation from Dexie first (we need it for auto-session and message)
+    const conversation = await db.llmConversations.get(conversationId);
+    if (!conversation) {
+      throw new Error(`Conversation ${conversationId} not found`);
+    }
+
+    // Auto-open session if it doesn't exist
+    let session = this.getSession(conversationId);
     if (!session) {
-      throw new Error(`No session found for conversation ${conversationId}`);
+      session = this.openSession(
+        conversationId,
+        conversation.providerInstanceId,
+        conversation.modelId,
+      );
     }
 
     if (session.isLoading) {
       throw new Error("Session is already generating a response");
     }
 
-    // Get conversation from Dexie
-    const conversation = await db.llmConversations.get(conversationId);
-    if (!conversation) {
-      throw new Error(`Conversation ${conversationId} not found`);
-    }
-
     // Create user message
     const userMessage: LLMMessage = {
       id: crypto.randomUUID(),