Fix AI chat performance and UX

- Single JOIN query instead of N+1 selects for sessions
- Auto-create session when sending without one
- Send button enabled when typing

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/app/ai/page.tsx

@@ -70,25 +70,53 @@ export default function AIChatPage() {
   const currentSession = sessions.find(s => s.id === currentSessionId);
 
   const handleSend = async () => {
-    if (!input.trim() || loading || !currentSession) return;
+    if (!input.trim() || loading) return;
     setLoading(true);
 
     const userContent = input.trim();
     setInput("");
 
+    // Auto-create session if none selected
+    let sessionId = currentSessionId;
+    if (!sessionId && childId) {
+      try {
+        const res = await fetch("/api/chat", {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({ childId, title: userContent.slice(0, 30) }),
+        });
+        const data = await res.json();
+        if (data.session) {
+          sessionId = data.session.id;
+          const newSession = { ...data.session, messages: [] };
+          setSessions([newSession, ...sessions]);
+          setCurrentSessionId(sessionId);
+        }
+      } catch (err) {
+        console.error("Failed to create session:", err);
+        setLoading(false);
+        return;
+      }
+    }
+
+    if (!sessionId) {
+      setLoading(false);
+      return;
+    }
+
     try {
       // Save user message
       await fetch("/api/chat", {
         method: "PATCH",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ sessionId: currentSessionId, role: "user", content: userContent }),
+        body: JSON.stringify({ sessionId, role: "user", content: userContent }),
       });
 
       // Get AI response
       const aiRes = await fetch("/api/ai", {
         method: "POST",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ messages: currentSession.messages.concat({ id: "", role: "user", content: userContent, createdAt: "" }) }),
+        body: JSON.stringify({ messages: [{ role: "user", content: userContent }] }),
       });
       const aiData = await aiRes.json();
 
@@ -97,7 +125,7 @@ export default function AIChatPage() {
         await fetch("/api/chat", {
           method: "PATCH",
           headers: { "Content-Type": "application/json" },
-          body: JSON.stringify({ sessionId: currentSessionId, role: "assistant", content: aiData.reply }),
+          body: JSON.stringify({ sessionId, role: "assistant", content: aiData.reply }),
         });
       }
 
@@ -173,7 +201,7 @@ export default function AIChatPage() {
               className="flex-1 p-3 border rounded-lg"
               disabled={loading}
             />
-            <button onClick={handleSend} disabled={loading || !currentSession} className={`px-4 py-2 text-white rounded-lg ${loading || !currentSession ? "bg-gray-300 cursor-not-allowed" : "bg-rose-400"}`}>
+            <button onClick={handleSend} disabled={loading || !input.trim()} className={`px-4 py-2 text-white rounded-lg ${loading || !input.trim() ? "bg-gray-300 cursor-not-allowed" : "bg-rose-400"}`}>
               {loading ? "..." : "Send"}
             </button>
           </div>

src/app/api/chat/route.ts

@@ -7,28 +7,24 @@ export async function GET(request: Request) {
   const childId = searchParams.get("childId") || "default";
 
   try {
-    // Fetch sessions
-    const sessions = await sql`
-      SELECT id, title, created_at as "createdAt", updated_at as "updatedAt"
-      FROM chat_sessions
-      WHERE child_id = ${childId}
-      ORDER BY updated_at DESC
-    `;
+    // Single query with JOIN for better performance
+    const sessions = await sql.unsafe(`
+      SELECT
+        cs.id, cs.title, cs.created_at as "createdAt", cs.updated_at as "updatedAt",
+        COALESCE(
+          json_agg(
+            json_build_object('id', cm.id, 'role', cm.role, 'content', cm.content, 'createdAt', cm.created_at ORDER BY cm.created_at)
+          ) FILTER (WHERE cm.id IS NOT NULL),
+          '[]'::json
+        ) as messages
+      FROM chat_sessions cs
+      LEFT JOIN chat_messages cm ON cm.session_id = cs.id
+      WHERE cs.child_id = $1
+      GROUP BY cs.id
+      ORDER BY cs.updated_at DESC
+    `, [childId]);
 
-    // Fetch messages for each session
-    const sessionsWithMessages = await Promise.all(
-      (sessions || []).map(async (session: any) => {
-        const messages = await sql`
-          SELECT id, role, content, created_at as "createdAt"
-          FROM chat_messages
-          WHERE session_id = ${session.id}
-          ORDER BY created_at
-        `;
-        return { ...session, messages: messages || [] };
-      })
-    );
-
-    return NextResponse.json({ sessions: sessionsWithMessages || [] });
+    return NextResponse.json({ sessions: sessions || [] });
   } catch (error) {
     console.error(error);
     return NextResponse.json({ error: String(error) }, { status: 500 });