added cors support and started chat client

packages/chat-client/src/hooks/useSession.js

@@ -0,0 +1,97 @@
+import { useState, useEffect, useCallback } from 'react';
+import { fetchSessions, fetchSessionHistory } from '../api/orchestration';
+import { v4 as uuidv4 } from 'uuid';
+
+export function useSession() {
+  const [sessions, setSessions] = useState([]);
+  const [activeSession, setActiveSession] = useState(null);
+  const [messages, setMessages] = useState([]);
+  const [loadingHistory, setLoadingHistory] = useState(false);
+  const [error, setError] = useState(null);
+
+  // Load session list on mount
+  useEffect(() => {
+    loadSessions();
+  }, []);
+
+  async function loadSessions() {
+    try {
+      const data = await fetchSessions();
+      setSessions(data);
+    } catch (err) {
+      setError(err.message);
+    }
+  }
+
+  // Switch to an existing session and load its history
+  const selectSession = useCallback(async (session) => {
+    setActiveSession(session);
+    setMessages([]);
+    setLoadingHistory(true);
+
+    try {
+      const data = await fetchSessionHistory(session.external_id);
+      // History comes back newest-first — reverse for display
+      const history = data.episodes.reverse().map(ep => ([
+        { id: `${ep.id}-user`, role: 'user',      text: ep.user_message },
+        { id: `${ep.id}-ai`,   role: 'assistant', text: ep.ai_response  },
+      ])).flat();
+
+      setMessages(history);
+    } catch (err) {
+      setError(err.message);
+    } finally {
+      setLoadingHistory(false);
+    }
+  }, []);
+
+  // Create a new session with a generated UUID — no backend call needed yet,
+  // orchestration auto-creates the session on the first message
+  const createSession = useCallback(() => {
+    const newSession = {
+      external_id: uuidv4(),
+      metadata: null,
+      isNew: true, // flag so SessionList can style it differently
+    };
+    setSessions(prev => [newSession, ...prev]);
+    setActiveSession(newSession);
+    setMessages([]);
+  }, []);
+
+  // Called by useChat after a message completes — keeps session list fresh
+  const refreshSessions = useCallback(async () => {
+    try {
+      const data = await fetchSessions();
+      setSessions(data);
+    } catch {
+      // non-critical — sidebar just won't update
+    }
+  }, []);
+
+  // Append a message to the current thread (used by useChat)
+  const appendMessage = useCallback((message) => {
+    setMessages(prev => [...prev, message]);
+  }, []);
+
+  // Update the last message in the thread (used by useChat during streaming)
+  const updateLastMessage = useCallback((updater) => {
+    setMessages(prev => {
+      const updated = [...prev];
+      updated[updated.length - 1] = updater(updated[updated.length - 1]);
+      return updated;
+    });
+  }, []);
+
+  return {
+    sessions,
+    activeSession,
+    messages,
+    loadingHistory,
+    error,
+    selectSession,
+    createSession,
+    refreshSessions,
+    appendMessage,
+    updateLastMessage,
+  };
+}