feat(Agnet): support multi agents (#385)

src/stores/chat.ts

@@ -87,6 +87,7 @@ interface ChatState {
   // Sessions
   sessions: ChatSession[];
   currentSessionKey: string;
+  currentAgentId: string;
   /** First user message text per session key, used as display label */
   sessionLabels: Record<string, string>;
   /** Last message timestamp (ms) per session key, used for sorting */
@@ -657,6 +658,19 @@ function getCanonicalPrefixFromSessions(sessions: ChatSession[]): string | null
   return `${parts[0]}:${parts[1]}`;
 }
 
+function getAgentIdFromSessionKey(sessionKey: string): string {
+  if (!sessionKey.startsWith('agent:')) return 'main';
+  const parts = sessionKey.split(':');
+  return parts[1] || 'main';
+}
+
+function getCanonicalPrefixFromSessionKey(sessionKey: string): string | null {
+  if (!sessionKey.startsWith('agent:')) return null;
+  const parts = sessionKey.split(':');
+  if (parts.length < 2) return null;
+  return `${parts[0]}:${parts[1]}`;
+}
+
 function isToolOnlyMessage(message: RawMessage | undefined): boolean {
   if (!message) return false;
   if (isToolResultRole(message.role)) return true;
@@ -923,6 +937,7 @@ export const useChatStore = create<ChatState>((set, get) => ({
 
   sessions: [],
   currentSessionKey: DEFAULT_SESSION_KEY,
+  currentAgentId: 'main',
   sessionLabels: {},
   sessionLastActivity: {},
 
@@ -964,7 +979,7 @@ export const useChatStore = create<ChatState>((set, get) => ({
           return true;
         });
 
-        const { currentSessionKey } = get();
+        const { currentSessionKey, sessions: localSessions } = get();
         let nextSessionKey = currentSessionKey || DEFAULT_SESSION_KEY;
         if (!nextSessionKey.startsWith('agent:')) {
           const canonicalMatch = canonicalBySuffix.get(nextSessionKey);
@@ -973,9 +988,10 @@ export const useChatStore = create<ChatState>((set, get) => ({
           }
         }
         if (!dedupedSessions.find((s) => s.key === nextSessionKey) && dedupedSessions.length > 0) {
-          // Current session not found in the backend list
-          const isNewEmptySession = get().messages.length === 0;
-          if (!isNewEmptySession) {
+          // Preserve only locally-created pending sessions. On initial boot the
+          // default ghost key (`agent:main:main`) should yield to real history.
+          const hasLocalPendingSession = localSessions.some((session) => session.key === nextSessionKey);
+          if (!hasLocalPendingSession) {
             nextSessionKey = dedupedSessions[0].key;
           }
         }
@@ -987,7 +1003,11 @@ export const useChatStore = create<ChatState>((set, get) => ({
           ]
           : dedupedSessions;
 
-        set({ sessions: sessionsWithCurrent, currentSessionKey: nextSessionKey });
+        set({
+          sessions: sessionsWithCurrent,
+          currentSessionKey: nextSessionKey,
+          currentAgentId: getAgentIdFromSessionKey(nextSessionKey),
+        });
 
         if (currentSessionKey !== nextSessionKey) {
           get().loadHistory();
@@ -1038,6 +1058,7 @@ export const useChatStore = create<ChatState>((set, get) => ({
     const leavingEmpty = !currentSessionKey.endsWith(':main') && messages.length === 0;
     set((s) => ({
       currentSessionKey: key,
+      currentAgentId: getAgentIdFromSessionKey(key),
       messages: [],
       streamingText: '',
       streamingMessage: null,
@@ -1108,6 +1129,7 @@ export const useChatStore = create<ChatState>((set, get) => ({
         lastUserMessageAt: null,
         pendingToolImages: [],
         currentSessionKey: next?.key ?? DEFAULT_SESSION_KEY,
+        currentAgentId: getAgentIdFromSessionKey(next?.key ?? DEFAULT_SESSION_KEY),
       }));
       if (next) {
         get().loadHistory();
@@ -1128,13 +1150,16 @@ export const useChatStore = create<ChatState>((set, get) => ({
     // NOTE: We intentionally do NOT call sessions.reset on the old session.
     // sessions.reset archives (renames) the session JSONL file, making old
     // conversation history inaccessible when the user switches back to it.
-    const { currentSessionKey, messages } = get();
+    const { currentSessionKey, messages, sessions } = get();
     const leavingEmpty = !currentSessionKey.endsWith(':main') && messages.length === 0;
-    const prefix = getCanonicalPrefixFromSessions(get().sessions) ?? DEFAULT_CANONICAL_PREFIX;
+    const prefix = getCanonicalPrefixFromSessionKey(currentSessionKey)
+      ?? getCanonicalPrefixFromSessions(sessions)
+      ?? DEFAULT_CANONICAL_PREFIX;
     const newKey = `${prefix}:session-${Date.now()}`;
     const newSessionEntry: ChatSession = { key: newKey, displayName: newKey };
     set((s) => ({
       currentSessionKey: newKey,
+      currentAgentId: getAgentIdFromSessionKey(newKey),
       sessions: [
         ...(leavingEmpty ? s.sessions.filter((sess) => sess.key !== currentSessionKey) : s.sessions),
         newSessionEntry,