Agent startup holds the manager's global lock

internal/agents/inbox.go

@@ -281,8 +281,8 @@ func (m *Manager) newItem(l *live, id, thread string, kind api.InboxItemKind, pa
 }
 
 func (m *Manager) Deliver(ctx context.Context, sessionID string) error {
-	m.deliverMu.Lock()
-	defer m.deliverMu.Unlock()
+	unlock := m.lockDelivery(sessionID)
+	defer unlock()
 
 	sess, err := m.store.GetSession(ctx, sessionID)
 	if err != nil {
@@ -356,8 +356,8 @@ func (m *Manager) deliverMidTurn(ctx context.Context, l *live) string {
 		return m.recordQueued(ctx, l, msgs)
 	}
 
-	m.deliverMu.Lock()
-	defer m.deliverMu.Unlock()
+	unlock := m.lockDelivery(l.id)
+	defer unlock()
 
 	discard, err := m.store.GetDiscard(ctx, l.taskID)
 	if err != nil {