feat: add invite registration links with configurable usage limits

Admins can create one-time registration links (1–5× or unlimited uses)
with optional expiry (1d–14d or never). Recipients can register even
when public registration is disabled. Atomic usage counting prevents
race conditions, all endpoints are rate-limited.

client/src/pages/AdminPage.tsx

@@ -12,7 +12,7 @@ import CategoryManager from '../components/Admin/CategoryManager'
 import BackupPanel from '../components/Admin/BackupPanel'
 import GitHubPanel from '../components/Admin/GitHubPanel'
 import AddonManager from '../components/Admin/AddonManager'
-import { Users, Map, Briefcase, Shield, Trash2, Edit2, Camera, FileText, Eye, EyeOff, Save, CheckCircle, XCircle, Loader2, UserPlus, ArrowUpCircle, ExternalLink, Download, AlertTriangle, RefreshCw, GitBranch, Sun } from 'lucide-react'
+import { Users, Map, Briefcase, Shield, Trash2, Edit2, Camera, FileText, Eye, EyeOff, Save, CheckCircle, XCircle, Loader2, UserPlus, ArrowUpCircle, ExternalLink, Download, AlertTriangle, RefreshCw, GitBranch, Sun, Link2, Copy, Plus } from 'lucide-react'
 import CustomSelect from '../components/shared/CustomSelect'
 
 interface AdminUser {
@@ -79,6 +79,11 @@ export default function AdminPage(): React.ReactElement {
   // Registration toggle
   const [allowRegistration, setAllowRegistration] = useState<boolean>(true)
 
+  // Invite links
+  const [invites, setInvites] = useState<any[]>([])
+  const [showCreateInvite, setShowCreateInvite] = useState<boolean>(false)
+  const [inviteForm, setInviteForm] = useState<{ max_uses: number; expires_in_days: number | '' }>({ max_uses: 1, expires_in_days: 7 })
+
   // File types
   const [allowedFileTypes, setAllowedFileTypes] = useState<string>('jpg,jpeg,png,gif,webp,heic,pdf,doc,docx,xls,xlsx,txt,csv')
   const [savingFileTypes, setSavingFileTypes] = useState<boolean>(false)
@@ -114,12 +119,14 @@ export default function AdminPage(): React.ReactElement {
   const loadData = async () => {
     setIsLoading(true)
     try {
-      const [usersData, statsData] = await Promise.all([
+      const [usersData, statsData, invitesData] = await Promise.all([
         adminApi.users(),
         adminApi.stats(),
+        adminApi.listInvites().catch(() => ({ invites: [] })),
       ])
       setUsers(usersData.users)
       setStats(statsData)
+      setInvites(invitesData.invites || [])
     } catch (err: unknown) {
       toast.error(t('admin.toast.loadError'))
     } finally {
@@ -240,6 +247,38 @@ export default function AdminPage(): React.ReactElement {
     }
   }
 
+  const handleCreateInvite = async () => {
+    try {
+      const data = await adminApi.createInvite({
+        max_uses: inviteForm.max_uses,
+        expires_in_days: inviteForm.expires_in_days || undefined,
+      })
+      setInvites(prev => [data.invite, ...prev])
+      setShowCreateInvite(false)
+      setInviteForm({ max_uses: 1, expires_in_days: 7 })
+      // Copy link to clipboard
+      const link = `${window.location.origin}/register?invite=${data.invite.token}`
+      navigator.clipboard.writeText(link).then(() => toast.success(t('admin.invite.copied')))
+    } catch (err: unknown) {
+      toast.error(getApiErrorMessage(err, t('admin.invite.createError')))
+    }
+  }
+
+  const handleDeleteInvite = async (id: number) => {
+    try {
+      await adminApi.deleteInvite(id)
+      setInvites(prev => prev.filter(i => i.id !== id))
+      toast.success(t('admin.invite.deleted'))
+    } catch {
+      toast.error(t('admin.invite.deleteError'))
+    }
+  }
+
+  const copyInviteLink = (token: string) => {
+    const link = `${window.location.origin}/register?invite=${token}`
+    navigator.clipboard.writeText(link).then(() => toast.success(t('admin.invite.copied')))
+  }
+
   const handleEditUser = (user) => {
     setEditingUser(user)
     setEditForm({ username: user.username, email: user.email, role: user.role, password: '' })
@@ -501,6 +540,109 @@ export default function AdminPage(): React.ReactElement {
             </div>
           )}
 
+          {/* Invite Links (inside users tab) */}
+          {activeTab === 'users' && (
+            <div className="bg-white rounded-xl border border-slate-200 overflow-hidden mt-6">
+              <div className="p-5 border-b border-slate-100 flex items-center justify-between">
+                <div>
+                  <h2 className="font-semibold text-slate-900">{t('admin.invite.title')}</h2>
+                  <p className="text-xs text-slate-400 mt-1">{t('admin.invite.subtitle')}</p>
+                </div>
+                <button
+                  onClick={() => setShowCreateInvite(true)}
+                  className="flex items-center gap-1.5 px-3 py-1.5 text-sm bg-slate-900 text-white rounded-lg hover:bg-slate-700 transition-colors"
+                >
+                  <Plus className="w-4 h-4" />
+                  {t('admin.invite.create')}
+                </button>
+              </div>
+
+              {invites.length === 0 ? (
+                <div className="p-8 text-center text-sm text-slate-400">{t('admin.invite.empty')}</div>
+              ) : (
+                <div className="divide-y divide-slate-100">
+                  {invites.map(inv => {
+                    const isExpired = inv.expires_at && new Date(inv.expires_at) < new Date()
+                    const isUsedUp = inv.max_uses > 0 && inv.used_count >= inv.max_uses
+                    const isActive = !isExpired && !isUsedUp
+                    return (
+                      <div key={inv.id} className="px-5 py-3 flex items-center gap-4">
+                        <Link2 className="w-4 h-4 flex-shrink-0" style={{ color: isActive ? 'var(--text-primary)' : '#d1d5db' }} />
+                        <div className="flex-1 min-w-0">
+                          <div className="flex items-center gap-2">
+                            <code className="text-xs font-mono text-slate-600 truncate">{inv.token.slice(0, 12)}...</code>
+                            <span className={`text-xs px-1.5 py-0.5 rounded-full font-medium ${
+                              isActive ? 'bg-green-50 text-green-700' : 'bg-slate-100 text-slate-400'
+                            }`}>
+                              {isUsedUp ? t('admin.invite.usedUp') : isExpired ? t('admin.invite.expired') : t('admin.invite.active')}
+                            </span>
+                          </div>
+                          <div className="text-xs text-slate-400 mt-0.5">
+                            {inv.used_count}/{inv.max_uses === 0 ? '∞' : inv.max_uses} {t('admin.invite.uses')}
+                            {inv.expires_at && ` · ${t('admin.invite.expiresAt')} ${new Date(inv.expires_at).toLocaleDateString(locale)}`}
+                            {` · ${t('admin.invite.createdBy')} ${inv.created_by_name}`}
+                          </div>
+                        </div>
+                        {isActive && (
+                          <button onClick={() => copyInviteLink(inv.token)} title={t('admin.invite.copyLink')}
+                            className="p-1.5 rounded-lg hover:bg-slate-100 text-slate-400 hover:text-slate-700 transition-colors">
+                            <Copy className="w-3.5 h-3.5" />
+                          </button>
+                        )}
+                        <button onClick={() => handleDeleteInvite(inv.id)} title={t('common.delete')}
+                          className="p-1.5 rounded-lg hover:bg-red-50 text-slate-400 hover:text-red-500 transition-colors">
+                          <Trash2 className="w-3.5 h-3.5" />
+                        </button>
+                      </div>
+                    )
+                  })}
+                </div>
+              )}
+            </div>
+          )}
+
+          {/* Create Invite Modal */}
+          <Modal isOpen={showCreateInvite} onClose={() => setShowCreateInvite(false)} title={t('admin.invite.create')} size="sm">
+            <div className="space-y-4">
+              <div>
+                <label className="block text-xs font-semibold text-slate-500 uppercase tracking-wider mb-1.5">{t('admin.invite.maxUses')}</label>
+                <div className="flex gap-2">
+                  {[1, 2, 3, 4, 5, 0].map(n => (
+                    <button key={n} type="button" onClick={() => setInviteForm(f => ({ ...f, max_uses: n }))}
+                      className={`flex-1 py-2 rounded-lg text-sm font-semibold border transition-colors ${
+                        inviteForm.max_uses === n ? 'bg-slate-900 text-white border-slate-900' : 'bg-white text-slate-600 border-slate-200 hover:border-slate-400'
+                      }`}>
+                      {n === 0 ? '∞' : `${n}×`}
+                    </button>
+                  ))}
+                </div>
+              </div>
+              <div>
+                <label className="block text-xs font-semibold text-slate-500 uppercase tracking-wider mb-1.5">{t('admin.invite.expiry')}</label>
+                <div className="flex gap-2">
+                  {[
+                    { value: 1, label: '1d' },
+                    { value: 3, label: '3d' },
+                    { value: 7, label: '7d' },
+                    { value: 14, label: '14d' },
+                    { value: '', label: '∞' },
+                  ].map(opt => (
+                    <button key={String(opt.value)} type="button" onClick={() => setInviteForm(f => ({ ...f, expires_in_days: opt.value as number | '' }))}
+                      className={`flex-1 py-2 rounded-lg text-sm font-semibold border transition-colors ${
+                        inviteForm.expires_in_days === opt.value ? 'bg-slate-900 text-white border-slate-900' : 'bg-white text-slate-600 border-slate-200 hover:border-slate-400'
+                      }`}>
+                      {opt.label}
+                    </button>
+                  ))}
+                </div>
+              </div>
+              <div className="flex justify-end gap-2 pt-2 border-t border-slate-100">
+                <button onClick={() => setShowCreateInvite(false)} className="px-4 py-2 text-sm text-slate-500 hover:text-slate-700">{t('common.cancel')}</button>
+                <button onClick={handleCreateInvite} className="px-4 py-2 text-sm bg-slate-900 text-white rounded-lg hover:bg-slate-700">{t('admin.invite.createAndCopy')}</button>
+              </div>
+            </div>
+          </Modal>
+
           {activeTab === 'categories' && <CategoryManager />}
 
           {activeTab === 'addons' && <AddonManager />}

client/src/pages/LoginPage.tsx

@@ -25,6 +25,8 @@ export default function LoginPage(): React.ReactElement {
   const [isLoading, setIsLoading] = useState<boolean>(false)
   const [error, setError] = useState<string>('')
   const [appConfig, setAppConfig] = useState<AppConfig | null>(null)
+  const [inviteToken, setInviteToken] = useState<string>('')
+  const [inviteValid, setInviteValid] = useState<boolean>(false)
 
   const { login, register, demoLogin } = useAuthStore()
   const { setLanguageLocal } = useSettingsStore()
@@ -38,8 +40,23 @@ export default function LoginPage(): React.ReactElement {
       }
     })
 
-    // Handle OIDC callback via short-lived auth code (secure exchange)
+    // Handle query params (invite token, OIDC callback)
     const params = new URLSearchParams(window.location.search)
+
+    // Check for invite token in URL (/register?invite=xxx or /login?invite=xxx)
+    const invite = params.get('invite')
+    if (invite) {
+      setInviteToken(invite)
+      setMode('register')
+      authApi.validateInvite(invite).then(() => {
+        setInviteValid(true)
+      }).catch(() => {
+        setError('Invalid or expired invite link')
+      })
+      window.history.replaceState({}, '', window.location.pathname)
+    }
+
+    // Handle OIDC callback via short-lived auth code (secure exchange)
     const oidcCode = params.get('oidc_code')
     const oidcError = params.get('oidc_error')
     if (oidcCode) {
@@ -93,7 +110,7 @@ export default function LoginPage(): React.ReactElement {
       if (mode === 'register') {
         if (!username.trim()) { setError('Username is required'); setIsLoading(false); return }
         if (password.length < 6) { setError('Password must be at least 6 characters'); setIsLoading(false); return }
-        await register(username, email, password)
+        await register(username, email, password, inviteToken || undefined)
       } else {
         await login(email, password)
       }
@@ -105,7 +122,7 @@ export default function LoginPage(): React.ReactElement {
     }
   }
 
-  const showRegisterOption = (appConfig?.allow_registration || !appConfig?.has_users) && !appConfig?.oidc_only_mode
+  const showRegisterOption = (appConfig?.allow_registration || !appConfig?.has_users || inviteValid) && !appConfig?.oidc_only_mode
 
   // In OIDC-only mode, show a minimal page that redirects directly to the IdP
   const oidcOnly = appConfig?.oidc_only_mode && appConfig?.oidc_configured