feat: admin invite codes with plan assignment + user detail page

- Migration 030: add email, assigned_plan, trial_duration_days, email_sent_at
  to invite_codes with CHECK constraints
- Resend email integration (graceful degradation when API key not set)
- Invite codes now support plan assignment (free/pro/team) and trial duration (1-90 days)
- Registration applies invite code plan/trial to new subscription
- Auto-downgrade expired trials on authenticated access
- Enriched GET /admin/users/{id} with account, subscription, sessions, audit logs
- New endpoints: PUT /admin/users/{id}/subscription/plan and extend-trial
- Frontend: enhanced invite codes page with email, plan, trial fields
- Frontend: new user detail page at /admin/users/:userId
- Fixed API path drift: /invite-codes -> /invites
- 11 new backend tests, 416 total passing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/admin/InviteCodesPage.tsx

@@ -1,33 +1,45 @@
 import { useState, useEffect, useCallback } from 'react'
-import { Plus, Copy, Trash2, Ticket } from 'lucide-react'
+import { Plus, Copy, Trash2, Ticket, Mail, MailCheck } from 'lucide-react'
 import { DataTable, PageHeader, StatusBadge, ActionMenu, EmptyState } from '@/components/admin'
 import type { Column } from '@/components/admin'
 import { Modal } from '@/components/common/Modal'
 import { adminApi } from '@/api/admin'
 import { toast } from '@/lib/toast'
 import { cn } from '@/lib/utils'
+import type { InviteCodeResponse, InviteCodeCreateRequest } from '@/types/admin'
 
-interface InviteCode {
-  id: string
-  code: string
-  created_by_id: string
-  used_by_id: string | null
-  is_active: boolean
-  expires_at: string | null
-  created_at: string
+const PLAN_OPTIONS = [
+  { value: 'free', label: 'Free' },
+  { value: 'pro', label: 'Pro' },
+  { value: 'team', label: 'Team' },
+] as const
+
+const planBadgeVariant = (plan: string): 'success' | 'destructive' | 'warning' | 'default' => {
+  switch (plan) {
+    case 'pro': return 'success'
+    case 'team': return 'warning'
+    default: return 'default'
+  }
 }
 
 export function InviteCodesPage() {
-  const [codes, setCodes] = useState<InviteCode[]>([])
+  const [codes, setCodes] = useState<InviteCodeResponse[]>([])
   const [loading, setLoading] = useState(true)
   const [createOpen, setCreateOpen] = useState(false)
+  const [creating, setCreating] = useState(false)
+
+  // Form state
+  const [email, setEmail] = useState('')
   const [expiresInDays, setExpiresInDays] = useState('')
+  const [assignedPlan, setAssignedPlan] = useState<'free' | 'pro' | 'team'>('free')
+  const [trialDays, setTrialDays] = useState('')
+  const [note, setNote] = useState('')
 
   const fetchCodes = useCallback(async () => {
     setLoading(true)
     try {
       const data = await adminApi.listInviteCodes()
-      setCodes(Array.isArray(data) ? data : data.items || [])
+      setCodes(Array.isArray(data) ? data : [])
     } catch {
       toast.error('Failed to load invite codes')
     } finally {
@@ -37,18 +49,36 @@ export function InviteCodesPage() {
 
   useEffect(() => { fetchCodes() }, [fetchCodes])
 
+  const resetForm = () => {
+    setEmail('')
+    setExpiresInDays('')
+    setAssignedPlan('free')
+    setTrialDays('')
+    setNote('')
+  }
+
   const handleCreate = async () => {
+    setCreating(true)
     try {
-      const expiresAt = expiresInDays
-        ? new Date(Date.now() + parseInt(expiresInDays) * 86400000).toISOString()
-        : undefined
-      await adminApi.createInviteCode(expiresAt ? { expires_at: expiresAt } : undefined)
+      const data: InviteCodeCreateRequest = {}
+      if (expiresInDays) {
+        data.expires_at = new Date(Date.now() + parseInt(expiresInDays) * 86400000).toISOString()
+      }
+      if (email.trim()) data.email = email.trim()
+      if (note.trim()) data.note = note.trim()
+      data.assigned_plan = assignedPlan
+      if (assignedPlan !== 'free' && trialDays) {
+        data.trial_duration_days = parseInt(trialDays)
+      }
+      await adminApi.createInviteCode(data)
       toast.success('Invite code created')
       setCreateOpen(false)
-      setExpiresInDays('')
+      resetForm()
       fetchCodes()
     } catch {
       toast.error('Failed to create invite code')
+    } finally {
+      setCreating(false)
     }
   }
 
@@ -57,9 +87,9 @@ export function InviteCodesPage() {
     toast.success('Code copied to clipboard')
   }
 
-  const handleDelete = async (id: string) => {
+  const handleDelete = async (code: string) => {
     try {
-      await adminApi.deleteInviteCode(id)
+      await adminApi.deleteInviteCode(code)
       toast.success('Invite code deleted')
       fetchCodes()
     } catch {
@@ -67,7 +97,12 @@ export function InviteCodesPage() {
     }
   }
 
-  const columns: Column<InviteCode>[] = [
+  const inputClass = cn(
+    'w-full rounded-md border border-white/10 bg-black/50 px-3 py-2 text-sm text-white',
+    'placeholder:text-white/40 focus:outline-none focus:border-white/30 focus:ring-2 focus:ring-white/20'
+  )
+
+  const columns: Column<InviteCodeResponse>[] = [
     {
       key: 'code',
       header: 'Code',
@@ -75,14 +110,48 @@ export function InviteCodesPage() {
         <code className="rounded bg-white/10 px-2 py-1 text-sm font-mono text-white/70">{c.code}</code>
       ),
     },
+    {
+      key: 'email',
+      header: 'Recipient',
+      render: (c) => c.email ? (
+        <div className="flex items-center gap-1.5">
+          {c.email_sent ? (
+            <MailCheck className="h-3.5 w-3.5 text-emerald-400" />
+          ) : (
+            <Mail className="h-3.5 w-3.5 text-white/30" />
+          )}
+          <span className="text-sm text-white/60">{c.email}</span>
+        </div>
+      ) : (
+        <span className="text-sm text-white/30">&mdash;</span>
+      ),
+    },
+    {
+      key: 'plan',
+      header: 'Plan',
+      render: (c) => (
+        <StatusBadge variant={planBadgeVariant(c.assigned_plan)}>
+          {c.assigned_plan.charAt(0).toUpperCase() + c.assigned_plan.slice(1)}
+        </StatusBadge>
+      ),
+    },
+    {
+      key: 'trial',
+      header: 'Trial',
+      render: (c) => c.has_trial ? (
+        <span className="text-sm text-white/60">{c.trial_duration_days}d</span>
+      ) : (
+        <span className="text-sm text-white/30">&mdash;</span>
+      ),
+    },
     {
       key: 'status',
       header: 'Status',
       render: (c) => {
-        if (c.used_by_id) return <StatusBadge variant="default">Used</StatusBadge>
-        if (!c.is_active) return <StatusBadge variant="destructive">Inactive</StatusBadge>
-        if (c.expires_at && new Date(c.expires_at) < new Date()) return <StatusBadge variant="warning">Expired</StatusBadge>
-        return <StatusBadge variant="success">Active</StatusBadge>
+        if (c.is_used) return <StatusBadge variant="default">Used</StatusBadge>
+        if (c.is_expired) return <StatusBadge variant="warning">Expired</StatusBadge>
+        if (c.is_valid) return <StatusBadge variant="success">Active</StatusBadge>
+        return <StatusBadge variant="destructive">Inactive</StatusBadge>
       },
     },
     {
@@ -114,12 +183,12 @@ export function InviteCodesPage() {
             icon: <Copy className="h-4 w-4" />,
             onClick: () => handleCopy(c.code),
           },
-          {
+          ...(!c.is_used ? [{
             label: 'Delete',
             icon: <Trash2 className="h-4 w-4" />,
-            onClick: () => handleDelete(c.id),
+            onClick: () => handleDelete(c.code),
             destructive: true,
-          },
+          }] : []),
         ]} />
       ),
     },
@@ -129,7 +198,7 @@ export function InviteCodesPage() {
     <div className="space-y-6">
       <PageHeader
         title="Invite Codes"
-        description="Manage registration invite codes"
+        description="Create and manage registration invite codes with plan assignment"
         action={
           <button
             onClick={() => setCreateOpen(true)}
@@ -160,27 +229,73 @@ export function InviteCodesPage() {
 
       <Modal
         isOpen={createOpen}
-        onClose={() => setCreateOpen(false)}
+        onClose={() => { setCreateOpen(false); resetForm() }}
         title="Create Invite Code"
         size="sm"
         footer={
           <div className="flex justify-end gap-3">
             <button
-              onClick={() => setCreateOpen(false)}
+              onClick={() => { setCreateOpen(false); resetForm() }}
               className="rounded-md border border-white/10 px-4 py-2 text-sm font-medium text-white/60 hover:bg-white/10 hover:text-white"
             >
               Cancel
             </button>
             <button
               onClick={handleCreate}
-              className="rounded-md bg-white px-4 py-2 text-sm font-medium text-black hover:bg-white/90"
+              disabled={creating}
+              className="rounded-md bg-white px-4 py-2 text-sm font-medium text-black hover:bg-white/90 disabled:opacity-50"
             >
-              Create
+              {creating ? 'Creating...' : 'Create'}
             </button>
           </div>
         }
       >
         <div className="space-y-4">
+          <div>
+            <label className="mb-1 block text-sm font-medium text-white">Recipient Email</label>
+            <input
+              type="email"
+              value={email}
+              onChange={(e) => setEmail(e.target.value)}
+              placeholder="Optional — will send invite email"
+              className={inputClass}
+            />
+          </div>
+
+          <div>
+            <label className="mb-1 block text-sm font-medium text-white">Plan</label>
+            <select
+              aria-label="Plan"
+              value={assignedPlan}
+              onChange={(e) => {
+                const plan = e.target.value as 'free' | 'pro' | 'team'
+                setAssignedPlan(plan)
+                if (plan === 'free') setTrialDays('')
+              }}
+              className={inputClass}
+            >
+              {PLAN_OPTIONS.map(o => (
+                <option key={o.value} value={o.value}>{o.label}</option>
+              ))}
+            </select>
+          </div>
+
+          {assignedPlan !== 'free' && (
+            <div>
+              <label className="mb-1 block text-sm font-medium text-white">Trial Duration (days)</label>
+              <input
+                type="number"
+                value={trialDays}
+                onChange={(e) => setTrialDays(e.target.value)}
+                placeholder="e.g. 14 (1-90)"
+                min={1}
+                max={90}
+                className={inputClass}
+              />
+              <p className="mt-1 text-xs text-white/40">Leave empty for no trial — account gets full plan immediately.</p>
+            </div>
+          )}
+
           <div>
             <label className="mb-1 block text-sm font-medium text-white">Expires in (days)</label>
             <input
@@ -188,10 +303,18 @@ export function InviteCodesPage() {
               value={expiresInDays}
               onChange={(e) => setExpiresInDays(e.target.value)}
               placeholder="Leave empty for no expiry"
-              className={cn(
-                'w-full rounded-md border border-white/10 bg-black/50 px-3 py-2 text-sm text-white',
-                'placeholder:text-white/40 focus:outline-none focus:border-white/30 focus:ring-2 focus:ring-white/20'
-              )}
+              className={inputClass}
+            />
+          </div>
+
+          <div>
+            <label className="mb-1 block text-sm font-medium text-white">Note</label>
+            <input
+              type="text"
+              value={note}
+              onChange={(e) => setNote(e.target.value)}
+              placeholder="Optional note (e.g. who this is for)"
+              className={inputClass}
             />
           </div>
         </div>