feat(portal-auth): URL fragment for activation/reset tokens

Step 8 per PRE-DEPLOY-PLAN § 1.2.5.

Activation + password-reset links now carry the token in the URL
fragment (`#token=…`) instead of the query string (`?token=…`). URL
fragments are client-side only — the token never hits the server,
never lands in proxy logs, never sits in the Referer header, and is
invisible to upstream CDN/cache layers. The form still POSTs the
token in the request body to authenticate.

Changes:
- portal-auth.service.ts URL builders for activation + reset switch
  to `#token=`. Inline comments cite the security rationale.
- password-set-form.tsx reads the token via useSyncExternalStore so
  the SSR snapshot returns `null` and the client snapshot reads
  window.location.hash post-hydration (no set-state-in-effect
  Compiler violation). Helper prefers the fragment but falls back to
  the legacy `?token=` search param for the back-compat TTL window —
  so links sent before the switchover still work for their remaining
  lifetime. Component renders a "Loading…" placeholder during the
  pre-hydration null state.

No DB changes; tokens themselves unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/portal/password-set-form.tsx

@@ -1,8 +1,7 @@
 'use client';
 
 import Link from 'next/link';
-import { useSearchParams } from 'next/navigation';
+import { useState, useSyncExternalStore } from 'react';
-import { useState } from 'react';
 import { CheckCircle2, Loader2 } from 'lucide-react';
 
 import { Button } from '@/components/ui/button';
@@ -23,11 +22,41 @@ interface PasswordSetFormProps {
 const MIN_LENGTH = 9;
 
 /**
- * Shared form used by both the activation and password-reset flows. The
+ * Shared form used by both the activation and password-reset flows.
- * activation token is read from the `?token=` query string. Empty / missing
+ *
- * tokens land the user in an explicit error state instead of submitting a
+ * The activation/reset token is read from the URL fragment (`#token=…`)
- * doomed request.
+ * — not the query string — so the token never travels to the server,
+ * never lands in proxy / reverse-proxy logs, never sits in the Referer
+ * header, and is invisible to upstream CDN/cache layers. The browser
+ * still sends it on form-submit via the explicit POST body.
+ *
+ * Pre-2026-05-14 the token was passed as `?token=…`; the legacy
+ * search-param read is kept as a fallback so links sent before the
+ * switchover still work for the remaining TTL.
+ *
+ * Empty / missing tokens land the user in an explicit error state
+ * instead of submitting a doomed request.
  */
+function readTokenFromUrl(): string {
+  if (typeof window === 'undefined') return '';
+  const hash = window.location.hash.replace(/^#/, '');
+  if (hash) {
+    const params = new URLSearchParams(hash);
+    const fromFragment = params.get('token');
+    if (fromFragment) return fromFragment;
+  }
+  // Back-compat: pre-fragment links still carry `?token=…`. Drop after
+  // every outstanding activation/reset link past TTL has been consumed.
+  const search = new URLSearchParams(window.location.search);
+  return search.get('token') ?? '';
+}
+
+// Tiny no-op subscriber — we don't actually need to react to
+// hashchange events (the token is set once when the user lands on the
+// page). The store integration is here so React knows the source is
+// external and skips the SSR / hydration mismatch warning.
+const subscribe = () => () => undefined;
+
 export function PasswordSetForm({
   endpoint,
   title,
@@ -36,8 +65,15 @@ export function PasswordSetForm({
   successDescription,
   submitLabel,
 }: PasswordSetFormProps) {
-  const search = useSearchParams();
+  // Read the token via useSyncExternalStore — fragment is client-only
-  const token = search.get('token') ?? '';
+  // so the server-snapshot returns `null` and the client snapshot reads
+  // window.location.hash post-hydration. `null` distinguishes "not yet
+  // hydrated" from "missing"; empty string means "hydrated, none found".
+  const token = useSyncExternalStore<string | null>(
+    subscribe,
+    () => readTokenFromUrl(),
+    () => null,
+  );
 
   const [password, setPassword] = useState('');
   const [confirm, setConfirm] = useState('');
@@ -73,6 +109,14 @@ export function PasswordSetForm({
     }
   }
 
+  if (token === null) {
+    return (
+      <BrandedAuthShell>
+        <div className="text-center text-sm text-gray-500">Loading…</div>
+      </BrandedAuthShell>
+    );
+  }
+
   if (!token) {
     return (
       <BrandedAuthShell>

src/lib/services/portal-auth.service.ts

@@ -144,7 +144,11 @@ async function issueActivationToken(
   const port = await db.query.ports.findFirst({ where: eq(ports.id, portId) });
   const portName = port?.name ?? 'Port Nimara';
 
-  const link = `${env.APP_URL}/portal/activate?token=${encodeURIComponent(raw)}`;
+  // URL fragment (#token=…) instead of query string — keeps the
+  // activation token out of server logs, proxy logs, Referer header,
+  // and any CDN/edge cache. The portal /activate page reads the token
+  // client-side via `window.location.hash`. See PRE-DEPLOY-PLAN § 1.2.5.
+  const link = `${env.APP_URL}/portal/activate#token=${encodeURIComponent(raw)}`;
   const subjectOverride = await loadSubjectOverride(portId, 'portal_activation');
   const branding = await getBrandingShell(portId);
   const { subject, html, text } = await activationEmail(
@@ -406,7 +410,9 @@ export async function requestPasswordReset(email: string): Promise<void> {
 
   const port = await db.query.ports.findFirst({ where: eq(ports.id, user.portId) });
   const portName = port?.name ?? 'Port Nimara';
-  const link = `${env.APP_URL}/portal/reset-password?token=${encodeURIComponent(raw)}`;
+  // Same URL-fragment treatment as activation links — token never
+  // travels server-side. See PRE-DEPLOY-PLAN § 1.2.5.
+  const link = `${env.APP_URL}/portal/reset-password#token=${encodeURIComponent(raw)}`;
   const subjectOverride = await loadSubjectOverride(user.portId, 'portal_reset');
   const branding = await getBrandingShell(user.portId);
   const { subject, html, text } = await resetEmail(