feat: lift 5-account cap on HTTP/2

app/api/auth/session/route.ts

@@ -13,6 +13,7 @@ import { configManager } from '@/lib/admin/config-manager';
 import { isPublicHttpUrl } from '@/lib/security/url-guard';
 import { recordLogin } from '@/lib/telemetry/login-tracker';
 import { parseJmapServers, resolveTrustedJmapUrl } from '@/lib/admin/jmap-servers';
+import { MAX_ACCOUNT_SLOTS } from '@/lib/account-utils';
 
 const COOKIE_OPTIONS = {
   ...getCookieOptions(),
@@ -23,7 +24,7 @@ function getSlot(request: NextRequest): number {
   const raw = request.nextUrl.searchParams.get('slot');
   if (raw === null) return 0;
   const slot = parseInt(raw, 10);
-  if (isNaN(slot) || slot < 0 || slot > 4) return 0;
+  if (isNaN(slot) || slot < 0 || slot >= MAX_ACCOUNT_SLOTS) return 0;
   return slot;
 }
 
@@ -70,7 +71,7 @@ export async function POST(request: NextRequest) {
       return NextResponse.json({ error: 'JMAP server not configured' }, { status: 500 });
     }
 
-    const slot = typeof bodySlot === 'number' && bodySlot >= 0 && bodySlot <= 4 ? bodySlot : getSlot(request);
+    const slot = typeof bodySlot === 'number' && bodySlot >= 0 && bodySlot < MAX_ACCOUNT_SLOTS ? bodySlot : getSlot(request);
     const cookieName = sessionCookieName(slot);
     const authHeader = `Basic ${Buffer.from(`${username}:${password}`).toString('base64')}`;
     const normalizedServerUrl = await verifyJmapAuth(upstreamUrl, authHeader, { trusted: upstreamTrusted });
@@ -185,8 +186,8 @@ export async function DELETE(request: NextRequest) {
     const all = request.nextUrl.searchParams.get('all') === 'true';
 
     if (all) {
-      // Delete all session cookies (slots 0-4)
-      for (let i = 0; i <= 4; i++) {
+      // Delete all session cookies across every slot.
+      for (let i = 0; i < MAX_ACCOUNT_SLOTS; i++) {
         cookieStore.delete(sessionCookieName(i));
         clearStalwartAuthContextInStore(cookieStore, i);
       }