feat: lift 5-account cap on HTTP/2

lib/stalwart/credentials.ts

@@ -2,6 +2,7 @@ import { cookies } from 'next/headers';
 import { NextRequest } from 'next/server';
 import { sessionCookieName } from '@/lib/auth/session-cookie';
 import { readStalwartAuthContextFromStore } from '@/lib/stalwart/auth-context';
+import { MAX_ACCOUNT_SLOTS } from '@/lib/account-utils';
 
 export interface StalwartCredentials {
   /** URL of the JMAP server (used for JMAP + management method calls) */
@@ -15,14 +16,16 @@ export interface StalwartCredentials {
 function parseSlot(raw: string | null): number | null {
   if (raw === null) return null;
   const slot = parseInt(raw, 10);
-  return Number.isNaN(slot) || slot < 0 || slot > 4 ? null : slot;
+  return Number.isNaN(slot) || slot < 0 || slot >= MAX_ACCOUNT_SLOTS ? null : slot;
 }
 
+const ALL_SLOTS = Array.from({ length: MAX_ACCOUNT_SLOTS }, (_, i) => i);
+
 function getCandidateSlots(request: NextRequest): number[] {
   const requestedSlot = parseSlot(request.headers.get('X-JMAP-Cookie-Slot'))
     ?? parseSlot(request.nextUrl.searchParams.get('slot'));
 
-  return requestedSlot === null ? [0, 1, 2, 3, 4] : [requestedSlot];
+  return requestedSlot === null ? ALL_SLOTS : [requestedSlot];
 }
 
 export async function getStalwartCredentials(request: NextRequest): Promise<StalwartCredentials | null> {