Function checkPlatformBan

server/src/middleware/auth.ts:120–135

* Check platform ban with caching. Returns the ban if active, or null if not banned.

(cacheKey: string, checker: () => Promise<{ banned: boolean; ban?: Ban }>)

 * Check platform ban with caching. Returns the ban if active, or null if not banned.
 */
async function checkPlatformBan(cacheKey: string, checker: () => Promise<{ banned: boolean; ban?: Ban }>): Promise<Ban | null> {
  const now = Date.now();
  const cached = banCache.get(cacheKey);
  if (cached && cached.expiresAt > now) {
    return cached.banned ? (cached.ban ?? null) : null;
  }

  const result = await checker();
  if (banCache.size > 10_000) banCache.clear();
  banCache.set(cacheKey, {
    banned: result.banned,
    ban: result.ban,
    expiresAt: now + BAN_CACHE_TTL_MS,
  });
  return result.banned ? (result.ban ?? null) : null;
}

/**
 * Send a 403 ban response.