eod_reconcile, backfill_journal and the admin health block were hardwired to AlpacaPaperClient — on a BROKER=tradier stack they would silently reconcile/report against the wrong broker. make_trading_client() honors BROKER env with no silent cross-broker fallback (missing Tradier keys => skip with reason, never fall back to Alpaca). Admin UI shows the active broker label; JSON key stays 'alpaca' for compatibility. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>