Probe-verified: IBKR historical TRADES volume works (no subscription); bid/ask blocked (Error 354, subscription needed -> spread stays estimated). Fetch in rebalancer context (netpol) -> ibkr_pit_volume DB -> daemon reads. Source flag ucits_volume_source yahoo|ibkr. CronJob for the fetch. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>