OPEC+ delegates are gathering in Vienna this week to tackle one of the cartel’s most divisive issues: how to measure members’ maximum production capacity. The outcome will shape 2027 production baselines and, by extension, who gets to pump more oil. The politics are thorny. The UAE, having invested billions to raise capacity, wants higher quotas to match. African members, meanwhile, have seen their productive capability erode and fear losing ground. Angola quit the group entirely last year over a quota dispute, underscoring how fraught…