Feedback and accretion toward proto-O-stars at ALMA's highest resolution I will present ALMA observations of the high-mass star-forming complex W51 in which dozens of O-stars have already formed and many more OB stars are vigorously accreting. We have used ALMA to probe scales from 200 AU to 0.5 pc both toward the known proto-O-stars and in the surrounding protocluster cloud. These data have allowed us to compare the impact of different feedback mechanisms on the formation of both low- and high-mass stars. We detect dozens of collimated outflows with lengths 0.03-0.5 pc, many of which originate in barely resolved or even unresolved sources at 200 AU resolution, which identify the accreting massive stars. Where the central source is resolved in the dust continuum, it is elongated orthogonal to the outflow. Observations of temperature probes reveal that regions within about 0.1 parsecs of these high-mass protostars are significantly warmer than their surroundings, reaching temperatures of 100-200 K. The enhanced temperature only occurs around the accreting proto-massive-stars, not around their main sequence colleagues or nearby compact HII regions. These high-mass stars are able to maintain their food source by heating their surroundings, suppressing the fragmentation of infalling and orbiting gas, thereby keeping it available for future accretion.