Imagine a solo maintainer waking to three hundred AI-generated pull requests overnight, each plausible, none tested. Define open source as code under licenses that guarantee use, study, modification, and sharing. Define AI agents as autonomous systems that generate, consume, and modify code at scale. My framework is sustainability: can volunteer communities absorb that volume and keep their licenses meaningful? They cannot. Agents can strip attribution, clone functionality instantly, and turn maintainers into unpaid data suppliers for closed models. The other side may point to AI-assisted coding, but that helps producers, not the commons. Open source as we know it is doomed.