You don’t need jj for this anymore. The whole premise of optimizing human workflows around source control is becoming obsolete.

When LLMs are driving development, source control stops being an active cognitive concern and becomes a passive implementation detail. The unit of work is no longer “branches” or “commits,” it’s intent. You describe what you want, the model generates, refactors, and reconciles changes across parallel streams automatically.

Parallel workstreams used to require careful coordination: rebasing, merging, conflict resolution, mental bookkeeping of state. That overhead existed because humans were the bottleneck. Once an LLM is managing the codebase, it can reason over the entire state space continuously and resolve those conflicts as part of generation, not as a separate step.

In that world, tools like jj are optimizing a layer that’s already being abstracted away. It’s similar to how no one optimizes around assembly anymore. It still exists, it still matters at a lower level, but it’s no longer where productivity is gained.

With jj worktrees, you can even have agents working on each of those sub-megamerge branches in parallel.

I've been playing around with agent-native source annotation to specifically address the massively parallel work problem. Check it out here: https://github.com/draxl-org/draxl