I avoid this with one spec = one agent, with worktrees if there is a chance of code clashing. Not ideal for parallelism though.

The worktree approach is interesting - keeps the filesystem separation clean. The parallelism tradeoff makes sense if the tasks are truly independent, which in practice is most of the time anyway.

What does your spec file look like when you kick off a new agent? Curious if you start from scratch each time or carry over context from previous sessions on the same project.