TL;DR
I started running multiple autonomous Claude Code sessions on the same repo at once to speed things up, and it backfired — collisions, half-written diffs, and one memorable case where two agents "fixed" the same bug in opposite directions. Git worktrees fixed it. Here's what I learned about isolating parallel agents, when isolation is actually worth the overhead, and how to merge the results back without losing your mind.
The Problem
Once you've got one autonomous coding agent working reliably, the obvious next move is: why not run three? Three agents, three tasks, done in a third of the time.
I tried it on a single checkout of the repo. Bad idea.
