Pattern: Worktree Isolation Is Winning as the Parallel-Agent Default — and Its Bugs Are Now the Serious Ones

Claude Code Changelog·medium signal

Three separate v2.1.210/211 entries touch worktrees: isolated subagents mutating the main repo, killed sessions leaving permanent worktree locks, and always-allow rules persisting at repo root. That concentration says worktree isolation has moved from advanced trick to the assumed substrate for parallel agents. The maturity signal to watch is not new worktree features but the class of bug — these are containment failures, which is what you get once the isolation boundary is load-bearing.