Parallel agents from throwaway /tmp checkouts, no worktrees

Run Claude Code and Codex in parallel from fresh /tmp checkouts. Simon Willison's parallel-agent workflow.

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what to steal

For quick parallel tasks, a fresh clone in /tmp beats worktree bookkeeping.

Our takeaway from the source, not a quote.

Drawn from this card's sourced fields. Amber = older model named by the source. Rose = cut or replaced.

willison-parallel-agents.toml

# Run Claude Code and Codex in parallel from fresh /tmp checkouts
# source: https://simonwillison.net/2025/Oct/5/parallel-coding-agents/

[rig]
who     = "Simon Willison's parallel-agent workflow"
author  = "Simon Willison"
date    = "2025-10-05"

harness = ["Claude Code", "Codex"]
models  = ["Claude Sonnet 4.5", "GPT-5-Codex"]

[keep]
  - YOLO mode for safe tasks
  - Fresh checkouts in /tmp
[cut]
  - Git worktrees

⚠ Claude Sonnet 4.5, GPT-5-Codex: older model(s), named by the source on 2025-10-05. See current models.

thing	status	why (per source)
Git worktrees	not used	Uses fresh checkouts in /tmp instead

Source: https://simonwillison.net/2025/Oct/5/parallel-coding-agents/ · checked 2026-10-14

Claude manages, Codex grinds

steal → Use one model to plan architecture and another to churn through build steps.

Claude CodeCodex Claude Fable as manageGPT-6 Astra on Codex

by @Merlin412188240

~/rigs/stefancrncic-t3-three-machin….toml𝕏 · 2026-10-13

Five harnesses, three machines, one orchestrator

steal → Install several harnesses on worker machines and drive them from one place.

Claude CodeCodexCursor

by Stefan (@stefancrncic)

~/rigs/mikeholp-route-claude-codex.toml2026-10-11

Route by task type and make each agent review the other

steal → Have the agent that didn't write the change review it.

Claude CodeCodexCursor Claude Opus 5.5Claude Sonnet 5.5 git push / commit in C

by Mike Holp