How to AI Code in parallel
Great (as usual) post from Simon Willison https://simonwillison.net/2025/Oct/5/parallel-coding-agents/
References couple of other good posts:
Jesse Vincent wrote How I’m using coding agents in September, 2025 which describes his workflow for parallel agents in detail, including having an architect agent iterate on a plan which is then reviewed and implemented by fresh instances of Claude Code.
In The 7 Prompting Habits of Highly Effective Engineers Josh Bleecher Snyder describes several patterns for this kind of work. I particularly like this one:
Send out a scout. Hand the AI agent a task just to find out where the sticky bits are, so you don’t have to make those mistakes.
I’ve tried this a few times with good results: give the agent a genuinely difficult task against a large codebase, with no intention of actually landing its code, just to get ideas from which files it modifies and how it approaches the problem.
Peter Steinberger’s Just Talk To It—the no-bs Way of Agentic Engineering provides a very detailed description of his current process built around Codex CLI.
Extras
It starts from the moment you fire up your coding agent. As soon as it sees that you're building something, it doesn't just jump into trying to write code. Instead, it steps back and asks you what you're really trying to do.
Once it's teased a spec out of the conversation, it shows it to you in chunks short enough to actually read and digest.