# Use parallel agents to migrate code and filter false positives

Markdown copy of https://realalpha.app/s/use-parallel-agents-to-migrate-code-and-filter-false/ on Real Alpha, the best minutes from long interviews with the people building AI. Cite and link the page, not this copy.

- Speaker: [Boris Cherny](https://realalpha.app/builders/boris-cherny/) · Creator of Claude Code, Anthropic · Created Claude Code at Anthropic and leads its team; previously spent about five years at Meta.
- Host: [Dan Shipper](https://realalpha.app/people/dan-shipper/) · Co-founder & CEO, Every · Sold his first startup, Firefly, to Pegasystems; writes Every's Chain of Thought.
- Show: AI & I
- Episode: [The Secrets of Claude Code From the Engineers Who Built It](https://realalpha.app/v/IDSAMqip6ms/), Oct 29, 2025
- Moment: 21:43 to 26:17 of the episode (5 min), playing on https://realalpha.app/s/use-parallel-agents-to-migrate-code-and-filter-false/; the episode from there: https://realalpha.app/v/IDSAMqip6ms/?t=1303

## Quote

> “And so then we spawn like **five more subagents**. And these are all just like checking for false positives.”
> — [Boris Cherny](https://realalpha.app/builders/boris-cherny/) at [22:57](https://realalpha.app/v/IDSAMqip6ms/?t=1377) · AI & I

## Takeaways

1. Give subagents separate checks, such as history, bugs, and conventions.
2. Use follow-up agents to check findings for false positives.
3. Migrations are a strong fit when output is easy to verify.

## About this segment

Boris Cherny describes splitting code review and migrations across subagents, then using more agents to check their findings. Parallel work can speed up large changes without trusting every result blindly.

From “The Secrets of Claude Code From the Engineers Who Built It”, Oct 29, 2025. [Watch the full episode](https://realalpha.app/v/IDSAMqip6ms/)

## Transcript

From the transcript AI & I publishes with the episode.

[21:47](https://realalpha.app/v/IDSAMqip6ms/?t=1307) And if you don't do this, then all models are going to equal. But if you give it a pretty hard task, you can tell the difference. What subagents do you use? I have a few. I have like a planner subagent that I use. I have a code review subagent. Code review is actually something where sometimes I use a subagent. Sometimes I use a slash command. So usually in CI, it's a slash command. But in synchronous use, I use a subagent for the same thing.

[22:11](https://realalpha.app/v/IDSAMqip6ms/?t=1331) Um, it's a good question. Yeah, maybe it's like a matter of taste. Yeah, I don't know. I don't know. I think it's maybe when you're running synchronously, it's kind of nice to fork off the context window a little bit, because all the stuff that's going on in the code review, it's not relevant to what I'm doing next. But in CI, it just doesn't matter. Are you ever spawning like 10 subagents at once?

[22:33](https://realalpha.app/v/IDSAMqip6ms/?t=1353) And for what? For me, I do it mostly for big migrations. Okay. That's the big thing. Actually, we have this coder.reus slash command that we use. There's a bunch of subagents there. And so one of the steps is find all the issues. And so there's one subagent that's checking for QuadMD compliance. There's another subagent that's looking through Git history to see what's going on. Another subagent that's looking for kind of obvious bugs.

[22:55](https://realalpha.app/v/IDSAMqip6ms/?t=1375) Yeah. And then we do this like kind of deduping quality step after. So they find a bunch of stuff. A lot of these are false positives. And so then we spawn like five more subagents. And these are all just like checking for false positives. And in the end, the result is awesome. It finds like all the real issues without the false issues. That's great. I actually do that. So one of my non-technical cloud code use cases is expense filing.

[23:18](https://realalpha.app/v/IDSAMqip6ms/?t=1398) So like when I'm in SF right now, so like I have all these expenses. So it uses one of these, you know, finance APIs to just download all my credit card transactions. And then it decides, like, these are probably the expenses that I'm going to have to, like, file. And then I have two subagents, one that represents me and one that represents the company. And they, like, do battle to, like, figure out, like, what's the proper, like, actual set of expenses it's like an auditor or subagent and like you know pro dan subagent so um yeah that kind of thing the the sort of like opponent processor uh pattern seems to be like an interesting one yeah yeah it's it's it's it's cool i i feel like when subagents were first becoming a thing actually when inspired us there's like a reddit thread a while back

[24:05](https://realalpha.app/v/IDSAMqip6ms/?t=1445) where someone made subagents for like there was like a front-end dev and a back-end dev and like a i think like a designer testing dev like there was like a pm subagent and this is like you know it's cute like it feels like a little maybe too anthropomorphic um maybe maybe there's something to this but i i think like the value is actually like the uncorrelated context windows we have these two context windows that don't know about each other and this is kind of interesting um and you tend to get better results this way what about you do you have any interesting subagents you use So I've been tinkering with one that is really good at front-end testing.

[24:37](https://realalpha.app/v/IDSAMqip6ms/?t=1477) So it uses Playwright to see, all right, what are all the errors that are client-side and pull them in and try to test more steps of the app. It's not totally there yet, but I'm seeing signs of life. And I think it's the kind of thing that we could potentially bundle in one of our plugins marketplaces. Yeah, definitely. I've used something like that just with Puppeteer and just like watching it build something and then open up the browser and then be like, oh, I need to change this.

[25:08](https://realalpha.app/v/IDSAMqip6ms/?t=1508) It's like, this is like, oh, my God. Yeah, it's really cool. It's really cool. I think we're starting to see the beginnings of this like massive, like multi massive sub agents. I don't know what to call this, like swarms or something like that. There's a bunch of people, there's actually an increasing number of people internally at Anthropic that are using like a lot of credits every month, like spending like over a thousand bucks every month.

[25:29](https://realalpha.app/v/IDSAMqip6ms/?t=1529) And this percent of people is growing actually pretty fast. And I think the common use case is code migration. And so what they're doing is framework A to framework B, there's the main agent and makes a big to-do list for everything, and then just kind of map reduce over a bunch of sub-agents. So you instruct a lot of like, yeah, start 10 agents, and then just go 10 at a time and just migrate all the stuff over.

[25:50](https://realalpha.app/v/IDSAMqip6ms/?t=1550) That's interesting. What would be a concrete example of the kind of migration that you're talking about? I think the most classic is like lint rules. So there's like, you know, there's some kind of lint rule you're rolling out. There's no autofixer because it's like, you know, like AST analysis can't really. It's kind of too simplistic for it. I think other stuff is like framework migrations. Like we just migrated from like one testing framework to a different one.

[26:12](https://realalpha.app/v/IDSAMqip6ms/?t=1572) That's a pretty common one where it's super easy to verify the output.