A Fireside Chat with Cat and Thariq from the Claude Code team

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A Fireside Chat with Cat and Thariq from the Claude Code team

21st July 2026

Earlier this month I hosted a fireside chat session at the AI Engineer World’s Fair with Cat Wu and Thariq Shihipar from Anthropic’s Claude Code team. We talked about Claude Code, Claude Tag, Fable, coding agent security, evals, tool design, and how Anthropic use these tools themselves.

The full video of the session is now available on YouTube. Below is an edited copy of the transcript, with extra links and my own bolded highlights.

A few top-level notes if you don’t want to watch the video or wade through the whole transcript:

Claude Tag (Claude’s new collaborative Slack integration) now lands 65% of the product engineering PRs for the Claude Code team.

Claude Code ships features to Anthropic employees first, and only ships the features that demonstrate user retention with that cohort

Critical changes to Claude Code are still reviewed manually, but the team increasingly relies on automated code review for the “outer layers” of the product.

Adding examples to a system prompt is no longer best practice for models like Fable 5 or even Opus 4.8. The Claude Code system prompt recently reduced in size by 80% .

Likewise, lists of "don’t do X and don’t do Y " can reduce the quality of results from the latest models.

Dogfooding inside Anthropic is called "ant fooding ".

Anthropic really believe in their auto mode , and see that as an enabling technology for Claude Tag.

Thariq advises offsetting coding-agent-induced Deep Blue by "being more ambitious " with the work you take on.

Fable is competent at editing video , and Thariq used it to edit its own launch video.

Anthropic’s culture of working (internally) in public is key to their success, as demonstrated by the way they use Claude Tag in their public Slack Channels.

How has what you do day-to-day changed in the past year?

1:05

Simon: Claude Code came out in February of last year — it’s under a year and a half old, and it was originally just a bullet point on the Claude Sonnet 3.7 launch. How has what you do on a day-to-day basis changed in the past year , now that we have these coding agents that actually work for us?

Cat: I remember when we first came out with Claude Code and Sonnet 3.7, you would give it a task and you would have to closely monitor every single little thing it tried to do. I would read every permission prompt extremely carefully. I would frequently say no — no, no, no, did you check this file? Did you check that file? And now it’s been incredible with every model generation. I feel like we’ve all gotten a chance to take a step back and delegate a lot more of the menial implementation to Claude . It’s freed up a lot of our time to think about more creative work, like: what is the right experience that we should be providing to our users, now that we know Claude Code can implement a lot of it? And now with Fable it’s a totally different step change improvement. We see for a lot of our use cases that you can actually one-shot a ton of features with Fable now .

Thariq: I remember the first text I got about Claude Code. One of my best friends was like, “You need to go try Claude Code.” It was about when Opus 4 came out, and I tried it and I was like, “Oh, shit. I need to work at Anthropic now.” And that was Opus 4 — great model, but you were reading permission prompts. It’s kind of crazy how much amnesia we have, where I’m like, oh, auto mode has always been here, right? I don’t even remember pressing yes and allow. For me, the big thing I’m trying to push myself on is that we have to do higher quality work than we’ve ever done before . The outputs are incredibly high quality. I’ve been using it to edit videos a bunch , and I’m like, okay, it has to meet the very exacting demands of our brand team in a couple of hours or we just can’t do it. That’s how I’m trying to shift with Fable: the best work we’ve ever done, faster than we’ve ever done it before .

What piece of conventional software engineering no longer holds?

3:39

Simon: What’s a piece of conventional software engineering that was true a year ago that you don’t think holds anymore in this new world?

Cat: One of the biggest shifts we’re seeing in the eng skill set: two years ago it was pretty typical for a product manager to go talk to a bunch of customers, align over the course of six months with cross-functional teams on some PRD, and write a thorough spec on exactly how we’ll implement this before the first line of code gets written. Now things are completely turned the opposite way. For a lot of engineers, the push I would give to folks in the room is to develop...