• Anthropic platform engineering head Katelyn Lesse said that Claude now writes all her team's code.
• Lesse shared ways that Claude Code has helped the company become more efficient.
• Anthropic nears an initial public offering at a potential $2 trillion valuation.

A top Anthropic engineer says that Claude Code has already wiped out all human coding at one of the AI lab's central teams.

Katelyn Lesse leads the AI startup's platform engineering group, which handles the company's core services, developer tools, and product infrastructure — it's essentially the engine room of Anthropic. Lesse said at Grafana Labs' ObservabilityCON event on Tuesday that among her staff, which tallied 200 as of this summer, the era of human-written code is fully over.

"When it comes to our team and how we're actually building and maintaining our systems, all of our code is written by Claude," Lesse said. "Like, literally all of it."

Anthropic's heavy reliance on Claude Code has helped it remain relatively small, as it approaches an initial public offering that could value it at nearly $2 trillion. The company's revenue growth slowed in the third quarter of this year. Maintaining its lofty valuation may depend on selling more companies on the AI-first approach espoused by Lesse and other Anthropic leaders.

Lesse said that people on her teams are still designing systems and verifications, and then offloading the actual coding to Claude. She said that when the company changed the programming language of a major codebase from Python to Rust, workers developed a way to verify the final product.

"But the grunt work of building the pieces and actually monitoring the pieces and actually making sure that we felt good about it, that was agents all the way down," Lesse said.

Lesse said Anthropic already lets agents fix tests autonomously, with no human interaction, and it's thinking about how staff can get comfortable with agents autonomously making changes to the actual codebase, given the improvements in AI models over the last year.

"As engineering leaders, we're like terrified, and we're like, let's be really careful about this, but I think the line is starting to push," Lesse said.

Anthropic has also embraced Claude Code companywide. It released a report last week saying that as AI agents have worked more inside the company, it has hired for a smaller share of junior technical positions. And in May, Anthropic said that Claude then wrote more than 80% of the entire company's production code.

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• A sign instructing San Francisco gym-goers not to vibe code between sets went viral.
• The sign was an "AI-generated fake," according to the gym.
• Amid tech's vibe-coding obsession and fitness boom, it's no surprise the image has gotten heat.

Don't hog the leg press while prompting Claude.

A screen with the logo of Fitness SF, a Bay Area chain of gyms, went viral among techies on X and Instagram on Monday. The image instructed gym-goers to refrain from writing code or prompting AI during their workouts. "Be present. Lift harder. Ship later," the image reads.

Troy Macfarland, Fitness SF's director of marketing, said, however, that the image was an "AI-generated fake." The gym does have etiquette signs that mention phone usage and being courteous, he wrote, but none mention vibe coding.

"This person altered our actual images displayed on the screen," Macfarland wrote. "I will give an 'A' for creativity to him."

It's not clear whether the image was generated with AI, Photoshop, or some other tool. Ian Brash, whose post with the image got almost 7,000 likes, did not respond to a request for comment.

In San Francisco's AI mania, it's no surprise a sign like that blew up on X. Techies weighed in, cracking their own jokes about how tied they were to their coding agents.

One X user told Fitness SF to give their copywriter a raise. A Cognition engineer said that vibe coding between sets was encouraged at his company's gym.

"Vibe coding at the gym?" one X user wrote. "You're worried about the wrong weights."

One reaction image often appears in the comment sections of posts like this one. It shows a muscled man, holding a giant nuclear bomb in his hands, jumping into the city of San Francisco. One VC posted it with the message: "Even I have limits."

Claude Code and cardio

The sign tapped into two of the buzziest subcultures in tech.

First, there's AI coding. Ever since the launch of Claude Code and OpenAI's Codex, engineers have been tied to their phones (or walking around with half-open laptops) to continue building. Some techies told Business Insider that their love of vibe coding created distance between them and their girlfriends.

Then there's the gym. Tech bros are getting fit, pumping themselves full of peptides and getting shredded at early-morning Equinox sessions. A developer at the gym used to be an anomaly; now, it's the norm.

Some techies seemed skeptical from the start. One X user quoted the post, writing that there was "no way this is real."

Another user responded that they didn't know about that specific sign, but they did know about the underlying issue. "This is a real problem at the Equinox in San Francisco," they wrote.

• Google is injecting more AI into the interview process.
• The company has been testing a new format that tests candidates on their AI fluency.
• The pilot has recently rolled out more broadly across Google, internal docs show.

AI is changing how Google employees work — and how Google hires them.

The company has been testing several AI-related changes to its hiring process for software engineers, according to documents reviewed by Business Insider. These changes, which Google has been rolling out in phases throughout this year, include allowing the use of AI in coding interviews and permitting interviewers to use Gemini to give candidates feedback.

Many engineers are also now expected to show some degree of AI fluency as a bare minimum, the documents show.

In May, Business Insider reported that Google was piloting ways to integrate AI into the interview process with a small handful of orgs. This included a new "code comprehension" interview in which candidates are assessed on AI fluency and prompt engineering. Candidates can also use Google's Gemini AI as an assistant during the interview.

The new formats have since been rolled out more broadly across the company, according to the internal documents. However, a spokesperson said they were still considered to be in the pilot phase for now.

"We're piloting updates to our interview process for software engineers, including evaluating for AI fluency, to be more reflective of how our teams are operating," Brian Ong, vice president of recruiting at Google, told Business Insider in a statement.

Like other companies, Google is adapting its hiring process to keep pace with the huge transformation AI is having on software engineering. As developers increasingly rely on AI coding assistants, hiring companies want to know how competent they are with these tools.

In April, Google said that three-quarters of new code created at the company is generated by AI and reviewed by humans, a trend that has since continued across the tech industry. Google has said that its employees are increasingly using the company's own Gemini models to both improve other Google products and to build the next generation of Gemini.

The documents say that for some roles, including software engineering, AI fluency and AI product integration are now used as measures of a candidate's abilities. A Google spokesperson said that AI fluency is a requirement for all software engineering jobs, while AI product integration is required for most roles outside entry-level positions.

Google is also piloting the use of Gemini for interview transcription and note-taking in some job interviews conducted via the company's videoconferencing platform, Google Meet, one document shows.

Google wants to speed up the feedback process using AI, too. The same document states that Google is working to enable interviewers to use Gemini to draft role-tailored feedback.

As Google builds out this new interview system, employees were told they may be asked to participate in some of the pilots — but were warned against using AI tools to generate their own interviewing "solutions."

"Do not use GenAI or LLMs to create your own standalone solutions or agents for hiring or interviewing use cases," the document states, referring to large language models.

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