Cherny says Claude Code began as a small terminal chat app he made to learn Anthropic’s API, then grew as he experimented with tool use. After giving the model Bash, he was surprised when Sonnet 3.5 used AppleScript to identify the music playing on his Mac. He shared the prototype with his team within days, and engineers began using it before it was ready.
Inside Claude Code With Its Creator Boris Cherny
Speaker
Boris Cherny, creator and engineer of Claude Code at Anthropic, talks with Y Combinator’s The Lightcone hosts about building for improving models, product iteration, and how AI is changing software work.
Early users applied Claude Code to Git, Bash, Kubernetes, and unit tests, and started writing Markdown instructions that led to CLAUDE.md. Cherny calls this latent demand: make tasks people already try to do easier. He recommends starting with minimal instructions, adding guidance when the model gets something wrong, and expecting to revise scaffolding as models improve.
Cherny describes iterating on how much tool output Claude Code shows: employees wanted Bash output visible, while file reads and searches could later be summarized as the model became more reliable. He says plan mode grew from users asking Claude to work through an idea without coding; his own sessions often start there. As models improve, he expects people to need less babysitting and some workflow features to change or disappear.
Cherny describes Claude Code teams as one way to coordinate agents with separate context windows. For a plugins feature, an engineer gave Claude a spec and an Asana board; Claude created tickets and launched agents to work on them over a weekend. Cherny also says the team uses the Claude Agent SDK for tasks such as code review, security review, issue labeling, and production workflows.
Cherny advises founders to explore what current models struggle with and build for capabilities they expect within about six months. He says Claude Code is repeatedly rewritten, with tools added or removed every few weeks and little code remaining unchanged over six months. At Anthropic, he says productivity per engineer has risen 150% since Claude Code launched, and predicts engineers will spend more time on specs, users, and product work alongside coding.
Takeaways
- Watch what users already attempt, then make that workflow easier.
- Keep model instructions minimal and add them when a repeated failure shows they are needed.
- Revisit product scaffolding as model capabilities change; yesterday’s workaround may become unnecessary.
- Use multiple agents with separate contexts for difficult research or implementation tasks.
- Build toward likely model improvements while validating ideas with users.
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What was claimed 11
- builtBoris Cherny built
Claude Code
“the creator of Claude Code”
0:08inWe Cut 80% of Claude Code’s PromptYouTube Verified6 sources· Talk, Web· archived
- uses
Anthropic uses
Claude Code
“they were writing a lot of their code with Claude Code”
6:48inHow AI is changing Software Engineering: A Conversation with Gergely OroszYouTube Verified5 sources· Talk, Job posting
- role atBoris Cherny is creator and engineer of Claude Code at
Anthropic
“the creator and engineer of Claude Code”
YouTube Unverified1 source· Talk
- uses
Claude Code uses MCP
“Because it had an MCP connection to Slack”
2:10inYour Attention Is the Bottleneck, Not Your AgentsYouTube Verified5 sources· Talk
- feature
Claude Code: Plan Mode adds the instruction “Please don't code”
“All it does is add one sentence to the prompt: “Please don't code.””
YouTube Unverified1 source· Talk
- metric
Claude Code: About 80% of Cherny’s sessions start in Plan Mode
“probably 80% of my sessions start in plan mode”
YouTube Unverified1 source· Talk
- feature
Claude Code: Started as a terminal app and later became available on web, desktop, mobile, Slack, GitHub, VS Code, and JetBrains
“now it’s on the web, in the desktop app, in the Code tab, in the iOS and Android apps, in Slack, in GitHub, and in VS Code and JetBrains extensions”
YouTube Unverified1 source· Talk
- metric
Claude Code: Most of the codebase is a couple of months old or newer
“Maybe a couple of months feels about right.”
YouTube Unverified1 source· Talk
- metric
Anthropic: Productivity per engineer grew about 70% last year
“productivity per engineer grew about 70%”
YouTube Unverified1 source· Talk
- metric
Anthropic: Productivity per engineer has grown 150% since Claude Code came out
“Since Claude Code came out, productivity per engineer at Anthropic has grown 150%.”
YouTube Unverified1 source· Talk
- featureCo-work: Runs in a virtual machine and includes deletion protection and permission prompts
“It runs in a virtual machine. There's a lot of deletion protection, permission prompts, and other guardrails”
YouTube Unverified1 source· Talk










