Inside the Claude Code source

Anthropic's Claude Code CLI source code leaked onto GitHub recently. All of it. About 1,900 files and a lot of TypeScript.

Claude Code CLI's source code was recently leaked on GitHub. This post breaks down how the system works, where Anthropic made clever engineering choices. Claude Code is about 500,000 lines of TypeScript, with the actual API call comprising 200 of them. Everything else in the harness.

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