I Analyzed Claude Code's Leaked Source — Here's How Anthropic's AI Agent Actually Works

On March 31, 2026, Anthropic's Claude Code source code leaked — again. A 60MB source map file ( cli.js.map ) was accidentally shipped in npm package v2.1.88, exposing ~1,900 TypeScript files and 512,000 lines of code. This is the second time this has happened. The first was February 2025. Instead of just reading the headlines, I did what any curious engineer would do: I read all of it. What I Found Claude Code is not what most people think. It's not a simple chat wrapper. It's a full agentic AI runtime with: QueryEngine — A conversation loop orchestrator that manages context assembly → API calls → tool execution → response rendering 40+ Tools — File operations, shell execution, web search, MCP integration, notebook editing, and more Task System — Sub-agent orchestration for parallelizing complex work 100+ Slash Commands — /commit , /review , /security-review , /ultraplan Bridge System — Remote session control from desktop/mobile via WebSocket Plugin & Skills — User-defined extensions l