Inside Claude Code: A Source-Level Architectural Analysis

Sunday, Apr 12, 2026 | 1 minute read | Updated at Sunday, Apr 12, 2026

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Inside Claude Code: A Source-Level Architectural Analysis

AUTHOR: Zhuoran Yang

AFFILIATIONS: Department of Statistics and Data Science, Yale University

LINKS: GitHub: Source & Data  |  Explorer: Interactive Code Explorer

Overview

A 20-post deep-dive into the architecture of Claude Code (v2.1.88), Anthropic’s AI coding agent — 512K lines of TypeScript, approximately 40 tools behind a three-tier permission system, and ML classifiers that gate every shell command. Topics span the agent loop, context engineering, prompt assembly, tool system, safety sandbox, multi-agent orchestration, MCP, skills, plugins, and more.

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