Show HN: Open-agent-SDK – Claude Code's internals, extracted and open-sourced (github.com)

Claude Code's source map leaked last month. Instead of just reading it, I fed the entire source into Claude Code itself and asked it to extract the core agent loop logic.

The result: open-agent-sdk — a drop-in replacement for claude-agent-sdk that's fully open source and doesn't spawn a CLI subprocess.

Why this matters if you've built with claude-agent-sdk:

claude-agent-sdk is just a thin wrapper around the Claude Code binary. It works, but it's a black box — when something breaks, you're stuck.

Every query creates a new Claude Code process. That's fine on a laptop, not fine when you're running thousands of concurrent agents in the cloud.

What open-agent-sdk does differently:

Pure function calls, no CLI process spawning — cloud-native from day one Fully compatible interface with claude-agent-sdk — swap the package name, done

MIT licensed — fork it, patch it, make it yours

→ https://github.com/codeany-ai/open-agent-sdk-typescript