Claude’s Custom Agent Creator (Wizard) Update

On March 31st, 2026, researcher Chiao Fanhaw discovered that Anthropic had accidentally leaked their Claude Code source code through a routine update to version 2.188 on the NPM registry. The leak contained 512,000 lines of TypeScript across nearly 2,000 files, caused by human error when a debug file was included in the public release. The post about the leak received over 21 million views and was forked over 10,000 times on GitHub before Anthropic confirmed the incident and implemented measures to prevent future occurrences.

The leaked code revealed Claude Code's agentic harness - the software layer that manages tools, memory, and tasks - rather than the actual model weights or training data. Key discoveries included feature flags for unreleased capabilities, a background daemon called Chyros that maintains work during idle periods, a three-layer memory system, internal model code names, and a hidden Tamagotchi-style virtual pet.

The most significant discovery was the custom sub-agent system with an interactive wizard accessed through the 'arch agents' command. This system allows users to create specialized AI workers with configurable parameters including name/description (for task routing), model selection (Sonnet for efficiency, Opus for complex reasoning), tool access restrictions, memory persistence, and scope settings. Sub-agents solve context window limitations by spawning separate processes with clean contexts for specific tasks, moving beyond Claude Code's original single-session approach.

The leaked code also revealed future developments including Chyros for always-on background processing and agent teams (already shipped experimentally with Opus 4.6) that enable multiple Claude sessions to work as coordinated teams. The speaker positions this evolution as transforming Claude Code from a terminal assistant into a multi-agent orchestration platform, emphasizing that users who master custom agent creation will have significant productivity advantages.