When Your JavaScript Runtime and LLM Provider Become One Company

Anthropic's acquisition of Bun in December 2025 means teams using its JavaScript runtime alongside Claude Code and Anthropic's LLM service now depend on a single vendor for their entire AI stack. With recent LLM billing incidents showing vendor-side cost controls consistently fail, teams must implement out-of-band budget enforcement—local cost checks that execute before API calls leave the application—to protect against runaway spending.