Claude Code 2.1.154: Dynamic Workflows Orchestrate Hundreds of Agents in Background

Claude Code Changelog·high signal

The May 28 release makes Opus 4.8 the default model with high effort, introduces dynamic workflows that orchestrate tens to hundreds of agents in the background (viewable via /workflows), and ships a lean system prompt as default for all models except Haiku, Sonnet, and Opus 4.7. Fast mode on Opus 4.8 is 3x cheaper than previous models at 2x standard rate for 2.5x speed. Also includes plugin defaultEnabled:false, improved data exfiltration detection, and the ability to run shell commands as attachable background sessions via `! <command>`.