Cursor Team Unveils Agent Swarm System: Fable 5 Task Cost Reduced to $1,300

The Cursor team has developed an Agent Swarm system that automates implementing SQLite from scratch for the Fable 5 task. The new tree architecture uses a strong model for planning and cheap models for execution, drastically cutting costs ($1,300 for Opus planning + Composer execution vs. $9,373 for pure GPT-5.5). The article highlights that context division, not parallelism, is key for scaling large AI tasks, and outlines five coordination failure modes and countermeasures.