Claude Code's Agent Summary Burns 15-20% of User Tokens Generating 3-Word Status Lines

A Flamerix AI gist trending on Hacker News documents that Claude Code's agent_summary feature sends every background agent's full transcript to Opus every ~30 seconds to generate a 3-5 word status line, burning 15-20% of total token spend. OpenTelemetry logs from one user's week show agent_summary accounting for 16.4% of Claude Code spend and 19.7% of all API requests, with input-to-output around 9,000:1. The feature has been on by default since version 2.1.232 in August 2026 with no toggle to disable it; the gist ships a Bun preload script that suppresses the timers without patching the binary.