Claude Sonnet 5 Becomes the Default Coding Model — 80.4% on Terminal-Bench 2.1 at ~60% of Opus 4.8's Price

Terminal-Bench·medium signal

Sonnet 5 is now the default for Pro/Team/Enterprise seats and debuted at 80.4% on Terminal-Bench 2.1 — reportedly ~97% of Opus 4.8's score at ~60% of the price — with a native 1M-token context and adaptive thinking on by default (+13.4 pts over Sonnet 4.6). For agent loops where you were routing to Opus for everything, this is the new default-tier reason to re-check your model routing on cost-per-task.