Claude Sonnet 4

A context window routing error caused requests to be misrouted to incorrect server configurations, with sticky routing amplifying the impact. At peak, 16% of Sonnet 4 requests were affected, with fix rollout spanning multiple platforms over weeks.

A precision mismatch bug in the XLA:TPU compiler caused incorrect token selection by the approximate top-k operation, affecting Haiku 3.5 and potentially Sonnet 4 and Opus 3. The issue was masked by a previous workaround that was inadvertently removed.