Evidence-backed signal

Anthropic releases Sonnet 4.5 alongside agent development and context-management tools. Long-horizon vendor demonstrations do not establish unattended success rates across real production tasks.

supported inference 90% confidence increasing

Downward provenance

event

Claude Sonnet 4.5 is released

Mon Sep 29 2025 00:00:00 GMT+0000 (Coordinated Universal Time)
96% confidence
artifact

Claude Sonnet 4.5 is released

official_announcement
art-2025q3-sonnet45
original source

Claude Sonnet 4.5 is released

Anthropic
src-2025q3-sonnet45