Anthropic identified and resolved three separate issues that degraded Claude Code quality between March and April 2026: a change to default reasoning effort, a caching bug that caused progressive context loss, and a verbosity-reduction prompt that hurt coding performance. The central technical issue was a bug in the clear_thinking API that repeatedly cleared reasoning history throughout sessions rather than just once, causing the forgetfulness and odd tool choices reported by users. All issues were fixed by April 20 and usage limits were reset for affected subscribers.
