Anthropic Traces Six Weeks of Claude Code Quality Complaints to Three Overlapping Product Changes
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Anthropic's Claude Code postmortem is highly novel, technical, and directly relevant to AI agent quality.
Anthropic traced six weeks of Claude Code quality complaints to three overlapping product changes shipped between March and April 2026: a reasoning effort downgrade from high to medium (reverted April 7), a caching bug that cleared reasoning history on every turn instead of once after idle (fixed April 10), and a system prompt verbosity limit of 25 words between tool calls and 100 for final responses (reverted April 20). All issues resolved by v2.1.116; API and model weights were unaffected. Notably, Opus 4.7 could identify the caching bug when given repository context, while Opus 4.6 could not.