[Bug] Model Performance Degradation: Increased Errors and Instruction Non-Compliance

Bug Description
Claude Code was wonderful up until april came. It started doing obvious mistakes, cutting corners, taking shortcuts, ignoring orders... to the point where it's almost unusable.

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.92
• Feedback ID: a4fef58a-f3eb-4363-94d6-e1df38f340e6

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/pmh/.local/share/claude/versions/2.1.92 (expected in multi-process scenarios)\n    at im_ (/$bunfs/root/src/entrypoints/cli.js:1884:2153)\n    at An6 (/$bunfs/root/src/entrypoints/cli.js:1884:1233)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-07T19:59:03.100Z"}]