[Bug] Claude model degradation: Basic tasks failing (changelog updates, unit tests)

Bug Description
Since yesterday, Claude is doing the simplest tasks wrong. Like adding to the CHANGELOG planned tasks, uncommited changes, etc. Unit tests were awful,Claude insisted on keeping tests that do nothing as a way to validate the app.

Environment Info

• Platform: linux
• Terminal: WarpTerminal
• Version: 2.0.55
• Feedback ID: 137a7200-5128-475b-a0de-3af536ca8550

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /home/matias/.local/share/claude/versions/2.0.55 (expected in multi-process scenarios)\n    at tPD (/$bunfs/root/claude:2664:1622)\n    at o4A (/$bunfs/root/claude:2664:1300)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-11-30T20:39:15.107Z"},{"error":"Error: NON-FATAL: Lock acquisition failed for /home/matias/.local/share/claude/versions/2.0.55 (expected in multi-process scenarios)\n    at tPD (/$bunfs/root/claude:2664:1622)\n    at n4A (/$bunfs/root/claude:2662:34066)\n    at async kB9 (/$bunfs/root/claude:2662:35268)\n    at async vb (/$bunfs/root/claude:2664:236)\n    at async <anonymous> (/$bunfs/root/claude:2664:12465)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-11-30T20:39:23.338Z"}]