[Bug] Claude Opus ignoring documented project context for Docker configuration

Bug Description
Subject: Opus regression — model ignoring documented project context (again)

Hey Anthropic,

I have to flag what looks like another quality regression on Opus.

I run dockerized Rails applications. The setup is documented in CLAUDE.md / AGENTS.md / README files at
the project root. For weeks, models read those files, picked up that everything runs through Docker,
and used docker compose run / docker compose exec without issue. It just worked.

For the last 2–3 days, the same model on the same projects suddenly bypasses all of that. It tries to
run bin/rails, bundle, rspec directly on the host. Of course it fails — I'm on macOS with system Ruby
2.6, the project needs 3.3, gems aren't installed locally, and that's exactly the reason the project is
dockerized in the first place. The model then flails: tries to switch Ruby versions, suggests gem
install bundler, asks me about rbenv. None of which is necessary because the answer is in the file it
was supposed to read at session start.

This is not a prompting problem on my end. The instructions haven't changed. The repo hasn't changed.
The only thing that changed is whatever you shipped on your side.

So a few honest questions:

1. Did you silently nerf Opus again? Quantization, routing, "efficiency improvements," whatever you

want to call it?

1. If yes — when's the post-mortem? Because last time we got one a month later, after thousands of

users had already eaten the degraded output and burned tokens debugging your regression instead of
their code.

1. If no — what changed? Because something clearly did, and "it's just vibes" is not a satisfying

answer when I'm paying Max-tier prices.

Stop shipping silent quality changes to the most expensive model in the lineup and pretending nothing
happened until people complain loud enough on Twitter. If a model gets cheaper to serve at the cost of
quality, say so. Give us a switch. Don't quietly downgrade the thing we're paying premium for.

Frustrated,

Environment Info

• Platform: darwin
• Terminal: vscode
• Version: 2.1.119
• Feedback ID: b907d92f-4a7a-418b-a452-e40b860f38d7