Claude Opus 4.6 Blocks Kaggle Competition Workflow for Code Review

What Happened

A developer using Claude AI for Kaggle competition work reports that Opus 4.6 is now blocking legitimate workflows. The user emphasizes this is not a bug but a policy change affecting their specific use case.

Specific Workflow Details

The developer is working on the NVIDIA Nemotron Reasoning Challenge, a public competition active on Kaggle. Categories in the competition include:

• Binary arithmetic
• Substitution ciphers
• Roman numerals
• Unit conversion
• Gravity
• Similar toy reasoning tasks

Their workflow involves:

• Reverse-engineering all 9,500 competition problems across 8 categories
• Building their own DSL trace factories in Python
• Writing solvers for the problems
• Generating synthetic training data with reasoning traces
• Using Claude to audit sample batches for format compliance and verbosity calibration before committing to training

The Blocking Incident

The specific trigger was when the user pasted a substitution cipher training example containing plaintext to ciphertext pairs like "king watches cave" to "lyvawpo ayjp" with a step-by-step reasoning trace. Claude paused the chat with the message: "safety filters flagged this chat," and offered to retry with Sonnet 4.

User Clarification

The developer explicitly states they are NOT using Claude to:

• Think for them
• Solve puzzles for them
• Reverse-engineer the competition

They emphasize: "Claude's role here is auditing reasoning traces I generate to make sure my SFT training data is well-formed before I spend compute fine-tuning on it. That's it. Claude is a code reviewer for already-solved problems."

Timing and Context

The user notes they've experienced similar issues before, right around the time Opus 4.5 transitioned to 4.6, when safety settings were noticeably tightened. They speculate this might indicate another model is coming within the next month, but the immediate impact is affecting their work.