Root cause: 90% of system prompts exceed max_seq_len (2048 tokens)
by 2.5x, so model trained on truncated fragments with no user/assistant
content. Plus mixed paradigm (55% tool_call / 45% JSON), 6 JSON schema
variants, contaminated examples, and /no_think misuse.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Mortdecai