Claude Opus 4.7 Deep Dive — Adaptive Thinking, Mythos, and the Hallucination Lead

Claude Opus 4.7 (April 16, 2026) is Anthropic's current flagship — 87.6% SWE-bench Verified, 64.3% SWE-bench Pro, 36% hallucination rate on AA-Omniscience. Extended thinking is gone; Adaptive Thinking is in. Above Opus 4.7 sits Mythos Preview: a more capable model now available only in restricted invite-only form for defensive cybersecurity use.