CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING

Description

Environment variable confirmed by Boris Cherny as the interim workaround for the zero-reasoning adaptive thinking bug. When set to '1', forces a fixed high reasoning budget instead of letting the model decide per-turn reasoning allocation. Key fix for fabrication-on-zero-budget turns introduced by the Opus 4.6 (Feb 9, 2026) switch from fixed thinking budgets to adaptive thinking default.

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Sources

src-20260409-35a0e20bf159