Use it now Notable
Adaptive thinking is now default; an env var can revert to the old mode for certain models.
Adaptive thinking mode is now the shipped default for per-turn thinking behavior. Setting CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING forces the older enabled mode instead, but only when the canonical model name includes opus-4-6 or sonnet-4-6; otherwise adaptive mode applies as normal.
Names in the bundleCLAUDE_CODE_DISABLE_ADAPTIVE_THINKING
Documented inclaude-code/desktop
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed since
Anthropic's documentation has since written up CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING, on Connect Claude Code to an LLM gateway.
| `400` errors naming `thinking` or `adaptive`, such as `Input tag 'adaptive' found` | The upstream model build doesn't accept adaptive reasoning, which Claude Code requests for Claude 4.6 and later models | Upgrade the gateway's upstream.…llm-gateway-connect see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING, on Connect Claude Code to an LLM gateway.