Anthropic forced adaptive thinking on Claude models, deprecating fixed budgets. Users report quality drops and the change reduces API revenue potential. Anthropic deprecated manual extended thinking budgets for Claude Opus 4.7, returning a 400 error for fixed budget requests. Opus 4.6 and Sonnet 4.6 still support manual configuration but it is deprecated and will be removed in a future release. Key facts Opus 4.7 returns 400 error for fixed thinking budget requests. Opus 4.6 and Sonnet 4.6 manual thinking deprecated, removal planned. Users report quality drop after adaptive thinking became default. Anthropic has not published benchmarks comparing adaptive vs fixed thinking. Fourth API/subscription change in six weeks from Anthropic. Anthropic has deprecated manual extended thinking budgets for its latest Claude models, forcing adaptive thinking as the default.…