Claude Developer Platform Release Notes

• We've launched Claude Opus 4.6, our most intelligent model for complex agentic tasks and long-horizon work. Opus 4.6 recommends adaptive thinking (thinking: {type: "adaptive"}); manual thinking (type: "enabled" with budget_tokens) is deprecated. Opus 4.6 does not support prefilling assistant messages. Learn more in What's new in Claude 4.6.

• The effort parameter is now generally available (no beta header required) and supports Claude Opus 4.6. Effort replaces budget_tokens for controlling thinking depth on new models.

• We've launched the compaction API in beta, providing server-side context summarization for effectively infinite conversations. Available on Opus 4.6.

• We've introduced data residency controls, allowing you to specify where model inference runs with the inference_geo parameter. US-only inference is available at 1.1x pricing for models released after February 1, 2026.

• The 1M token context window is now available in beta for Claude Opus 4.6, in addition to Sonnet 4.5 and Sonnet 4. Long context pricing applies to requests exceeding 200K input tokens.

• Fine-grained tool streaming is now generally available on all models and platforms (no beta header required). The output_format parameter for structured outputs has been moved to output_config.format.

Structured outputs

• Structured outputs are now generally available on the Claude API for Claude Sonnet 4.5, Claude Opus 4.5, and Claude Haiku 4.5. GA includes expanded schema support, improved grammar compilation latency, and a simplified integration path with no beta header required. The output_format parameter has moved to output_config.format. Existing beta users can continue using the beta header during the transition period. Structured outputs remain in public beta on Amazon Bedrock and Microsoft Foundry.

• We've retired the Claude Opus 3 model (claude-3-opus-20240229). All requests to this model will now return an error. We recommend upgrading to Claude Opus 4.5, which offers significantly improved intelligence at a third of the cost. Researchers can request ongoing access to Claude Opus 3 on the API through the External Researcher Access Program.