What's New in Claude Sonnet 4.6? A Developer's Feature Checklist
Dillip Chowdary
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Founder & AI Researcher
February 15, 2026 — Anthropic's product velocity is accelerating. The release of Claude Sonnet 4.6 brings a suite of new capabilities that go beyond simple "intelligence" upgrades. Here is the definitive checklist of what is new.
1. Ephemeral Style Tuning
This is the biggest quality-of-life update. Instead of fine-tuning, you can now pass a `style_reference` object in your API call. This lets you enforce brand voice (e.g., "Terse Engineer" vs. "Friendly Support Agent") without training a custom model.
2. The Batch API (50% Off)
For asynchronous tasks like data labeling or nightly report generation, the new Batch API offers a 50% discount if you can wait up to 24 hours for results. This makes high-volume processing viable for startups.
3. 1M Context Window (Beta)
Previously exclusive to Opus, the 1 Million Token Context Window is now available in beta for Sonnet 4.6. This allows mid-tier models to analyze entire codebases or legal dockets at a fraction of the cost.
Community Note: Looking for a dev team to hack on these new features? Find local co-founders and tech meetups safely with StrangerMeetup.