Adopt
Claude Sonnet 4.6, released February 17, 2026, is Anthropic's current flagship model for software engineering — combining frontier-level coding performance with a 1M token context window at the same pricing as its predecessor.
Why It's in Adopt
Claude Sonnet 4.6 is the default model in Claude Code, and early testing showed users preferred it over Sonnet 4.5 roughly 70% of the time for coding tasks. Key improvements over the previous generation:
- Better context reading: More effectively reads and understands large amounts of code before modifying it — reducing the "AI trashes your file" problem in long sessions
- Less code duplication: Consolidates shared logic rather than repeating it across files
- Stronger prompt injection resistance: A major safety improvement for agentic use cases where the model is acting autonomously on your behalf
- Computer use: Major improvements in GUI automation (clicking, typing, navigating browsers)
- 1M token context window: Feed in entire codebases or massive documentation sets
Performance
- Tops or ties on SWE-bench Verified (real GitHub issue resolution)
- Matches Claude Opus 4.6 on OfficeQA (enterprise document comprehension)
- Preferred over Opus 4.5 in Claude Code agentic workflows 59% of the time despite lower cost
How to Access It
- Claude.ai — the default free and paid model
- Anthropic API —
claude-sonnet-4-6model ID - Amazon Bedrock and Google Vertex AI for enterprise access
- Claude Code CLI — the default model
Key Characteristics
| Property | Value |
|---|---|
| License | Proprietary |
| Context window | 1,000,000 tokens (1M, beta) |
| Pricing | $3/M input, $15/M output |
| Provider | Anthropic |
| API model ID | claude-sonnet-4-6 |
Cost-Saving Features
- Prompt caching: Up to 90% cost reduction on repeated context (great for long agentic sessions)
- Batch processing: 50% cost reduction for non-real-time tasks