Claude Sonnet 4 supports a context window of 1M tokens on Vercel AI Gateway, enabling full codebase analysis of 75,000+ lines or large document sets, while scoring 72.7% on SWE-bench Verified with hybrid extended thinking and enhanced steerability.
import { streamText } from 'ai'
const result = streamText({ model: 'anthropic/claude-sonnet-4', prompt: 'Why is the sky blue?'})Claude Sonnet 4 launched on May 22, 2025 alongside Claude Opus 4, positioned as a significant upgrade over Claude Sonnet 3.7 with superior coding, reasoning, and instruction-following precision. It scored 72.7% on SWE-bench Verified, matching or exceeding Opus 4's 72.5% on the coding benchmark that matters most to software engineering teams. GitHub announced it would power the new coding agent in GitHub Copilot. Manus highlighted improvements in complex instruction following and aesthetic outputs. iGent reported navigation errors dropping from 20% to near zero.
The context window of 1M tokens lets you process full codebases of approximately 75,000+ lines of code or equivalently large document sets in a single request. Access this by adding the anthropic-beta: context-1m-2025-08-07 request header and routing through the Anthropic provider specifically.
Sonnet 4 is a hybrid model offering both near-instant standard responses and extended thinking for deeper reasoning. Extended thinking with tool use is also available in beta. Both Sonnet 4 and Opus 4 can use tools in parallel. The Claude 4 generation introduced one-hour prompt caching as a new API capability. Steerability was a highlighted design improvement: the model responds more precisely to instructions, reducing the gap between what you ask and what you get.
The 65% reduction in shortcut-taking behavior compared to Sonnet 3.7 applies to Sonnet 4 as well as Opus 4, making it more reliable in production agentic deployments.