Rumors are swirling that Anthropic is set to release Claude 3.5 Sonnet 5 (or simply Sonnet 5) as early as today or later this week, coinciding with the lead-up to Super Bowl LX.
The speculation reached a fever pitch after developers spotted a “claude-sonnet-5” identifier in Vertex AI and Google Cloud error logs yesterday. Here is a breakdown of what we know about the rumored release:
The “Fennec” Leak
The new model is reportedly codenamed “Fennec” internally. Unlike previous mid-generation updates, leaks suggest Sonnet 5 might be a “generation-skipping” leap that could outpace current frontier models like Gemini 3 and GPT-5.1 in specific areas.
Rumored Capabilities & Pricing
- Performance: Insider leaks claim Sonnet 5 surpasses 80.9% on SWE-Bench, potentially making it the most powerful coding model available.
- Speed & Efficiency: It is expected to be significantly faster than Claude Opus 4.5, optimized specifically for Google TPUs to lower latency.
- Context Window: While early tests showed a 128k window, it is widely expected to launch with a 1 million token context window (matching Sonnet 4.5’s beta capacity but with improved recall).
- Pricing: Rumors suggest an aggressive price point, potentially 50% cheaper than Opus 4.5, following Anthropic’s pattern of delivering “Opus-level intelligence at Sonnet prices.”
New Feature: “Dev Team” Mode
One of the most anticipated rumors is a major upgrade to the Claude Code CLI. Sonnet 5 reportedly enables a “Dev Team” mode where the AI can spawn specialized sub-agents (e.g., a “QA Agent,” “Backend Agent,” and “Researcher”) to work on different parts of a codebase in parallel.
Release Timeline
- Leaked Date: February 3, 2026 (Today).
- Alternative Window: Some analysts believe the launch is timed for February 8 to maximize exposure during the Super Bowl.
