Featured Snippet Answer: DeepSeek V4 Pro offers near-frontier performance at ~1/5 to 1/10th the price of GPT-5.5, excelling in long-context efficiency and open-source flexibility. GPT-5.5 leads in agentic coding (e.g., 82.7% Terminal-Bench 2.0) and polished reasoning but at significantly higher costs. For most high-volume or cost-sensitive workloads, DeepSeek V4 provides superior value. In April 2026, the AI landscape shifted dramatically. OpenAI released GPT-5.5 on April 23, positioning it as "a new class of intelligence for real work" with strong gains in agentic coding, computer use, and knowledge work. Just a day later, DeepSeek countered with the V4 preview (V4-Pro and V4-Flash), delivering near-frontier performance at a fraction of the cost, backed by open weights and a groundbreaking 1M-token context efficiency. This isn't just another model release—it's a battle between proprietary frontier excellence and open, democratized power.…