Spud Was the Rumored GPT-6. It Shipped as GPT-5.5, Two Tiers Inside.

The highly anticipated GPT-6, codenamed "Spud," was released as GPT-5.5 on April 23, featuring new reasoning effort knobs and a 60% reduction in hallucinations. The article highlights the significance of its tiered reasoning architecture for future analysis, despite the perceived "delay" in its release.