The AI race spent two years being about models. This week it moved to the plumbing. On the eve of GPT-5’s first birthday, OpenAI and four rivals published Agent Plugins, an open standard that lets a single agent extension work across competing products. The pitch is “build once, run anywhere”. Today, every agent tool expects a different folder layout and setup. Agent Plugins replaces that with one package format. It bundles two things developers already use. The first is Model Context Protocol s...