OpenAI Plugin Extensions: Plugins Stop Being Add-ons and Become Apps Inside ChatGPT
Plugin Extensions, announced at DevDay 2026 (Sep 29), let a plugin put a home in the ChatGPT sidebar, a panel beside the conversation, and a viewer for its file types — up to three entrypoints per MCP App. A plugin is now Skill + MCP + external services + UI, which adds a new product question: which capabilities should ship as a plugin an agent can install?