ChatGPT is the new browser and memory is the new cookie (babin.posthaven.com)

OpenAI has launched an Apps SDK that lets developers build apps inside ChatGPT, using an MCP protocol extension called MCP-UI to expose interactive widgets (like the product cards shown in demos) that the host can choose to render. In practice this turns ChatGPT into a mini platform/browser where third‑party functionality and UIs run inside the chat interface, and where OpenAI can surface secure, rich interactions without leaving the model. Technical highlights: an SDK for inside‑chat apps, MCP‑UI for widget exposure and rendering, and integration hooks that let apps access conversational context. The strategic implication is that "memory"—a persistent layer capturing your hotels, food preferences, purchase patterns and other context—becomes the new cookie and the core battleground for lock‑in. As chat apps converge on similar capabilities, a deep, federated memory plus "Sign in with ChatGPT" federated auth could give OpenAI persistent cross‑app context and powerful network effects around commerce and daily tasks. That creates a platform play much like a browser shift, with device strategy amplifying the opportunity. Risks remain: engineering hard problems, privacy/consent questions, and fast followers (e.g., Google) could copy features, so first‑mover advantage is useful but not decisive.