The "Web app" standard for the Agentic Web/OS has arrived. It is essentially the open standardization of the third-party app/plugin ecosystem found in ChatGPT. It consists of Skills and MCP, with MCP covering standards such as MCP Apps and MCP-UI, which allow third-party apps to embed GenUI-based interactive interfaces directly into the main Agentic Web/OS interface. WebMCP is about "embedding Tools within UI," while Agent Plugins / MCP Apps are about "optionally embedding UI within Tools." The core of this kind of "app" ecosystem are Tools, rather than any specific UI representation, such as cards, icon + Activity, or windows. AppFunctions / AppIntents / AppActions on Android, iOS, and Windows, like WebMCP, also belong to the "embedding Tools within UI" model. The current CLI ecosystems around Coding Agents such as Codex and Claude Code are effectively local "native app" ecosystems: apps have to be pre-packaged, downloaded, and installed, and users cannot realistically install too many of them. By contrast, Agent Plugins / MCP Apps can be regarded as a kind of "Web app" ecosystem, because their core functionality is retrieved from the Web on demand. Skills, like manifest-style files such as mcp.json, are lightweight distributions of code with declared metadata, somewhat like HTML: they can be discovered, loaded, activated, and used on demand, in a process analogous to HTML rendering but much more intelligent. This creates an opportunity to extend existing Web standards, which are centered around the distribution of UI resources. Instead of RESTful HTTP exposing only a limited set of actions over resources, the Web could expose a vast long tail of Tools that AI can discover and understand, and that can optionally embed UI. A general-purpose Agent capable of discovering, loading, and running Agent Plugins / MCP Apps on demand would be equivalent to "the browser + Google" of the desktop Internet era. If such an Agent becomes a super app, it could easily abstract away the operating system and become the single dominant super app for most user scenarios, much like the desktop Internet era, rather than the mobile Internet era with many parallel super apps. So such an Agent will naturally tend to integrate into the entire OS and even the hardware itself, much like IE vs. Netscape. That is also why Google, OpenAI, and even ByteDance are determined to build consumer electronics hardware products.