Pinned or Split Screen MCP Apps

Is your feature request related to a problem? Please describe.
For a single chat session, sometimes you'll want to continually reference the initial MCP App with additional chat context. Right now as the chat progresses, the MCP App scrolls off the screen and eventually loses context. An example would be a Map UI that the calling agent could control or interact with across an entire conversation. Clearly this is for the implementing client like Claude but the bidirectional nature of this spec lends itself to short/medium running conversations with a embedded UI

Describe the solution you'd like
Something like the split screen for artifacts or preview in the Claude UI right now. Or when the MCP App go into full screen mode, the chat input window hovers over it, this would work too if you could see the chat exchange in some limited form as your work with the MCP App UI

Describe alternatives you've considered
Pairing an external tab (or app) with an MCP App that serves as a relay via websockets works but there's not great way to set this up for a user and feels somewhat like a hack when used from Claude Desktop and a separate browser window. Image below shows a browser split tab with the Claude chat on the left, the MCP App is small shim UI to relays commands and state to and from the agent context. This works but would be a lot easier without the entire relay, it could just happen with the embedded iFrame and the chat context directly

Additional context
There are endless ways where this could be used for more complex applications where the local agent is driving the orchestration and intelligence instead of the server (visualization, CAD, GIS/Mapping, 3D model creation etc). Here is an example of a measurement tool for local contractors to help with roofing estimates (json result from the measurement is sent to agent and paired with a Skill), this flow works really well as a single turn in the chat but it would be even better if the local agent could make suggestions or alterations to the UI as well (eg how does this roof look? or help me design a fence for this property).

more info here: https://x.com/bFlood/status/2061564604178981256

Start by reviewing the MCP Apps spec and SDK in this repository, then determine whether pinned or split-screen behavior belongs in the protocol or in implementing clients. Done should define a clear way for an MCP App to remain visible alongside chat while preserving interaction and context across the conversation.