mcp: update tasks to spec, fix not restoring after hiding sidebar

[connor4312]

• Adopt rename viewport->containerDimensions
• Add some code to fix the postMessage.source validation issues
• Fix apps not restoring when chat is remounted

[Copilot]

Pull request overview

This PR updates the MCP (Model Context Protocol) Apps implementation to align with the latest specification and fixes bugs related to webview restoration when the chat sidebar is hidden and shown again.

Key Changes:

• Renamed viewport to containerDimensions in the protocol spec to match the MCP Apps spec
• Refactored width tracking from a simple number to an IObservable<number> to enable reactive updates
• Added remounting logic triggered by visibility changes to restore webviews when chat becomes visible again

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
modelContextProtocolApps.ts	Updates protocol types to rename viewport to containerDimensions with more flexible type structure; adds --color-text-ghost CSS variable; converts JSDoc comment to regular block comment
chatListRenderer.ts	Converts _currentLayoutWidth from a number to an observable, propagates as observable to render context
chatToolInvocationPart.ts	Adds context parameter to ChatMcpAppSubPart constructor
chatMcpAppSubPart.ts	Adds visibility change listener to remount apps when chat becomes visible; passes observables for maxHeight and currentWidth to model
chatMcpAppModel.ts	Removes ResizeObserver-based viewport tracking; accepts maxHeight and currentWidth as observables; adds postMessage event listener wrapping to fix source validation; removes unused import
chatToolOutputContentSubPart.ts	Updates to call .get() on observable currentWidth
chatToolInputOutputContentPart.ts	Updates to call .get() on observable currentWidth
chatMarkdownContentPart.ts	Updates to call .get() on observable currentWidth
chatContentParts.ts	Changes currentWidth from a function to an IObservable; adds onDidChangeVisibility event
chatConfirmationWidget.ts	Updates to call .get() on observable currentWidth