feat : webmcp integration

[raiden-staging]

Summary

• integrate WebMCP early preview
• websocket endpoint (/webmcp) for realtime webmcp tool discovery, events monitoring, and tool call execution via cdp bridge

Background

• WebMCP is an early-preview browser API that lets web pages register MCP tools (navigator.modelContextTesting)
• enables AI agents to discover and invoke structured tools exposed by web applications directly through the browser

Architecture

Client ──WebSocket──> /webmcp ──> Handler ──> Bridge (per session)
                                                  │
                                            Chrome CDP (WS)
                                                  │
                                            ├── Target.attachToTarget
                                            ├── Runtime.evaluate
                                            │     ├── navigator.modelContextTesting.listTools()
                                            │     └── navigator.modelContextTesting.executeTool()
                                            └── Target.targetInfoChanged

WebSocket Protocol

Direction	Type	Description
Client → Server	subscribe	Start real-time tool monitoring
Client → Server	unsubscribe	Stop monitoring
Client → Server	list_tools	Query registered tools
Client → Server	call_tool	Execute a tool by name with arguments
Server → Client	webmcp_available	Availability changed
Server → Client	tools_changed	Tool list updated
Server → Client	tab_changed	Active tab navigated
Server → Client	tool_result	Tool execution result
Server → Client	tool_error	Tool execution error

Demo

demo from current implementation in webmcp-dev branch

webmcp_demo_realestate_app.mp4

Checklist

• A link to a related issue in our repository
• A description of the changes proposed in the pull request.
• @mentions of the person or team responsible for reviewing proposed changes.

[ @rgarcia ]

---

Note

Low Risk
This PR only adds planning documentation and does not modify runtime code paths or production behavior.

Overview
Adds a new plans/webmcp-integration.md document describing a proposed WebMCP early-preview integration, including /webmcp/status REST and /webmcp WebSocket APIs for tool discovery, event monitoring, and tool execution via CDP.

The plan also outlines required runtime/container changes (switch to Chrome Canary and enable WebMCPTesting) plus new server components (Bridge/handler/types, OpenAPI updates) to support navigator.modelContextTesting-based tool listing and execution.

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