feat(mcp-ui): add hook for posting data back to MCP client

[tsck]

Proposed changes

• Add useHostCommunication hook for sending UI actions to the parent window via postMessage
• Updates useRenderData hook to capture origin, to be used in comms once available for better security
• Adds tests for both data hooks

[coveralls]

Pull Request Test Coverage Report for Build 20349165663

Details

• 101 of 103 (98.06%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.3%) to 79.757%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/ui/hooks/index.ts	0	1	0.0%
src/ui/hooks/useRenderData.ts	2	3	66.67%

Totals
Change from base Build 20344372865:	0.3%
Covered Lines:	6849
Relevant Lines:	8506

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💛 - Coveralls

[Copilot]

Pull request overview

This PR introduces a new React hook for bidirectional communication between the MCP UI and its parent window, along with enhanced security through origin tracking.

• Adds useHostCommunication hook to enable the UI to send various types of messages (intents, notifications, prompts, tool calls, links, and size changes) back to the MCP client via postMessage
• Updates useRenderData hook to capture and return the parent window's origin for secure communication
• Includes comprehensive unit tests for both hooks

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/ui/hooks/useHostCommunication.ts	New hook providing six communication methods (intent, notify, prompt, tool, link, reportSizeChange) with configurable target origin
src/ui/hooks/useRenderData.ts	Enhanced to capture parent window origin from the first valid message and return it alongside existing data
src/ui/hooks/index.ts	Exports the new useHostCommunication hook
tests/unit/ui/useHostCommunication.test.ts	Tests covering all communication methods, origin configuration, and edge cases
tests/unit/ui/useRenderData.test.ts	Tests verifying the new parentOrigin field behavior and integration with existing functionality

Comments suppressed due to low confidence (1)

tests/unit/ui/useRenderData.test.ts:1

• Tests on lines 55-61, 63-67, and 79-85 contain redundant assertions about the initial state values. Consider consolidating these into a single comprehensive test case that checks both the object shape and initial values, reducing duplication while maintaining coverage.

import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";

[Copilot]

The type Mock is imported from vitest but the more specific type ReturnType<typeof vi.fn> is used in useRenderData.test.ts (line 34). For consistency across test files, consider using ReturnType<typeof vi.fn> here as well, which was the pattern established in the companion test file.