Feat/resource meta

[AshishJii]

What?

Closes #245

Preserve the MCP _meta field when building resources/read response contents, so metadata returned by resource ability callbacks is passed through to MCP clients.

Why?

The MCP spec allows any resource content object to carry an optional _meta field for arbitrary client-side hints. Previously, ResourcesHandler::create_content_dto() never extracted _meta from the raw content item array, meaning it was silently dropped before the DTO was constructed and the response was serialised. This broke spec compliance and caused clients to lose metadata they depended on.

How?

In ResourcesHandler::create_content_dto(), extract _meta from the raw content item and forward it into both BlobResourceContents::fromArray() and TextResourceContents::fromArray().

The is_array() guard ensures a callback that returns a non-array _meta value still produces a well-typed null rather than crashing the DTO constructor.

Use of AI Tools

AI assistance: Yes
Tool(s): Antigravity
Model(s): Claude Sonnet 4.6
Used for: Generating PHPUnit test stubs and drafting this PR description. The core bug fix in ResourcesHandler.php, fixture design, and final review were done by me.

Testing Instructions

1. Check out this branch.
2. Start the test environment: npm run wp-env:test -- start
3. Run the full PHPUnit suite: npm run test:php
4. Confirm output ends with OK (1011 tests, 3901 assertions) and no failures.

[github-actions]

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Co-authored-by: AshishJii <ashishjii@git.wordpress.org>
Co-authored-by: Utsav-Ladani <utsavladani@git.wordpress.org>

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[Copilot]

Pull request overview

This PR fixes MCP spec compliance in the adapter by preserving the optional _meta field on individual resources/read content items, ensuring metadata returned by resource callbacks is carried through into the serialized response.

Changes:

• Forward _meta from raw resource content items into TextResourceContents::fromArray() and BlobResourceContents::fromArray().
• Add fixture resources that return _meta for both text and blob contents.
• Add unit tests verifying _meta is preserved end-to-end for resources/read.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
includes/Handlers/Resources/ResourcesHandler.php	Extracts _meta from content items and forwards it into resource content DTO creation.
tests/phpunit/Fixtures/DummyAbility.php	Adds two test resource abilities that return _meta on text/blob content items.
tests/phpunit/Unit/Handlers/ResourcesHandlerReadTest.php	Adds coverage asserting _meta is preserved in ReadResourceResult contents for text and blob responses.
tests/phpunit/Unit/Core/McpAdapterConfigTest.php	Updates expected auto-discovered resources list to include the new meta test resources.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.95%. Comparing base (4d19d22) to head (79a74c6).

Additional details and impacted files

@@            Coverage Diff            @@
##              trunk     #258   +/-   ##
=========================================
  Coverage     87.94%   87.95%           
- Complexity     1257     1259    +2     
=========================================
  Files            53       53           
  Lines          4066     4069    +3     
=========================================
+ Hits           3576     3579    +3     
  Misses          490      490           

Flag	Coverage Δ
unit	87.95% <100.00%> (+<0.01%)	⬆️

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