Add Threads as an oEmbed provider

[pestevez]

Trac ticket: https://core.trac.wordpress.org/ticket/64858

Description

Adds Threads as a built-in oEmbed provider. Threads recently dropped the access token requirement, making tokenless oEmbed possible via graph.threads.com/oembed.

Changes

• Registered two provider patterns in class-wp-oembed.php covering both URL formats
• Added documentation table entries
• Added PHPUnit test file with 14 test cases

Supported URL formats

• https://www.threads.com/@{username}/post/{shortcode}
• https://www.threads.com/t/{shortcode}

Both threads.com and threads.net domains supported, with and without www., over http and https.

Testing

PHPUnit tests included: 10 positive match tests + 4 negative tests.

Manual: paste a Threads post URL in the classic editor or via the REST API oEmbed proxy and verify the embed resolves.

Use of AI Tools

Created using Claude Code (Opus 4.6)

[github-actions]

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[github-actions]

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Props pmestevez, westonruter.

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[github-actions]

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[mukeshpanchal27]

Suggested change

	/**
	* @dataProvider data_threads_provider_urls
	*
	* @param string $url The URL to test.
	* @param string $expected The expected oEmbed provider URL.
	*/
	/**
	* @ticket 64858
	*
	* @dataProvider data_threads_provider_urls
	*
	* @param string $url The URL to test.
	* @param string $expected The expected oEmbed provider URL.
	*/

Add @ticket annotation to all new tests