Fix admin notices and JITMs rendering inside page headers

[vianasw]

Fixes JETPACK-1420

Proposed changes

Admin notices and JITMs were rendering inside the page header (between the title and the page content) on several AdminPage-migrated pages. This PR moves them to the correct position:

• My Jetpack: Move GlobalNotices, JITM slot (#jp-admin-notices), and GlobalNotice into the tab panel's beforeContent prop so they render between the tab bar separator and tab content, not above the tabs.
• Social: Move ConnectionError and the JITM slot out of the Header component and into the main admin page layout, after AdminSectionHero. Also add the JITM slot to the pricing interstitial page branch.
• Search: Move the JITM container after MockedSearchInterface (the hero section). Add a useEffect to relocate stray JITMs placed by JITM JS before React mounts, and a CSS fallback to hide them in #wpbody-content.

Before / After

Page	Before	After
My Jetpack
Social
Social (pricing)
Search

Other information

• Generate changelog entries for this PR (using AI).

Related product discussion/links

• JETPACK-1420

Does this pull request change what data or activity we track or use?

No.

Testing instructions

Setup: Fake JITM

Add the following snippet to a mu-plugin (e.g. wp-content/mu-plugins/fake-jitm.php) to inject a test JITM on all Jetpack admin pages:

<?php
add_filter(
	'jetpack_jitm_received_envelopes',
	function ( $envelopes ) {
		$envelopes[] = (object) array(
			'id'                   => 'header-003-test',
			'feature_class'        => 'test',
			'content'              => (object) array(
				'message'     => 'HEADER-003 test JITM',
				'description' => 'This should appear below the header, not inside it.',
				'icon'        => '',
				'classes'     => '',
				'list'        => array(),
			),
			'CTA'                  => (object) array(
				'message'     => 'Learn more',
				'primary'     => true,
				'link'        => 'https://example.com',
				'newWindow'   => true,
				'ajax_action' => null,
			),
			'activate_module'      => null,
			'module_settings_link' => null,
			'is_dismissible'       => true,
			'url'                  => 'https://example.com',
			'jitm_stats_url'       => '',
			'message_path'         => '',
			'ttl'                  => 0,
			'expires'              => 0,
			'max_dismissal'        => 999,
			'template'             => 'default',
		);
		return $envelopes;
	}
);

My Jetpack

1. Go to My Jetpack (wp-admin/admin.php?page=my-jetpack)
2. Verify the JITM appears below the tab bar (Overview / Products / Help tabs), not between the page title and the tabs

Social

1. Go to Jetpack Social (wp-admin/admin.php?page=jetpack-social)
2. Verify the JITM appears below the "Write once, post everywhere" header section, not inside or above it

Search

1. Go to Jetpack Search (wp-admin/admin.php?page=jetpack-search)
2. Verify the JITM appears below the mocked search interface hero, not above or inside the header

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (Jetpack), and enable the fix/admin-notices-inside-header branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack fix/admin-notices-inside-header

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

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---

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 2 files.

File	Coverage	Δ%	Δ Uncovered
projects/packages/publicize/_inc/components/admin-page/header/index.js	6/6 (100.00%)	0.00%	0 💚
projects/packages/publicize/_inc/components/admin-page/index.tsx	20/20 (100.00%)	0.00%	0 💚

Full summary · PHP report · JS report

_{Coverage check overridden by I don't care about code coverage for this PR Use this label to ignore the check for insufficient code coveage. .}

[vianasw]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

🤖 Generated with Claude Code

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[enejb]

Thanks for these changes.

I found a couple of issue.

1. Search on mobile viewport doesn't look quite right.

See

2. the new newsletter admin page hasn't been updated. (Or maybe I am doing something wrong with building)

See

To enable it you need to add the following filter.

add_filter( 'jetpack_wp_admin_newsletter_settings_enabled', '__return_true' ); 

[CGastrell]

Code looks good and mostly works.

2 minor glitches:

• JITM container on Search seems to overflow
• Newsletters still show the JITM at the top

Both can be done either here or on a follow up. Other than that, looks good, let me know how you prefer to move forward.