[DO NOT MERGE] Expiry notices: stop the rollout (prepared revert, do not merge)

[Copons]

Related to DOTCOM-16615

⚠️ Prepared in advance. Do not merge unless the new expiry notices are actually causing trouble. Kept as a draft so it can't land by accident — mark it ready and merge when needed.

Proposed changes

• Take the rollout share to 0%.
• Move the zero check ahead of the per-site override, so zero means zero: a site still carrying wpcom_expiry_notices_enabled = 1 from before the stop does not stay on the new notices. Without that ordering this would stop most of the rollout, not the rollout.

Both halves of the swap read the same predicate, so this single change also brings the previous notices back — wpcomsh's Atomic banner here, and the legacy plan-renew prompt on the WordPress.com side. No site ends up with no notice, and none gets two.

The wpcom_expiry_notices_enabled filter still runs last, so a single site can be forced back in to verify a fix without restarting the ramp.

Related product discussion/links

• Linear: DOTCOM-16615
• WordPress.com companion stop, for a faster mitigation: see the Testing instructions below
• Feature PR this reverts: Expiry notices: wp-admin banner + shared foundation (DOTCOM-16615) #49304

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

No. It stops the new notices rendering, so their Tracks events stop firing too. Nothing is added.

Testing instructions

Sequencing matters. The gate lives in jetpack-mu-wpcom, which reaches production on a package release — slower than a WordPress.com deploy. If you need to stop the notices now, the WordPress.com-side stop is the fast lever; it forces the same predicate false and takes effect in minutes. This PR is the durable stop, and the only one that reaches Atomic sites.

1. On a site inside the rollout, confirm the new banner renders before merging.
2. Apply this change; confirm the new banner is gone and the previous notice has returned — Atomic sites get wpcomsh's, WordPress.com Simple sites get the legacy plan-renew prompt.
3. On a site carrying wp option update wpcom_expiry_notices_enabled 1, confirm it is also out. That option no longer pulls a site in.
4. Confirm the escape hatch still works: add_filter( 'wpcom_expiry_notices_enabled', '__return_true' ); puts that one site back on the new notices.

Unit tests describe the stopped contract rather than the running one, so they move with the change: 1038 pass in packages/jetpack-mu-wpcom.

To restart the rollout, put wpcom_expiry_notices_rollout_percentage() back to 10 (or higher) and restore the override-before-zero ordering if you want hand-picked sites to work while the share is 0 again.

[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 (WordPress.com Site Helper), and enable the revert/expiry-notices-rollout branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack-mu-wpcom-plugin revert/expiry-notices-rollout

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]

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Follow this PR Review Process:

1. Ensure all required checks appearing at the bottom of this PR are passing.
2. Make sure to test your changes on all platforms that it applies to. You're responsible for the quality of the code you ship.
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[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/packages/jetpack-mu-wpcom/src/features/expiry-notices/expiry-notices.php	27/38 (71.05%)	-15.79%	6 💔

Full summary · PHP report · JS report

_{Coverage check overridden by Covered by non-unit tests Use to ignore the Code coverage requirement check when E2Es or other non-unit tests cover the code .}