Social: Get rid of the UNIFIED_UI_V1 feature flag uses

[manzoorwanijk]

Completes SOCIAL-415

Proposed changes

Remove the UNIFIED_UI_V1 feature flag from the publicize package and make the unified UI the default. Since the UI changes have been in place for a while, the feature flag is no longer needed.

• Remove all siteHasFeature( features.UNIFIED_UI_V1 ) checks, keeping the enabled (truthy) code paths
• Remove the UNIFIED_UI_V1 constant from constants.ts
• Delete components that were only used in the legacy (flag-disabled) code paths:
  • EnhancedFeaturesNudge, SocialPostModal, MediaSection (old), SocialImageGeneratorPanel (panel/), ShareStatusModal, ShareList, GeneratedImagePreview
• Delete hooks that are no longer referenced: usePostCanUseSig, useSaveImageToLibrary
• Clean up store actions (openSharePostModal, closeSharePostModal, toggleSharePostModal, openShareStatusModal, closeShareStatusModal, toggleShareStatusModal), selectors (isSharePostModalOpen, isShareStatusModalOpen), reducer cases, constants, and related types
• Remove orphaned files from social-post-modal/ directory and move PostPreview to its only consumer (customize-and-preview/preview-section/)
• Remove unused style rules

The SOCIAL_UNIFIED_UI_V1 constant in wpcomsh is intentionally kept to support older plugin versions.

43 files changed, -2,153 lines net

Other information

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

Related product discussion/links

• https://linear.app/a8c/issue/SOCIAL-415/get-rid-of-the-unified-ui-v1-feature-flag-uses

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

No.

Testing instructions

• Verify the Social sidebar panel in the block editor works correctly (connections list, message box, media section)
• Verify the pre-publish panel shows the social preview
• Verify the share status modal trigger opens the unified modal
• Verify the SIG edit template button works in the unified modal
• Verify scheduling a share shows the "View" action in the snackbar
• Verify the admin page SIG settings modal (template picker) still works

[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 update/social/remove-unified-ui-feature-flag branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack update/social/remove-unified-ui-feature-flag

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:

• ✅ Include a description of your PR changes.
  
• ✅ Add a "[Status]" label (In Progress, Needs Review, ...).
  
• ✅ Add testing instructions.
  
• ✅ Specify whether this PR includes any changes to data or privacy.
  
• ✅ Add changelog entries to affected projects
  

This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

---

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.
3. You can use GitHub's Reviewers functionality to request a review.
4. When it's reviewed and merged, you will be pinged in Slack to deploy the changes to WordPress.com simple once the build is done.

If you have questions about anything, reach out in #jetpack-developers for guidance!

[jp-launch-control]

Code Coverage Summary

Coverage changed in 10 files. Only the first 5 are listed here.

File	Coverage	Δ%	Δ Uncovered
projects/packages/publicize/_inc/social-store/actions/constants.ts	24/24 (100.00%)	0.00%	0 💚
projects/packages/publicize/_inc/components/form/share-post-form.tsx	0/14 (0.00%)	0.00%	-1 💚
projects/packages/publicize/_inc/social-store/reducer/share-post.ts	2/3 (66.67%)	16.67%	-1 💚
projects/packages/publicize/_inc/social-store/reducer/share-status.ts	2/5 (40.00%)	6.67%	-1 💚
projects/packages/publicize/_inc/social-store/selectors/share-post.ts	0/1 (0.00%)	0.00%	-1 💚

1 file is newly checked for coverage.

File	Coverage
projects/packages/publicize/_inc/components/customize-and-preview/preview-section/post-preview.tsx	0/64 (0.00%) 💔

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. .}