Boost: Invalidate LCP when Cornerstone Page list is updated

[LiamSarsfield]

Note

Merge this PR after #43151 is merged.

Resolves HOG-82:Invalidate LCP when Cornerstone Page list is updated

Proposed changes:

• When the Cornerstone pages list is updated, the LCP Optimizer will now re-analyze the LCP for the updated Cornerstone Pages

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

pc9hqz-3tr-p2

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

N/A

Testing instructions:

Prerequisites:

• Jetpack Boost plugin installed and activated.

• Boost Premium is set up.

• LCP Optimization feature enabled.

  Click here for SQL to check LCP State Option and Storage Posts

  -- Check LCP State (in options table)
  SELECT option_name, option_value
  FROM wp_options -- Replace wp_ with your table prefix if different
  WHERE option_name = 'jetpack_boost_ds_lcp_state';
  
  -- Check LCP Storage (in posts table)
  SELECT ID, post_name, post_content, post_status, post_date_gmt, post_modified_gmt
  FROM wp_posts -- Replace wp_ with your table prefix if different
  WHERE post_type = 'jb_store_lcp';

Testing Cornerstone Page List Update:

1. Note the current LCP state option value and any existing LCP storage posts. Pay attention to the data, and note the post_modified_gmt timestamps of the existing posts.

   Click here for SQL to check initial LCP State and Storage

   -- Check LCP State (in options table)
   SELECT option_name, option_value
   FROM wp_options -- Replace wp_ with your table prefix if different
   WHERE option_name = 'jetpack_boost_ds_lcp_state';
   
   -- Check LCP Storage (in posts table)
   SELECT ID, post_name, post_content, post_status, post_date_gmt, post_modified_gmt
   FROM wp_posts -- Replace wp_ with your table prefix if different
   WHERE post_type = 'jb_store_lcp';

2. Go to Jetpack -> Boost.

3. Add, or remove a Cornerstone Page from the list. Note the approximate time of editing.

4. Wait a few seconds for the analysis to complete (it should be quick).

5. Re-check the jetpack_boost_ds_lcp_state option in the wp_options table. Verify its value has been updated (it won't have a timestamp, but the content should reflect recent analysis).

6. Re-check the wp_posts table for jb_store_lcp posts. Verify that new posts now exist, and their post_date_gmt or post_modified_gmt timestamps are after the time you activated the theme.

   Click here for SQL to check updated LCP State and new Storage posts

   -- Check LCP State (in options table)
   SELECT option_name, option_value
   FROM wp_options -- Replace wp_ with your table prefix if different
   WHERE option_name = 'jetpack_boost_ds_lcp_state';
   -- Expect option_value to contain data reflecting the new analysis state
   
   -- Check LCP Storage (in posts table)
   SELECT ID, post_name, post_content, post_status, post_date_gmt, post_modified_gmt
   FROM wp_posts -- Replace wp_ with your table prefix if different
   WHERE post_type = 'jb_store_lcp' AND post_status != 'trash';
   -- Expect new posts corresponding to visited pages with recent timestamps

7. Verify that there is a record for the LCP Storage results for each valid Cornerstone from the list.

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/plugins/boost/app/assets/src/js/features/cornerstone-pages/meta/meta.tsx	0/67 (0.00%)	0.00%	2 ❤️‍🩹

Full summary · PHP report · JS report

_{Coverage check overridden by Coverage tests to be added later Use to ignore the Code coverage requirement check when tests will be added in a follow-up PR .}

[dilirity]

While testing this, I noticed that it sends requests to the cloud and analyses the LCP, but the UI is never updated.

Then I checked how Cloud CSS is handled and found this PR - https://github.com/Automattic/jetpack/pull/40009/files

I think it makes more sense to handle the re-analyze via the UI so we give the user feedback right away. Otherwise, they'd have to refresh the page to see that LCP was optimized again.

Nitpick: However, looking at the way Cloud CSS is handled, although simple, I wonder if it make sense to do it via the UI. That means that we're unable to do this via PHP. Ideally, we'd update the cornerstone pages list and dispatch a new LCP analysis via the back-end. Then at the same time, update the UI to a polling state. Though this seems clunky and I think we should stick with updating via the UI. If we decided that it's necessary to start the analysis via the back-end, we can always update it.

EDIT:
@LiamSarsfield I've updated the LCP analysis request to happen via the UI in 4a4aca0.

Take a look and tell me what you think.

[LiamSarsfield]

Good catch @dilirity, I took the majority of inspiration from Cache Preloading, but that didn't need a UI aspect to it, hence it wasn't needed.

Though this seems clunky and I think we should stick with updating via the UI. If we decided that it's necessary to start the analysis via the back-end, we can always update it.

I think this is okay for now as this is the only place where Cornerstone Pages are being updated, but we should be aware of UI side effects such as this if we ever do allow Cornerstone Pages to be updated elsewhere (unlikely though).

[dilirity]