Forms: Add webhook logging and initialization flag

[CGastrell]

Proposed changes

This PR adds enhanced logging and a feature flag for the webhook functionality in Jetpack Forms:

• Add logging for skipped webhooks (invalid format, method, or empty URL)
• Add jetpack_forms_webhooks_enabled filter flag to control webhook initialization
• Improve webhook validation by logging specific skip reasons via jetpack_forms_log action
• Fix method validation to be case-insensitive (convert to uppercase before comparison)

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

No

Testing instructions

1. Enable webhooks via the filter flag:

   add_filter( 'jetpack_forms_webhooks_enabled', '__return_true' );

2. Create a form with webhook configuration in the block editor

3. Test logging for skipped webhooks:

   • Try an empty webhook URL (should log webhook_skipped with reason url_empty)
   • Try an invalid format value (should log webhook_skipped with reason format_invalid)
   • Try an invalid method value (should log webhook_skipped with reason method_invalid)

4. Verify that without the filter flag enabled, webhooks are not initialized even if configured in the form

5. Hook into the jetpack_forms_log action to capture the logging:

   add_action( 'jetpack_forms_log', function( $event, $reason, $data = null ) {
       error_log( "Forms Log - Event: $event, Reason: $reason" );
       if ( $data ) {
           error_log( print_r( $data, true ) );
       }
   }, 10, 3 );

[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 add/form-webhooks-skipped-logging branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack add/form-webhooks-skipped-logging

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!

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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.
3. You can use GitHub's Reviewers functionality to request a review.
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If you have questions about anything, reach out in #jetpack-developers for guidance!

---

Jetpack plugin:

The Jetpack plugin has different release cadences depending on the platform:

• WordPress.com Simple releases happen as soon as you deploy your changes after merging this PR (PCYsg-Jjm-p2).
• WoA releases happen weekly.
• Releases to self-hosted sites happen monthly:
  • Scheduled release: December 2, 2025

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.

[jp-launch-control]

Code Coverage Summary

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If that commit is a feature branch rather than a trunk commit, this is expected. Otherwise, this should be updated once coverage for 079abaf is available.

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_{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 .}