Blaze: extract campaign preparer (ADS-1036)

[j6ll]

Fixes ADS-1036

Proposed changes

• Extract prepare-campaign target resolution, default derivation, prefill payload construction, and prefill URL creation into Campaign_Preparer.
• Keep Blaze_Abilities focused on registration, permissions, guardrails, and MCP-specific message formatting.
• Add focused preparer tests for structured output, target hard stops, overrides, and language/country normalization.

Related product discussion/links

• Linear: ADS-1036
• Stacked on Blaze: add MCP-exposed prepare-campaign write ability (ADS-953) #48349 / ADS-953.

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

No. This refactors existing prepare-campaign behavior behind the same public response and does not add tracking.

Testing instructions

• From projects/packages/blaze, run composer run phpunit -- --filter Campaign_Preparer_Test.
• From projects/packages/blaze, run composer run phpunit -- --filter Blaze_Abilities_Test.
• From projects/packages/blaze, run composer run phpunit -- --filter 'Campaign_Preparer_Test|Blaze_Abilities_Test'.
• From the repo root, run php -l projects/packages/blaze/src/class-campaign-preparer.php && php -l projects/packages/blaze/src/abilities/class-blaze-abilities.php && php -l projects/packages/blaze/tests/php/Campaign_Preparer_Test.php.

Note: I also ran the full Blaze package PHPUnit suite locally; the preparer and ability tests passed, but the full suite hit the existing Dashboard_Test::test_load_admin_scripts style assertion because ignored local projects/packages/blaze/dist/build.min.* files make the dashboard load local assets instead of CDN assets in this checkout.

[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 or WordPress.com Site Helper), and enable the add/ads-1036-campaign-preparer branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack add/ads-1036-campaign-preparer

bin/jetpack-downloader test jetpack-mu-wpcom-plugin add/ads-1036-campaign-preparer

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[github-actions]

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[jp-launch-control]

Code Coverage Summary

Cannot generate coverage summary while tests are failing. 🤐

Please fix the tests, or re-run the Code coverage job if it was something being flaky.

Full summary · PHP report · JS report

[j6ll]

Quick ADS-1036 test/status pass — 2026-05-06

Local focused Blaze tests pass:

cd projects/packages/blaze
composer phpunit -- tests/php/Campaign_Preparer_Test.php tests/php/abilities/Blaze_Abilities_Test.php
# OK (20 tests, 103 assertions)

Status notes:

• PR is open and non-draft.
• Linear ADS-1036 is already in review, which still looks like the right status.
• CI is not fully settled/green yet. The WP Cloud wpcomsh PHPUnit job failed before running tests with: Unable to run a basic wp command! Something is wrong with the site.
• The main Tests workflow was still in progress when checked; it already showed failures for PHP 7.3 WP latest and PHP 7.4 WP latest with WooCommerce, but GitHub would not expose failed logs until the run completes.

Next action: wait for the remaining CI logs/rerun signal before marking ADS-1036 complete. ADS-1044 is now the right follow-up for the broader audience targeting options contract.