Fix bulk actions re-running on sort and pagination clicks - #928

What?

Bulk admin actions in three experiments re-run on every sort and pagination click after the action has finished. This fixes all three: Content Summarization, Alt Text Generation, and Comment Moderation.

Why?

Each bulk action puts a trigger param in the redirect URL, and the sort and pagination links the list table renders keep carrying that param. So the action fires again whenever the list is sorted or paginated:

• Content Summarization (Posts list) re-generates summaries. This makes provider API calls and overwrites the summary blocks on every click.
• Alt Text Generation (Media Library) re-generates alt text. Same cost.
• Comment Moderation (Comments list) re-shows the "N comments queued" notice. This one is cosmetic, nothing is re-queued.

The first two cost money and overwrite user edits, so this is not just a visual issue.

How?

The same two part fix that core uses for its own one-shot params like trashed and deleted:

1. Register the trigger params through the removable_query_args filter. Core then strips them from pagination links and cleans the address bar on load.
2. Scrub the params from $_SERVER['REQUEST_URI'] once they have been read, the same way core does in wp-admin/edit.php, upload.php, and edit-comments.php. This cleans the sort header links, which do not honour the removable list, they only strip paged.

No JavaScript change is needed. The bulk scripts get their IDs from wp_localize_script, not from the URL. Comment Moderation reads its params from $_GET, which the scrub does not touch, so its notice still shows once on the redirect.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code (Anthropic)
Model(s): Claude
Used for: Investigating the bug, writing the fix, the unit tests, and the e2e tests, and running the full verification. I reviewed, tested, and take responsibility for all of it before submitting.

Testing Instructions

1. Enable one of the three experiments with a configured provider.
2. Have more than one page of items in the relevant list (Posts, Media in list mode, or Comments).
3. Select some items, run the bulk action, and wait for the notice.
4. Click a sortable column header or a pagination link.

Before this change, the action runs again (for Summarization and Alt Text you will see post_modified change and fresh provider calls; for Comment Moderation the notice re-appears). After this change, the list only sorts or paginates and nothing re-fires.

Automated coverage:

• New integration tests for all three features. Each fails with its fix reverted.
• New e2e tests for all three. Each checks the rendered sort link is clean and that sorting does not re-fire the action.
• Full PHPUnit suite passes (1244 tests). composer lint and npm run lint:js are clean. PHPStan adds no new errors.

Changelog Entry

Fixed - Bulk actions (Generate Summary, Generate Alt Text, Analyze comments) no longer re-run when sorting or paginating the list after the action completes.