Forms: Add ability output schemas

[DevinWalker]

Fixes JETPACK-1770

This PR is open because Forms is already the strongest Jetpack Abilities API integration, and agents need dependable response shapes to use it safely. It keeps the change limited to output contracts and a small no-op guard so the broader rollout can stay reviewable.

This follows the WordPress wp_register_ability() documentation: schemas define the expected structure of ability inputs and outputs, support validation, and make the API contract self-documenting for developers and tools.

Proposed changes

• Add explicit output schemas for the Jetpack Forms abilities so agent clients can reason about response shapes.
• Tighten jetpack-forms/update-response so calls must include a mutation field, matching the declared object output contract.
• Return the admin edit URL from jetpack-forms/get-form instead of the public permalink.
• Strengthen Forms ability tests for public metadata, output schemas, no-op update handling, and edit URL behavior.

Related product discussion/links

• JETPACK-1770: https://linear.app/a8c/issue/JETPACK-1770/forms-add-ability-output-schemas
• Supersedes Forms: Add ability output schemas #49950 after renaming the branch from codex/forms-abilities-output-schemas to add/forms-abilities-output-schemas.

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

No.

Testing instructions

• From projects/packages/forms, run:
  • php vendor/bin/phpunit-select-config phpunit.#.xml.dist --colors=always tests/php/abilities/Forms_Abilities_Test.php
• Confirm the test passes with 30 tests, 227 assertions.
• Optional broader check: CI=true jp test php packages/forms -v currently reaches PHPUnit but fails in existing webhook localhost tests unrelated to these Forms abilities changes.

[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/forms-abilities-output-schemas branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack add/forms-abilities-output-schemas

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• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
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[github-actions]

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Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/packages/forms/src/abilities/class-forms-abilities.php	600/651 (92.17%)	1.56%	0 💚

Full summary · PHP report · JS report

[enejb]

Review — standard depth (296 lines, 1 project). No blockers; the change is correct and consistent with existing patterns. Three non-blocking suggestions, all around schema-vs-reality fidelity and test coverage of the new contracts.

1. [suggestion] update-response output_schema likely doesn't match the actual return shape. The execute callback returns the raw merged REST data from POST /wp/v2/feedback/{id} and /feedback/{id}/read, not a curated { id, status, is_unread, count } object. test_every_ability_declares_output_schema_for_current_return_shape only asserts the declared property types, never that a real return conforms — so the schema can drift from reality unnoticed. Since this is the contract agents reason about, consider verifying it against an actual dispatch result (or documenting that extra properties may appear).
   

   jetpack/projects/packages/forms/src/abilities/class-forms-abilities.php

   Lines 445 to 456 in ed08f60

   	'output_schema' => array(
   	'type' => 'object',
   	'properties' => array(
   	'id' => array( 'type' => 'integer' ),
   	'status' => array( 'type' => 'string' ),
   	'is_unread' => array( 'type' => 'boolean' ),
   	'count' => array( 'type' => 'integer' ),
   	),
   	),
   	'execute_callback' => array( __CLASS__, 'update_form_response' ),
   	'permission_callback' => array( __CLASS__, 'can_edit_pages' ),
   	'meta' => array(

2. [suggestion] get-responses output_schema is array of bare object with no properties — it documents almost nothing for the one ability whose payload (sender info, fields, metadata) an agent most needs to understand. If the shape is stable enough, declaring a few top-level keys would make the contract useful; otherwise a comment noting the intentional looseness would help future maintainers.
   

   jetpack/projects/packages/forms/src/abilities/class-forms-abilities.php

   Lines 391 to 396 in ed08f60

   	'output_schema' => array(
   	'type' => 'array',
   	'items' => array(
   	'type' => 'object',
   	),
   	),

3. [suggestion] Behavioral change worth calling out: update-response now returns WP_Error('missing_update') for an id-only call that previously returned an empty-array no-op. Intentional and reasonable, but the class's own init() docblock stresses not silently breaking existing consumers — worth confirming no caller relies on the old no-op. Also, the new anyOf input-schema constraint isn't directly tested (only the execute-callback guard is); a one-line test that input validation rejects { id } would pin the anyOf + additionalProperties: false combination.
   

   jetpack/projects/packages/forms/src/abilities/class-forms-abilities.php

   Lines 808 to 811 in ed08f60

   	if ( ! isset( $args['status'] ) && ! isset( $args['is_unread'] ) ) {
   	return new \WP_Error( 'missing_update', __( 'Provide a status or read state to update.', 'jetpack-forms' ) );
   	}