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   1  <?php
   2  /**
   3   * Abilities API: core functions for registering and managing abilities.
   4   *
   5   * The Abilities API provides a unified, extensible framework for registering
   6   * and executing discrete capabilities within WordPress. An "ability" is a
   7   * self-contained unit of functionality with defined inputs, outputs, permissions,
   8   * and execution logic.
   9   *
  10   * ## Overview
  11   *
  12   * The Abilities API enables developers to:
  13   *
  14   *  - Register custom abilities with standardized interfaces.
  15   *  - Define permission checks and execution callbacks.
  16   *  - Organize abilities into logical categories.
  17   *  - Validate inputs and outputs using JSON Schema.
  18   *  - Expose abilities to clients such as the REST API.
  19   *
  20   * ## Working with Abilities
  21   *
  22   * Abilities must be registered on the `wp_abilities_api_init` action hook.
  23   * Attempting to register an ability outside of this hook will fail and
  24   * trigger a `_doing_it_wrong()` notice.
  25  
  26   * Example:
  27   *
  28   *     function my_plugin_register_abilities(): void {
  29   *         wp_register_ability(
  30   *             'my-plugin/export-users',
  31   *             array(
  32   *                 'label'               => __( 'Export Users', 'my-plugin' ),
  33   *                 'description'         => __( 'Exports user data to CSV format.', 'my-plugin' ),
  34   *                 'category'            => 'data-export',
  35   *                 'execute_callback'    => 'my_plugin_export_users',
  36   *                 'permission_callback' => function(): bool {
  37   *                     return current_user_can( 'export' );
  38   *                 },
  39   *                 'input_schema'        => array(
  40   *                     'type'        => 'string',
  41   *                     'enum'        => array( 'subscriber', 'contributor', 'author', 'editor', 'administrator' ),
  42   *                     'description' => __( 'Limits the export to users with this role.', 'my-plugin' ),
  43   *                     'required'    => false,
  44   *                 ),
  45   *                 'output_schema'       => array(
  46   *                     'type'        => 'string',
  47   *                     'description' => __( 'User data in CSV format.', 'my-plugin' ),
  48   *                     'required'    => true,
  49   *                 ),
  50   *                 'meta'                => array(
  51   *                     'public' => true,
  52   *                 ),
  53   *             )
  54   *         );
  55   *     }
  56   *     add_action( 'wp_abilities_api_init', 'my_plugin_register_abilities' );
  57   *
  58   * Once registered, abilities can be checked, retrieved, and managed:
  59   *
  60   *     // Checks if an ability is registered, and prints its label.
  61   *     if ( wp_has_ability( 'my-plugin/export-users' ) ) {
  62   *         $ability = wp_get_ability( 'my-plugin/export-users' );
  63   *
  64   *         echo $ability->get_label();
  65   *     }
  66   *
  67   *     // Gets all registered abilities.
  68   *     $all_abilities = wp_get_abilities();
  69   *
  70   *     // Unregisters when no longer needed.
  71   *     wp_unregister_ability( 'my-plugin/export-users' );
  72   *
  73   * ## Best Practices
  74   *
  75   *  - Always register abilities on the `wp_abilities_api_init` hook.
  76   *  - Use namespaced ability names to prevent conflicts.
  77   *  - Implement robust permission checks in permission callbacks.
  78   *  - Provide an `input_schema` to ensure data integrity and document expected inputs.
  79   *  - Define an `output_schema` to describe return values and validate responses.
  80   *  - Return `WP_Error` objects for failures rather than throwing exceptions.
  81   *  - Use internationalization functions for all user-facing strings.
  82   *
  83   * @package WordPress
  84   * @subpackage Abilities_API
  85   * @since 6.9.0
  86   */
  87  
  88  declare( strict_types = 1 );
  89  
  90  /**
  91   * Registers a new ability using the Abilities API. It requires three steps:
  92   *
  93   *  1. Hook into the `wp_abilities_api_init` action.
  94   *  2. Call `wp_register_ability()` with a namespaced name and configuration.
  95   *  3. Provide execute and permission callbacks.
  96   *
  97   * Example:
  98   *
  99   *     function my_plugin_register_abilities(): void {
 100   *         wp_register_ability(
 101   *             'my-plugin/analyze-text',
 102   *             array(
 103   *                 'label'               => __( 'Analyze Text', 'my-plugin' ),
 104   *                 'description'         => __( 'Performs sentiment analysis on provided text.', 'my-plugin' ),
 105   *                 'category'            => 'text-processing',
 106   *                 'input_schema'        => array(
 107   *                     'type'        => 'string',
 108   *                     'description' => __( 'The text to be analyzed.', 'my-plugin' ),
 109   *                     'minLength'   => 10,
 110   *                     'required'    => true,
 111   *                 ),
 112   *                 'output_schema'       => array(
 113   *                     'type'        => 'string',
 114   *                     'enum'        => array( 'positive', 'negative', 'neutral' ),
 115   *                     'description' => __( 'The sentiment result: positive, negative, or neutral.', 'my-plugin' ),
 116   *                     'required'    => true,
 117   *                 ),
 118   *                 'execute_callback'    => 'my_plugin_analyze_text',
 119   *                 'permission_callback' => 'my_plugin_can_analyze_text',
 120   *                 'meta'                => array(
 121   *                     'annotations' => array(
 122   *                         'readonly' => true,
 123   *                     ),
 124   *                     'public'      => true,
 125   *                 ),
 126   *             )
 127   *         );
 128   *     }
 129   *     add_action( 'wp_abilities_api_init', 'my_plugin_register_abilities' );
 130   *
 131   * ### Naming Conventions
 132   *
 133   * Ability names must follow these rules:
 134   *
 135   *  - Include a namespace prefix (e.g., `my-plugin/my-ability`).
 136   *  - Use only lowercase alphanumeric characters, dashes, and forward slashes.
 137   *  - Use descriptive, action-oriented names (e.g., `process-payment`, `generate-report`).
 138   *
 139   * ### Categories
 140   *
 141   * Abilities must be organized into categories. Ability categories provide better
 142   * discoverability and must be registered before the abilities that reference them:
 143   *
 144   *     function my_plugin_register_categories(): void {
 145   *         wp_register_ability_category(
 146   *             'text-processing',
 147   *             array(
 148   *                 'label'       => __( 'Text Processing', 'my-plugin' ),
 149   *                 'description' => __( 'Abilities for analyzing and transforming text.', 'my-plugin' ),
 150   *             )
 151   *         );
 152   *     }
 153   *     add_action( 'wp_abilities_api_categories_init', 'my_plugin_register_categories' );
 154   *
 155   * ### Input and Output Schemas
 156   *
 157   * Schemas define the expected structure, type, and constraints for ability inputs
 158   * and outputs using JSON Schema syntax. They serve two critical purposes: automatic
 159   * validation of data passed to and returned from abilities, and self-documenting
 160   * API contracts for developers.
 161   *
 162   * WordPress implements a validator based on a subset of the JSON Schema Version 4
 163   * specification (https://json-schema.org/specification-links.html#draft-4).
 164   * For details on supported JSON Schema properties and syntax, see the
 165   * related WordPress REST API Schema documentation:
 166   * https://developer.wordpress.org/rest-api/extending-the-rest-api/schema/#json-schema-basics
 167   *
 168   * Defining schemas is mandatory when there is a value to pass or return.
 169   * They ensure data integrity, improve developer experience, and enable
 170   * better documentation:
 171   *
 172   *     'input_schema' => array(
 173   *         'type'        => 'string',
 174   *         'description' => __( 'The text to be analyzed.', 'my-plugin' ),
 175   *         'minLength'   => 10,
 176   *         'required'    => true,
 177   *     ),
 178   *     'output_schema'       => array(
 179   *         'type'        => 'string',
 180   *         'enum'        => array( 'positive', 'negative', 'neutral' ),
 181   *         'description' => __( 'The sentiment result: positive, negative, or neutral.', 'my-plugin' ),
 182   *         'required'    => true,
 183   *     ),
 184   *
 185   * ### Callbacks
 186   *
 187   * #### Execute Callback
 188   *
 189   * The execute callback performs the ability's core functionality. It receives
 190   * optional input data and returns either a result or `WP_Error` on failure.
 191   *
 192   *     function my_plugin_analyze_text( string $input ): string|WP_Error {
 193   *         $score = My_Plugin::perform_sentiment_analysis( $input );
 194   *         if ( is_wp_error( $score ) ) {
 195   *             return $score;
 196   *         }
 197   *         return My_Plugin::interpret_sentiment_score( $score );
 198   *     }
 199   *
 200   * #### Permission Callback
 201   *
 202   * The permission callback determines whether the ability can be executed.
 203   * It receives the same input as the execute callback and must return a
 204   * boolean or `WP_Error`. Common use cases include checking user capabilities,
 205   * validating API keys, or verifying system state:
 206   *
 207   *     function my_plugin_can_analyze_text( string $input ): bool|WP_Error {
 208   *         return current_user_can( 'edit_posts' );
 209   *     }
 210   *
 211   * ### Client Exposure
 212   *
 213   * Set the high-level `public` flag to make an ability available to clients
 214   * such as the REST API, MCP, or AI agents:
 215   *
 216   *     'meta' => array(
 217   *         'public' => true,
 218   *     ),
 219   *
 220   * The `public` flag seeds the default for each per-channel flag. For the REST
 221   * API it seeds `show_in_rest`, which lets the ability be invoked via HTTP
 222   * requests. Set a per-channel flag directly to override that default. For
 223   * example, keep a public ability out of the REST API:
 224   *
 225   *     'meta' => array(
 226   *         'public'       => true,
 227   *         'show_in_rest' => false,
 228   *     ),
 229   *
 230   * @since 6.9.0
 231   *
 232   * @see WP_Abilities_Registry::register()
 233   * @see wp_register_ability_category()
 234   * @see wp_unregister_ability()
 235   *
 236   * @param string               $name The name of the ability. Must be a namespaced string containing
 237   *                                   a prefix, e.g., `my-plugin/my-ability`. Can only contain lowercase
 238   *                                   alphanumeric characters, dashes, and forward slashes.
 239   * @param array<string, mixed> $args {
 240   *     An associative array of arguments for configuring the ability.
 241   *
 242   *     @type string               $label               Required. The human-readable label for the ability.
 243   *     @type string               $description         Required. A detailed description of what the ability does
 244   *                                                     and when it should be used.
 245   *     @type string               $category            Required. The ability category slug this ability belongs to.
 246   *                                                     The ability category must be registered via `wp_register_ability_category()`
 247   *                                                     before registering the ability.
 248   *     @type callable             $execute_callback    Required. A callback function to execute when the ability is invoked.
 249   *                                                     Receives optional mixed input data and must return either a result
 250   *                                                     value (any type) or a `WP_Error` object on failure.
 251   *     @type callable             $permission_callback Required. A callback function to check permissions before execution.
 252   *                                                     Receives optional mixed input data (same as `execute_callback`) and
 253   *                                                     must return `true`/`false` for simple checks, or `WP_Error` for
 254   *                                                     detailed error responses.
 255   *     @type array<string, mixed> $input_schema        Optional. JSON Schema definition for validating the ability's input.
 256   *                                                     Must be a valid JSON Schema object defining the structure and
 257   *                                                     constraints for input data. Used for automatic validation and
 258   *                                                     API documentation.
 259   *     @type array<string, mixed> $output_schema       Optional. JSON Schema definition for the ability's output.
 260   *                                                     Describes the structure of successful return values from
 261   *                                                     `execute_callback`. Used for documentation and validation.
 262   *     @type array<string, mixed> $meta                {
 263   *         Optional. Additional metadata for the ability.
 264   *
 265   *         @type array<string, bool|null> $annotations  {
 266   *             Optional. Semantic annotations describing the ability's behavioral characteristics.
 267   *             These annotations are hints for tooling and documentation.
 268   *
 269   *             @type bool|null $readonly    Optional. If true, the ability does not modify its environment.
 270   *             @type bool|null $destructive Optional. If true, the ability may perform destructive updates to its environment.
 271   *                                          If false, the ability performs only additive updates.
 272   *             @type bool|null $idempotent  Optional. If true, calling the ability repeatedly with the same arguments
 273   *                                          will have no additional effect on its environment.
 274   *         }
 275   *         @type bool                     $public       Optional. Whether the ability is meant to be available to
 276   *                                                      clients such as the REST API, MCP, or AI agents. Seeds
 277   *                                                      the default for per-channel flags like `$show_in_rest`.
 278   *                                                      Defaults to false.
 279   *         @type bool                     $show_in_rest Optional. Whether to expose this ability in the REST API.
 280   *                                                      When true, the ability can be invoked via HTTP requests.
 281   *                                                      Default is the value of `$public` when set, false otherwise.
 282   *     }
 283   *     @type string               $ability_class       Optional. Fully-qualified custom class name to instantiate
 284   *                                                     instead of the default `WP_Ability` class. The custom class
 285   *                                                     must extend `WP_Ability`. Useful for advanced customization
 286   *                                                     of ability behavior.
 287   * }
 288   * @return WP_Ability|null The registered ability instance on success, `null` on failure.
 289   */
 290  function wp_register_ability( string $name, array $args ): ?WP_Ability {
 291      if ( ! doing_action( 'wp_abilities_api_init' ) ) {
 292          _doing_it_wrong(
 293              __FUNCTION__,
 294              sprintf(
 295                  /* translators: 1: wp_abilities_api_init, 2: string value of the ability name. */
 296                  __( 'Abilities must be registered on the %1$s action. The ability %2$s was not registered.' ),
 297                  '<code>wp_abilities_api_init</code>',
 298                  '<code>' . esc_html( $name ) . '</code>'
 299              ),
 300              '6.9.0'
 301          );
 302          return null;
 303      }
 304  
 305      $registry = WP_Abilities_Registry::get_instance();
 306      if ( null === $registry ) {
 307          return null;
 308      }
 309  
 310      return $registry->register( $name, $args );
 311  }
 312  
 313  /**
 314   * Unregisters an ability from the Abilities API.
 315   *
 316   * Removes a previously registered ability from the global registry. Use this to
 317   * disable abilities provided by other plugins or when an ability is no longer needed.
 318   *
 319   * Can be called at any time after the ability has been registered.
 320   *
 321   * Example:
 322   *
 323   *     if ( wp_has_ability( 'other-plugin/some-ability' ) ) {
 324   *         wp_unregister_ability( 'other-plugin/some-ability' );
 325   *     }
 326   *
 327   * @since 6.9.0
 328   *
 329   * @see WP_Abilities_Registry::unregister()
 330   * @see wp_register_ability()
 331   *
 332   * @param string $name The name of the ability to unregister, including namespace prefix
 333   *                     (e.g., 'my-plugin/my-ability').
 334   * @return WP_Ability|null The unregistered ability instance on success, `null` on failure.
 335   */
 336  function wp_unregister_ability( string $name ): ?WP_Ability {
 337      $registry = WP_Abilities_Registry::get_instance();
 338      if ( null === $registry ) {
 339          return null;
 340      }
 341  
 342      return $registry->unregister( $name );
 343  }
 344  
 345  /**
 346   * Checks if an ability is registered.
 347   *
 348   * Use this for conditional logic and feature detection before attempting to
 349   * retrieve or use an ability.
 350   *
 351   * Example:
 352   *
 353   *     // Displays different UI based on available abilities.
 354   *     if ( wp_has_ability( 'premium-plugin/advanced-export' ) ) {
 355   *         echo 'Export with Premium Features';
 356   *     } else {
 357   *         echo 'Basic Export';
 358   *     }
 359   *
 360   * @since 6.9.0
 361   *
 362   * @see WP_Abilities_Registry::is_registered()
 363   * @see wp_get_ability()
 364   *
 365   * @param string $name The name of the ability to check, including namespace prefix
 366   *                     (e.g., 'my-plugin/my-ability').
 367   * @return bool `true` if the ability is registered, `false` otherwise.
 368   */
 369  function wp_has_ability( string $name ): bool {
 370      $registry = WP_Abilities_Registry::get_instance();
 371      if ( null === $registry ) {
 372          return false;
 373      }
 374  
 375      return $registry->is_registered( $name );
 376  }
 377  
 378  /**
 379   * Retrieves a registered ability.
 380   *
 381   * Returns the ability instance for inspection or use. The instance provides access
 382   * to the ability's configuration, metadata, and execution methods.
 383   *
 384   * Example:
 385   *
 386   *     // Prints information about a registered ability.
 387   *     $ability = wp_get_ability( 'my-plugin/export-data' );
 388   *     if ( $ability ) {
 389   *         echo $ability->get_label() . ': ' . $ability->get_description();
 390   *     }
 391   *
 392   * @since 6.9.0
 393   *
 394   * @see WP_Abilities_Registry::get_registered()
 395   * @see wp_has_ability()
 396   *
 397   * @param string $name The name of the ability, including namespace prefix
 398   *                     (e.g., 'my-plugin/my-ability').
 399   * @return WP_Ability|null The registered ability instance, or `null` if not registered.
 400   */
 401  function wp_get_ability( string $name ): ?WP_Ability {
 402      $registry = WP_Abilities_Registry::get_instance();
 403      if ( null === $registry ) {
 404          return null;
 405      }
 406  
 407      return $registry->get_registered( $name );
 408  }
 409  
 410  /**
 411   * Retrieves registered abilities, optionally filtered by the given arguments.
 412   *
 413   * When called without arguments, returns all registered abilities. When called
 414   * with an $args array, returns only abilities that match every specified condition.
 415   *
 416   * Filtering pipeline (executed in order):
 417   *
 418   * 1. Declarative filters (`category`, `namespace`, `meta`) — per-item, AND logic between
 419   *    arg types.
 420   * 2. `item_include_callback` — per-item, caller-scoped. Return true to include, false to exclude.
 421   * 3. `wp_get_abilities_item_include` filter — per-item, ecosystem-scoped. Plugins can enforce
 422   *    universal inclusion rules regardless of what the caller passed.
 423   * 4. `result_callback` — on the full matched array, caller-scoped. Sort, slice, or reshape.
 424   * 5. `wp_get_abilities_result` filter — on the full array, ecosystem-scoped.
 425   *
 426   * Steps 1–3 run inside a single loop over the registry — no extra iteration.
 427   *
 428   * Examples:
 429   *
 430   *     // All abilities (unchanged behaviour).
 431   *     $abilities = wp_get_abilities();
 432   *
 433   *     // Filter by category.
 434   *     $abilities = wp_get_abilities( array( 'category' => 'content' ) );
 435   *
 436   *     // Filter by namespace.
 437   *     $abilities = wp_get_abilities( array( 'namespace' => 'woocommerce' ) );
 438   *
 439   *     // Filter by meta.
 440   *     $abilities = wp_get_abilities( array( 'meta' => array( 'show_in_rest' => true ) ) );
 441   *
 442   *     // Combine filters (AND logic between arg types).
 443   *     $abilities = wp_get_abilities( array(
 444   *         'category'  => 'content',
 445   *         'namespace' => 'core',
 446   *         'meta'      => array( 'show_in_rest' => true ),
 447   *     ) );
 448   *
 449   *     // Caller-scoped per-item callback.
 450   *     $abilities = wp_get_abilities( array(
 451   *         'item_include_callback' => function ( WP_Ability $ability ) {
 452   *             return current_user_can( 'manage_options' );
 453   *         },
 454   *     ) );
 455   *
 456   *     // Caller-scoped result callback (sort + paginate).
 457   *     $abilities = wp_get_abilities( array(
 458   *         'result_callback' => function ( array $abilities ) {
 459   *             usort( $abilities, fn( $a, $b ) => strcasecmp( $a->get_label(), $b->get_label() ) );
 460   *             return array_slice( $abilities, 0, 10 );
 461   *         },
 462   *     ) );
 463   *
 464   * The pipeline always runs, even when called with no arguments. This ensures that the
 465   * `wp_get_abilities_item_include` and `wp_get_abilities_result` filters always fire,
 466   * giving plugins a reliable place to enforce universal inclusion or shaping rules.
 467   * For raw, unfiltered registry data that bypasses the filter pipeline entirely, use
 468   * {@see WP_Abilities_Registry::get_all_registered()} directly.
 469   *
 470   * @since 6.9.0
 471   * @since 7.1.0 Added the `$args` parameter for filtering support.
 472   *
 473   * @see WP_Abilities_Registry::get_all_registered()
 474   *
 475   * @param array $args {
 476   *     Optional. Arguments to filter the returned abilities. Default empty array (returns all).
 477   *
 478   *     @type string          $category              Filter by category slug. Only abilities whose category
 479   *                                                  exactly matches the given slug are included.
 480   *     @type string          $namespace             Filter by ability namespace prefix. Pass the namespace
 481   *                                                  without a trailing slash, e.g. `'woocommerce'` matches
 482   *                                                  `'woocommerce/create-order'`.
 483   *     @type array           $meta                  Filter by meta key/value pairs. All conditions must
 484   *                                                  match (AND logic). Supports nested arrays for structured
 485   *                                                  meta, e.g. `array( 'mcp' => array( 'public' => true ) )`.
 486   *     @type callable        $item_include_callback Optional. A callback invoked per ability after declarative
 487   *                                                  filters. Receives a WP_Ability instance, returns bool.
 488   *                                                  Return true to include, false to exclude.
 489   *     @type callable        $result_callback       Optional. A callback invoked once on the full matched
 490   *                                                  array. Receives WP_Ability[], must return WP_Ability[].
 491   *                                                  Use for sorting, slicing, or reshaping the result.
 492   * }
 493   * @return WP_Ability[] An array of registered WP_Ability instances matching the given args,
 494   *                      keyed by ability name. Returns an empty array if no abilities are
 495   *                      registered, the registry is unavailable, or no abilities match the
 496   *                      given args.
 497   */
 498  function wp_get_abilities( array $args = array() ): array {
 499      $registry = WP_Abilities_Registry::get_instance();
 500      if ( null === $registry ) {
 501          return array();
 502      }
 503  
 504      $abilities = $registry->get_all_registered();
 505  
 506      $category              = isset( $args['category'] ) && is_string( $args['category'] ) ? $args['category'] : '';
 507      $namespace             = isset( $args['namespace'] ) && is_string( $args['namespace'] ) ? rtrim( $args['namespace'], '/' ) . '/' : '';
 508      $meta                  = isset( $args['meta'] ) && is_array( $args['meta'] ) ? $args['meta'] : array();
 509      $item_include_callback = isset( $args['item_include_callback'] ) && is_callable( $args['item_include_callback'] ) ? $args['item_include_callback'] : null;
 510      $result_callback       = isset( $args['result_callback'] ) && is_callable( $args['result_callback'] ) ? $args['result_callback'] : null;
 511  
 512      $matched = array();
 513  
 514      foreach ( $abilities as $name => $ability ) {
 515          // Step 1a: Filter by category.
 516          if ( '' !== $category && $ability->get_category() !== $category ) {
 517              continue;
 518          }
 519  
 520          // Step 1b: Filter by namespace prefix.
 521          if ( '' !== $namespace && ! str_starts_with( $ability->get_name(), $namespace ) ) {
 522              continue;
 523          }
 524  
 525          // Step 1c: Filter by meta key/value pairs (AND logic, supports nested arrays).
 526          if ( ! empty( $meta ) && ! _wp_get_abilities_match_meta( $ability->get_meta(), $meta ) ) {
 527              continue;
 528          }
 529  
 530          // Step 2: Caller-scoped per-item callback.
 531          $include = true;
 532          if ( null !== $item_include_callback ) {
 533              $include = (bool) call_user_func( $item_include_callback, $ability );
 534          }
 535  
 536          /**
 537           * Filters whether an individual ability should be included in the result set.
 538           *
 539           * Fires after the declarative filters and the caller-scoped item_include_callback.
 540           * Plugins can use this to enforce universal inclusion rules regardless of
 541           * what the caller passed in $args.
 542           *
 543           * @since 7.1.0
 544           *
 545           * @param bool       $include Whether to include the ability. Default true (after declarative filters pass).
 546           * @param WP_Ability $ability The ability instance being evaluated.
 547           * @param array      $args    The full $args array passed to wp_get_abilities().
 548           */
 549          $include = (bool) apply_filters( 'wp_get_abilities_item_include', $include, $ability, $args );
 550  
 551          if ( $include ) {
 552              $matched[ $name ] = $ability;
 553          }
 554      }
 555  
 556      // Step 4: Caller-scoped result callback.
 557      if ( null !== $result_callback ) {
 558          $matched = (array) call_user_func( $result_callback, $matched );
 559      }
 560  
 561      /**
 562       * Filters the full list of matched abilities after all per-item filtering is complete.
 563       *
 564       * Fires after the caller-scoped result_callback. Plugins can use this to sort,
 565       * paginate, or reshape the final result set universally.
 566       *
 567       * @since 7.1.0
 568       *
 569       * @param WP_Ability[] $matched The matched abilities after all filtering.
 570       * @param array        $args    The full $args array passed to wp_get_abilities().
 571       */
 572      return (array) apply_filters( 'wp_get_abilities_result', $matched, $args );
 573  }
 574  
 575  /**
 576   * Checks whether an ability's meta array matches a set of required key/value conditions.
 577   *
 578   * All conditions must match (AND logic). Supports nested arrays for structured meta,
 579   * e.g. `array( 'mcp' => array( 'public' => true ) )`.
 580   *
 581   * @since 7.1.0
 582   * @access private
 583   *
 584   * @param array $meta       The ability's meta array.
 585   * @param array $conditions The required key/value conditions to match against.
 586   * @return bool True if all conditions match, false otherwise.
 587   */
 588  function _wp_get_abilities_match_meta( array $meta, array $conditions ): bool {
 589      foreach ( $conditions as $key => $value ) {
 590          if ( ! array_key_exists( $key, $meta ) ) {
 591              return false;
 592          }
 593  
 594          if ( is_array( $value ) ) {
 595              if ( ! is_array( $meta[ $key ] ) || ! _wp_get_abilities_match_meta( $meta[ $key ], $value ) ) {
 596                  return false;
 597              }
 598          } elseif ( $meta[ $key ] !== $value ) {
 599              return false;
 600          }
 601      }
 602  
 603      return true;
 604  }
 605  
 606  /**
 607   * Registers a new ability category.
 608   *
 609   * Ability categories provide a way to organize and group related abilities for better
 610   * discoverability and management. Ability categories must be registered before abilities
 611   * that reference them.
 612   *
 613   * Ability categories must be registered on the `wp_abilities_api_categories_init` action hook.
 614   *
 615   * Example:
 616   *
 617   *     function my_plugin_register_categories() {
 618   *         wp_register_ability_category(
 619   *             'content-management',
 620   *             array(
 621   *                 'label'       => __( 'Content Management', 'my-plugin' ),
 622   *                 'description' => __( 'Abilities for managing and organizing content.', 'my-plugin' ),
 623   *             )
 624   *         );
 625   *     }
 626   *     add_action( 'wp_abilities_api_categories_init', 'my_plugin_register_categories' );
 627   *
 628   * @since 6.9.0
 629   *
 630   * @see WP_Ability_Categories_Registry::register()
 631   * @see wp_register_ability()
 632   * @see wp_unregister_ability_category()
 633   *
 634   * @param string               $slug The unique slug for the ability category. Must contain only lowercase
 635   *                                   alphanumeric characters and dashes (e.g., 'data-export').
 636   * @param array<string, mixed> $args {
 637   *     An associative array of arguments for the ability category.
 638   *
 639   *     @type string               $label       Required. The human-readable label for the ability category.
 640   *     @type string               $description Required. A description of what abilities in this category do.
 641   *     @type array<string, mixed> $meta        Optional. Additional metadata for the ability category.
 642   * }
 643   * @return WP_Ability_Category|null The registered ability category instance on success, `null` on failure.
 644   */
 645  function wp_register_ability_category( string $slug, array $args ): ?WP_Ability_Category {
 646      if ( ! doing_action( 'wp_abilities_api_categories_init' ) ) {
 647          _doing_it_wrong(
 648              __FUNCTION__,
 649              sprintf(
 650                  /* translators: 1: wp_abilities_api_categories_init, 2: ability category slug. */
 651                  __( 'Ability categories must be registered on the %1$s action. The ability category %2$s was not registered.' ),
 652                  '<code>wp_abilities_api_categories_init</code>',
 653                  '<code>' . esc_html( $slug ) . '</code>'
 654              ),
 655              '6.9.0'
 656          );
 657          return null;
 658      }
 659  
 660      $registry = WP_Ability_Categories_Registry::get_instance();
 661      if ( null === $registry ) {
 662          return null;
 663      }
 664  
 665      return $registry->register( $slug, $args );
 666  }
 667  
 668  /**
 669   * Unregisters an ability category.
 670   *
 671   * Removes a previously registered ability category from the global registry. Use this to
 672   * disable ability categories that are no longer needed.
 673   *
 674   * Can be called at any time after the ability category has been registered.
 675   *
 676   * Example:
 677   *
 678   *     if ( wp_has_ability_category( 'deprecated-category' ) ) {
 679   *         wp_unregister_ability_category( 'deprecated-category' );
 680   *     }
 681   *
 682   * @since 6.9.0
 683   *
 684   * @see WP_Ability_Categories_Registry::unregister()
 685   * @see wp_register_ability_category()
 686   *
 687   * @param string $slug The slug of the ability category to unregister.
 688   * @return WP_Ability_Category|null The unregistered ability category instance on success, `null` on failure.
 689   */
 690  function wp_unregister_ability_category( string $slug ): ?WP_Ability_Category {
 691      $registry = WP_Ability_Categories_Registry::get_instance();
 692      if ( null === $registry ) {
 693          return null;
 694      }
 695  
 696      return $registry->unregister( $slug );
 697  }
 698  
 699  /**
 700   * Checks if an ability category is registered.
 701   *
 702   * Use this for conditional logic and feature detection before attempting to
 703   * retrieve or use an ability category.
 704   *
 705   * Example:
 706   *
 707   *     // Displays different UI based on available ability categories.
 708   *     if ( wp_has_ability_category( 'premium-features' ) ) {
 709   *         echo 'Premium Features Available';
 710   *     } else {
 711   *         echo 'Standard Features';
 712   *     }
 713   *
 714   * @since 6.9.0
 715   *
 716   * @see WP_Ability_Categories_Registry::is_registered()
 717   * @see wp_get_ability_category()
 718   *
 719   * @param string $slug The slug of the ability category to check.
 720   * @return bool `true` if the ability category is registered, `false` otherwise.
 721   */
 722  function wp_has_ability_category( string $slug ): bool {
 723      $registry = WP_Ability_Categories_Registry::get_instance();
 724      if ( null === $registry ) {
 725          return false;
 726      }
 727  
 728      return $registry->is_registered( $slug );
 729  }
 730  
 731  /**
 732   * Retrieves a registered ability category.
 733   *
 734   * Returns the ability category instance for inspection or use. The instance provides access
 735   * to the ability category's configuration and metadata.
 736   *
 737   * Example:
 738   *
 739   *     // Prints information about a registered ability category.
 740   *     $ability_category = wp_get_ability_category( 'content-management' );
 741   *     if ( $ability_category ) {
 742   *         echo $ability_category->get_label() . ': ' . $ability_category->get_description();
 743   *     }
 744   *
 745   * @since 6.9.0
 746   *
 747   * @see WP_Ability_Categories_Registry::get_registered()
 748   * @see wp_has_ability_category()
 749   * @see wp_get_ability_categories()
 750   *
 751   * @param string $slug The slug of the ability category.
 752   * @return WP_Ability_Category|null The ability category instance, or `null` if not registered.
 753   */
 754  function wp_get_ability_category( string $slug ): ?WP_Ability_Category {
 755      $registry = WP_Ability_Categories_Registry::get_instance();
 756      if ( null === $registry ) {
 757          return null;
 758      }
 759  
 760      return $registry->get_registered( $slug );
 761  }
 762  
 763  /**
 764   * Retrieves all registered ability categories.
 765   *
 766   * Returns an array of all ability category instances currently registered in the system.
 767   * Use this for discovery, debugging, or building administrative interfaces.
 768   *
 769   * Example:
 770   *
 771   *     // Prints information about all available ability categories.
 772   *     $ability_categories = wp_get_ability_categories();
 773   *     foreach ( $ability_categories as $ability_category ) {
 774   *         echo $ability_category->get_label() . ': ' . $ability_category->get_description() . "\n";
 775   *     }
 776   *
 777   * @since 6.9.0
 778   *
 779   * @see WP_Ability_Categories_Registry::get_all_registered()
 780   * @see wp_get_ability_category()
 781   *
 782   * @return WP_Ability_Category[] An array of registered ability category instances. Returns an empty array
 783   *                               if no ability categories are registered or if the registry is unavailable.
 784   */
 785  function wp_get_ability_categories(): array {
 786      $registry = WP_Ability_Categories_Registry::get_instance();
 787      if ( null === $registry ) {
 788          return array();
 789      }
 790  
 791      return $registry->get_all_registered();
 792  }