Fix language status detection for plugins/themes with text domain different from slug

features/language-plugin.feature

@@ -444,3 +444,35 @@ Feature: Manage plugin translation files for a WordPress install
       | akismet  | en_US    | active    |
       | akismet  | nl_NL    | installed |
     And STDERR should be empty
+
+  @require-wp-4.0
+  Scenario: Handle plugins with text domain different from slug
+    Given a WP install
+    And an empty cache
+
+    # Create a test plugin with a different text domain
+    And a wp-content/plugins/test-plugin/test-plugin.php file:
+      """
+      <?php
+      /**
+       * Plugin Name: Test Plugin
+       * Text Domain: different-text-domain
+       * Domain Path: /languages
+       */
+      """
+
+    # Manually create a translation file using the text domain (not the plugin slug)
+    And a wp-content/languages/plugins/different-text-domain-de_DE.l10n.php file:
+      """
+      """
+
+    When I run `wp language plugin list test-plugin --fields=language,status --format=csv`
+    Then STDOUT should contain:
+      """
+      en_US,active
+      """
+    And STDERR should be empty
+
+    # If the fix is working, installed languages should be detected via text domain
+    When I run `wp language plugin is-installed test-plugin de_DE`
+    Then the return code should be 0

features/language-theme.feature

@@ -328,3 +328,33 @@ Feature: Manage theme translation files for a WordPress install
       | en_US    | active    |
       | nl_NL    | installed |
     And STDERR should be empty
+
+  @require-wp-4.0
+  Scenario: Handle themes with text domain different from slug
+    Given a WP install
+    And an empty cache
+
+    # Create a test theme with a different text domain
+    And a wp-content/themes/test-theme/style.css file:
+      """
+      /*
+      Theme Name: Test Theme
+      Text Domain: different-text-domain
+      */
+      """
+
+    # Manually create a translation file using the text domain (not the theme slug)
+    And a wp-content/languages/themes/different-text-domain-de_DE.l10n.php file:
+      """
+      """
+
+    When I run `wp language theme list test-theme --fields=language,status --format=csv`
+    Then STDOUT should contain:
+      """
+      en_US,active
+      """
+    And STDERR should be empty
+
+    # If the fix is working, installed languages should be detected via text domain
+    When I run `wp language theme is-installed test-theme de_DE`
+    Then the return code should be 0

src/WP_CLI/CommandWithTranslation.php

@@ -283,8 +283,33 @@ protected function get_installed_languages( $slug = 'default' ) {
 		/**
 		 * @var array<string, array<string, array<string, mixed>>> $available
 		 */
-		$available   = wp_get_installed_translations( $this->obj_type );
-		$available   = ! empty( $available[ $slug ] ) ? array_keys( $available[ $slug ] ) : array();
+		$available = wp_get_installed_translations( $this->obj_type );
+
+		// For plugins and themes, check if the text domain differs from the slug.
+		$text_domain = $slug;
+		if ( 'default' !== $slug ) {
+			if ( 'plugins' === $this->obj_type ) {
+				$plugins = get_plugins( '/' . $slug );
+				if ( ! empty( $plugins ) ) {
+					$plugin_data = array_shift( $plugins );
+					// Use the TextDomain header if available, otherwise fall back to slug.
+					if ( ! empty( $plugin_data['TextDomain'] ) ) {
+						$text_domain = $plugin_data['TextDomain'];
+					}
+				}
+			} elseif ( 'themes' === $this->obj_type ) {
+				$theme_data = wp_get_theme( $slug );
+				if ( $theme_data->exists() ) {
+					// Use the TextDomain property if available, otherwise fall back to slug.
+					$theme_text_domain = $theme_data->get( 'TextDomain' );
+					if ( ! empty( $theme_text_domain ) ) {
+						$text_domain = $theme_text_domain;
+					}
+				}
+			}
+		}
+
+		$available   = ! empty( $available[ $text_domain ] ) ? array_keys( $available[ $text_domain ] ) : array();
 		$available[] = 'en_US';
 
 		return $available;