add_filter( 'bulk_actions-upload', function( $actions ){
      $actions['make_gallery'] = 'ギャラリーコードを作成';
      return $actions;
}, 20 );

add_filter( 'handle_bulk_actions-upload', function( $redirect_to, $action, $ids ){
      if( $action !== 'make_gallery' ){
              return $redirect_to;
      }
      $id_str = implode( ',', $ids );
      $code = '[gallery ids="' . $id_str . '" columns="1" size="full"]';
      set_transient(
              'kb_gallery_code_' . get_current_user_id(),
              $code,
              60
      );
      return add_query_arg( 'kb_gallery_code', '1', $redirect_to );
}, 10, 3 );

add_action( 'admin_notices', function(){
      $screen = get_current_screen();
      if( !$screen || $screen->id !== 'upload' ){
              return;
      }
      if( empty( $_GET['kb_gallery_code'] ) ){
              return;
      }
      $code = get_transient(
              'kb_gallery_code_' . get_current_user_id()
      );
      if( !$code ){
              return;
      }
      delete_transient(
              'kb_gallery_code_' . get_current_user_id()
      );
      echo '<div class="notice notice-success"><p>';
      echo '下のコードを記事本文にそのまま貼り付けてください';
      echo '</p>';
      echo '<textarea readonly style="width:100%;height:80px;" onclick="this.select();">';
      echo esc_textarea( $code );
      echo '</textarea></div>';
});


<title>XML Sitemap</title><style type="text/css">
					body {
						font-family:"Lucida Grande","Lucida Sans Unicode",Tahoma,Verdana;
						font-size:13px;
					}
					
					#intro {
						background-color:#cfebf7;
						border:1px #2580B2 solid;
						padding:5px 13px 5px 13px;
						margin:10px;
					}
					
					#intro p {
						line-height:16.8667px;
					}
					#intro strong {
						font-weight:normal;
					}
					
					td {
						font-size:11px;
					}
					
					th {
						text-align:left;
						padding-right:30px;
						font-size:11px;
					}
					
					tr.high {
						background-color:whitesmoke;
					}
					
					#footer {
						padding:2px;
						margin-top:10px;
						font-size:8pt;
						color:gray;
					}
					
					#footer a {
						color:gray;
					}
					
					a {
						color:black;
					}
				</style><h1>XML Sitemap Index</h1><div id="intro"><p>
                This XML sitemap is used by search engines which follow the <a rel="external nofollow" href="https://sitemaps.org">XML sitemap standard</a>. This file contains links to sub-sitemaps, follow them to see the actual sitemap content.
            </p><p>
                This file was dynamically generated using the <a rel="external nofollow" href="https://wordpress.org/">WordPress</a> content management system and <strong><a rel="external nofollow" href="https://auctollo.com/products/google-xml-sitemap-generator/" title="XML Sitemap Generator for Google">XML Sitemap Generator for Google</a></strong> by <a rel="external nofollow" href="https://auctollo.com/">Auctollo</a>.
            </p></div><div id="content"><table><tr style="border-bottom:1px black solid"><th>URL of sub-sitemap</th><th>Last modified (GMT)</th></tr><tr><td><a href="https://kyarabetsunijiero.net/sitemap-misc.html">https://kyarabetsunijiero.net/sitemap-misc.html</a></td><td>2026-09-22T21:00:00+00:00</td></tr><tr class="high"><td><a href="https://kyarabetsunijiero.net/post-sitemap.html">https://kyarabetsunijiero.net/post-sitemap.html</a></td><td>2026-09-22T17:56:37+00:00</td></tr><tr><td><a href="https://kyarabetsunijiero.net/post-sitemap2.html">https://kyarabetsunijiero.net/post-sitemap2.html</a></td><td>2026-09-22T17:56:37+00:00</td></tr><tr class="high"><td><a href="https://kyarabetsunijiero.net/post-sitemap3.html">https://kyarabetsunijiero.net/post-sitemap3.html</a></td><td>2026-09-22T17:56:37+00:00</td></tr><tr><td><a href="https://kyarabetsunijiero.net/post-sitemap4.html">https://kyarabetsunijiero.net/post-sitemap4.html</a></td><td>2026-09-22T17:56:37+00:00</td></tr><tr class="high"><td><a href="https://kyarabetsunijiero.net/post-sitemap5.html">https://kyarabetsunijiero.net/post-sitemap5.html</a></td><td>2026-09-22T17:56:37+00:00</td></tr><tr><td><a href="https://kyarabetsunijiero.net/post-sitemap6.html">https://kyarabetsunijiero.net/post-sitemap6.html</a></td><td>2026-09-22T17:56:37+00:00</td></tr><tr class="high"><td><a href="https://kyarabetsunijiero.net/post-sitemap7.html">https://kyarabetsunijiero.net/post-sitemap7.html</a></td><td>2026-09-22T17:56:37+00:00</td></tr><tr><td><a href="https://kyarabetsunijiero.net/page-sitemap.html">https://kyarabetsunijiero.net/page-sitemap.html</a></td><td>2023-11-07T05:12:14+00:00</td></tr></table></div><div id="footer"><p>
						Dynamically generated with <a rel="external nofollow" href="https://auctollo.com/products/google-xml-sitemap-generator/" title="XML Sitemap Generator for Google">XML Sitemap Generator for Google</a> by <a rel="external nofollow" href="https://auctollo.com/">Auctollo</a>. This XSLT template is released under the GPL and free to use.
            		</p><p>
	                    If you have problems with your sitemap please visit the <a rel="external nofollow" href="https://auctollo.com/products/google-xml-sitemap-generator/help/" title="Frequently Asked Questions">FAQ</a> or the <a rel="external nofollow" href="https://wordpress.org/support/plugin/google-sitemap-generator">support forum</a>.
            		</p></div>