Add a Notes section in the Dashboard Activity widget

src/wp-admin/css/dashboard.css

@@ -929,21 +929,29 @@ body #dashboard-widgets .postbox form .submit {
 }
 
 #future-posts ul,
-#published-posts ul {
+#published-posts ul,
+#latest-notes ul {
 	margin: 8px -12px 0 -12px;
 }
 
 #future-posts li,
-#published-posts li {
+#published-posts li,
+#latest-notes li {
 	display: grid;
 	grid-template-columns: clamp(160px, calc(2vw + 140px), 200px) auto;
 	column-gap: 10px;
 	color: #646970;
 	padding: 4px 12px;
 }
 
+/* Recent Notes rows add a third column for the number of open notes. */
+#latest-notes li {
+	grid-template-columns: clamp(160px, calc(2vw + 140px), 200px) auto max-content;
+}
+
 #future-posts li:nth-child(odd),
-#published-posts li:nth-child(odd) {
+#published-posts li:nth-child(odd),
+#latest-notes li:nth-child(odd) {
 	background-color: #f6f7f7;
 }
 

src/wp-admin/includes/dashboard.php

@@ -967,7 +967,9 @@ function wp_dashboard_site_activity() {
 
 	$recent_comments = wp_dashboard_recent_comments();
 
-	if ( ! $future_posts && ! $recent_posts && ! $recent_comments ) {
+	$recent_notes = wp_dashboard_recent_notes();
+
+	if ( ! $future_posts && ! $recent_posts && ! $recent_comments && ! $recent_notes ) {
 		echo '<div class="no-activity">';
 		echo '<p>' . __( 'No activity yet!' ) . '</p>';
 		echo '</div>';
@@ -1152,6 +1154,172 @@ function wp_dashboard_recent_comments( $total_items = 5 ) {
 	return true;
 }
 
+/**
+ * Show Notes section.
+ *
+ * Lists the posts the current user can edit that have at least one open note,
+ * ordered by the note or reply most recently added to them.
+ *
+ * @since 7.2.0
+ *
+ * @global wpdb $wpdb WordPress database abstraction object.
+ *
+ * @param int $total_items Optional. Number of posts to display. Default 5.
+ * @return bool False if no posts with open notes were found. True otherwise.
+ *
+ * @phpstan-param positive-int $total_items
+ */
+function wp_dashboard_recent_notes( int $total_items = 5 ): bool {
+	global $wpdb;
+
+	if ( $total_items < 1 ) {
+		return false;
+	}
+
+	/*
+	 * Only look at posts the current user may be able to edit: any post of a type
+	 * they can edit others' posts of, and their own posts of the other types.
+	 */
+	$any_author_types = array();
+	$own_types        = array();
+
+	foreach ( get_post_types( array( 'show_ui' => true ), 'objects' ) as $post_type ) {
+		if ( current_user_can( $post_type->cap->edit_others_posts ) ) {
+			$any_author_types[] = $post_type->name;
+		} elseif ( current_user_can( $post_type->cap->edit_posts ) ) {
+			$own_types[] = $post_type->name;
+		}
+	}
+
+	if ( ! $any_author_types && ! $own_types ) {
+		return false;
+	}
+
+	$post_type_clauses = array();
+
+	if ( $any_author_types ) {
+		$post_type_clauses[] = $wpdb->prepare(
+			'posts.post_type IN (' . implode( ', ', array_fill( 0, count( $any_author_types ), '%s' ) ) . ')',
+			$any_author_types
+		);
+	}
+
+	if ( $own_types ) {
+		$post_type_clauses[] = $wpdb->prepare(
+			'( posts.post_type IN (' . implode( ', ', array_fill( 0, count( $own_types ), '%s' ) ) . ') AND posts.post_author = %d )',
+			array_merge( $own_types, array( get_current_user_id() ) )
+		);
+	}
+
+	/*
+	 * One row per post, dated by its most recent open note or reply, with the
+	 * number of open threads on it. Resolving a thread approves the note that
+	 * starts it while its replies stay on hold, so a reply only counts while its
+	 * thread is open.
+	 */
+	$notes_sql = "SELECT notes.comment_post_ID AS post_id, MAX( notes.comment_date_gmt ) AS latest_date_gmt, SUM( notes.comment_parent = 0 ) AS open_threads
+		FROM {$wpdb->comments} AS notes
+		INNER JOIN {$wpdb->posts} AS posts ON ( posts.ID = notes.comment_post_ID )
+		LEFT JOIN {$wpdb->comments} AS threads ON ( threads.comment_ID = notes.comment_parent )
+		WHERE notes.comment_type = 'note'
+			AND notes.comment_approved = '0'
+			AND ( notes.comment_parent = 0 OR threads.comment_approved = '0' )
+			AND ( " . implode( ' OR ', $post_type_clauses ) . ' )
+		GROUP BY notes.comment_post_ID
+		ORDER BY latest_date_gmt DESC';
+
+	$salt = array( wp_cache_get_last_changed( 'comment' ), wp_cache_get_last_changed( 'posts' ) );
+	$rows = array();
+
+	/*
+	 * A post can still be one the user cannot edit, such as a private post of
+	 * someone else, so the posts are checked and paged through. Paging stops
+	 * after a few pages, so the section costs a bounded number of queries.
+	 */
+	$page_size = $total_items * 2;
+
+	for ( $page = 0; $page < 5; $page++ ) {
+		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- The query is built from prepared clauses above.
+		$page_sql  = $wpdb->prepare( $notes_sql . ' LIMIT %d, %d', $page * $page_size, $page_size );
+		$cache_key = 'wp_dashboard_recent_notes:' . md5( $page_sql );
+		$page_rows = wp_cache_get_salted( $cache_key, 'comment-queries', $salt );
+
+		if ( ! is_array( $page_rows ) ) {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- Prepared above.
+			$page_rows = $wpdb->get_results( $page_sql );
+			wp_cache_set_salted( $cache_key, $page_rows, 'comment-queries', $salt );
+		}
+
+		_prime_post_caches( wp_list_pluck( $page_rows, 'post_id' ), false, false );
+
+		foreach ( $page_rows as $row ) {
+			$edit_post_link = get_edit_post_link( (int) $row->post_id );
+
+			// Notes are only visible to users who can edit the post they belong to.
+			if ( ! $edit_post_link ) {
+				continue;
+			}
+
+			$rows[] = array(
+				'post_id'         => (int) $row->post_id,
+				'latest_date_gmt' => $row->latest_date_gmt,
+				'open_threads'    => (int) $row->open_threads,
+				'edit_post_link'  => $edit_post_link,
+			);
+
+			if ( count( $rows ) === $total_items ) {
+				break 2;
+			}
+		}
+
+		if ( count( $page_rows ) < $page_size ) {
+			break;
+		}
+	}
+
+	if ( ! $rows ) {
+		return false;
+	}
+
+	?>
+	<div id="latest-notes" class="activity-block">
+		<h3><?php _e( 'Recent Notes' ); ?></h3>
+		<ul>
+		<?php
+		foreach ( $rows as $row ) :
+			$note_time      = strtotime( $row['latest_date_gmt'] . ' +0000' );
+			$note_time_diff = '';
+
+			// Leave the date out for a note with no valid date.
+			if ( is_int( $note_time ) && $note_time > 0 ) {
+				/* translators: %s: Human-readable time difference. */
+				$note_time_diff = sprintf( __( '%s ago' ), human_time_diff( min( $note_time, time() ) ) );
+			}
+
+			$note_post_title = _draft_or_post_title( $row['post_id'] );
+
+			/* translators: %s: Post title. */
+			$note_post_label = sprintf( __( 'Edit &#8220;%s&#8221;' ), $note_post_title );
+
+			$note_count = sprintf(
+				/* translators: %s: Number of open note threads. */
+				_n( '%s open thread', '%s open threads', $row['open_threads'] ),
+				number_format_i18n( $row['open_threads'] )
+			);
+			?>
+			<li>
+				<span><?php echo $note_time_diff; ?></span>
+				<a href="<?php echo esc_url( $row['edit_post_link'] ); ?>" aria-label="<?php echo esc_attr( $note_post_label ); ?>"><?php echo $note_post_title; ?></a>
+				<span class="open-notes-count"><?php echo $note_count; ?></span>
+			</li>
+		<?php endforeach; ?>
+		</ul>
+	</div>
+	<?php
+
+	return true;
+}
+
 /**
  * Display generic dashboard RSS widget feed.
  *

src/wp-admin/includes/upgrade.php

@@ -166,10 +166,12 @@ function wp_install(
 	/**
 	 * Creates the initial content for a newly-installed site.
 	 *
-	 * Adds the default "Uncategorized" category, the first post (with comment),
-	 * first page, and default widgets for default theme for the current version.
+	 * Adds the default "Uncategorized" category, the first post (with comment
+	 * and note), first page, and default widgets for default theme for the
+	 * current version.
 	 *
 	 * @since 2.1.0
+	 * @since 7.2.0 Adds a note to the first block of the first post.
 	 *
 	 * @global wpdb       $wpdb         WordPress database abstraction object.
 	 * @global WP_Rewrite $wp_rewrite   WordPress rewrite component.
@@ -306,6 +308,68 @@ function wp_install_defaults( $user_id ) {
 			)
 		);
 
+		/*
+		 * Default note, attached to the first block of the first post.
+		 * A note is linked to its block through the block's `metadata.noteId`
+		 * attribute, so no note is added when the post has no blocks.
+		 */
+		if ( is_multisite() ) {
+			$first_note = get_site_option( 'first_note' );
+		}
+
+		$first_note = ! empty( $first_note ) ? $first_note : __( 'Hi, this is a note. Notes let you leave feedback on a block for anyone else working on this post. To add one, select some text or an entire block and choose Add note from its options menu. Resolve a note once its feedback has been addressed.' );
+
+		$first_block = new WP_Block_Processor( $first_post );
+		$note_author = get_userdata( $user_id );
+
+		if ( $first_block->next_block() && $note_author ) {
+			$first_block_span  = $first_block->get_span();
+			$first_block_name  = $first_block->get_printable_block_type();
+			$first_block_attrs = $first_block->allocate_and_return_parsed_attributes() ?? array();
+			$first_block_void  = WP_Block_Processor::VOID === $first_block->get_delimiter_type();
+
+			// Leave a block with attributes that cannot be parsed untouched.
+			if ( JSON_ERROR_NONE === $first_block->get_last_json_error() && $first_block_span && $first_block_name ) {
+				$note_inserted = $wpdb->insert(
+					$wpdb->comments,
+					array(
+						'comment_post_ID'      => 1,
+						'comment_author'       => $note_author->display_name,
+						'comment_author_email' => $note_author->user_email,
+						'comment_author_url'   => $note_author->user_url,
+						'comment_date'         => $now,
+						'comment_date_gmt'     => $now_gmt,
+						'comment_content'      => $first_note,
+						// Notes are open until they are resolved, which approves them.
+						'comment_approved'     => '0',
+						'comment_type'         => 'note',
+						'user_id'              => $user_id,
+					)
+				);
+
+				if ( $note_inserted ) {
+					$first_block_meta = isset( $first_block_attrs['metadata'] ) && is_array( $first_block_attrs['metadata'] ) ? $first_block_attrs['metadata'] : array();
+
+					$first_block_meta['noteId']    = $wpdb->insert_id;
+					$first_block_attrs['metadata'] = $first_block_meta;
+
+					// Only the first block's opening delimiter is rewritten, the rest of the post is kept as is.
+					$first_block_delimiter = sprintf(
+						'<!-- wp:%s %s %s-->',
+						strip_core_block_namespace( $first_block_name ),
+						serialize_block_attributes( $first_block_attrs ),
+						$first_block_void ? '/' : ''
+					);
+
+					$wpdb->update(
+						$wpdb->posts,
+						array( 'post_content' => substr_replace( $first_post, $first_block_delimiter, $first_block_span->start, $first_block_span->length ) ),
+						array( 'ID' => 1 )
+					);
+				}
+			}
+		}
+
 		// First page.
 		if ( is_multisite() ) {
 			$first_page = get_site_option( 'first_page' );

src/wp-admin/network/settings.php

@@ -106,6 +106,7 @@
 		'WPLANG',
 		'new_admin_email',
 		'first_comment_email',
+		'first_note',
 	);
 
 	// Handle translation installation.
@@ -395,6 +396,16 @@
 					</p>
 				</td>
 			</tr>
+			<tr>
+				<th scope="row"><label for="first_note"><?php _e( 'First Note' ); ?></label></th>
+				<td>
+					<textarea name="first_note" id="first_note" aria-describedby="first-note-desc" rows="5" cols="45" class="large-text">
+<?php echo esc_textarea( get_site_option( 'first_note' ) ); ?></textarea>
+					<p class="description" id="first-note-desc">
+						<?php _e( 'The first note on the first post of a new site.' ); ?>
+					</p>
+				</td>
+			</tr>
 		</table>
 		<h2 id="wp-settings-section-upload-settings"><?php _e( 'Upload Settings' ); ?></h2>
 		<table class="form-table" role="presentation">