diff --git a/api.wordpress.org/public_html/dotorg/slack/announce.php b/api.wordpress.org/public_html/dotorg/slack/announce.php
index 04a7c8918b..b9bc0c5f02 100644
--- a/api.wordpress.org/public_html/dotorg/slack/announce.php
+++ b/api.wordpress.org/public_html/dotorg/slack/announce.php
@@ -1,38 +1,72 @@
 <?php
+/**
+ * Slack slash-command handler for @here and @channel announcements.
+ *
+ * Standalone handler: WordPress is not loaded, so request data is never slashed. Slack
+ * authenticates itself with one of the shared `WEBHOOK_TOKEN_*` secrets below; nonces do
+ * not exist in server-to-server webhooks.
+ *
+ * phpcs:disable WordPress.Security.NonceVerification, WordPress.Security.ValidatedSanitizedInput.MissingUnslash
+ *
+ * @package WordPressdotorg\API\Slack
+ */
 
-namespace {
-	require dirname( dirname( __DIR__ ) ) . '/includes/hyperdb/bb-10-hyper-db.php';
-	require dirname( dirname( __DIR__ ) ) . '/includes/slack-config.php';
-}
-
-namespace Dotorg\Slack\Announce {
+namespace Dotorg\Slack\Announce;
 
-require dirname( dirname( __DIR__ ) ) . '/includes/slack/announce/lib.php';
+require dirname( __DIR__, 2 ) . '/includes/hyperdb/bb-10-hyper-db.php';
+require dirname( __DIR__, 2 ) . '/includes/slack-config.php';
+require dirname( __DIR__, 2 ) . '/includes/slack/announce/lib.php';
 
-function get_avatar( $username, $slack_id, $team_id ) {
+/**
+ * Returns the Gravatar URL for the WordPress.org account linked to a Slack user.
+ *
+ * Defined in this namespace so that `run()` in lib.php picks it up as an optional hook;
+ * it falls back to the Slack profile image when this function is not available.
+ *
+ * @param string $username The Slack user name. Unused, part of the hook signature.
+ * @param string $slack_id The Slack user ID to look up.
+ * @param string $team_id  The Slack team ID. Unused, part of the hook signature.
+ * @return string The Gravatar URL, or an empty string when the Slack account is not linked.
+ */
+function get_avatar( $username, $slack_id, $team_id ) { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter -- Signature is fixed by the call in lib.php.
 	global $wpdb;
 
-	$wp_user_id = $wpdb->get_var( $wpdb->prepare(
-		"SELECT user_id FROM slack_users WHERE slack_id = %s",
-		$slack_id
-	) );
+	$wp_user_id = $wpdb->get_var(
+		$wpdb->prepare(
+			'SELECT user_id FROM slack_users WHERE slack_id = %s',
+			$slack_id
+		)
+	);
+
+	if ( ! $wp_user_id ) {
+		return '';
+	}
+
+	$email = $wpdb->get_var(
+		$wpdb->prepare(
+			"SELECT user_email FROM $wpdb->users WHERE ID = %d",
+			$wp_user_id
+		)
+	);
 
-	$email = $wpdb->get_var( $wpdb->prepare(
-		"SELECT user_email FROM $wpdb->users WHERE ID = %d",
-		$wp_user_id
-	) );
+	if ( ! $email ) {
+		return '';
+	}
 
 	$hash = hash( 'sha256', strtolower( trim( $email ) ) );
-	return sprintf( 'https://secure.gravatar.com/avatar/%s?s=96d=mm&r=G&%s', $hash, time() );
+	return sprintf( 'https://secure.gravatar.com/avatar/%s?s=96&d=mm&r=G&%s', $hash, time() );
+}
+
+// Slack sends the token as POST data; anything else is not a webhook request.
+if ( ! isset( $_POST['token'] ) || ! is_string( $_POST['token'] ) || '' === $_POST['token'] ) {
+	return;
 }
 
 $i = 0;
 // WEBHOOK_TOKEN_1, WEBHOOK_TOKEN_2, etc.
-while ( defined( __NAMESPACE__ . '\\WEBHOOK_TOKEN_' . ++$i ) ) {
+while ( defined( __NAMESPACE__ . '\\WEBHOOK_TOKEN_' . ( ++$i ) ) ) {
 	if ( hash_equals( constant( __NAMESPACE__ . '\\WEBHOOK_TOKEN_' . $i ), $_POST['token'] ) ) {
 		run( $_POST );
+		break;
 	}
 }
-
-}
-
diff --git a/api.wordpress.org/public_html/dotorg/slack/committers.php b/api.wordpress.org/public_html/dotorg/slack/committers.php
index e89f6a820b..a4e11150f9 100644
--- a/api.wordpress.org/public_html/dotorg/slack/committers.php
+++ b/api.wordpress.org/public_html/dotorg/slack/committers.php
@@ -1,19 +1,39 @@
 <?php
-
-// Allow committers to publicly mention other committers via @committers.
+/**
+ * Slack outgoing-webhook handler that redirects @committers mentions to the slash command.
+ *
+ * Standalone handler: WordPress is not loaded, so request data is never slashed. Slack
+ * authenticates itself with the shared `WEBHOOK_TOKEN` secret below; nonces do not exist
+ * in server-to-server webhooks.
+ *
+ * phpcs:disable WordPress.Security.NonceVerification, WordPress.Security.ValidatedSanitizedInput.MissingUnslash
+ *
+ * @package WordPressdotorg\API\Slack
+ */
 
 namespace Dotorg\Slack\Committers;
 
-require dirname( dirname( __DIR__ ) ) . '/includes/slack-config.php';
+require dirname( __DIR__, 2 ) . '/includes/slack-config.php';
+
+// Slack sends the token as POST data; anything else is not a webhook request.
+if ( ! isset( $_POST['token'] ) || ! is_string( $_POST['token'] ) || '' === $_POST['token'] ) {
+	return;
+}
 
 if ( ! hash_equals( WEBHOOK_TOKEN, $_POST['token'] ) ) {
 	return;
 }
 
-echo json_encode( array(
-	'username'   => 'wordpressdotorg',
-	'link_names' => 1,
-	'text'       => sprintf( '@%s: Use the `/committers` command.', $_POST['user_name'] ),
-) );
+// The Slack user name of whoever triggered the webhook, echoed back in the JSON response below.
+$user_name = (string) filter_var( $_POST['user_name'] ?? '', FILTER_UNSAFE_RAW, FILTER_FLAG_STRIP_LOW );
+
+// phpcs:ignore WordPress.WP.AlternativeFunctions.json_encode_json_encode -- No WP loaded.
+echo json_encode(
+	array(
+		'username'   => 'wordpressdotorg',
+		'link_names' => 1,
+		'text'       => sprintf( '@%s: Use the `/committers` command.', $user_name ),
+	)
+);
 
 exit;