Example of extracting commenter names from the offline issues HTML from https://github.com/jreinhardt/handkerchief/pull/33

issue-commenters.php

// https://github.com/indieweb/php-mf2/blob/master/Mf2/Parser.php
require_once 'Mf2/Parser.php';

$parsed = Mf2\parse(file_get_contents('issues-webmention.html'));

$authors = [];

foreach($parsed['items'][0]['children'] as $comment) {
  $author = strtolower($comment['properties']['author'][0]);
  if(!in_array($author, $authors))
    $authors[] = $author;
}

sort($authors);

print_r($authors);

issue-commenters.txt

Array
(
    [0] => aaronpk
    [1] => aphillips
    [2] => azaroth42
    [3] => bblfish
    [4] => bear
    [5] => csarven
    [6] => dissolve
    [7] => domenicodefelice
    [8] => dret
    [9] => gobengo
    [10] => gregorlove
    [11] => hvdsomp
    [12] => kevinmarks
    [13] => kousu
    [14] => mblaney
    [15] => melvincarvalho
    [16] => perlkonig
    [17] => r12a
    [18] => rhiaro
    [19] => sandhawke
    [20] => singpolyma
    [21] => sknebel
    [22] => snarfed
    [23] => tantek
    [24] => wilkie
    [25] => willnorris
)