UserScript to decorate #1234 issue links with their actual title. Needs an access token: https://github.com/settings/tokens

userscripts.github.issueLinkTitle.js

// ==UserScript==
// @name         GitHub Issue Link Title (GHILT)
// @version      0.0.1
// @author       dirkraft
// Must match aggressively due to HTML5 History, which won't trigger Tampermonkey @match.
// @match        https://github.com/*/*
// @grant        none
// @require      https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js
// ==/UserScript==

(function($) {

    const localStorageKey = 'GHILT.githubApiKey';
    let apiKey = localStorage.getItem(localStorageKey);
    if (!apiKey) {
        apiKey = prompt('GHILT: I need a GitHub API key!');
        localStorage.setItem(localStorageKey, apiKey.trim());
    }

    if (apiKey) {
        checkLinks();
        console.log('GHILT:initialized. 💣');
    }

    function checkLinks() {
        let locationParts = location.href.split('/');
        let org = locationParts[3];
        let repo = locationParts[4];
        $('.discussion-timeline .issue-link:not(.GHILT-decorated)').each((idx, el) => {
            let $el = $(el);
            // Immediately to prevent retrying continually.
            $el.addClass('GHILT-decorated');

            let issueMatch = $el.text().match(/^(\S+\/\S+)?#(\d+)$/);
            if (issueMatch) {
                let isCrossRepo = !!issueMatch[1];
                let orgRepo = issueMatch[1] || (org + '/' + repo);
                let issue = issueMatch[2];
                $.getJSON('https://api.github.com/repos/' + orgRepo + '/issues/' + issue + '?access_token=' + apiKey, (data) => {
                    if (isCrossRepo) {
                        $el.text('[' + orgRepo + '#' + issue + ' ' + data.title + ']');
                    } else {
                        $el.text('[#' + issue + ' ' + data.title + ']');
                    }
                });
            }
        });
        setTimeout(checkLinks, 1000);
    }
})(jQuery);