collab-email.user.js

// ==UserScript==
// @name     collab email helper
// @version  0.33
// @grant    none
// @match    https://mail.google.com/*
// @run-at   document-idle
// @downloadURL https://gist.github.com/maxtheaxe/04304ba7caf25d55fb94748818c5819f/raw/a04400197abeda9aa815c8f4ae1efb510732ee61/collab-email.user.js
// @updateURL https://gist.github.com/maxtheaxe/04304ba7caf25d55fb94748818c5819f/raw/a04400197abeda9aa815c8f4ae1efb510732ee61/collab-email.user.js
// ==/UserScript==

(() => {
  'use strict';

  const LABEL_PREFIX = 'collab/';
  const TARGET_BUTTON_TEXT = 'Reply all';
  const DEBOUNCE_MS = 150;

  // threadId -> WeakSet<HTMLElement>
  const processedByThread = new Map();

  function getThreadPermId() {
    // In thread view Gmail commonly renders the subject as h2 with data-thread-perm-id
    const h2 = document.querySelector('div[role="main"] h2[data-thread-perm-id]');
    return h2?.getAttribute('data-thread-perm-id') ?? null;
  }

  function findReplyAllSpan() {
    const xpath = `//button[normalize-space(.)="${TARGET_BUTTON_TEXT}"]`;
    return document
      .evaluate(xpath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null)
      .singleNodeValue;
  }

  function findState() {
    const threadPermId = getThreadPermId();
    if (!threadPermId) return null;

    const labelEl = document.querySelector(`[aria-label^="Remove label ${LABEL_PREFIX}"]`);
    if (!labelEl || !labelEl.isConnected) return null;

    const replyAllSpan = findReplyAllSpan();
    if (!replyAllSpan || !replyAllSpan.isConnected) return null;

    return { threadPermId, labelEl, replyAllSpan };
  }

  function apply({ threadPermId, replyAllSpan }) {
    let set = processedByThread.get(threadPermId);
    if (!set) {
      set = new WeakSet();
      processedByThread.set(threadPermId, set);
    }

    // If we already styled THIS exact node for THIS thread, don't do it again.
    if (set.has(replyAllSpan)) return;

    set.add(replyAllSpan);
    replyAllSpan.style.border = '2px solid lime';
  }

  let runTimer = null;
  function debouncedCheck() {
    if (runTimer) clearTimeout(runTimer);
    runTimer = setTimeout(() => {
      runTimer = null;
      const state = findState();
      if (state) apply(state);
    }, DEBOUNCE_MS);
  }

  const obs = new MutationObserver(debouncedCheck);
  obs.observe(document.documentElement, { childList: true, subtree: true });
  debouncedCheck();
})();