// ==UserScript==
// @name         YouTube Layout Plus
// @namespace    https://qazwsx123.uk/
// @version      0.2.6
// @description  Home: collapse guide, 5 videos per row, hide Shorts. Watch: hide recommendations sidebar and center the player/content, while preserving live chat on streams/replays. Adds a topbar theme switcher that triggers YouTube's official Appearance modes.
// @author       Codex
// @match        https://www.youtube.com/*
// @run-at       document-idle
// @grant        none
// @downloadURL none
// ==/UserScript==

(function () {
  'use strict';

  const STYLE_ID = 'tm-youtube-layout-plus-style';
  const THEME_SWITCHER_ID = 'tm-youtube-layout-plus-theme-switcher';
  const THEME_STATUS_ID = 'tm-youtube-layout-plus-theme-status';
  const THEME_BUSY_CLASS = 'tm-youtube-layout-plus-theme-busy';
  const THEME_MODE_STORAGE_KEY = 'tm-youtube-layout-plus-theme-mode';
  const THEME_MODES = [
    { mode: 'auto', label: 'Auto', prefF6: '80', signal: 'TOGGLE_DARK_THEME_DEVICE' },
    { mode: 'light', label: 'Light', prefF6: '80080', signal: 'TOGGLE_DARK_THEME_OFF' },
    { mode: 'dark', label: 'Dark', prefF6: '480', signal: 'TOGGLE_DARK_THEME_ON' },
  ];

  let currentUrl = location.href;
  let applyFrame = 0;
  let applyDelayTimer = null;
  let bodyObserver = null;
  let routeTimer = null;
  let watchLayoutRetryTimer = null;
  let watchLayoutRetryStep = 0;
  let watchChatStateTimer = null;
  let lastWatchChatExpanded = null;
  let playerSyncTimer = null;
  let lastPlayerSyncKey = '';
  let lastAutoCollapsedHomeUrl = '';
  let lastAutoCollapsedWatchChatKey = '';
  let currentThemeMode = loadStoredThemeMode();
  let themeSwitchInFlight = false;
  let pendingThemeMode = null;
  const WATCH_LAYOUT_RETRY_DELAYS = [0, 40, 120, 260, 520, 900, 1400, 2200, 3200, 4500];

  function isHomePage() {
    return location.pathname === '/';
  }

  function isWatchPage() {
    return location.pathname === '/watch';
  }

  function getWatchPageKey() {
    if (!isWatchPage()) return location.pathname;

    const params = new URLSearchParams(location.search);
    const videoId = params.get('v');
    return videoId ? `/watch?v=${videoId}` : location.pathname;
  }

  function getWatchTeaserText() {
    const teaserCarousel = document.querySelector('ytd-watch-metadata #teaser-carousel');
    return (teaserCarousel?.innerText || teaserCarousel?.textContent || '').trim();
  }

  function hasLiveWatchPrompt(teaserText = getWatchTeaserText()) {
    return /join the conversation to interact with the creator and others watching this live stream/i.test(teaserText)
      || (/watching now/i.test(document.body.innerText) && /started streaming/i.test(document.body.innerText));
  }

  function hasReplayWatchPrompt(teaserText = getWatchTeaserText()) {
    return /live chat replay/i.test(teaserText)
      || /see what others said about this video while it was live/i.test(teaserText);
  }

  function hasWatchSidebarChat(watchFlexy) {
    if (!watchFlexy) return false;

    if (
      watchFlexy.hasAttribute('is-live')
      || watchFlexy.hasAttribute('is-live-content')
      || watchFlexy.hasAttribute('live-chat-collapsed')
    ) {
      return true;
    }

    const liveBadge = watchFlexy.querySelector(
      'ytd-badge-supported-renderer[system-icons][icon="LIVE"], ' +
      'ytd-thumbnail-overlay-time-status-renderer[overlay-style="LIVE"], ' +
      'yt-icon[icon="yt-icons:live"]'
    );
    if (liveBadge && isVisibleElement(liveBadge)) {
      return true;
    }

    const teaserText = getWatchTeaserText();
    if (hasLiveWatchPrompt(teaserText)) {
      return true;
    }

    const chatFrame = watchFlexy.querySelector(
      'ytd-live-chat-frame#chat, #chat ytd-live-chat-frame, #chat-container ytd-live-chat-frame'
    );
    const chatHost = chatFrame?.closest('#chat') || watchFlexy.querySelector('#chat, #chat-container');
    const hasStampedChat = watchFlexy.hasAttribute('should-stamp-chat') || !!chatFrame || !!chatHost;
    if (hasReplayWatchPrompt(teaserText) && hasStampedChat) {
      return true;
    }

    if (!chatFrame) return false;
    if (chatFrame.hasAttribute('hidden')) return false;
    if (chatFrame.hasAttribute('collapsed')) {
      return hasStampedChat;
    }

    return isVisibleElement(chatFrame) || isVisibleElement(chatHost);
  }

  function ensureStyle() {
    if (document.getElementById(STYLE_ID)) return;

    const style = document.createElement('style');
    style.id = STYLE_ID;
    style.textContent = `
      html.tm-youtube-layout-plus-home {
        --tm-guide-collapsed-width: 72px;
        --tm-chip-overlay-shift: 18px;
        --tm-chip-strip-bg:
          radial-gradient(circle at 18% 0%, rgba(255, 255, 255, 0.42) 0%, rgba(255, 255, 255, 0) 34%),
          radial-gradient(circle at 82% 6%, rgba(255, 255, 255, 0.22) 0%, rgba(255, 255, 255, 0) 28%),
          linear-gradient(180deg, rgba(214, 223, 233, 0.32) 0%, rgba(191, 201, 212, 0.22) 100%);
        --tm-chip-active-bg:
          radial-gradient(circle at 20% 0%, rgba(255, 255, 255, 0.52) 0%, rgba(255, 255, 255, 0) 42%),
          linear-gradient(180deg, rgba(250, 252, 255, 0.52) 0%, rgba(229, 236, 243, 0.28) 100%);
        --tm-chip-text: #3b424b;
        --tm-chip-text-active: #1f2328;
        --tm-chip-separator: rgba(70, 77, 88, 0.18);
        --tm-chip-strip-border: rgba(255, 255, 255, 0.24);
        --tm-chip-strip-top-line: rgba(156, 164, 175, 0.32);
        --tm-chip-strip-shadow-top: rgba(255, 255, 255, 0.24);
        --tm-chip-strip-shadow-bottom: rgba(43, 50, 59, 0.12);
        --tm-chip-hover-bg: rgba(255, 255, 255, 0.12);
        --tm-chip-active-border: rgba(148, 157, 169, 0.22);
        --tm-chip-active-top-stroke: rgba(148, 157, 169, 0.2);
        --tm-chip-active-shadow-top: rgba(255, 255, 255, 0.4);
        --tm-chip-active-shadow-bottom: rgba(148, 157, 169, 0.24);
        --tm-chip-active-shadow-mid: rgba(60, 64, 67, 0.1);
        --tm-chip-active-shadow-ring: rgba(118, 126, 137, 0.1);
        --tm-chip-arrow-bg:
          radial-gradient(circle at 20% 0%, rgba(255, 255, 255, 0.28) 0%, rgba(255, 255, 255, 0) 38%),
          linear-gradient(180deg, rgba(248, 251, 255, 0.28) 0%, rgba(228, 235, 242, 0.18) 100%);
        --tm-chip-arrow-shadow-top: rgba(255, 255, 255, 0.18);
        --tm-chip-arrow-shadow-mid: rgba(60, 64, 67, 0.08);
        --tm-chip-glass-blur: 34px;
      }

      html[dark].tm-youtube-layout-plus-home {
        --tm-chip-strip-bg:
          radial-gradient(circle at 18% 0%, rgba(255, 255, 255, 0.08) 0%, rgba(255, 255, 255, 0) 34%),
          linear-gradient(180deg, rgba(46, 51, 58, 0.52) 0%, rgba(28, 31, 37, 0.38) 100%);
        --tm-chip-active-bg:
          radial-gradient(circle at 20% 0%, rgba(255, 255, 255, 0.12) 0%, rgba(255, 255, 255, 0) 40%),
          linear-gradient(180deg, rgba(86, 92, 100, 0.38) 0%, rgba(61, 66, 73, 0.26) 100%);
        --tm-chip-text: rgba(231, 234, 237, 0.9);
        --tm-chip-text-active: #ffffff;
        --tm-chip-separator: rgba(255, 255, 255, 0.1);
        --tm-chip-strip-border: rgba(255, 255, 255, 0.1);
        --tm-chip-strip-top-line: rgba(255, 255, 255, 0.12);
        --tm-chip-strip-shadow-top: rgba(255, 255, 255, 0.08);
        --tm-chip-strip-shadow-bottom: rgba(0, 0, 0, 0.28);
        --tm-chip-hover-bg: rgba(255, 255, 255, 0.08);
        --tm-chip-active-border: rgba(255, 255, 255, 0.12);
        --tm-chip-active-top-stroke: rgba(255, 255, 255, 0.08);
        --tm-chip-active-shadow-top: rgba(255, 255, 255, 0.06);
        --tm-chip-active-shadow-bottom: rgba(255, 255, 255, 0.04);
        --tm-chip-active-shadow-mid: rgba(0, 0, 0, 0.18);
        --tm-chip-active-shadow-ring: rgba(255, 255, 255, 0.06);
        --tm-chip-arrow-bg:
          radial-gradient(circle at 20% 0%, rgba(255, 255, 255, 0.12) 0%, rgba(255, 255, 255, 0) 38%),
          linear-gradient(180deg, rgba(255, 255, 255, 0.1) 0%, rgba(255, 255, 255, 0.06) 100%);
        --tm-chip-arrow-shadow-top: rgba(255, 255, 255, 0.06);
        --tm-chip-arrow-shadow-mid: rgba(0, 0, 0, 0.2);
        --tm-chip-glass-blur: 28px;
      }

      #${THEME_SWITCHER_ID} {
        position: relative;
        display: flex;
        align-items: center;
        gap: 0;
        margin-left: 12px;
        padding: 4px 6px;
        border: 1px solid var(--yt-spec-10-percent-layer, rgba(0, 0, 0, 0.12));
        border-radius: 20px;
        background: var(--yt-spec-badge-chip-background, rgba(0, 0, 0, 0.05));
      }

      #${THEME_STATUS_ID} {
        position: fixed;
        top: 72px;
        right: 24px;
        z-index: 2200;
        max-width: 320px;
        padding: 10px 14px;
        border: 1px solid rgba(190, 60, 60, 0.28);
        border-radius: 14px;
        background: rgba(126, 28, 28, 0.92);
        color: #fff;
        font: 500 13px/1.4 Roboto, Arial, sans-serif;
        box-shadow: 0 10px 24px rgba(0, 0, 0, 0.24);
        opacity: 0;
        transform: translateY(-6px);
        pointer-events: none;
        transition: opacity 160ms ease, transform 160ms ease;
      }

      #${THEME_STATUS_ID}[data-visible="true"] {
        opacity: 1;
        transform: translateY(0);
      }

      #${THEME_SWITCHER_ID} .tm-theme-switch-track {
        display: inline-flex;
        align-items: center;
        gap: 4px;
      }

      #${THEME_SWITCHER_ID} .tm-theme-switch-option {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        min-width: 52px;
        height: 28px;
        padding: 0 10px;
        border: 0;
        border-radius: 14px;
        background: transparent;
        color: var(--yt-spec-text-primary, #0f0f0f);
        cursor: pointer;
        font: 600 12px/1 Roboto, Arial, sans-serif;
        transition: background 140ms ease, color 140ms ease, box-shadow 140ms ease;
      }

      #${THEME_SWITCHER_ID} .tm-theme-switch-option:hover {
        background: var(--yt-spec-badge-chip-background-hover, rgba(0, 0, 0, 0.08));
      }

      #${THEME_SWITCHER_ID} .tm-theme-switch-option[data-active="true"] {
        background: var(--yt-spec-brand-background-solid, rgba(15, 15, 15, 0.92));
        color: var(--yt-spec-static-brand-white, #fff);
        box-shadow: 0 1px 2px rgba(0, 0, 0, 0.18);
      }

      html[dark] #${THEME_SWITCHER_ID} {
        border-color: rgba(255, 255, 255, 0.14);
        background: rgba(255, 255, 255, 0.04);
      }

      html[dark] #${THEME_SWITCHER_ID} .tm-theme-switch-option {
        color: rgba(255, 255, 255, 0.92);
      }

      html[dark] #${THEME_SWITCHER_ID} .tm-theme-switch-option[data-active="true"] {
        background: rgba(255, 255, 255, 0.14);
        color: #fff;
        box-shadow: 0 1px 2px rgba(0, 0, 0, 0.32);
      }

      html.tm-youtube-layout-plus-home ytd-app[mini-guide-visible]:not([guide-persistent-and-visible]) ytd-feed-filter-chip-bar-renderer,
      html.tm-youtube-layout-plus-home ytd-app[mini-guide-visible]:not([guide-persistent-and-visible]) #chips-wrapper {
        left: var(--tm-guide-collapsed-width) !important;
        width: calc(100vw - var(--tm-guide-collapsed-width)) !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer {
        padding: 0 14px !important;
        background: transparent !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #chips-wrapper,
      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #chips {
        align-items: center !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #chips-wrapper {
        transform: translateY(var(--tm-chip-overlay-shift)) !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #chips-content {
        position: relative !important;
        overflow: hidden !important;
        isolation: isolate !important;
        padding: 5px 8px !important;
        margin-top: 0 !important;
        border: 1px solid var(--tm-chip-strip-border) !important;
        border-radius: 22px !important;
        background: var(--tm-chip-strip-bg) !important;
        backdrop-filter: blur(var(--tm-chip-glass-blur)) saturate(220%) contrast(1.05) brightness(1.08) !important;
        -webkit-backdrop-filter: blur(var(--tm-chip-glass-blur)) saturate(220%) contrast(1.05) brightness(1.08) !important;
        box-shadow:
          inset 0 1px 0 var(--tm-chip-strip-top-line),
          inset 0 1px 0 var(--tm-chip-strip-shadow-top),
          0 2px 0 rgba(34, 40, 49, 0.11),
          0 3px 2px rgba(34, 40, 49, 0.06),
          0 5px 7px rgba(34, 40, 49, 0.03) !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #chips-content::before {
        content: '' !important;
        position: absolute !important;
        inset: 0 !important;
        border-radius: inherit !important;
        background:
          linear-gradient(180deg, rgba(255, 255, 255, 0.26) 0%, rgba(255, 255, 255, 0.08) 36%, rgba(255, 255, 255, 0.02) 100%) !important;
        pointer-events: none !important;
        z-index: 0 !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #chips-content::after {
        content: '' !important;
        position: absolute !important;
        inset: 0 !important;
        border-radius: inherit !important;
        background:
          radial-gradient(circle at 50% 100%, rgba(180, 198, 220, 0.12) 0%, rgba(180, 198, 220, 0) 58%) !important;
        pointer-events: none !important;
        z-index: 0 !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer {
        position: relative !important;
        z-index: 1 !important;
        margin: 0 !important;
        padding: 0 2px !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer + yt-chip-cloud-chip-renderer::before {
        content: '' !important;
        position: absolute !important;
        left: -1px !important;
        top: 9px !important;
        bottom: 9px !important;
        width: 1px !important;
        border-radius: 999px !important;
        background: var(--tm-chip-separator) !important;
        pointer-events: none !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer button.ytChipShapeButtonReset {
        border-radius: 18px !important;
        overflow: visible !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer .ytChipShapeChip {
        position: relative !important;
        min-height: 38px !important;
        padding: 0 22px !important;
        border: 0 !important;
        border-radius: 18px !important;
        background: transparent !important;
        box-shadow: none !important;
        color: var(--tm-chip-text) !important;
        font-weight: 600 !important;
        letter-spacing: -0.01em !important;
        transition:
          background 140ms ease,
          box-shadow 140ms ease,
          color 140ms ease,
          transform 140ms ease,
          backdrop-filter 140ms ease !important;
        backdrop-filter: blur(calc(var(--tm-chip-glass-blur) * 0.7)) saturate(170%) brightness(1.04) !important;
        -webkit-backdrop-filter: blur(calc(var(--tm-chip-glass-blur) * 0.7)) saturate(170%) brightness(1.04) !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer .ytChipShapeChip > div {
        font-size: 15px !important;
        line-height: 36px !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer:hover .ytChipShapeChip,
      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer button:focus-visible .ytChipShapeChip {
        background: var(--tm-chip-hover-bg) !important;
        color: var(--tm-chip-text-active) !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer[selected] .ytChipShapeChip,
      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer .ytChipShapeChip.ytChipShapeActive {
        background: var(--tm-chip-active-bg) !important;
        border: 1px solid var(--tm-chip-active-border) !important;
        box-shadow: none !important;
        color: var(--tm-chip-text-active) !important;
        transform: none !important;
        z-index: 1 !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer[selected]::before,
      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer[selected] + yt-chip-cloud-chip-renderer::before {
        opacity: 0 !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer yt-touch-feedback-shape,
      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer .yt-spec-touch-feedback-shape__stroke,
      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer yt-chip-cloud-chip-renderer .yt-spec-touch-feedback-shape__fill {
        border-radius: 18px !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #right-arrow.ytd-feed-filter-chip-bar-renderer,
      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #left-arrow.ytd-feed-filter-chip-bar-renderer {
        margin-top: 0 !important;
        transform: none !important;
      }

      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #right-arrow button,
      html.tm-youtube-layout-plus-home ytd-feed-filter-chip-bar-renderer #left-arrow button {
        border: 0 !important;
        border-radius: 18px !important;
        background: var(--tm-chip-arrow-bg) !important;
        transform: none !important;
        backdrop-filter: blur(calc(var(--tm-chip-glass-blur) * 0.72)) saturate(175%) brightness(1.04) !important;
        -webkit-backdrop-filter: blur(calc(var(--tm-chip-glass-blur) * 0.72)) saturate(175%) brightness(1.04) !important;
        box-shadow:
          inset 0 1px 0 var(--tm-chip-arrow-shadow-top),
          0 4px 12px var(--tm-chip-arrow-shadow-mid) !important;
      }

      html.tm-youtube-layout-plus-home ytd-app[mini-guide-visible]:not([guide-persistent-and-visible]) ytd-page-manager {
        margin-left: var(--tm-guide-collapsed-width) !important;
        width: calc(100% - var(--tm-guide-collapsed-width)) !important;
      }

      html.tm-youtube-layout-plus-home ytd-browse {
        overflow: visible !important;
      }

      html.tm-youtube-layout-plus-home ytd-app[mini-guide-visible]:not([guide-persistent-and-visible]) ytd-two-column-browse-results-renderer,
      html.tm-youtube-layout-plus-home ytd-app[mini-guide-visible]:not([guide-persistent-and-visible]) ytd-rich-grid-renderer,
      html.tm-youtube-layout-plus-home ytd-app[mini-guide-visible]:not([guide-persistent-and-visible]) #contents.ytd-rich-grid-renderer {
        margin-left: 0 !important;
        width: auto !important;
      }

      html.tm-youtube-layout-plus-home #contents.ytd-rich-grid-renderer {
        margin-top: 0 !important;
        padding-top: calc(var(--tm-chip-overlay-shift) + 8px) !important;
        padding-left: 14px !important;
        padding-right: 12px !important;
        box-sizing: border-box !important;
      }

      html.tm-youtube-layout-plus-home ytd-rich-grid-renderer {
        --ytd-rich-grid-items-per-row: 5 !important;
        --ytd-rich-grid-posts-per-row: 5 !important;
      }

      html.tm-youtube-layout-plus-home ytd-rich-item-renderer,
      html.tm-youtube-layout-plus-home ytd-rich-grid-row,
      html.tm-youtube-layout-plus-home ytd-rich-grid-media,
      html.tm-youtube-layout-plus-home #contents.ytd-rich-grid-renderer > * {
        max-width: none !important;
      }

      html.tm-youtube-layout-plus-home ytd-rich-item-renderer {
        position: relative !important;
        z-index: 0 !important;
        margin-left: 0 !important;
        margin-right: 10px !important;
        transform-origin: center top !important;
        transition:
          transform 160ms ease,
          box-shadow 160ms ease,
          z-index 160ms ease !important;
        will-change: transform !important;
      }

      html.tm-youtube-layout-plus-home ytd-rich-item-renderer:hover,
      html.tm-youtube-layout-plus-home ytd-rich-item-renderer:focus-within {
        transform: scale(1.1) !important;
        z-index: 4 !important;
      }

      html.tm-youtube-layout-plus-home ytd-rich-section-renderer,
      html.tm-youtube-layout-plus-home ytd-rich-shelf-renderer,
      html.tm-youtube-layout-plus-home ytd-reel-shelf-renderer {
        display: none !important;
      }

      html.tm-youtube-layout-plus-watch-plain ytd-watch-flexy #secondary,
      html.tm-youtube-layout-plus-watch-plain ytd-watch-flexy #related,
      html.tm-youtube-layout-plus-watch-plain ytd-watch-flexy #secondary-inner,
      html.tm-youtube-layout-plus-watch-plain ytd-watch-next-secondary-results-renderer,
      html.tm-youtube-layout-plus-watch-chat ytd-watch-flexy #related,
      html.tm-youtube-layout-plus-watch-chat ytd-watch-next-secondary-results-renderer {
        display: none !important;
      }

      html.tm-youtube-layout-plus-watch-plain ytd-watch-flexy[is-two-columns_] #primary {
        max-width: none !important;
        width: min(1400px, calc(100vw - 48px)) !important;
        margin: 0 auto !important;
      }

      html.tm-youtube-layout-plus-watch-plain ytd-watch-flexy[is-two-columns_] #columns {
        display: block !important;
      }

      html.tm-youtube-layout-plus-watch-plain ytd-watch-flexy[is-two-columns_] #primary-inner,
      html.tm-youtube-layout-plus-watch-plain ytd-watch-flexy[is-two-columns_] #above-the-fold,
      html.tm-youtube-layout-plus-watch-plain ytd-watch-flexy[is-two-columns_] #below {
        max-width: none !important;
      }

      html.tm-youtube-layout-plus-watch-chat-collapsed ytd-watch-flexy #secondary,
      html.tm-youtube-layout-plus-watch-chat-collapsed ytd-watch-flexy #secondary-inner {
        display: none !important;
      }

      html.tm-youtube-layout-plus-watch-chat-collapsed ytd-watch-flexy[is-two-columns_] #primary {
        max-width: none !important;
        width: min(1400px, calc(100vw - 48px)) !important;
        margin: 0 auto !important;
      }

      html.tm-youtube-layout-plus-watch-chat-collapsed ytd-watch-flexy[is-two-columns_] #columns {
        display: block !important;
      }

      html.tm-youtube-layout-plus-watch-chat-collapsed ytd-watch-flexy[is-two-columns_] #primary-inner,
      html.tm-youtube-layout-plus-watch-chat-collapsed ytd-watch-flexy[is-two-columns_] #above-the-fold,
      html.tm-youtube-layout-plus-watch-chat-collapsed ytd-watch-flexy[is-two-columns_] #below {
        max-width: none !important;
      }
    `;

    document.head.appendChild(style);
  }

  function collapseGuide() {
    const app = document.querySelector('ytd-app');
    if (app) {
      app.removeAttribute('guide-persistent-and-visible');
      app.setAttribute('mini-guide-visible', '');
    }

    const drawer = document.querySelector('tp-yt-app-drawer#guide');
    if (drawer) {
      drawer.removeAttribute('opened');
      drawer.style.width = '';
      drawer.style.minWidth = '';
      drawer.style.visibility = '';
    }

    const guideRenderer = document.querySelector('ytd-guide-renderer');
    if (guideRenderer) {
      guideRenderer.style.display = '';
      guideRenderer.style.width = '';
      guideRenderer.style.minWidth = '';
    }
  }

  function applyHomeLayout() {
    const richGrid = document.querySelector('ytd-rich-grid-renderer');
    if (!richGrid) return;

    document.documentElement.classList.add('tm-youtube-layout-plus-home');

    if (lastAutoCollapsedHomeUrl !== location.href) {
      collapseGuide();
      lastAutoCollapsedHomeUrl = location.href;
    }
  }

  function applyWatchLayout() {
    const watchFlexy = document.querySelector('ytd-watch-flexy');
    if (!watchFlexy) return;

    document.documentElement.classList.add('tm-youtube-layout-plus-watch');

    if (hasWatchSidebarChat(watchFlexy)) {
      document.documentElement.classList.add('tm-youtube-layout-plus-watch-chat');
      updateWatchChatPanelState(watchFlexy);
      autoCollapseLiveChatPanel(watchFlexy);
      syncWatchPlayerSize();
      schedulePlayerSync(120);
      return;
    }

    document.documentElement.classList.add('tm-youtube-layout-plus-watch-plain');
    hideWatchReplayPrompt();
    syncWatchPlayerSize();
    schedulePlayerSync(120);
  }

  function hideWatchReplayPrompt() {
    const teaserCarousel = document.querySelector('ytd-watch-metadata #teaser-carousel');
    if (!teaserCarousel) return;

    const teaserText = getWatchTeaserText();
    if (hasLiveWatchPrompt(teaserText)) {
      return;
    }

    const watchFlexy = document.querySelector('ytd-watch-flexy');
    if (watchFlexy && hasReplayWatchPrompt(teaserText) && hasWatchSidebarChat(watchFlexy)) {
      return;
    }

    const replayPrompt = Array.from(
      teaserCarousel.querySelectorAll('yt-video-metadata-carousel-view-model')
    ).find((card) => {
      const text = (card.innerText || card.textContent || '').trim();
      return /live chat replay/i.test(text)
        || /see what others said about this video while it was live/i.test(text);
    });

    if (!replayPrompt) return;

    teaserCarousel.style.display = 'none';
  }

  function updateWatchChatPanelState(watchFlexy) {
    const chatFrame = watchFlexy.querySelector('ytd-live-chat-frame#chat');
    const openPanelButton = findOpenPanelButton();

    const chatVisible = !!chatFrame && isVisibleElement(chatFrame);
    const panelExpanded = chatVisible || !!(openPanelButton && openPanelButton.disabled);

    document.documentElement.classList.toggle('tm-youtube-layout-plus-watch-chat-open', panelExpanded);
    document.documentElement.classList.toggle('tm-youtube-layout-plus-watch-chat-collapsed', !panelExpanded);

    if (lastWatchChatExpanded !== panelExpanded) {
      lastWatchChatExpanded = panelExpanded;

      // Let the class change apply first, then resync the player size so
      // collapsing/expanding chat updates the video dimensions immediately.
      window.requestAnimationFrame(() => {
        syncWatchPlayerSize();
        schedulePlayerSync(120);
      });
    }
  }

  function stopWatchChatStateSync() {
    if (!watchChatStateTimer) return;
    window.clearInterval(watchChatStateTimer);
    watchChatStateTimer = null;
  }

  function startWatchChatStateSync() {
    stopWatchChatStateSync();

    if (!isWatchPage()) return;

    watchChatStateTimer = window.setInterval(() => {
      if (!isWatchPage()) {
        stopWatchChatStateSync();
        return;
      }

      const watchFlexy = document.querySelector('ytd-watch-flexy');
      if (!watchFlexy) {
        return;
      }

      const hasSidebarChat = hasWatchSidebarChat(watchFlexy);
      const hasWatchChatClass = document.documentElement.classList.contains('tm-youtube-layout-plus-watch-chat');

      if (hasSidebarChat && !hasWatchChatClass) {
        scheduleApply();
        return;
      }

      if (!hasSidebarChat || !hasWatchChatClass) {
        return;
      }

      updateWatchChatPanelState(watchFlexy);
    }, 500);
  }

  function findOpenPanelButton() {
    return Array.from(document.querySelectorAll('button, yt-button-shape button, tp-yt-paper-button')).find(
      (button) => /open panel/i.test((button.innerText || button.textContent || '').trim())
    ) || null;
  }

  function autoCollapseLiveChatPanel(watchFlexy) {
    const watchPageKey = getWatchPageKey();
    if (lastAutoCollapsedWatchChatKey === watchPageKey) return;

    const chatFrameHost = watchFlexy.querySelector('ytd-live-chat-frame#chat');
    const openPanelButton = findOpenPanelButton();
    if (openPanelButton && !openPanelButton.disabled) {
      lastAutoCollapsedWatchChatKey = watchPageKey;
      return;
    }

    if (chatFrameHost?.hasAttribute('collapsed')) {
      lastAutoCollapsedWatchChatKey = watchPageKey;
      return;
    }

    const hostToggleButton = chatFrameHost?.querySelector(
      '#show-hide-button button, #show-hide-button yt-button-shape button, #show-hide-button tp-yt-paper-button'
    );
    if (hostToggleButton) {
      hostToggleButton.click();
      lastAutoCollapsedWatchChatKey = watchPageKey;
      window.setTimeout(scheduleApply, 80);
      return;
    }

    const chatFrame = watchFlexy.querySelector(
      'ytd-live-chat-frame#chat #chatframe, ytd-live-chat-frame#chat iframe, #chatframe'
    );
    const chatDoc = chatFrame?.contentDocument;
    if (!chatDoc) return;

    const closeButton = Array.from(chatDoc.querySelectorAll('button')).find(
      (button) => /close/i.test(button.getAttribute('aria-label') || '')
    );
    if (!closeButton) return;

    closeButton.click();
    lastAutoCollapsedWatchChatKey = watchPageKey;
    window.setTimeout(scheduleApply, 80);
  }

  function syncWatchPlayerSize() {
    if (!isWatchPage()) return;

    const playerContainer = document.getElementById('player');
    const moviePlayer = document.getElementById('movie_player');
    if (!playerContainer || !moviePlayer) return;

    const rect = playerContainer.getBoundingClientRect();
    const width = Math.round(rect.width);
    const height = Math.round(rect.height);
    if (!width || !height) return;

    const syncKey = `${location.href}|${width}x${height}`;
    if (lastPlayerSyncKey === syncKey) return;

    try {
      if (typeof moviePlayer.setInternalSize === 'function') {
        moviePlayer.setInternalSize(width, height);
      }
      if (typeof moviePlayer.setSize === 'function') {
        moviePlayer.setSize(width, height);
      }
      if (typeof moviePlayer.setSizeStyle === 'function') {
        moviePlayer.setSizeStyle(width, height);
      }
    } catch (error) {
      console.debug('YouTube Layout Plus player sync failed:', error);
    }

    window.dispatchEvent(new Event('resize'));
    lastPlayerSyncKey = syncKey;
  }

  function schedulePlayerSync(delay = 0) {
    if (playerSyncTimer) {
      window.clearTimeout(playerSyncTimer);
      playerSyncTimer = null;
    }

    playerSyncTimer = window.setTimeout(() => {
      playerSyncTimer = null;
      syncWatchPlayerSize();
    }, delay);
  }

  function clearModeClasses() {
    document.documentElement.classList.remove(
      'tm-youtube-layout-plus-home',
      'tm-youtube-layout-plus-watch',
      'tm-youtube-layout-plus-watch-chat',
      'tm-youtube-layout-plus-watch-chat-open',
      'tm-youtube-layout-plus-watch-chat-collapsed',
      'tm-youtube-layout-plus-watch-plain'
    );
  }

  function loadStoredThemeMode() {
    try {
      const mode = window.localStorage.getItem(THEME_MODE_STORAGE_KEY);
      return THEME_MODES.some((item) => item.mode === mode) ? mode : null;
    } catch {
      return null;
    }
  }

  function persistThemeMode(mode) {
    try {
      if (THEME_MODES.some((item) => item.mode === mode)) {
        window.localStorage.setItem(THEME_MODE_STORAGE_KEY, mode);
      } else {
        window.localStorage.removeItem(THEME_MODE_STORAGE_KEY);
      }
    } catch {
      // Ignore storage failures.
    }
  }

  function delay(ms) {
    return new Promise((resolve) => {
      window.setTimeout(resolve, ms);
    });
  }

  function getThemePrefValue(mode) {
    return THEME_MODES.find((item) => item.mode === mode)?.prefF6 || null;
  }

  function getThemeSignal(mode) {
    return THEME_MODES.find((item) => item.mode === mode)?.signal || null;
  }

  function getThemeModeFromOptionText(text) {
    const normalizedText = (text || '').trim();
    if (!normalizedText) return null;
    if (/use device theme|device theme/i.test(normalizedText)) return 'auto';
    if (/light theme/i.test(normalizedText)) return 'light';
    if (/dark theme/i.test(normalizedText)) return 'dark';
    return null;
  }

  function getThemeOptionSignal(option) {
    return option?.data?.serviceEndpoint?.signalServiceEndpoint?.actions?.[0]?.signalAction?.signal || null;
  }

  function getThemeModeFromPrefCookie() {
    const prefEntries = document.cookie
      .split('; ')
      .filter((entry) => entry.startsWith('PREF='));
    const lastEntry = prefEntries[prefEntries.length - 1];
    if (!lastEntry) return null;

    try {
      const pref = decodeURIComponent(lastEntry.slice(5));
      const f6Match = pref.match(/(?:^|&)f6=(\d+)/);
      if (!f6Match) return null;

      const f6Value = f6Match[1];
      if (/80080$/.test(f6Value)) return 'light';
      if (/480$/.test(f6Value)) return 'dark';
      if (/80$/.test(f6Value)) return 'auto';
      return 'auto';
    } catch {
      return null;
    }
  }

  function inferThemeModeFromDocument() {
    return document.documentElement.hasAttribute('dark') ? 'dark' : 'light';
  }

  function getObservedThemeMode() {
    return getThemeModeFromPrefCookie()
      || detectThemeModeFromOptions()
      || inferThemeModeFromDocument();
  }

  function showThemeStatusMessage(message) {
    let status = document.getElementById(THEME_STATUS_ID);
    if (!status) {
      status = document.createElement('div');
      status.id = THEME_STATUS_ID;
      status.dataset.visible = 'false';
      document.body.appendChild(status);
    }

    status.textContent = message;
    status.dataset.visible = 'true';
    window.clearTimeout(showThemeStatusMessage.hideTimer);
    showThemeStatusMessage.hideTimer = window.setTimeout(() => {
      status.dataset.visible = 'false';
    }, 2600);
  }

  function hideThemeStatusMessage() {
    const status = document.getElementById(THEME_STATUS_ID);
    if (!status) return;
    status.dataset.visible = 'false';
    window.clearTimeout(showThemeStatusMessage.hideTimer);
  }

  function isVisibleElement(element) {
    if (!element) return false;
    if (element.hidden) return false;

    const style = window.getComputedStyle(element);
    if (style.display === 'none' || style.visibility === 'hidden') return false;

    const rect = element.getBoundingClientRect();
    return rect.width > 0 && rect.height > 0;
  }

  function getOfficialThemeOptions(options = {}) {
    const { visibleOnly = false } = options;
    return Array.from(document.querySelectorAll('ytd-compact-link-renderer')).filter(
      (option) => {
        const optionSignal = getThemeOptionSignal(option);
        const optionMode = getThemeModeFromOptionText(option.innerText || option.textContent);
        return (
          (THEME_MODES.some((mode) => optionSignal === mode.signal) || !!optionMode)
        && (!visibleOnly || isVisibleElement(option))
        );
      }
    );
  }

  function detectThemeModeFromOptions(options = getOfficialThemeOptions({ visibleOnly: true })) {
    const selectedOption = options.find((option) => option?.data?.icon?.iconType === 'CHECK');
    if (!selectedOption) return null;
    return THEME_MODES.find((mode) => mode.signal === getThemeOptionSignal(selectedOption))?.mode
      || getThemeModeFromOptionText(selectedOption.innerText || selectedOption.textContent);
  }

  function findAccountMenuButton() {
    return document.querySelector('button#avatar-btn')
      || Array.from(document.querySelectorAll('ytd-topbar-menu-button-renderer button, button')).find((button) => {
        if (button.id === 'avatar-btn') return true;
        if (button.querySelector('img') && button.getAttribute('aria-haspopup') === 'true') return true;
        return false;
      })
      || null;
  }

  function findAppearanceMenuEntry() {
    return Array.from(
      document.querySelectorAll('ytd-toggle-theme-compact-link-renderer, a, button, tp-yt-paper-item')
    ).find((entry) => {
      const text = (entry.innerText || entry.textContent || '').trim();
      return /^appearance:/i.test(text) && isVisibleElement(entry);
    }) || null;
  }

  function clickMenuEntry(entry) {
    const target = entry?.querySelector?.('a#endpoint, button, tp-yt-paper-item')
      || entry?.closest?.('a, button')
      || entry;
    target?.click?.();
  }

  function closeOfficialThemeMenus() {
    document.dispatchEvent(
      new KeyboardEvent('keydown', { key: 'Escape', bubbles: true, cancelable: true })
    );
    document.dispatchEvent(
      new KeyboardEvent('keydown', { key: 'Escape', bubbles: true, cancelable: true })
    );
  }

  async function waitFor(getValue, timeout = 2200) {
    const startedAt = Date.now();
    while (Date.now() - startedAt < timeout) {
      const value = getValue();
      if (value) return value;
      await delay(50);
    }
    return null;
  }

  async function ensureOfficialThemeOptionsVisible() {
    const existingOptions = getOfficialThemeOptions({ visibleOnly: true });
    if (existingOptions.length) return existingOptions;

    const existingAppearanceEntry = findAppearanceMenuEntry();
    if (existingAppearanceEntry) {
      clickMenuEntry(existingAppearanceEntry);
      return await waitFor(() => {
        const options = getOfficialThemeOptions({ visibleOnly: true });
        return options.length ? options : null;
      });
    }

    closeOfficialThemeMenus();
    await delay(80);

    const accountMenuButton = findAccountMenuButton();
    if (!accountMenuButton) return null;

    accountMenuButton.click();
    const appearanceEntry = await waitFor(findAppearanceMenuEntry);
    if (!appearanceEntry) return null;

    clickMenuEntry(appearanceEntry);
    return await waitFor(() => {
      const options = getOfficialThemeOptions({ visibleOnly: true });
      return options.length ? options : null;
    });
  }

  function updateThemeSwitcherUI() {
    const switcher = document.getElementById(THEME_SWITCHER_ID);
    if (!switcher) return;

    if (!pendingThemeMode) {
      const observedMode = getObservedThemeMode();
      if (observedMode) {
        currentThemeMode = observedMode;
        persistThemeMode(observedMode);
      }
    } else if (!currentThemeMode) {
      currentThemeMode = loadStoredThemeMode()
        || inferThemeModeFromDocument();
    }

    const visibleMode = pendingThemeMode || currentThemeMode;

    const optionButtons = switcher.querySelectorAll('.tm-theme-switch-option[data-mode]');
    for (const button of optionButtons) {
      const isActive = button.dataset.mode === visibleMode;
      button.dataset.active = String(isActive);
      button.setAttribute('aria-pressed', String(isActive));
      button.disabled = themeSwitchInFlight;
    }
  }

  async function verifyThemeMode(mode) {
    const expectedDark = mode === 'dark'
      || (mode === 'auto' && window.matchMedia('(prefers-color-scheme: dark)').matches);
    let lastResult = null;

    for (let attempt = 0; attempt < 12; attempt += 1) {
      const cookieMode = getThemeModeFromPrefCookie();
      const hasDark = document.documentElement.hasAttribute('dark');
      const actualMode = cookieMode || inferThemeModeFromDocument();
      const cookieConsistent = cookieMode === mode;
      const darkConsistent = hasDark === expectedDark;

      lastResult = {
        ok: cookieConsistent && darkConsistent,
        actualMode,
        cookieMode,
        hasDark,
      };

      if (lastResult.ok) {
        return lastResult;
      }

      await delay(120);
    }

    return lastResult || {
      ok: false,
      actualMode: getObservedThemeMode(),
      cookieMode: getThemeModeFromPrefCookie(),
      hasDark: document.documentElement.hasAttribute('dark'),
    };
  }

  async function setThemeMode(mode) {
    if (themeSwitchInFlight) return;
    if (!THEME_MODES.some((item) => item.mode === mode)) return;

    const previousMode = currentThemeMode
      || loadStoredThemeMode()
      || getThemeModeFromPrefCookie()
      || detectThemeModeFromOptions()
      || (document.documentElement.hasAttribute('dark') ? 'dark' : 'light');
    if (previousMode === mode) {
      currentThemeMode = mode;
      persistThemeMode(mode);
      pendingThemeMode = null;
      updateThemeSwitcherUI();
      return;
    }

    themeSwitchInFlight = true;
    document.documentElement.classList.add(THEME_BUSY_CLASS);
    pendingThemeMode = mode;

    try {
      updateThemeSwitcherUI();

      const options = await ensureOfficialThemeOptionsVisible();
      if (!options?.length) {
        currentThemeMode = previousMode;
        persistThemeMode(previousMode);
        updateThemeSwitcherUI();
        return;
      }

      const visibleMode = detectThemeModeFromOptions(options);
      let didRequestOfficialMode = visibleMode === mode;
      if (visibleMode !== mode) {
        const targetOption = options.find((option) => getThemeOptionSignal(option) === getThemeSignal(mode));
        if (!targetOption) {
          currentThemeMode = previousMode;
          persistThemeMode(previousMode);
          updateThemeSwitcherUI();
          return;
        }

        clickMenuEntry(targetOption);
        didRequestOfficialMode = true;
      }

      // Once the official menu action is triggered, trust the requested mode for the switcher UI.
      currentThemeMode = mode;
      persistThemeMode(mode);
      updateThemeSwitcherUI();

      const verification = await verifyThemeMode(mode);
      if (!verification.ok) {
        currentThemeMode = verification.actualMode || previousMode;
        persistThemeMode(currentThemeMode);
        pendingThemeMode = null;
        updateThemeSwitcherUI();
        showThemeStatusMessage(
          `Theme switch failed: expected ${mode}, actual ${currentThemeMode || 'unknown'}.`
        );
        return;
      }

      currentThemeMode = verification.actualMode || mode;
      persistThemeMode(currentThemeMode);
      hideThemeStatusMessage();
    } finally {
      closeOfficialThemeMenus();
      themeSwitchInFlight = false;
      document.documentElement.classList.remove(THEME_BUSY_CLASS);
      pendingThemeMode = null;
      currentThemeMode = currentThemeMode || loadStoredThemeMode() || getThemeModeFromPrefCookie() || previousMode;
      updateThemeSwitcherUI();
    }
  }

  function ensureThemeSwitcher() {
    const logoRenderer = document.querySelector('ytd-topbar-logo-renderer');
    if (!logoRenderer) return;

    let switcher = document.getElementById(THEME_SWITCHER_ID);
    if (!switcher) {
      const track = document.createElement('div');
      track.className = 'tm-theme-switch-track';
      track.setAttribute('role', 'group');
      track.setAttribute('aria-label', 'Theme switcher');

      switcher = document.createElement('div');
      switcher.id = THEME_SWITCHER_ID;

      for (const item of THEME_MODES) {
        const optionButton = document.createElement('button');
        optionButton.type = 'button';
        optionButton.className = 'tm-theme-switch-option';
        optionButton.dataset.mode = item.mode;
        optionButton.dataset.active = 'false';
        optionButton.textContent = item.label;
        optionButton.setAttribute('aria-pressed', 'false');
        optionButton.addEventListener('click', async (event) => {
          event.preventDefault();
          event.stopPropagation();
          await setThemeMode(item.mode);
        });
        track.appendChild(optionButton);
      }

      switcher.append(track);

      logoRenderer.insertAdjacentElement('afterend', switcher);
    } else if (switcher.previousElementSibling !== logoRenderer) {
      logoRenderer.insertAdjacentElement('afterend', switcher);
    }

    updateThemeSwitcherUI();
  }

  function applyLayout() {
    ensureStyle();
    clearModeClasses();

    try {
      ensureThemeSwitcher();
    } catch (error) {
      console.error('YouTube Layout Plus theme switcher failed:', error);
    }

    if (isHomePage()) {
      applyHomeLayout();
      return;
    }

    if (isWatchPage()) {
      applyWatchLayout();
    }
  }

  function queueApply() {
    if (applyFrame) return;

    applyFrame = window.requestAnimationFrame(() => {
      applyFrame = 0;
      applyLayout();
    });
  }

  function scheduleApply(delay = 0) {
    if (delay > 0) {
      window.clearTimeout(applyDelayTimer);
      applyDelayTimer = window.setTimeout(() => {
        applyDelayTimer = null;
        queueApply();
      }, delay);
      return;
    }

    if (applyDelayTimer) {
      window.clearTimeout(applyDelayTimer);
      applyDelayTimer = null;
    }

    queueApply();
  }

  function stopWatchLayoutRetry() {
    if (!watchLayoutRetryTimer) return;
    window.clearTimeout(watchLayoutRetryTimer);
    watchLayoutRetryTimer = null;
  }

  function startWatchLayoutRetry() {
    stopWatchLayoutRetry();

    if (!isWatchPage()) return;

    watchLayoutRetryStep = 0;

    const run = () => {
      if (!isWatchPage()) {
        stopWatchLayoutRetry();
        return;
      }

      scheduleApply();

      if (watchLayoutRetryStep >= WATCH_LAYOUT_RETRY_DELAYS.length - 1) {
        stopWatchLayoutRetry();
        return;
      }

      watchLayoutRetryStep += 1;
      watchLayoutRetryTimer = window.setTimeout(run, WATCH_LAYOUT_RETRY_DELAYS[watchLayoutRetryStep]);
    };

    run();
  }

  function handleRouteChange(force = false) {
    const nextUrl = location.href;
    if (!force && nextUrl === currentUrl) return;

    currentUrl = nextUrl;

    if (!isHomePage()) {
      lastAutoCollapsedHomeUrl = '';
    }

    if (!isWatchPage()) {
      lastAutoCollapsedWatchChatKey = '';
      stopWatchLayoutRetry();
      stopWatchChatStateSync();
      lastWatchChatExpanded = null;
      lastPlayerSyncKey = '';
      if (playerSyncTimer) {
        window.clearTimeout(playerSyncTimer);
        playerSyncTimer = null;
      }
    } else {
      lastWatchChatExpanded = null;
      lastPlayerSyncKey = '';
      startWatchLayoutRetry();
      startWatchChatStateSync();
    }

    scheduleApply();
  }

  function startObservers() {
    if (bodyObserver) return;

    bodyObserver = new MutationObserver((mutations) => {
      if (isWatchPage()) {
        return;
      }

      const hasRelevantMutation = mutations.some((mutation) => {
        const target = mutation.target instanceof Element
          ? mutation.target
          : mutation.target?.parentElement;
        if (!target) return false;

        // Ignore the player's internal UI churn elsewhere. Those mutations are
        // high-frequency and do not require reapplying layout classes.
        if (target.closest('#movie_player, .html5-video-player, #chatframe')) {
          return false;
        }

        return true;
      });

      if (hasRelevantMutation) {
        scheduleApply();
      }
    });

    bodyObserver.observe(document.body, {
      childList: true,
      subtree: true,
    });
  }

  function startNavigationListeners() {
    document.addEventListener('yt-navigate-finish', handleRouteChange, true);
    window.addEventListener('popstate', handleRouteChange, true);
  }

  function startInteractionListeners() {
    document.addEventListener('click', (event) => {
      const trigger = event.target instanceof Element
        ? event.target.closest('button, yt-button-shape button, tp-yt-paper-button')
        : null;
      if (!trigger) return;

      const text = (trigger.innerText || trigger.textContent || '').trim();
      if (/open panel/i.test(text) && isWatchPage()) {
        lastAutoCollapsedWatchChatKey = getWatchPageKey();
        scheduleApply(80);
      }
    }, true);
  }

  function watchRoute() {
    if (routeTimer) return;

    routeTimer = window.setInterval(() => {
      if (location.href === currentUrl) return;
      handleRouteChange();
    }, 1000);
  }

  function init() {
    ensureStyle();
    handleRouteChange(true);
    startObservers();
    startNavigationListeners();
    startInteractionListeners();
    watchRoute();
  }

  init();
})();