README.md

@@ -344,6 +344,16 @@ Then put it behind your existing reverse proxy like everything else
       action — resolved server-side (one atomic operation, not one
       request per track) the same way launching a playlist already
       expands into everything it contains — see docs/architecture.md
+- [x] Picture-in-picture for the video player (standard
+      `requestPictureInPicture`, confirmed present on Android Chrome) —
+      asked for directly for mobile, where there's no second window to
+      put this app in while switching apps — see docs/architecture.md
+- [x] Installable as a PWA (manifest + icons, standalone display,
+      no service worker — this app has nothing worth caching offline)
+      — see docs/architecture.md
+- [x] Mobile navigation redesigned as a bottom sheet (Accueil /
+      Bibliothèques / Listes de lecture) instead of a horizontally
+      scrolling sidebar — see docs/architecture.md
 - [x] Music UI reworked to look like a music app instead of reusing
       movie-poster tiles — circular artist tiles, square album tiles,
       a real hero header, and a mobile "now playing" full-screen player

client/build.mjs

@@ -11,7 +11,7 @@
 //   npm run watch   -> rebuilds on save, for local dev (see README's
 //                      Running locally section)
 import * as esbuild from 'esbuild';
-import { copyFileSync, mkdirSync } from 'fs';
+import { copyFileSync, cpSync, mkdirSync } from 'fs';
 import path from 'path';
 import { fileURLToPath } from 'url';
 
@@ -20,6 +20,11 @@ const outdir = path.join(here, 'dist');
 
 mkdirSync(outdir, { recursive: true });
 copyFileSync(path.join(here, 'src', 'index.html'), path.join(outdir, 'index.html'));
+// PWA manifest + icons (manifest.webmanifest, icons/*) - see
+// docs/architecture.md's "Progressive Web App" section. Copied wholesale
+// rather than named file-by-file like index.html above, so adding another
+// icon later needs no build.mjs change.
+cpSync(path.join(here, 'src', 'public'), outdir, { recursive: true });
 
 const buildOptions = {
   entryPoints: [path.join(here, 'src', 'app.ts')],

client/src/index.html

@@ -4,6 +4,24 @@
   <meta charset="utf-8" />
   <meta name="viewport" content="width=device-width, initial-scale=1" />
   <title>Watch Party</title>
+
+  <!-- PWA - see docs/architecture.md's "Progressive Web App" section.
+       theme-color/background_color both come straight from base.css's
+       --bg-header/--bg (the manifest can't read CSS custom properties,
+       so these are duplicated by hand - if that palette ever changes,
+       update manifest.webmanifest to match). -->
+  <link rel="manifest" href="manifest.webmanifest" />
+  <meta name="theme-color" content="#221d24" />
+  <link rel="icon" type="image/png" href="icons/favicon.png" />
+
+  <!-- iOS ignores the manifest above for installed-app chrome - Safari
+       needs its own separate meta tags/link for the equivalent
+       standalone/home-screen-icon behavior. -->
+  <link rel="apple-touch-icon" href="icons/apple-touch-icon.png" />
+  <meta name="apple-mobile-web-app-capable" content="yes" />
+  <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
+  <meta name="apple-mobile-web-app-title" content="Watch Party" />
+
   <link rel="stylesheet" href="app.css" />
   <script src="https://cdnjs.cloudflare.com/ajax/libs/hls.js/1.5.17/hls.min.js"></script>
   <script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/4.7.5/socket.io.min.js"></script>

client/src/musicBar/MusicBar.css

@@ -6,13 +6,13 @@
    able to browse/add tracks while it plays). Sits above .mainContent, at
    a lower z-index than .playerWrap (20) so a video party's takeover still
    correctly covers it - moot in practice since joining a video party
-   calls leaveMusicParty() first (see Player.ts), but cheap to get right. */
+   calls leaveMusicParty() first (see Player.ts), but cheap to get right.
+   The fixed-to-viewport positioning itself lives one level up, on
+   Shell.css's .bottomStack wrapper - not here - so that on a narrow
+   screen the mobile nav trigger right below it in that wrapper always
+   sits flush above this bar's own actual rendered height (its content
+   can wrap taller on a narrow screen), never a hardcoded guess at it. */
 .musicBar {
-  position: fixed;
-  left: 0;
-  right: 0;
-  bottom: 0;
-  z-index: 15;
   background: var(--bg-header);
   border-top: 1px solid rgba(255, 255, 255, .08);
   box-shadow: 0 -4px 16px rgba(0, 0, 0, .3);

client/src/public/manifest.webmanifest

@@ -0,0 +1,16 @@
+{
+  "name": "Watch Party",
+  "short_name": "Watch Party",
+  "description": "Regardez et écoutez en même temps que les autres utilisateurs de votre serveur Emby.",
+  "lang": "fr",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#151216",
+  "theme_color": "#221d24",
+  "categories": ["entertainment", "multimedia"],
+  "icons": [
+    { "src": "icons/icon-192.png", "sizes": "192x192", "type": "image/png", "purpose": "any" },
+    { "src": "icons/icon-512.png", "sizes": "512x512", "type": "image/png", "purpose": "any" },
+    { "src": "icons/icon-512-maskable.png", "sizes": "512x512", "type": "image/png", "purpose": "maskable" }
+  ]
+}

client/src/shell/Shell.css

@@ -62,20 +62,162 @@
   padding: 24px clamp(16px, 3vw, 48px) 80px;
 }
 
-/* Sidebar becomes a horizontal scrollable topbar on narrow screens. */
+/* ==== Mobile navigation (<=720px) ====
+   Replaces the sidebar outright - see docs/architecture.md's "Mobile
+   navigation" section for why a bottom sheet was chosen over reshaping
+   the sidebar into a horizontal bar. Every rule below the base
+   `display: none` only ever applies once the 720px media query turns
+   it back on, so none of this affects desktop. */
+.mobileTopBar,
+.mobileNavTrigger,
+.mobileNavScrim,
+.mobileNavSheet {
+  display: none;
+}
+
+.mobileTopBar {
+  position: sticky;
+  top: 0;
+  z-index: 3;
+  padding: 14px 16px;
+  background: var(--bg-header);
+}
+
+.mobileBrand { font-size: 16px; font-weight: 700; }
+
+/* position:fixed, not sticky - #musicBar below already relies on a
+   fixed wrapper to stay docked regardless of how far #mainContent's
+   own (whole-page, not internally-scrolled) content runs. */
+.bottomStack {
+  position: fixed;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  z-index: 15;
+  display: flex;
+  flex-direction: column;
+}
+
+.mobileNavTrigger {
+  align-items: center;
+  justify-content: center;
+  gap: 8px;
+  background: var(--bg-header);
+  border: none;
+  border-top: 1px solid rgba(255, 255, 255, .08);
+  color: var(--text);
+  font-family: inherit;
+  font-size: 13px;
+  font-weight: 600;
+  padding: 13px;
+  padding-bottom: calc(13px + env(safe-area-inset-bottom, 0px));
+}
+
+.mobileNavScrim {
+  position: fixed;
+  inset: 0;
+  z-index: 20;
+  background: rgba(0, 0, 0, .5);
+  opacity: 0;
+  pointer-events: none;
+  transition: opacity .2s;
+}
+
+.mobileNavScrim.open { opacity: 1; pointer-events: auto; }
+
+.mobileNavSheet {
+  position: fixed;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  z-index: 21;
+  max-height: 75vh;
+  overflow-y: auto;
+  background: var(--bg-header);
+  border-radius: 16px 16px 0 0;
+  padding: 8px 16px calc(20px + env(safe-area-inset-bottom, 0px));
+  transform: translateY(100%);
+  transition: transform .22s ease;
+  box-shadow: 0 -8px 24px rgba(0, 0, 0, .3);
+}
+
+.mobileNavSheet.open { transform: translateY(0); }
+
+.sheetGrabber {
+  width: 36px;
+  height: 4px;
+  border-radius: 99px;
+  background: var(--muted);
+  margin: 10px auto 6px;
+}
+
+/* Accueil and the (conditional) Listes de lecture row both use this -
+   same visual weight, bookending the "Bibliothèques" group between
+   them, so the one part whose size actually varies (however many
+   libraries Emby returns) reads as visually distinct from the two
+   fixed rows around it. */
+.sheetPrimary {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  width: 100%;
+  background: var(--panel);
+  border: none;
+  border-radius: 10px;
+  color: var(--text);
+  font-family: inherit;
+  font-size: 14px;
+  font-weight: 600;
+  padding: 12px;
+  margin: 4px 0;
+  text-decoration: none;
+}
+
+.sheetPrimary.active { background: var(--accent); color: #fff; }
+
+.sheetGrid {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 8px;
+  margin: 4px 0 10px;
+}
+
+.sheetItem {
+  display: flex;
+  align-items: center;
+  gap: 9px;
+  background: var(--panel);
+  border-radius: 10px;
+  color: var(--text);
+  font-size: 13px;
+  padding: 12px 10px;
+  text-decoration: none;
+}
+
+.sheetItem.active { background: var(--accent); color: #fff; font-weight: 600; }
+
+.navIcon { width: 20px; height: 20px; flex-shrink: 0; display: block; }
+.navIcon svg { width: 100%; height: 100%; }
+
+.sheetLogout {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 8px;
+  width: 100%;
+  margin-top: 8px;
+  padding: 12px;
+  border: 1px solid rgba(255, 255, 255, .15);
+  border-radius: 10px;
+  color: var(--muted);
+  font-size: 13px;
+}
+
 @media (max-width: 720px) {
   .appShell { flex-direction: column; }
-  .sidebar {
-    width: 100%;
-    height: auto;
-    flex-direction: row;
-    align-items: center;
-    padding: 10px 12px;
-    overflow-x: auto;
-    overflow-y: hidden;
-  }
-  .sidebarBrand { padding: 0 12px 0 0; }
-  .sidebarNav { flex-direction: row; flex: none; }
-  .navSectionLabel { display: none; }
-  .sidebarLogout { margin: 0 0 0 12px; }
+  .sidebar { display: none; }
+  .mobileTopBar { display: flex; align-items: center; }
+  .mobileNavTrigger { display: flex; }
+  .mobileNavScrim { display: block; }
+  .mobileNavSheet { display: block; }
 }

client/src/shell/Shell.html

@@ -6,8 +6,37 @@
       <div class="navSectionLabel">Bibliothèques</div>
       <p class="hint" id="libStatus"><span class="spinner"></span>Chargement...</p>
     </nav>
-    <button class="linklike sidebarLogout" id="logout"></button>
+    <button class="linklike sidebarLogout logoutBtn" id="logout"></button>
   </aside>
+
+  <!-- Mobile-only (see Shell.css's 720px breakpoint) - the sidebar
+       above is display:none there instead of reshaping into a
+       horizontal bar. See docs/architecture.md's "Mobile navigation". -->
+  <header class="mobileTopBar">
+    <span class="mobileBrand">Watch Party</span>
+  </header>
+
   <main id="mainContent" class="mainContent"></main>
+
+  <!-- Wraps #musicBar so the trigger below always sits directly above
+       whatever height the bar actually renders at - see Shell.css. -->
+  <div class="bottomStack">
     <div id="musicBar" class="musicBar"></div>
+    <button class="mobileNavTrigger" id="mobileNavTrigger" aria-expanded="false" aria-controls="mobileNavSheet">
+      Parcourir
+      <svg viewBox="0 0 24 24" width="14" height="14" aria-hidden="true">
+        <path d="M6 9l6 6 6-6" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></path>
+      </svg>
+    </button>
+  </div>
+
+  <div class="mobileNavScrim" id="mobileNavScrim"></div>
+  <div class="mobileNavSheet" id="mobileNavSheet">
+    <div class="sheetGrabber"></div>
+    <a href="#/home" class="navItem sheetPrimary"><span class="navIcon" data-icon="home"></span>Accueil</a>
+    <div class="navSectionLabel">Bibliothèques</div>
+    <div class="sheetGrid" id="mobileLibGrid"></div>
+    <div id="mobilePlaylistsSlot"></div>
+    <button class="linklike sheetLogout logoutBtn" id="mobileLogout"></button>
+  </div>
 </div>

client/src/shell/Shell.ts

@@ -5,41 +5,97 @@ import './Shell.css';
 import html from './Shell.html';
 import { auth, getLibraries, logout } from '../api/embyApi';
 import { initMusicBar } from '../musicBar/MusicBar';
+import type { LibraryDto } from '../types';
+
+// One icon per Emby CollectionType - only used by the mobile bottom
+// sheet (see docs/architecture.md's "Mobile navigation"); the desktop
+// sidebar stays plain text, unchanged. Same small inline-SVG-constant
+// convention as views/player/Player.ts's own icon strings.
+const HOME_ICON_SVG = '<svg viewBox="0 0 24 24"><path d="M3.5 11.5 12 4l8.5 7.5" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/><path d="M5.5 10v9a1 1 0 0 0 1 1H10v-5.5a1 1 0 0 1 1-1h2a1 1 0 0 1 1 1V20h3.5a1 1 0 0 0 1-1v-9" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>';
+const MOVIES_ICON_SVG = '<svg viewBox="0 0 24 24"><rect x="3.5" y="6" width="17" height="13" rx="1.5" fill="none" stroke="currentColor" stroke-width="1.8"/><path d="M3.5 6 7 3h3l-2.5 3M11 6l2.5-3h3L14 6m3.5 0 2.5-3" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>';
+const SHOWS_ICON_SVG = '<svg viewBox="0 0 24 24"><rect x="3" y="5.5" width="18" height="12" rx="1.5" fill="none" stroke="currentColor" stroke-width="1.8"/><path d="M9 20.5h6M12 17.5v3" stroke="currentColor" stroke-width="1.8" stroke-linecap="round"/></svg>';
+const MUSIC_ICON_SVG = '<svg viewBox="0 0 24 24"><circle cx="8" cy="17" r="2.6" fill="none" stroke="currentColor" stroke-width="1.8"/><path d="M10.5 17V5.5l7-1.5v10" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/><circle cx="17.5" cy="14" r="2.6" fill="none" stroke="currentColor" stroke-width="1.8"/></svg>';
+const MUSICVIDEOS_ICON_SVG = '<svg viewBox="0 0 24 24"><rect x="3" y="5.5" width="18" height="13" rx="1.5" fill="none" stroke="currentColor" stroke-width="1.8"/><path d="M10 9.5 15.5 12 10 14.5Z" fill="currentColor"/></svg>';
+const PLAYLISTS_ICON_SVG = '<svg viewBox="0 0 24 24"><circle cx="4.5" cy="7" r="1.3" fill="currentColor"/><circle cx="4.5" cy="12" r="1.3" fill="currentColor"/><circle cx="4.5" cy="17" r="1.3" fill="currentColor"/><line x1="9" y1="7" x2="20" y2="7" stroke="currentColor" stroke-width="1.8" stroke-linecap="round"/><line x1="9" y1="12" x2="20" y2="12" stroke="currentColor" stroke-width="1.8" stroke-linecap="round"/><line x1="9" y1="17" x2="20" y2="17" stroke="currentColor" stroke-width="1.8" stroke-linecap="round"/></svg>';
+// Emby could in principle add a CollectionType this app doesn't map yet
+// (server/src/services/CatalogService.ts's VISIBLE_COLLECTION_TYPES
+// would need updating first either way) - falls back to a plain folder
+// glyph rather than rendering an empty icon slot.
+const GENERIC_LIBRARY_ICON_SVG = '<svg viewBox="0 0 24 24"><rect x="3.5" y="5" width="17" height="14" rx="2" fill="none" stroke="currentColor" stroke-width="1.8"/></svg>';
+
+const COLLECTION_ICONS: Record<string, string> = {
+  movies: MOVIES_ICON_SVG,
+  tvshows: SHOWS_ICON_SVG,
+  music: MUSIC_ICON_SVG,
+  musicvideos: MUSICVIDEOS_ICON_SVG,
+  playlists: PLAYLISTS_ICON_SVG,
+};
+
+/** One `<a>` per library, shared by the desktop sidebar (plain text)
+ *  and the mobile sheet (icon + text) - `withIcon` is the only
+ *  difference between the two call sites below. */
+function createLibraryLink(lib: LibraryDto, className: string, withIcon: boolean): HTMLAnchorElement {
+  const a = document.createElement('a');
+  a.href = `#/library/${lib.id}`;
+  a.className = className;
+  if (withIcon) {
+    const icon = document.createElement('span');
+    icon.className = 'navIcon';
+    icon.innerHTML = COLLECTION_ICONS[lib.collectionType] || GENERIC_LIBRARY_ICON_SVG;
+    a.appendChild(icon);
+  }
+  a.appendChild(document.createTextNode(lib.name));
+  return a;
+}
 
 export async function renderShell(appEl: HTMLElement): Promise<HTMLElement> {
   appEl.innerHTML = html;
-  appEl.querySelector('#logout')!.textContent = `Se déconnecter (${auth.userName || ''})`;
+
+  appEl.querySelector('[data-icon="home"]')!.innerHTML = HOME_ICON_SVG;
 
   // Mounted once, outside #mainContent, so a listen party survives
   // navigating the router - see musicBar/MusicBar.ts's header comment.
   initMusicBar(appEl.querySelector('#musicBar') as HTMLElement);
 
-  appEl.querySelector('#logout')!.addEventListener('click', async () => {
+  // Both the sidebar's and the mobile sheet's logout button - same
+  // label, same handler, one line each instead of a shared DOM node
+  // fought over by two very differently-laid-out containers.
+  appEl.querySelectorAll<HTMLButtonElement>('.logoutBtn').forEach((btn) => {
+    btn.textContent = `Se déconnecter (${auth.userName || ''})`;
+    btn.addEventListener('click', async () => {
       await logout();
       // Simplest reliable way back to a bare login screen: a real reload,
       // rather than hand-tearing-down every shell/router listener in place.
       location.hash = '';
       location.reload();
     });
+  });
 
   const nav = appEl.querySelector('#sidebarNav')!;
   const status = appEl.querySelector('#libStatus')!;
+  const mobileLibGrid = appEl.querySelector('#mobileLibGrid')!;
+  const mobilePlaylistsSlot = appEl.querySelector('#mobilePlaylistsSlot')!;
   try {
     const libraries = await getLibraries();
     status.remove();
     libraries.forEach((lib) => {
-      const a = document.createElement('a');
-      a.href = `#/library/${lib.id}`;
-      a.className = 'navItem';
-      a.textContent = lib.name;
-      nav.appendChild(a);
+      nav.appendChild(createLibraryLink(lib, 'navItem', false));
+      // 'playlists' gets pulled out of the "Bibliothèques" group into
+      // its own fixed row - see docs/architecture.md. Everything else
+      // (movies/tvshows/music/musicvideos, whatever mix this server
+      // actually has) lands in the grid, unchanged in count or order.
+      if (lib.collectionType === 'playlists') {
+        mobilePlaylistsSlot.appendChild(createLibraryLink(lib, 'navItem sheetPrimary', true));
+      } else {
+        mobileLibGrid.appendChild(createLibraryLink(lib, 'navItem sheetItem', true));
+      }
     });
   } catch {
     status.textContent = 'Bibliothèques indisponibles.';
   }
 
   const highlight = () => {
-    nav.querySelectorAll('.navItem').forEach((a) => {
+    appEl.querySelectorAll('.navItem').forEach((a) => {
       const isHome = a.getAttribute('href') === '#/home';
       a.classList.toggle('active', a.getAttribute('href') === location.hash || (isHome && !location.hash));
     });
@@ -47,5 +103,29 @@ export async function renderShell(appEl: HTMLElement): Promise<HTMLElement> {
   highlight();
   window.addEventListener('hashchange', highlight);
 
+  // ---- Mobile bottom sheet - see Shell.css's "Mobile navigation". ----
+  const navTrigger = appEl.querySelector('#mobileNavTrigger') as HTMLButtonElement;
+  const navSheet = appEl.querySelector('#mobileNavSheet')!;
+  const navScrim = appEl.querySelector('#mobileNavScrim')!;
+  const closeMobileNav = () => {
+    navSheet.classList.remove('open');
+    navScrim.classList.remove('open');
+    navTrigger.setAttribute('aria-expanded', 'false');
+  };
+  navTrigger.addEventListener('click', () => {
+    const opening = !navSheet.classList.contains('open');
+    navSheet.classList.toggle('open', opening);
+    navScrim.classList.toggle('open', opening);
+    navTrigger.setAttribute('aria-expanded', String(opening));
+  });
+  navScrim.addEventListener('click', closeMobileNav);
+  // Any of the three zones (Accueil, a library, Listes de lecture) -
+  // the sheet itself has no other clickable children, so this one
+  // delegated listener covers all of them without a per-link handler.
+  navSheet.addEventListener('click', (e) => {
+    if ((e.target as HTMLElement).closest('.navItem')) closeMobileNav();
+  });
+  window.addEventListener('hashchange', closeMobileNav);
+
   return appEl.querySelector('#mainContent') as HTMLElement;
 }

client/src/views/player/Player.css

@@ -366,6 +366,15 @@
 
 .fsBtn:hover { background: rgba(255, 255, 255, .18); }
 
+/* #pipBtn while active - same "clearly-on" treatment as .iconBtn's own
+   [aria-pressed="true"] rule (#castBtn), just scoped to .fsBtn instead -
+   the two aren't combined onto one shared class since .iconBtn and
+   .fsBtn otherwise disagree on padding/border-radius/background. */
+.fsBtn[aria-pressed="true"] {
+  color: #ff9800;
+  background: rgba(255, 152, 0, .18);
+}
+
 /* Replaces the video content while casting - the local <video> is
    paused/torn down (see Player.ts's startCasting/cast.ts), so leaving
    its last frame frozen with no explanation would just look stuck. */

client/src/views/player/Player.html

@@ -127,6 +127,17 @@
         <span id="ambientNotice" class="ambientNotice hide"></span>
       </div>
       <div class="bottomBarZone right">
+        <!-- Hidden by default, shown only once Player.ts confirms
+             document.pictureInPictureEnabled - not every browser supports
+             this (see its own comment), and there's no live
+             "availability changed" event to react to the way the cast
+             button has, since this never changes mid-session. -->
+        <button id="pipBtn" class="fsBtn hide" title="Picture-in-picture" aria-label="Picture-in-picture" aria-pressed="false">
+          <svg viewBox="0 0 24 24" width="16" height="16" aria-hidden="true">
+            <rect x="3" y="4" width="18" height="14" rx="2" fill="none" stroke="currentColor" stroke-width="2"></rect>
+            <rect x="12" y="11" width="7" height="5" rx="1" fill="currentColor"></rect>
+          </svg>
+        </button>
         <button id="fullscreenBtn" class="fsBtn" title="Plein écran" aria-label="Plein écran"></button>
       </div>
     </div>

client/src/views/player/Player.ts

@@ -196,6 +196,7 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
   const qualitySelect = root.querySelector('#qualitySelect') as HTMLSelectElement;
   const burnInHint = root.querySelector('#burnInHint')!;
   const castBtn = root.querySelector('#castBtn') as HTMLButtonElement;
+  const pipBtn = root.querySelector('#pipBtn') as HTMLButtonElement;
   const fullscreenBtn = root.querySelector('#fullscreenBtn') as HTMLButtonElement;
   const bottomBar = root.querySelector('#bottomBar') as HTMLElement;
   const progressBar = root.querySelector('#progressBar') as HTMLElement;
@@ -996,6 +997,44 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
   });
   updateFullscreenBtn();
 
+  /**
+   * Picture-in-picture - asked for directly, mobile in particular: the
+   * one way to keep watching in a small floating window while switching
+   * to another app, since a phone has no second window/screen to put
+   * this app in the way a desktop might. Feature-detected once at mount,
+   * not live like #castBtn's own onCastAvailabilityChanged - unlike a
+   * Chromecast appearing/disappearing on the network mid-session,
+   * browser support for this is fixed for the lifetime of the page, so
+   * there's nothing to react to after this first check. video itself
+   * needs no new attribute for this to work - unlike disableremoteplayback
+   * (added specifically to suppress Chrome's own auto cast icon), there's
+   * no equivalent auto-injected native PiP control this app needs to
+   * fight with.
+   */
+  if (document.pictureInPictureEnabled && !video.disablePictureInPicture) {
+    pipBtn.classList.remove('hide');
+    pipBtn.addEventListener('click', () => {
+      if (document.pictureInPictureElement) {
+        document.exitPictureInPicture().catch(() => {});
+      } else {
+        video.requestPictureInPicture().catch((err) => {
+          // Can genuinely fail even when supported (no user gesture in
+          // some browsers' stricter reading of that, video not yet
+          // ready) - same "try it, log it, don't crash anything else"
+          // instinct as every other best-effort browser API this app
+          // calls (video.play().catch, requestFullscreen().catch, ...).
+          console.error('[watchparty player] picture-in-picture failed', err);
+        });
+      }
+    });
+    // Reflects state via the same [aria-pressed] treatment #castBtn
+    // uses (see Player.css's .fsBtn[aria-pressed="true"]) - covers the
+    // browser's own PiP window being closed directly (its native close
+    // button, or the OS), not just this button's own click.
+    video.addEventListener('enterpictureinpicture', () => pipBtn.setAttribute('aria-pressed', 'true'));
+    video.addEventListener('leavepictureinpicture', () => pipBtn.setAttribute('aria-pressed', 'false'));
+  }
+
   async function onItemChanged(msg: ItemChangedMsg) {
     itemTitleEl.textContent = msg.itemName || '';
     hasNextQueued = !!msg.hasNext;

docs/architecture.md

@@ -3343,6 +3343,67 @@ Authorization` Device/Client/Version header a real client would, only
 `X-Emby-Token` - is genuinely unconfirmed. Worth watching the real
 dashboard the first time a party runs after this ships.
 
+## Picture-in-picture
+
+Asked for directly, mobile in particular: a phone has no second window
+to put this app in the way a desktop might, so the standard browser
+Picture-in-Picture API - popping the `<video>` out into a small,
+OS-managed floating window - is the one way to keep watching while
+switching to another app. Standard `HTMLVideoElement
+.requestPictureInPicture()`/`document.exitPictureInPicture()`, not the
+Chromecast-adjacent `disableremoteplayback` trick or anything WebKit-
+prefixed - confirmed directly in a real Chromium build that
+`document.pictureInPictureEnabled`/`requestPictureInPicture`/
+`exitPictureInPicture` are all present, which is what actually matters
+for Android Chrome, the mobile browser this was asked for.
+
+New `#pipBtn`, right next to `#fullscreenBtn` (`.bottomBarZone.right`)
+- both are "how is this displayed" toggles, so they share the same
+`.fsBtn` sizing, and a new `.fsBtn[aria-pressed="true"]` rule gives PiP
+the identical "clearly on" orange treatment `#castBtn` already has
+(kept as its own rule rather than combined onto `.iconBtn` - that class
+and `.fsBtn` disagree on padding/border-radius/background, so
+combining them risked an inconsistent size instead of a clean shared
+look). Feature-detected once at mount (`document.pictureInPictureEnabled
+&& !video.disablePictureInPicture`), not live the way `#castBtn`'s own
+`onCastAvailabilityChanged` is - browser support for this doesn't
+appear/disappear mid-session the way a Chromecast on the network does,
+so there's nothing to react to after the first check. No new attribute
+needed on `<video>` itself either - unlike `disableremoteplayback`
+(added specifically to suppress Chrome's own auto-injected cast icon),
+there's no equivalent native PiP affordance this app needs to
+suppress.
+
+State (`aria-pressed`) is kept in sync via the video's own
+`enterpictureinpicture`/`leavepictureinpicture` events rather than the
+button's own click handler alone - covers the browser's native PiP
+window being closed directly (its own close control, or the OS), not
+just a second click back in this app. Requires no cleanup on route
+navigation: like every other per-mount element here, `<video>` itself
+is destroyed and replaced by the next `root.innerHTML = html` (router.ts
+runs this unconditionally on any navigation) - browsers already close
+an active PiP window automatically once its source element leaves the
+document, matching this app's very deliberate opposite choice for
+casting (leaving an active Chromecast session running after
+navigating away - see "Casting to a Chromecast" above): PiP has no
+independent existence apart from the `<video>` element it mirrors, a
+Chromecast session does.
+
+Verified: full `typecheck`/`build` (client only - this is a pure
+client-side feature, no server involved). Confirmed directly in a real
+browser, not just type-checked: `document.pictureInPictureEnabled` is
+`true` here, and running the exact show/hide + click-handling logic
+against a real (sourceless) `<video>` correctly shows the button and
+catches the resulting `InvalidStateError` from `requestPictureInPicture()`
+without it becoming an uncaught exception - the same rejection a real
+video would throw for a different reason (already in PiP, or the
+document not focused), confirming the error handling path itself
+rather than just assuming it. **Not verified**: an actual floating PiP
+window on a real mobile browser, playing a real Emby stream - no
+device/login reachable from this sandbox, same standing gap as this
+project's other browser-native integrations (casting, the intro-skip
+buttons).
+
 ## Queuing a whole album, or an artist's entire discography, in one action
 
 Asked for directly: `views/album`'s and `views/artist`'s per-track/
@@ -3419,6 +3480,183 @@ tokens) rather than eyeballed. **Not verified**: an actual large
 discography queuing correctly end to end against a real server - no
 Emby login reachable from this sandbox.
 
+## Progressive Web App
+
+Asked for directly, as a follow-up to Picture-in-picture above: since
+that feature's automatic-on-backgrounding variant turned out not to be
+achievable (browsers require a *fresh* user gesture for
+`requestPictureInPicture()` - confirmed empirically, not just from
+docs, by calling it from a real `visibilitychange` listener in a real
+Chromium tab and getting `NotAllowedError` even with
+`navigator.userActivation.hasBeenActive === true` from an earlier real
+click), a PWA install was asked for instead. **Worth being explicit
+about, since it'd be easy to assume otherwise**: installing this app
+does not change that outcome - the transient-activation requirement is
+part of the Picture-in-Picture spec itself, not something tied to
+being loaded in a browser tab versus an installed, `display: standalone`
+window. The one Chrome feature that skips that requirement
+(media-session-handler-based automatic PiP) stays desktop-only and
+getUserMedia-gated regardless of install state, and nothing above
+touches that gate. So the manual `#pipBtn` toggle remains the way to
+enter PiP either way - a PWA install is its own, independently useful
+feature here (an icon on the home screen, no browser chrome/URL bar
+around the player, an OS-level app-switcher entry), not a workaround
+for the previous section's limitation.
+
+Three pieces, all standard and Chromium/Android-focused since that's
+this app's stated mobile target (see Picture-in-picture above):
+
+- **`client/src/public/manifest.webmanifest`** - `name`/`short_name`,
+  `display: "standalone"`, and `background_color`/`theme_color` copied
+  by hand from `base.css`'s `--bg`/`--bg-header` (a manifest can't read
+  CSS custom properties, so these two are duplicated on purpose - if
+  that palette ever changes, update both places). `start_url: "/"`,
+  `lang: "fr"` matching `index.html`'s own `<html lang="fr">`. No
+  `service worker` - confirmed against MDN's own installability
+  requirements that Chrome does not require one for the install
+  prompt, and this app has no real use for one: every page is either
+  live party/socket state or a proxied Emby catalog, and caching either
+  offline would mean showing stale library data or a stale party that's
+  already gone, not a working offline mode - so skipping it avoids a
+  whole stale-cache-invalidation problem this app doesn't need to
+  solve.
+- **Icons** - hand-authored SVG (this project has no existing
+  logo/brand asset), rasterized to PNG at the sizes each consumer
+  needs (192/512 for the manifest, 180 for `apple-touch-icon`, 32 for
+  the browser-tab favicon) via a `<canvas>` in a real browser rather
+  than an image-editing tool, since that's what was available here.
+  Two source SVGs, not one: `icon.svg` fills the canvas (used for the
+  manifest's `"any"` purpose, the favicon, and `apple-touch-icon` -
+  none of those get OS-mask-cropped) and `icon-maskable.svg` scales
+  the same design down (~75%) so its farthest content point sits
+  inside Android's adaptive-icon safe zone (a circle of ~30.5% of the
+  icon's radius from center) - checked by computing the actual
+  farthest-point distance for both versions, not just eyeballed,
+  since a maskable icon that ignores that zone gets silently clipped
+  by circular-mask launchers.
+- **`index.html`** - `<link rel="manifest">`, a `theme-color` meta
+  (Chrome/Android chrome), and the separate iOS-only tags Safari needs
+  instead of reading the manifest for the equivalent behavior
+  (`apple-touch-icon` link, `apple-mobile-web-app-capable`,
+  `apple-mobile-web-app-status-bar-style`, `apple-mobile-web-app-title`).
+
+`build.mjs` gained one `cpSync(src/public, dist, { recursive: true })`
+call alongside its existing `index.html` copy, rather than naming the
+manifest and every icon individually - adding another icon later needs
+no build.mjs change. `express.static` (already serving all of
+`client/dist` unconditionally) picks up `manifest.webmanifest` and
+`icons/*` with no server-side change at all.
+
+Verified: full `typecheck`/`build` (client only). Confirmed directly
+against a real running instance of this server, not just assumed:
+`manifest.webmanifest` and all three manifest icons resolve `200` with
+the correct `application/manifest+json`/`image/png` content types
+(express's static middleware infers both from the file extension
+correctly on its own), the `apple-touch-icon` link resolves `200`, the
+generated PNGs are genuinely the declared dimensions (32/180/192/512),
+and the page's own console shows no manifest-related warnings after
+loading it. **Not verified**: an actual "Add to Home Screen"/install
+prompt, or the installed app's standalone window, on a real device -
+no device reachable from this sandbox, same standing gap as every
+other browser-native integration in this project (casting, PiP, the
+intro-skip buttons).
+
+## Mobile navigation: a bottom sheet, not a reshaped sidebar
+
+Asked for directly: the sidebar's old mobile treatment just reshaped
+itself into a horizontally-scrolling top bar under 720px (a single
+media query in Shell.css) - functional, but easy to miss (nothing
+signals there's more to scroll to) and it buried "Se déconnecter" at
+the far end of that scroll. Explored as a set of mockups first (four
+patterns compared side by side, including the tradeoffs of each) before
+writing any real code - the bottom sheet won out over a bottom tab bar
+(too few slots for an unbounded number of Emby libraries), a hamburger
+drawer (still the smallest code delta, but two taps for "Accueil" too),
+and a merely-polished version of the existing horizontal bar.
+
+**Structure mirrors the real data shape, not a flat list**: `getLibraries()`
+already returns each library's Emby `CollectionType` as `collectionType`
+on `LibraryDto` (`server/src/services/CatalogService.ts`) - confirmed by
+reading that service directly rather than assumed. The sheet uses it to
+render three zones instead of one flat list:
+
+- **Accueil** - one fixed row, always first.
+- **Bibliothèques** - a section label over a 2-column grid of every
+  library *except* the one whose `collectionType` is `'playlists'` -
+  this is the part whose count and contents genuinely depend on what
+  the connected Emby server has (2 libraries or 10, movies-only or
+  every type at once).
+- **Listes de lecture** - pulled out of that grid into its own fixed
+  row, same visual weight as Accueil, bookending the group. Only
+  rendered at all when a `'playlists'`-type library is actually
+  present - same conditional-presence rule the sidebar already applies
+  to every library type, just applied one level deeper here.
+
+Zero server-side work for this split - `collectionType` was already
+being sent, just never read on the client before now.
+
+**One `createLibraryLink()` builds both trees.** The desktop sidebar's
+existing plain-text links and the mobile sheet's icon+text links are
+different enough (icon or not, grid cell or plain row) that unifying
+them into one shared DOM subtree styled two ways would need more CSS
+trickery than it saves - so `Shell.ts` keeps two small render call
+sites, both reading the one `getLibraries()` result, sharing the one
+link-building function. The two logout buttons (sidebar footer, sheet
+footer) are separate DOM nodes for the same reason - same label, same
+`click` handler, wired once via `.logoutBtn` rather than `#logout`.
+
+**Icons are new** - the sidebar has never had any. Small inline SVGs,
+same "constant string, `currentColor`" convention `views/player/Player.ts`
+already uses for its own icons, one per Emby `CollectionType`
+(`movies`/`tvshows`/`music`/`musicvideos`/`playlists`) plus a generic
+fallback for any future type this app hasn't mapped yet.
+
+**The music bar's stacking, made structural instead of a magic number.**
+`MusicBar.css`'s `.musicBar` no longer positions itself - a new
+`.bottomStack` (`position: fixed; bottom: 0`, plain flex column) wraps
+it together with the new mobile nav trigger button, so the trigger
+always sits flush above the bar's *actual* rendered height. That
+height isn't constant - `.musicBarRow` wraps onto a second line on a
+narrow screen with a long track/artist name plus presence avatars -
+so a hardcoded pixel offset would have drifted; normal flow inside one
+shared fixed wrapper can't. Transparent to desktop: the trigger is
+`display: none` there, so `.bottomStack` just becomes a plain wrapper
+around the bar, unchanged from before.
+
+The sheet itself (`.mobileNavSheet`) and its scrim are independent
+`position: fixed` overlays above `.bottomStack`'s z-index, sliding up
+via `transform: translateY` - closes on: tapping the scrim, tapping any
+of the three zones' links (one delegated click listener, not one per
+link), or any `hashchange` (covers browser back/forward too, alongside
+the existing `highlight()` listener that already ran on that event for
+the active-link state - now widened from `#sidebarNav .navItem` to
+every `.navItem` on the page, so both trees highlight consistently).
+
+Verified: full `typecheck`/`build` (client only). The interaction logic
+- open/close, closing on a link tap, active-state highlighting, the
+grouped Accueil/Bibliothèques/Listes-de-lecture split, the conditional
+playlists row - was proven first in the mockup artifact (identical
+logic), then re-verified here directly against the real shipped
+`Shell.ts`/`Shell.html`/compiled `Shell.css`, wired up with fake library
+data (no Emby login reachable from this sandbox) since the real Shell
+only ever mounts after a real login: the desktop tree still renders
+correctly untouched at desktop width, the compiled CSS's media query
+and base mobile rules match what was written byte-for-byte, and the
+mobile sheet's open/close/navigate/logout interactions were driven
+programmatically end to end (`element.click()` still fires listeners on
+a `display: none` element, so this didn't need a real narrow viewport
+to exercise the logic itself). The music-bar/trigger stacking was
+confirmed visually with a synthetic long-track-title music bar sitting
+flush above the trigger, no gap or overlap. **Not verified**: the
+actual rendered layout at a genuinely narrow viewport - this sandbox's
+browser tool's viewport-emulation stopped taking effect partway through
+this session (`screen.width` reflected the requested size, `innerWidth`
+and `matchMedia` did not - a tooling issue hit repeatedly this session,
+not something in this app's code), so the mobile-width visual check
+above was done by forcing the same CSS rules through an injected
+override instead of a real ≤720px viewport. Worth an early real-phone
+check once deployed.
+
 ## Music UI rework: circles and squares instead of movie posters, a real now-playing screen
 
 Asked for directly, "inspired by other apps": the music side of this