diff --git a/frontend/index.html b/frontend/index.html
index 4146b10..9eb844f 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -1572,5 +1572,37 @@ curl -X POST https://votre-serveur.com/webhook \
   </div>
 
   <script type="module" src="/static/js/app.js"></script>
+
+  <!-- ── Mobile Bottom Toolbar ── -->
+  <nav class="mobile-toolbar" id="mobile-toolbar" aria-label="Barre d'outils mobile">
+    <button class="mt-btn" id="mt-explorer" title="Explorateur" aria-label="Explorateur de vault">
+      <i data-lucide="folder-open" style="width:20px;height:20px"></i>
+      <span class="mt-label">Explorer</span>
+    </button>
+    <button class="mt-btn" id="mt-search" title="Rechercher" aria-label="Rechercher">
+      <i data-lucide="search" style="width:20px;height:20px"></i>
+      <span class="mt-label">Recherche</span>
+    </button>
+    <button class="mt-btn mt-btn-primary" id="mt-palette" title="Palette" aria-label="Palette de fichiers">
+      <i data-lucide="command" style="width:20px;height:20px"></i>
+      <span class="mt-label">Palette</span>
+    </button>
+    <button class="mt-btn" id="mt-tabs" title="Onglets" aria-label="Onglets ouverts">
+      <i data-lucide="files" style="width:20px;height:20px"></i>
+      <span class="mt-badge" id="mt-tab-count" style="display:none">0</span>
+      <span class="mt-label">Onglets</span>
+    </button>
+  </nav>
+
+  <!-- ── Mobile Tab Switcher (bottom sheet) ── -->
+  <div class="mt-tab-switcher" id="mt-tab-switcher">
+    <div class="mt-sheet-handle"></div>
+    <div class="mt-sheet-header">
+      <span class="mt-sheet-title">Fichiers ouverts</span>
+      <button class="mt-sheet-close" id="mt-sheet-close" aria-label="Fermer">✕</button>
+    </div>
+    <div class="mt-sheet-list" id="mt-tab-list"></div>
+  </div>
+  <div class="mt-overlay" id="mt-overlay"></div>
  </body>
  </html>
diff --git a/frontend/js/app.js b/frontend/js/app.js
index 0f45232..2d4bbca 100644
--- a/frontend/js/app.js
+++ b/frontend/js/app.js
@@ -14,6 +14,7 @@ import * as Sync from './sync.js';
 import { initGraphView } from './graph.js';
 import * as Legacy from './legacy.js';
 import { initCommandPalette } from './palette.js';
+import { initMobileToolbar } from './mobile-toolbar.js';
 
 // =========================================================================
 // Initialization — mirrors the original app.js init() ordering
@@ -46,6 +47,7 @@ async function init() {
   UI.ContextMenuManager.init();
   UI.TabManager.init();
   initCommandPalette();
+  initMobileToolbar();
 
   const authOk = await Auth.AuthManager.initAuth();
 
diff --git a/frontend/js/mobile-toolbar.js b/frontend/js/mobile-toolbar.js
new file mode 100644
index 0000000..a6fd345
--- /dev/null
+++ b/frontend/js/mobile-toolbar.js
@@ -0,0 +1,162 @@
+/* ObsiGate — Mobile Bottom Toolbar (Obsidian-style)
+   Phases 1-5: fixed bar, vault home, file palette, commands, tab switcher */
+import { state } from './state.js';
+import { TabManager } from './ui.js';
+
+// ── Open file palette ──
+function openPalette() {
+  import('./palette.js').then(m => { m.open(''); });
+}
+
+// ── Open command palette ──
+function openCommands() {
+  import('./palette.js').then(m => { m.open('> '); });
+}
+
+// ── Tab switcher ──
+function openTabSwitcher() {
+  const sheet = document.getElementById('mt-tab-switcher');
+  const overlay = document.getElementById('mt-overlay');
+  if (!sheet || !overlay) return;
+
+  renderTabList();
+  sheet.classList.add('open');
+  overlay.classList.add('visible');
+}
+
+function closeTabSwitcher() {
+  const sheet = document.getElementById('mt-tab-switcher');
+  const overlay = document.getElementById('mt-overlay');
+  if (sheet) sheet.classList.remove('open');
+  if (overlay) overlay.classList.remove('visible');
+}
+
+function renderTabList() {
+  const list = document.getElementById('mt-tab-list');
+  if (!list) return;
+
+  const tabs = TabManager._tabs || [];
+  const activeId = TabManager._activeTabId;
+
+  if (tabs.length === 0) {
+    list.innerHTML = '<div class="cp-empty" style="padding:20px;text-align:center">Aucun fichier ouvert</div>';
+    return;
+  }
+
+  list.innerHTML = tabs.map(t => {
+    const isActive = t.id === activeId;
+    const icon = t.path.endsWith('.md') ? '📄' : '📝';
+    return `<div class="mt-tab-item${isActive ? ' active' : ''}" data-tab-id="${t.id}">
+      <span class="mt-tab-item-icon">${icon}</span>
+      <span class="mt-tab-item-name">${t.title || t.path.split('/').pop()}</span>
+      <button class="mt-tab-item-close" data-close="${t.id}" aria-label="Fermer">✕</button>
+    </div>`;
+  }).join('');
+
+  // Click handler for switching tabs
+  list.querySelectorAll('.mt-tab-item').forEach(el => {
+    el.addEventListener('click', (e) => {
+      if (e.target.closest('.mt-tab-item-close')) return;
+      const tabId = el.dataset.tabId;
+      if (tabId) {
+        TabManager.activate(tabId);
+        closeTabSwitcher();
+      }
+    });
+  });
+
+  // Click handler for closing tabs
+  list.querySelectorAll('.mt-tab-item-close').forEach(btn => {
+    btn.addEventListener('click', (e) => {
+      e.stopPropagation();
+      const tabId = btn.dataset.close;
+      if (tabId) {
+        TabManager.close(tabId);
+        setTimeout(() => renderTabList(), 100);
+      }
+    });
+  });
+}
+
+// ── Update tab count badge ──
+function updateTabCount() {
+  const badge = document.getElementById('mt-tab-count');
+  if (!badge) return;
+  const count = (TabManager._tabs || []).length;
+  if (count > 0) {
+    badge.style.display = 'flex';
+    badge.textContent = count;
+  } else {
+    badge.style.display = 'none';
+  }
+}
+
+// ── Vault home / sidebar toggle ──
+function toggleExplorer() {
+  // On mobile: toggle sidebar
+  const sidebar = document.getElementById('sidebar');
+  if (sidebar) {
+    if (sidebar.classList.contains('mobile-open')) {
+      sidebar.classList.remove('mobile-open');
+    } else {
+      sidebar.classList.add('mobile-open');
+    }
+  }
+  // Also focus the vault if none selected
+  if (!state.currentVault && state.allVaults && state.allVaults.length > 0) {
+    import('./sidebar.js').then(m => {
+      if (m.setSelectedVaultContext) m.setSelectedVaultContext(state.allVaults[0].name);
+    });
+  }
+}
+
+// ── Focus search ──
+function focusSearch() {
+  const searchInput = document.querySelector('.search-input');
+  if (searchInput) {
+    searchInput.focus();
+    searchInput.select();
+  }
+}
+
+// ── Init ──
+export function initMobileToolbar() {
+  // Only relevant on mobile, but attach handlers anyway
+  const explorerBtn = document.getElementById('mt-explorer');
+  const searchBtn = document.getElementById('mt-search');
+  const paletteBtn = document.getElementById('mt-palette');
+  const tabsBtn = document.getElementById('mt-tabs');
+  const sheetClose = document.getElementById('mt-sheet-close');
+  const overlay = document.getElementById('mt-overlay');
+
+  if (explorerBtn) explorerBtn.addEventListener('click', toggleExplorer);
+  if (searchBtn) searchBtn.addEventListener('click', focusSearch);
+  if (paletteBtn) paletteBtn.addEventListener('click', openPalette);
+  if (tabsBtn) tabsBtn.addEventListener('click', openTabSwitcher);
+  if (sheetClose) sheetClose.addEventListener('click', closeTabSwitcher);
+  if (overlay) overlay.addEventListener('click', closeTabSwitcher);
+
+  // Long-press palette for commands
+  if (paletteBtn) {
+    let pressTimer;
+    paletteBtn.addEventListener('touchstart', () => {
+      pressTimer = setTimeout(() => {
+        openCommands();
+      }, 500);
+    });
+    paletteBtn.addEventListener('touchend', () => clearTimeout(pressTimer));
+    paletteBtn.addEventListener('touchmove', () => clearTimeout(pressTimer));
+    // Click = file palette, right-click / context menu = commands
+    paletteBtn.addEventListener('contextmenu', (e) => {
+      e.preventDefault();
+      openCommands();
+    });
+  }
+
+  // Update tab count periodically
+  setInterval(updateTabCount, 2000);
+  updateTabCount();
+
+  // Also expose tab count update for external triggers
+  window._mtUpdateTabs = updateTabCount;
+}
diff --git a/frontend/style.css b/frontend/style.css
index 3134606..ff0374c 100644
--- a/frontend/style.css
+++ b/frontend/style.css
@@ -6547,3 +6547,225 @@ body.popup-mode .content-area {
     font-size: 0.88rem;
   }
 }
+
+/* ══════════════════════════════════════════
+   Mobile Bottom Toolbar (Obsidian-style)
+   ══════════════════════════════════════════ */
+.mobile-toolbar {
+  display: none;
+}
+
+@media (max-width: 768px) {
+  .mobile-toolbar {
+    display: flex;
+    position: fixed;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    height: 56px;
+    background: var(--bg-secondary);
+    border-top: 1px solid var(--border);
+    z-index: 900;
+    align-items: center;
+    justify-content: space-around;
+    padding: 0 4px;
+    padding-bottom: env(safe-area-inset-bottom, 0);
+    -webkit-backdrop-filter: blur(12px);
+    backdrop-filter: blur(12px);
+  }
+
+  /* Push content up to avoid toolbar overlap */
+  .main-layout {
+    padding-bottom: 56px;
+    padding-bottom: calc(56px + env(safe-area-inset-bottom, 0));
+  }
+  .editor-modal.active ~ .main-layout {
+    padding-bottom: 0;
+  }
+
+  .mt-btn {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    gap: 2px;
+    flex: 1;
+    height: 48px;
+    padding: 2px 4px;
+    border: none;
+    border-radius: 8px;
+    background: transparent;
+    color: var(--text-muted);
+    cursor: pointer;
+    transition: color 0.15s, background 0.15s;
+    position: relative;
+    -webkit-tap-highlight-color: transparent;
+  }
+  .mt-btn:active {
+    background: rgba(255,255,255,0.06);
+  }
+  .mt-btn svg {
+    flex-shrink: 0;
+  }
+  .mt-label {
+    font-size: 10px;
+    font-weight: 500;
+    line-height: 1;
+  }
+  .mt-btn-primary {
+    color: var(--accent);
+  }
+  .mt-btn-primary .mt-label {
+    color: var(--accent);
+  }
+
+  /* Tab count badge */
+  .mt-badge {
+    position: absolute;
+    top: 2px;
+    right: 50%;
+    transform: translateX(18px);
+    background: var(--accent);
+    color: #fff;
+    font-size: 9px;
+    font-weight: 700;
+    min-width: 16px;
+    height: 16px;
+    border-radius: 8px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    padding: 0 4px;
+    line-height: 1;
+  }
+
+  /* ── Tab Switcher Bottom Sheet ── */
+  .mt-overlay {
+    display: none;
+    position: fixed;
+    inset: 0;
+    background: rgba(0,0,0,0.5);
+    z-index: 950;
+    opacity: 0;
+    transition: opacity 0.25s;
+  }
+  .mt-overlay.visible {
+    display: block;
+    opacity: 1;
+  }
+
+  .mt-tab-switcher {
+    position: fixed;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    max-height: 60vh;
+    background: var(--bg-secondary);
+    border-radius: 16px 16px 0 0;
+    z-index: 960;
+    transform: translateY(100%);
+    transition: transform 0.3s cubic-bezier(0.32, 0.72, 0, 1);
+    display: flex;
+    flex-direction: column;
+    box-shadow: 0 -4px 24px rgba(0,0,0,0.4);
+    padding-bottom: env(safe-area-inset-bottom, 0);
+  }
+  .mt-tab-switcher.open {
+    transform: translateY(0);
+  }
+
+  .mt-sheet-handle {
+    width: 36px;
+    height: 4px;
+    background: var(--border);
+    border-radius: 2px;
+    margin: 10px auto 6px;
+    flex-shrink: 0;
+  }
+
+  .mt-sheet-header {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 8px 16px 12px;
+    flex-shrink: 0;
+  }
+  .mt-sheet-title {
+    font-family: "JetBrains Mono", monospace;
+    font-size: 0.8rem;
+    font-weight: 700;
+    text-transform: uppercase;
+    letter-spacing: 0.05em;
+    color: var(--text-muted);
+  }
+  .mt-sheet-close {
+    width: 28px; height: 28px;
+    padding: 0;
+    border: 1px solid var(--border);
+    border-radius: 6px;
+    background: transparent;
+    color: var(--text-secondary);
+    cursor: pointer;
+    font-size: 12px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+  }
+  .mt-sheet-close:hover { color: var(--accent); border-color: var(--accent); }
+
+  .mt-sheet-list {
+    flex: 1;
+    overflow-y: auto;
+    padding: 0 12px 12px;
+    -webkit-overflow-scrolling: touch;
+  }
+
+  .mt-tab-item {
+    display: flex;
+    align-items: center;
+    gap: 10px;
+    padding: 10px 12px;
+    border-radius: 8px;
+    cursor: pointer;
+    color: var(--text-primary);
+    font-size: 0.85rem;
+    transition: background 0.1s;
+    margin-bottom: 2px;
+  }
+  .mt-tab-item:active {
+    background: rgba(255,255,255,0.06);
+  }
+  .mt-tab-item.active {
+    background: color-mix(in srgb, var(--accent) 12%, transparent);
+    color: var(--accent);
+    font-weight: 600;
+  }
+  .mt-tab-item-icon {
+    flex-shrink: 0;
+    opacity: 0.6;
+  }
+  .mt-tab-item-name {
+    flex: 1;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+  }
+  .mt-tab-item-close {
+    width: 24px; height: 24px;
+    padding: 0;
+    border: none;
+    border-radius: 4px;
+    background: transparent;
+    color: var(--text-muted);
+    cursor: pointer;
+    font-size: 14px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    flex-shrink: 0;
+  }
+  .mt-tab-item-close:hover {
+    color: var(--danger, #ef4444);
+    background: rgba(239,68,68,0.1);
+  }
+}