diff --git a/frontend/app.js b/frontend/app.js
index a612617..93ea584 100644
--- a/frontend/app.js
+++ b/frontend/app.js
@@ -22,10 +22,8 @@
   let sidebarFilterCaseSensitive = false;
   let searchCaseSensitive = false;
   let _iconDebounceTimer = null;
-  const panelState = {
-    vault: true,
-    tag: true,
-  };
+  let activeSidebarTab = "vaults";
+  let filterDebounce = null;
 
   // ---------------------------------------------------------------------------
   // File extension → Lucide icon mapping
@@ -435,7 +433,7 @@
 
   function scrollTreeItemIntoView(element, alignToTop) {
     if (!element) return;
-    const scrollContainer = document.getElementById("vault-panel-content");
+    const scrollContainer = document.getElementById("sidebar-panel-vaults");
     if (!scrollContainer) return;
 
     const containerRect = scrollContainer.getBoundingClientRect();
@@ -483,7 +481,7 @@
   }
 
   async function focusVaultInSidebar(vaultName) {
-    setPanelExpanded("vault", true);
+    switchSidebarTab("vaults");
     const vaultItem = document.querySelector(`.vault-item[data-vault="${CSS.escape(vaultName)}"]`);
     if (!vaultItem) return;
     document.querySelectorAll(".vault-item.focused").forEach((el) => el.classList.remove("focused"));
@@ -567,7 +565,7 @@
   }
 
   async function focusPathInSidebar(vaultName, targetPath, options) {
-    setPanelExpanded("vault", true);
+    switchSidebarTab("vaults");
 
     const vaultItem = document.querySelector(`.vault-item[data-vault="${CSS.escape(vaultName)}"]`);
     if (!vaultItem) return;
@@ -701,46 +699,59 @@
   // ---------------------------------------------------------------------------
   // Sidebar filter
   // ---------------------------------------------------------------------------
-  async function initSidebarFilter() {
+  function initSidebarFilter() {
     const input = document.getElementById("sidebar-filter-input");
     const caseBtn = document.getElementById("sidebar-filter-case-btn");
     const clearBtn = document.getElementById("sidebar-filter-clear-btn");
-    
-    input.addEventListener("input", async () => {
+
+    input.addEventListener("input", () => {
       const hasText = input.value.length > 0;
       clearBtn.style.display = hasText ? "flex" : "none";
-      
-      const q = sidebarFilterCaseSensitive ? input.value.trim() : input.value.trim().toLowerCase();
-      
-      if (hasText) {
-        await performTreeSearch(q);
-      } else {
-        await restoreSidebarTree();
-      }
-      
-      filterTagCloud(q);
+      clearTimeout(filterDebounce);
+      filterDebounce = setTimeout(async () => {
+        const q = sidebarFilterCaseSensitive ? input.value.trim() : input.value.trim().toLowerCase();
+        if (hasText) {
+          if (activeSidebarTab === "vaults") {
+            await performTreeSearch(q);
+          } else {
+            filterTagCloud(q);
+          }
+        } else {
+          if (activeSidebarTab === "vaults") {
+            await restoreSidebarTree();
+          } else {
+            filterTagCloud("");
+          }
+        }
+      }, 220);
     });
-    
+
     caseBtn.addEventListener("click", async () => {
       sidebarFilterCaseSensitive = !sidebarFilterCaseSensitive;
       caseBtn.classList.toggle("active");
       const q = sidebarFilterCaseSensitive ? input.value.trim() : input.value.trim().toLowerCase();
       if (input.value.trim()) {
-        await performTreeSearch(q);
+        if (activeSidebarTab === "vaults") {
+          await performTreeSearch(q);
+        } else {
+          filterTagCloud(q);
+        }
       }
-      filterTagCloud(q);
     });
-    
-    clearBtn.addEventListener("click", () => {
+
+    clearBtn.addEventListener("click", async () => {
       input.value = "";
       clearBtn.style.display = "none";
       sidebarFilterCaseSensitive = false;
       caseBtn.classList.remove("active");
-      restoreSidebarTree();
-      filterTagCloud("");
+      clearTimeout(filterDebounce);
+      if (activeSidebarTab === "vaults") {
+        await restoreSidebarTree();
+      } else {
+        filterTagCloud("");
+      }
     });
-    
-    // Initially hide clear button
+
     clearBtn.style.display = "none";
   }
 
@@ -1284,47 +1295,36 @@
   }
 
   // ---------------------------------------------------------------------------
-  // Collapsible panels and help modal
+  // Sidebar tabs
   // ---------------------------------------------------------------------------
-  function initCollapsiblePanels() {
-    bindPanelToggle("vault", "vault-panel-toggle", "vault-panel-content");
-    bindPanelToggle("tag", "tag-panel-toggle", "tag-panel-content");
-    setPanelExpanded("vault", true);
-    setPanelExpanded("tag", true);
-  }
-
-  function bindPanelToggle(panelKey, toggleId, contentId) {
-    const toggle = document.getElementById(toggleId);
-    const content = document.getElementById(contentId);
-    if (!toggle || !content) return;
-    toggle.addEventListener("click", () => {
-      setPanelExpanded(panelKey, !panelState[panelKey]);
+  function initSidebarTabs() {
+    document.querySelectorAll(".sidebar-tab").forEach((tab) => {
+      tab.addEventListener("click", () => switchSidebarTab(tab.dataset.tab));
     });
   }
 
-  function setPanelExpanded(panelKey, expanded) {
-    panelState[panelKey] = expanded;
-    const sidebar = document.getElementById("sidebar");
-    const toggle = document.getElementById(`${panelKey}-panel-toggle`);
-    const content = document.getElementById(`${panelKey}-panel-content`);
-    if (!toggle || !content) return;
-    toggle.setAttribute("aria-expanded", expanded ? "true" : "false");
-    content.classList.toggle("collapsed", !expanded);
-    const iconEl = toggle.querySelector("[data-lucide]");
-    if (iconEl) {
-      iconEl.setAttribute("data-lucide", expanded ? "chevron-down" : "chevron-right");
+  function switchSidebarTab(tab) {
+    activeSidebarTab = tab;
+    document.querySelectorAll(".sidebar-tab").forEach((btn) => {
+      const isActive = btn.dataset.tab === tab;
+      btn.classList.toggle("active", isActive);
+      btn.setAttribute("aria-selected", isActive ? "true" : "false");
+    });
+    document.querySelectorAll(".sidebar-tab-panel").forEach((panel) => {
+      const isActive = panel.id === `sidebar-panel-${tab}`;
+      panel.classList.toggle("active", isActive);
+    });
+    const filterInput = document.getElementById("sidebar-filter-input");
+    if (filterInput) {
+      filterInput.placeholder = tab === "vaults" ? "Filtrer fichiers..." : "Filtrer tags...";
     }
-    if (panelKey === "tag") {
-      const tagSection = document.getElementById("tag-cloud-section");
-      const resizeHandle = document.getElementById("tag-resize-handle");
-      if (tagSection) tagSection.classList.toggle("collapsed-panel", !expanded);
-      if (resizeHandle) resizeHandle.classList.toggle("hidden", !expanded);
+    const query = filterInput
+      ? (sidebarFilterCaseSensitive ? filterInput.value.trim() : filterInput.value.trim().toLowerCase())
+      : "";
+    if (query) {
+      if (tab === "vaults") performTreeSearch(query);
+      else filterTagCloud(query);
     }
-    if (sidebar) {
-      sidebar.classList.toggle("vault-collapsed", !panelState.vault);
-      sidebar.classList.toggle("tag-collapsed", !panelState.tag);
-    }
-    safeCreateIcons();
   }
 
   function initHelpModal() {
@@ -2017,12 +2017,11 @@
     initSearch();
     initMobile();
     initVaultContext();
-    initCollapsiblePanels();
+    initSidebarTabs();
     initHelpModal();
     initConfigModal();
     initSidebarFilter();
     initSidebarResize();
-    initTagResize();
     initEditor();
 
     try {
diff --git a/frontend/index.html b/frontend/index.html
index 2463094..02c5201 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -158,23 +158,39 @@
 
       <!-- Sidebar -->
       <aside class="sidebar" id="sidebar" role="navigation" aria-label="Navigation des vaults">
-        <div class="sidebar-tree" id="sidebar-tree">
-          <!-- Sidebar filter -->
-          <div class="sidebar-filter">
-            <i data-lucide="filter" class="sidebar-filter-icon" style="width:14px;height:14px"></i>
-            <div class="sidebar-filter-input-wrapper">
-              <input type="text" id="sidebar-filter-input" placeholder="Filtrer fichiers et tags..." autocomplete="off">
-              <div class="sidebar-filter-actions">
-                <button class="sidebar-filter-btn" id="sidebar-filter-case-btn" type="button" title="Respecter la casse" aria-label="Respecter la casse">
-                  <span>Aa</span>
-                </button>
-                <button class="sidebar-filter-btn" id="sidebar-filter-clear-btn" type="button" title="Effacer le filtrage" aria-label="Effacer le filtrage">
-                  <i data-lucide="x" style="width:14px;height:14px"></i>
-                </button>
-              </div>
+
+        <!-- Sidebar filter -->
+        <div class="sidebar-filter">
+          <i data-lucide="filter" class="sidebar-filter-icon" style="width:14px;height:14px"></i>
+          <div class="sidebar-filter-input-wrapper">
+            <input type="text" id="sidebar-filter-input" placeholder="Filtrer fichiers..." autocomplete="off">
+            <div class="sidebar-filter-actions">
+              <button class="sidebar-filter-btn" id="sidebar-filter-case-btn" type="button" title="Respecter la casse" aria-label="Respecter la casse">
+                <span>Aa</span>
+              </button>
+              <button class="sidebar-filter-btn" id="sidebar-filter-clear-btn" type="button" title="Effacer le filtrage" aria-label="Effacer le filtrage">
+                <i data-lucide="x" style="width:14px;height:14px"></i>
+              </button>
             </div>
           </div>
+        </div>
 
+        <!-- Tab bar -->
+        <div class="sidebar-tabs" role="tablist" aria-label="Sections sidebar">
+          <button class="sidebar-tab active" id="sidebar-tab-vaults" role="tab"
+                  aria-selected="true" aria-controls="sidebar-panel-vaults" data-tab="vaults">
+            <i data-lucide="folder-tree" style="width:13px;height:13px"></i>
+            <span>Vaults</span>
+          </button>
+          <button class="sidebar-tab" id="sidebar-tab-tags" role="tab"
+                  aria-selected="false" aria-controls="sidebar-panel-tags" data-tab="tags">
+            <i data-lucide="tag" style="width:13px;height:13px"></i>
+            <span>Tags</span>
+          </button>
+        </div>
+
+        <!-- Vaults panel -->
+        <div class="sidebar-tab-panel active" id="sidebar-panel-vaults" role="tabpanel" aria-labelledby="sidebar-tab-vaults">
           <div class="custom-dropdown sidebar-dropdown" id="vault-quick-select-dropdown">
             <button class="custom-dropdown-trigger" type="button" aria-haspopup="listbox" aria-expanded="false">
               <span class="custom-dropdown-selected">Tous les vaults</span>
@@ -185,27 +201,14 @@
             </ul>
             <input type="hidden" id="vault-quick-select" value="all">
           </div>
-          <button class="sidebar-panel-toggle" id="vault-panel-toggle" type="button" aria-expanded="true" aria-controls="vault-panel-content">
-            <span class="sidebar-section-title">Vaults</span>
-            <i data-lucide="chevron-down" style="width:16px;height:16px"></i>
-          </button>
-          <div class="sidebar-panel-content" id="vault-panel-content">
-            <div id="vault-tree" role="tree" aria-label="Arborescence des fichiers"></div>
-          </div>
+          <div id="vault-tree" role="tree" aria-label="Arborescence des fichiers"></div>
         </div>
 
-        <!-- Tag resize handle -->
-        <div class="tag-resize-handle" id="tag-resize-handle"></div>
-
-        <div class="tag-cloud-section" id="tag-cloud-section">
-          <button class="sidebar-panel-toggle" id="tag-panel-toggle" type="button" aria-expanded="true" aria-controls="tag-panel-content">
-            <span class="tag-cloud-title">Tags</span>
-            <i data-lucide="chevron-down" style="width:16px;height:16px"></i>
-          </button>
-          <div class="sidebar-panel-content" id="tag-panel-content">
-            <div class="tag-cloud" id="tag-cloud"></div>
-          </div>
+        <!-- Tags panel -->
+        <div class="sidebar-tab-panel" id="sidebar-panel-tags" role="tabpanel" aria-labelledby="sidebar-tab-tags">
+          <div class="tag-cloud" id="tag-cloud"></div>
         </div>
+
       </aside>
 
       <!-- Sidebar resize handle -->
diff --git a/frontend/style.css b/frontend/style.css
index 3ef91d9..e9ae21c 100644
--- a/frontend/style.css
+++ b/frontend/style.css
@@ -548,29 +548,6 @@ select {
   flex-shrink: 0;
 }
 
-.sidebar.vault-collapsed .tag-cloud-section {
-  flex: 1 1 auto;
-  min-height: 0;
-  max-height: none;
-  height: auto;
-  padding-top: 0;
-}
-
-.sidebar.vault-collapsed .sidebar-tree {
-  flex: 0 0 auto;
-  min-height: 0;
-  padding-bottom: 0;
-}
-
-.sidebar.vault-collapsed .tag-resize-handle {
-  border-top: none;
-  height: 0;
-}
-
-.sidebar.tag-collapsed .sidebar-tree {
-  flex: 1 1 auto;
-  min-height: 0;
-}
 
 /* --- Sidebar filter --- */
 .sidebar-filter {
@@ -658,82 +635,77 @@ select {
   color: var(--accent);
 }
 
-.sidebar-tree {
-  flex: 1;
-  overflow: hidden;
-  padding: 12px 0;
-  min-height: 80px;
+/* --- Sidebar tabs --- */
+.sidebar-tabs {
   display: flex;
-  flex-direction: column;
+  flex-shrink: 0;
+  border-bottom: 1px solid var(--border);
+  padding: 0 8px;
+  gap: 2px;
+  background: var(--bg-sidebar);
 }
 
-.sidebar-tree::-webkit-scrollbar {
-  width: 6px;
-}
-.sidebar-tree::-webkit-scrollbar-thumb {
-  background: var(--scrollbar);
-  border-radius: 3px;
-}
-
-.sidebar-section-title {
+.sidebar-tab {
+  flex: 1;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 5px;
+  padding: 9px 8px 8px;
+  border: none;
+  border-bottom: 2px solid transparent;
+  background: transparent;
+  color: var(--text-muted);
   font-family: 'JetBrains Mono', monospace;
   font-size: 0.7rem;
   font-weight: 700;
   text-transform: uppercase;
-  letter-spacing: 0.08em;
-  color: var(--text-muted);
-  padding: 0;
-}
-
-.sidebar-panel-toggle {
-  width: 100%;
-  border: none;
-  background: transparent;
-  color: var(--text-muted);
-  display: flex;
-  align-items: center;
-  justify-content: space-between;
-  gap: 8px;
-  padding: 8px 16px 10px;
+  letter-spacing: 0.07em;
   cursor: pointer;
-  transition: color 150ms ease, background 150ms ease;
+  transition: color 150ms ease, border-color 150ms ease;
+  margin-bottom: -1px;
+  white-space: nowrap;
 }
 
-.sidebar-panel-toggle:hover {
+.sidebar-tab:hover {
   color: var(--text-primary);
-  background: var(--bg-hover);
 }
 
-.sidebar-panel-toggle .icon,
-.sidebar-panel-toggle [data-lucide] {
-  color: inherit;
+.sidebar-tab.active {
+  color: var(--accent);
+  border-bottom-color: var(--accent);
+}
+
+.sidebar-tab .icon {
   flex-shrink: 0;
+  color: inherit;
 }
 
-.sidebar-panel-content.collapsed {
-  max-height: 0 !important;
-  opacity: 0;
-  overflow: hidden;
-  pointer-events: none;
-}
-
-.sidebar-panel-content {
-  min-height: 0;
-  overflow: hidden;
-  opacity: 1;
-  transition: max-height 340ms ease, opacity 220ms ease;
-}
-
-#vault-panel-content {
+/* --- Sidebar tab panels --- */
+.sidebar-tab-panel {
+  display: none;
   flex: 1 1 auto;
   min-height: 0;
   overflow-y: auto;
-  max-height: 1000px;
   scroll-behavior: smooth;
+  flex-direction: column;
 }
 
-#tag-panel-content {
-  max-height: 320px;
+.sidebar-tab-panel.active {
+  display: flex;
+  flex-direction: column;
+}
+
+.sidebar-tab-panel::-webkit-scrollbar {
+  width: 6px;
+}
+.sidebar-tab-panel::-webkit-scrollbar-thumb {
+  background: var(--scrollbar);
+  border-radius: 3px;
+}
+
+#sidebar-panel-vaults .sidebar-dropdown {
+  padding: 10px 12px 6px;
 }
 
 .tree-item {
@@ -817,31 +789,32 @@ select {
 
 .filter-result-item {
   align-items: flex-start;
-  gap: 8px;
-  border-radius: 8px;
+  white-space: normal;
+  overflow: visible;
+  border-radius: 6px;
 }
 
 .filter-result-text {
+  flex: 1;
   min-width: 0;
   display: flex;
   flex-direction: column;
   gap: 2px;
-}
-
-.filter-result-primary,
-.filter-result-secondary {
-  min-width: 0;
-  overflow-wrap: anywhere;
-  word-break: break-word;
+  white-space: normal;
 }
 
 .filter-result-primary {
   color: var(--text-primary);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
 }
 
 .filter-result-secondary {
   color: var(--text-muted);
-  font-size: 0.78rem;
+  font-size: 0.75rem;
+  word-break: break-all;
+  opacity: 0.8;
 }
 
 .sidebar-filter-empty {
@@ -857,68 +830,13 @@ select {
   border-radius: 4px;
 }
 
-/* --- Tag resize handle --- */
-.tag-resize-handle {
-  height: 5px;
-  cursor: ns-resize;
-  background: transparent;
-  border-top: 1px solid var(--border);
-  flex-shrink: 0;
-  transition: background 150ms ease;
-}
-.tag-resize-handle:hover,
-.tag-resize-handle.active {
-  background: var(--accent);
-  opacity: 0.5;
-}
-
 /* --- Tag Cloud --- */
-.tag-cloud-section {
-  padding: 12px 0 0;
-  height: 180px;
-  min-height: 60px;
-  max-height: 400px;
-  overflow: hidden;
-  flex-shrink: 0;
-  display: flex;
-  flex-direction: column;
-  transition: height 340ms ease, min-height 340ms ease, max-height 340ms ease, flex 340ms ease;
-}
-.tag-cloud-section.collapsed-panel {
-  height: auto;
-  min-height: 0;
-  max-height: none;
-  overflow: hidden;
-  flex: 0 0 auto;
-}
-.tag-cloud-section::-webkit-scrollbar {
-  width: 6px;
-}
-.tag-cloud-section::-webkit-scrollbar-thumb {
-  background: var(--scrollbar);
-  border-radius: 3px;
-}
-
-.tag-cloud-title {
-  font-family: 'JetBrains Mono', monospace;
-  font-size: 0.7rem;
-  font-weight: 700;
-  text-transform: uppercase;
-  letter-spacing: 0.08em;
-  color: var(--text-muted);
-  margin-bottom: 0;
-}
-
 .tag-cloud {
   display: flex;
   flex-wrap: wrap;
   gap: 6px;
-  padding: 0 16px 12px;
-}
-
-.tag-cloud-section:not(.collapsed-panel) #tag-panel-content {
-  overflow-y: auto;
-  flex: 1 1 auto;
+  padding: 14px 16px 16px;
+  align-content: flex-start;
 }
 
 .tag-item {
@@ -939,14 +857,6 @@ select {
   display: none;
 }
 
-.tag-resize-handle.hidden {
-  display: none;
-}
-
-.sidebar.vault-collapsed .tag-panel-toggle {
-  border-top: 1px solid var(--border);
-}
-
 /* --- Sidebar resize handle (horizontal) --- */
 .sidebar-resize-handle {
   width: 5px;