diff --git a/aria-brain/main.py b/aria-brain/main.py
index 5800bee..c4b6902 100644
--- a/aria-brain/main.py
+++ b/aria-brain/main.py
@@ -817,6 +817,7 @@ def projects_archive(project_id: str):
 class ProjectUpdateBody(BaseModel):
     name: Optional[str] = None
     description: Optional[str] = None
+    hidden: Optional[bool] = None
 
 
 @app.patch("/projects/{project_id}")
diff --git a/aria-brain/projects.py b/aria-brain/projects.py
index fedd7f5..5d8bebe 100644
--- a/aria-brain/projects.py
+++ b/aria-brain/projects.py
@@ -132,6 +132,7 @@ def create_project(name: str, description: str = "") -> dict:
         "name": name,
         "description": description.strip(),
         "status": "active",  # active | ended | archived
+        "hidden": False,      # optisch aus Listen ausblenden (bleibt nutzbar)
         "created_at": now,
         "updated_at": now,
         "last_activity_at": now,
@@ -148,7 +149,7 @@ def update_project(project_id: str, patch: dict) -> Optional[dict]:
     projects = _load_all()
     for p in projects:
         if p["id"] == project_id:
-            for k in ("name", "description", "status"):
+            for k in ("name", "description", "status", "hidden"):
                 if k in patch and patch[k] is not None:
                     p[k] = patch[k]
             p["updated_at"] = _now()
diff --git a/diagnostic/index.html b/diagnostic/index.html
index 68edfa2..d2fe822 100644
--- a/diagnostic/index.html
+++ b/diagnostic/index.html
@@ -1095,6 +1095,7 @@
       <div style="display:flex;justify-content:space-between;align-items:center;margin-bottom:8px;">
         <h2 style="margin:0;">📁 Projekte</h2>
         <div>
+          <button class="btn secondary" id="toggle-hidden-btn" onclick="toggleShowHidden()" style="padding:4px 10px;font-size:11px;" title="Versteckte Projekte ein-/ausblenden">👁 Versteckte anzeigen</button>
           <button class="btn secondary" onclick="loadProjects()" style="padding:4px 10px;font-size:11px;">🔄 Aktualisieren</button>
           <button class="btn" onclick="openCreateProjectModal()" style="padding:4px 10px;font-size:11px;">+ Neues Projekt</button>
         </div>
@@ -3002,16 +3003,28 @@
             <div style="color:${!activeId ? '#34C759' : '#E0E0F0'};font-weight:600;">💬 Hauptchat ${!activeId ? '<span style="font-size:10px;font-weight:800;">✓ AKTIV</span>' : ''}</div>
             <div style="color:#555570;font-size:11px;margin-top:2px;">Standard-Verlauf, keine Projekt-Zuordnung</div>
           </div>`);
+        const showHidden = !!window.__showHidden;
+        let hiddenCount = 0, shownCount = 0;
         for (const p of projects) {
+          const hidden = !!p.hidden;
+          if (hidden) hiddenCount++;
+          // Versteckte nur zeigen wenn der Toggle an ist.
+          if (hidden && !showHidden) continue;
+          shownCount++;
           const isActive = p.id === activeId;
           const since = p.last_activity_at ? new Date(p.last_activity_at * 1000).toLocaleString('de-DE') : '?';
           const ended = p.status === 'ended';
+          // Auge: versteckt → 👁 (wieder sichtbar machen), sichtbar → 🙈 (verstecken).
+          const eyeIcon = hidden ? '👁' : '🙈';
+          const eyeTitle = hidden ? 'Wieder dauerhaft sichtbar machen' : 'Verstecken (aus Listen ausblenden)';
+          const eyeColor = hidden ? '#B392F0' : '#8888AA';
           rows.push(`
-            <div style="padding:12px 14px;border-bottom:1px solid #1E1E2E;${isActive ? 'background:rgba(52,199,89,0.08);border-left:3px solid #34C759;' : ''}">
+            <div style="padding:12px 14px;border-bottom:1px solid #1E1E2E;${isActive ? 'background:rgba(52,199,89,0.08);border-left:3px solid #34C759;' : ''}${hidden ? 'opacity:0.55;' : ''}">
               <div style="display:flex;justify-content:space-between;align-items:flex-start;gap:8px;">
                 <div onclick="switchProject('${p.id}')" style="cursor:pointer;flex:1;">
                   <div style="color:${isActive ? '#34C759' : '#E0E0F0'};font-weight:600;">
-                    📁 ${escapeHtml(p.name)}
+                    ${hidden ? '🙈' : '📁'} ${escapeHtml(p.name)}
+                    ${hidden ? '<span style="color:#B392F0;font-size:10px;font-weight:700;margin-left:6px;background:rgba(179,146,240,0.15);padding:2px 6px;border-radius:3px;">versteckt</span>' : ''}
                     ${ended ? '<span style="color:#FFD60A;font-size:10px;font-weight:700;margin-left:6px;background:rgba(255,214,10,0.15);padding:2px 6px;border-radius:3px;">beendet</span>' : ''}
                     ${isActive ? '<span style="color:#34C759;font-size:10px;font-weight:800;margin-left:6px;">✓ AKTIV</span>' : ''}
                   </div>
@@ -3019,6 +3032,7 @@
                   <div style="color:#555570;font-size:11px;margin-top:4px;">${p.turn_count} Turns · zuletzt ${since}</div>
                 </div>
                 <div style="display:flex;gap:4px;">
+                  <button class="btn secondary" onclick="setProjectHidden('${p.id}', ${!hidden})" style="padding:3px 8px;font-size:10px;color:${eyeColor};" title="${eyeTitle}">${eyeIcon}</button>
                   ${!ended ? `<button class="btn secondary" onclick="endProject('${p.id}', '${escapeHtmlAttr(p.name)}')" style="padding:3px 8px;font-size:10px;" title="Projekt beenden">⏹</button>` : ''}
                   <button class="btn secondary" onclick="archiveProject('${p.id}', '${escapeHtmlAttr(p.name)}')" style="padding:3px 8px;font-size:10px;color:#E55C5C;" title="Archivieren">🗑</button>
                 </div>
@@ -3027,13 +3041,43 @@
         }
         if (projects.length === 0) {
           rows.push('<div style="padding:18px;color:#555570;font-size:12px;text-align:center;">Noch keine Projekte. „+ Neues Projekt" oder sag ARIA „lass uns ein Projekt anlegen".</div>');
+        } else if (shownCount === 0) {
+          rows.push(`<div style="padding:18px;color:#555570;font-size:12px;text-align:center;">Alle ${hiddenCount} Projekte sind versteckt. Klick „👁 Versteckte anzeigen".</div>`);
         }
         listEl.innerHTML = rows.join('');
+
+        // Toggle-Button beschriften (mit Anzahl) + Zustand spiegeln.
+        const thBtn = document.getElementById('toggle-hidden-btn');
+        if (thBtn) {
+          thBtn.textContent = showHidden
+            ? `🙈 Versteckte ausblenden${hiddenCount ? ' ('+hiddenCount+')' : ''}`
+            : `👁 Versteckte anzeigen${hiddenCount ? ' ('+hiddenCount+')' : ''}`;
+          thBtn.style.opacity = hiddenCount ? '1' : '0.5';
+        }
       } catch (e) {
         listEl.innerHTML = `<div style="padding:14px;color:#FF6E6E;font-size:12px;">Fehler: ${e.message}</div>`;
       }
     }
 
+    function toggleShowHidden() {
+      window.__showHidden = !window.__showHidden;
+      loadProjects();
+    }
+
+    async function setProjectHidden(id, hidden) {
+      try {
+        const r = await fetch(`/api/brain/projects/${encodeURIComponent(id)}`, {
+          method: 'PATCH',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ hidden: !!hidden }),
+        });
+        if (!r.ok) throw new Error('HTTP ' + r.status);
+        // Beim Verstecken bleibt der „anzeigen"-Modus wie er ist; beim
+        // Wieder-Sichtbarmachen sieht man es sofort ohne Umschalten.
+        loadProjects();
+      } catch (e) { alert('Verstecken/Anzeigen fehlgeschlagen: ' + e.message); }
+    }
+
     async function switchProject(projectId) {
       try {
         await fetch('/api/brain/projects/switch', {