diff --git a/frontend/css/assistant.css b/frontend/css/assistant.css
index af598bf..7cf8a8c 100644
--- a/frontend/css/assistant.css
+++ b/frontend/css/assistant.css
@@ -5,10 +5,18 @@
  */
 
 /* Layout */
+.view.view-assistant {
+  height: calc(100vh - var(--header-height) - 52px);
+  overflow: hidden;
+  display: flex;
+  flex-direction: column;
+}
+
 .assistant-layout {
   display: grid;
   grid-template-columns: 280px 1fr;
-  height: calc(100vh - 120px);
+  flex: 1;
+  min-height: 0;
   overflow: hidden;
 }
 
@@ -110,6 +118,7 @@
 .assistant-chat {
   display: flex;
   flex-direction: column;
+  height: 100%;
   overflow: hidden;
   position: relative;
   background: var(--bg-main);
@@ -201,6 +210,7 @@
 /* Messages Area */
 .assistant-messages {
   flex: 1;
+  min-height: 0;
   overflow-y: auto;
   padding: 20px;
   display: flex;
@@ -365,10 +375,12 @@
 
 /* Empty State */
 .assistant-empty {
-  position: absolute;
-  top: 50%;
-  left: 50%;
-  transform: translate(-50%, -50%);
+  flex: 1;
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
   text-align: center;
   color: var(--text-muted);
   pointer-events: none;
@@ -391,12 +403,7 @@
 }
 
 /* Hide empty state when messages present */
-.assistant-messages:not(:empty) ~ .assistant-empty {
-  display: none;
-}
-
-/* Hide input bar when no session */
-.assistant-chat.no-session .assistant-input-bar {
+.assistant-messages:not(:empty) + .assistant-empty {
   display: none;
 }
 
diff --git a/frontend/index.html b/frontend/index.html
index 0aebf85..0885bbd 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -714,15 +714,6 @@
               <span id="assistant-status-badge" class="assistant-status-badge"></span>
             </div>
             <div id="assistant-messages" class="assistant-messages"></div>
-            <div class="assistant-input-bar">
-              <textarea id="assistant-input" class="assistant-input" placeholder="Nachricht eingeben..." rows="1"></textarea>
-              <button id="btn-send-message" class="btn btn-primary assistant-send-btn" title="Senden">
-                <svg viewBox="0 0 24 24" width="20" height="20" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-                  <line x1="22" y1="2" x2="11" y2="13"/>
-                  <polygon points="22 2 15 22 11 13 2 9 22 2"/>
-                </svg>
-              </button>
-            </div>
             <div id="assistant-empty" class="assistant-empty">
               <div class="assistant-empty-icon">
                 <svg viewBox="0 0 24 24" width="64" height="64" fill="none" stroke="currentColor" stroke-width="1.5">
@@ -732,6 +723,15 @@
               <h3>Claude Assistent</h3>
               <p>Starte eine neue Session oder waehle eine bestehende aus.</p>
             </div>
+            <div class="assistant-input-bar">
+              <textarea id="assistant-input" class="assistant-input" placeholder="Nachricht eingeben..." rows="1"></textarea>
+              <button id="btn-send-message" class="btn btn-primary assistant-send-btn" title="Senden">
+                <svg viewBox="0 0 24 24" width="20" height="20" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+                  <line x1="22" y1="2" x2="11" y2="13"/>
+                  <polygon points="22 2 15 22 11 13 2 9 22 2"/>
+                </svg>
+              </button>
+            </div>
           </main>
         </div>
       </div>
diff --git a/frontend/js/assistant.js b/frontend/js/assistant.js
index ffd47a6..c26ac81 100644
--- a/frontend/js/assistant.js
+++ b/frontend/js/assistant.js
@@ -94,10 +94,12 @@ class AssistantManager {
 
       this.setStatus(data.status);
 
-      // If session ended, finalize streaming
-      if (data.status === 'ended' || data.status === 'stopped') {
+      // Finalize streaming when message processing completes
+      if (data.status === 'ended' || data.status === 'stopped' || data.status === 'active') {
         this.finalizeStreaming();
-        this.loadSessions();
+        if (data.status !== 'active') {
+          this.loadSessions();
+        }
       }
     });
   }
@@ -178,7 +180,16 @@ class AssistantManager {
 
     if (session) {
       this.chatTitleEl.textContent = session.title;
-      this.setStatus(session.status === 'active' ? 'ended' : session.status);
+
+      if (session.status === 'active') {
+        // Aktive Session mit Backend verbinden
+        const socket = syncManager.socket;
+        if (socket) {
+          socket.emit('assistant:start', { sessionId: id });
+        }
+      } else {
+        this.setStatus(session.status);
+      }
     }
 
     this.renderSessionsList();
@@ -211,7 +222,7 @@ class AssistantManager {
       this.currentSessionId = session.id;
       this.chatTitleEl.textContent = session.title;
       this.messagesEl.innerHTML = '';
-      this.setStatus('running');
+      this.setStatus('active');
       this.updateChatState();
 
       // Start Claude process via Socket
@@ -261,10 +272,22 @@ class AssistantManager {
   // MESSAGING
   // =====================
 
-  sendMessage() {
+  async sendMessage() {
     const text = this.inputEl?.value?.trim();
     if (!text || !this.currentSessionId) return;
 
+    // Beendete/gestoppte Session zuerst reaktivieren
+    if (this.sessionStatus === 'ended' || this.sessionStatus === 'stopped') {
+      try {
+        await this._reactivateSession();
+        this.loadSessions();
+      } catch (err) {
+        console.error('[Assistant] Reaktivierung fehlgeschlagen:', err);
+        this.showToast('Session konnte nicht reaktiviert werden', 'error');
+        return;
+      }
+    }
+
     // Render user message
     this.renderMessage('user', text);
     this.inputEl.value = '';
@@ -285,6 +308,32 @@ class AssistantManager {
     this.setStatus('thinking');
   }
 
+  _reactivateSession() {
+    return new Promise((resolve, reject) => {
+      const socket = syncManager.socket;
+      if (!socket) return reject(new Error('Kein Socket'));
+
+      const onStatus = (data) => {
+        if (data.sessionId !== this.currentSessionId) return;
+        socket.off('assistant:status', onStatus);
+        clearTimeout(timeout);
+        if (data.status === 'error') {
+          reject(new Error(data.error || 'Fehler'));
+        } else {
+          resolve();
+        }
+      };
+
+      const timeout = setTimeout(() => {
+        socket.off('assistant:status', onStatus);
+        reject(new Error('Timeout'));
+      }, 10000);
+
+      socket.on('assistant:status', onStatus);
+      socket.emit('assistant:start', { sessionId: this.currentSessionId });
+    });
+  }
+
   handleOutput(content) {
     if (!this.streamingMessageEl) {
       // Create streaming bubble if not exists
@@ -401,6 +450,7 @@ class AssistantManager {
     }
 
     const labels = {
+      active: 'Bereit',
       running: 'Aktiv',
       thinking: 'Denkt...',
       ended: 'Beendet',