diff --git a/frontend/src/App.vue b/frontend/src/App.vue
index 587d7dc..ba6ab1e 100644
--- a/frontend/src/App.vue
+++ b/frontend/src/App.vue
@@ -1,6 +1,7 @@
 <script setup>
-import { ref, computed, watch, onMounted, onUnmounted, nextTick } from 'vue'
+import { ref, computed, watch, onMounted, nextTick } from 'vue'
 import { fetchGuides, fetchTopics, createTopic as apiCreateTopic, deleteTopic as apiDeleteTopic, createGuide as apiCreate, deleteGuide, cancelGuide as apiCancel, fetchBausteineStatus, fetchActiveBausteine, createBausteine as apiCreateBausteine, cancelBausteine as apiCancelBausteine, deleteBausteine as apiDeleteBausteine, fetchProjects, deleteProject as apiDeleteProject, fetchProviders, fetchStats, fetchTopicFortschritt } from './api.js'
+import { usePolling } from './composables/usePolling.js'
 import TopicSidebar from './components/TopicSidebar.vue'
 import TopicDetail from './components/TopicDetail.vue'
 import ElementsSidebar from './components/ElementsSidebar.vue'
@@ -56,7 +57,6 @@ async function loadProviders() {
     console.error('Fehler beim Laden der Provider:', e)
   }
 }
-let pollTimer = null
 
 function applyTheme() {
   document.documentElement.classList.toggle('dark', darkMode.value)
@@ -158,7 +158,7 @@ async function loadBausteine() {
       bausteine.value = { ...EMPTY_BAUSTEINE }
       fortschritt.value = {}
     }
-    if (activeBausteine.value.length && !pollTimer) startPolling()
+    if (activeBausteine.value.length && !polling.running()) startPolling()
   } catch (e) {
     console.error('Fehler beim Laden der Bausteine:', e)
   }
@@ -276,20 +276,11 @@ async function handleDeleteGuide(guideId, slots = false) {
   await loadGuides()
 }
 
-function startPolling() {
-  stopPolling()
-  pollTimer = setInterval(async () => {
-    await Promise.all([loadGuides(), loadBausteine(), loadTopics()])
-    if (!hasActiveGuides.value && !activeBausteine.value.length) stopPolling()
-  }, 3000)
-}
-
-function stopPolling() {
-  if (pollTimer) {
-    clearInterval(pollTimer)
-    pollTimer = null
-  }
-}
+const polling = usePolling(
+  () => Promise.all([loadGuides(), loadBausteine(), loadTopics()]),
+  () => hasActiveGuides.value || activeBausteine.value.length > 0,
+)
+const startPolling = polling.start
 
 async function handleCancel(guideId) {
   await apiCancel(guideId)
@@ -311,16 +302,6 @@ async function handleDeleteTopic(topic) {
   await loadGuides()
 }
 
-function onVisibility() {
-  if (document.hidden) {
-    stopPolling()
-  } else {
-    loadGuides()
-    loadBausteine()
-    if (hasActiveGuides.value || activeBausteine.value.length) startPolling()
-  }
-}
-
 onMounted(async () => {
   await Promise.all([loadGuides(), loadTopics(), loadProjects(), loadProviders()])
   const savedTopic = localStorage.getItem('lastTopic')
@@ -333,12 +314,6 @@ onMounted(async () => {
   } else if (!selectedTopic.value && topics.value.length) {
     selectTopic(topics.value[0])
   }
-  document.addEventListener('visibilitychange', onVisibility)
-})
-
-onUnmounted(() => {
-  stopPolling()
-  document.removeEventListener('visibilitychange', onVisibility)
 })
 </script>
 
diff --git a/frontend/src/components/TopicDetail.vue b/frontend/src/components/TopicDetail.vue
index 416cba3..be4abfe 100644
--- a/frontend/src/components/TopicDetail.vue
+++ b/frontend/src/components/TopicDetail.vue
@@ -2,6 +2,7 @@
 import { computed, ref, watch, nextTick, onMounted, onUnmounted } from 'vue'
 import { fetchGuideContent, chatGuide, fetchProgress, setProgress } from '../api.js'
 import { renderMarkdown } from '../markdown.js'
+import { useChat } from '../composables/useChat.js'
 
 const props = defineProps({
   previewGuide: { type: Object, default: null },
@@ -72,13 +73,16 @@ async function toggleChapter(title) {
   }
 }
 
-// --- Chat ---
+// --- Chat (Mechanik in useChat; Kontext-Extraktion bleibt hier) ---
+const chat = useChat((msgs) => {
+  const { section, outline } = extractContext()
+  return chatGuide(props.previewGuide.id, {
+    section, outline, messages: msgs, provider: props.provider,
+  })
+})
+const { messages, input, loading, messagesEl, inputEl, send } = chat
+const autoGrow = () => chat.autoGrow()
 const chatOpen = ref(false)
-const messages = ref([])
-const input = ref('')
-const loading = ref(false)
-const messagesEl = ref(null)
-const inputEl = ref(null)
 const panelEl = ref(null)
 
 function openChat() {
@@ -88,8 +92,7 @@ function openChat() {
 
 function closeChat() {
   chatOpen.value = false
-  messages.value = []
-  input.value = ''
+  chat.reset()
 }
 
 function onDocMouseDown(e) {
@@ -141,43 +144,6 @@ function extractContext() {
   return { section, outline }
 }
 
-async function scrollToBottom() {
-  await nextTick()
-  if (messagesEl.value) messagesEl.value.scrollTop = messagesEl.value.scrollHeight
-}
-
-function autoGrow() {
-  const el = inputEl.value
-  if (!el) return
-  el.style.height = 'auto'
-  el.style.height = Math.min(el.scrollHeight, 140) + 'px'
-}
-
-async function send() {
-  const text = input.value.trim()
-  if (!text || loading.value || !props.previewGuide) return
-  messages.value.push({ role: 'user', content: text })
-  input.value = ''
-  nextTick(autoGrow)
-  loading.value = true
-  scrollToBottom()
-  try {
-    const { section, outline } = extractContext()
-    const res = await chatGuide(props.previewGuide.id, {
-      section,
-      outline,
-      messages: messages.value,
-      provider: props.provider,
-    })
-    messages.value.push({ role: 'assistant', content: res.reply || '…' })
-  } catch {
-    messages.value.push({ role: 'assistant', content: 'Fehler bei der Anfrage.' })
-  } finally {
-    loading.value = false
-    scrollToBottom()
-    nextTick(() => inputEl.value?.focus())
-  }
-}
 </script>
 
 <template>
@@ -250,7 +216,12 @@ async function send() {
           @input="autoGrow"
           @keydown.enter.exact.prevent="send"
         ></textarea>
-        <button :disabled="!input.trim() || loading" @click="send">➤</button>
+        <button
+          :disabled="!input.trim() && !loading"
+          :class="{ cancel: loading }"
+          :title="loading ? 'Abbrechen' : 'Senden'"
+          @click="send"
+        >{{ loading ? '✕' : '➤' }}</button>
       </div>
     </div>
   </div>
@@ -698,4 +669,8 @@ async function send() {
   opacity: 0.4;
   cursor: not-allowed;
 }
+
+.chat-input button.cancel {
+  background: var(--danger);
+}
 </style>
diff --git a/frontend/src/components/TopicSidebar.vue b/frontend/src/components/TopicSidebar.vue
index 8c8d22f..0184a31 100644
--- a/frontend/src/components/TopicSidebar.vue
+++ b/frontend/src/components/TopicSidebar.vue
@@ -1,5 +1,6 @@
 <script setup>
 import { ref, computed } from 'vue'
+import { useConfirm } from '../composables/useConfirm.js'
 
 const props = defineProps({
   topics: { type: Array, required: true },
@@ -63,21 +64,7 @@ const activeGenerations = computed(() => {
   return [...bausteinLines, ...guideLines]
 })
 
-// Inline-Bestätigung statt confirm(): erster Klick scharfschalten („Sicher?"),
-// zweiter Klick führt aus. Browser-Dialoge können unterdrückt sein (Firefox).
-const pendingConfirm = ref(null)
-let confirmTimer = null
-
-function armOrRun(key, action) {
-  clearTimeout(confirmTimer)
-  if (pendingConfirm.value === key) {
-    pendingConfirm.value = null
-    action()
-  } else {
-    pendingConfirm.value = key
-    confirmTimer = setTimeout(() => { pendingConfirm.value = null }, 3000)
-  }
-}
+const { pending: pendingConfirm, armOrRun } = useConfirm()
 
 function confirmCancelBausteine() {
   armOrRun('bausteine', () => emit('cancelBausteine'))
diff --git a/frontend/src/composables/useChat.js b/frontend/src/composables/useChat.js
new file mode 100644
index 0000000..6b22541
--- /dev/null
+++ b/frontend/src/composables/useChat.js
@@ -0,0 +1,71 @@
+import { ref, nextTick } from 'vue'
+
+// Gemeinsame Chat-Mechanik: senden, abbrechen (Run-Counter), scrollen, Fokus.
+// performRequest(messages) → Promise<{ reply, … }>; send() gibt die Antwort
+// zurück, damit der Aufrufer Extras (z. B. changes) auswerten kann.
+export function useChat(performRequest) {
+  const messages = ref([])
+  const input = ref('')
+  const loading = ref(false)
+  const messagesEl = ref(null) // Template-Ref: Nachrichten-Container
+  const inputEl = ref(null)    // Template-Ref: Textarea
+  let run = 0 // laufende Anfrage identifizieren; Abbruch ignoriert ihr Ergebnis
+
+  async function scrollToBottom() {
+    await nextTick()
+    if (messagesEl.value) messagesEl.value.scrollTop = messagesEl.value.scrollHeight
+  }
+
+  function autoGrow(max = 140) {
+    const el = inputEl.value
+    if (!el) return
+    el.style.height = 'auto'
+    el.style.height = Math.min(el.scrollHeight, max) + 'px'
+  }
+
+  function cancel() {
+    run++
+    loading.value = false
+    messages.value.push({ role: 'assistant', content: 'Abgebrochen.' })
+  }
+
+  function reset() {
+    run++
+    loading.value = false
+    messages.value = []
+    input.value = ''
+  }
+
+  async function send() {
+    if (loading.value) { // zweiter Klick = abbrechen
+      cancel()
+      return null
+    }
+    const text = input.value.trim()
+    if (!text) return null
+    const current = ++run
+    messages.value.push({ role: 'user', content: text })
+    input.value = ''
+    nextTick(() => autoGrow())
+    loading.value = true
+    scrollToBottom()
+    try {
+      const res = await performRequest(messages.value)
+      if (current !== run) return null
+      messages.value.push({ role: 'assistant', content: res.reply || '…' })
+      return res
+    } catch {
+      if (current !== run) return null
+      messages.value.push({ role: 'assistant', content: 'Fehler bei der Anfrage.' })
+      return null
+    } finally {
+      if (current === run) {
+        loading.value = false
+        scrollToBottom()
+        nextTick(() => inputEl.value?.focus())
+      }
+    }
+  }
+
+  return { messages, input, loading, messagesEl, inputEl, send, cancel, reset, scrollToBottom, autoGrow }
+}
diff --git a/frontend/src/composables/useConfirm.js b/frontend/src/composables/useConfirm.js
new file mode 100644
index 0000000..422ea56
--- /dev/null
+++ b/frontend/src/composables/useConfirm.js
@@ -0,0 +1,32 @@
+import { ref, onUnmounted } from 'vue'
+
+// Inline-Bestätigung statt confirm(): erster Klick scharfschalten („Sicher?"),
+// zweiter Klick führt aus. Browser-Dialoge können unterdrückt sein (Firefox).
+export function useConfirm(timeoutMs = 3000) {
+  const pending = ref(null) // aktuell scharfgeschalteter Key
+  let timer = null
+
+  function armOrRun(key, action) {
+    clearTimeout(timer)
+    if (pending.value === key) {
+      pending.value = null
+      action()
+    } else {
+      pending.value = key
+      timer = setTimeout(() => { pending.value = null }, timeoutMs)
+    }
+  }
+
+  function isArmed(key) {
+    return pending.value === key
+  }
+
+  function reset() {
+    clearTimeout(timer)
+    pending.value = null
+  }
+
+  onUnmounted(() => clearTimeout(timer))
+
+  return { pending, isArmed, armOrRun, reset }
+}
diff --git a/frontend/src/composables/usePolling.js b/frontend/src/composables/usePolling.js
new file mode 100644
index 0000000..465d7c8
--- /dev/null
+++ b/frontend/src/composables/usePolling.js
@@ -0,0 +1,44 @@
+import { onUnmounted } from 'vue'
+
+// Polling mit Visibility-Pause: Tab unsichtbar → stoppen; wieder sichtbar →
+// sofortiger Tick, dann weiter, falls isActive(). Stoppt selbst, sobald
+// isActive() nach einem Tick false liefert.
+export function usePolling(tick, isActive, interval = 3000) {
+  let timer = null
+
+  function stop() {
+    if (timer) {
+      clearInterval(timer)
+      timer = null
+    }
+  }
+
+  function start() {
+    stop()
+    timer = setInterval(async () => {
+      await tick()
+      if (!isActive()) stop()
+    }, interval)
+  }
+
+  function running() {
+    return !!timer
+  }
+
+  async function onVisibility() {
+    if (document.hidden) {
+      stop()
+    } else {
+      await tick()
+      if (isActive()) start()
+    }
+  }
+
+  document.addEventListener('visibilitychange', onVisibility)
+  onUnmounted(() => {
+    stop()
+    document.removeEventListener('visibilitychange', onVisibility)
+  })
+
+  return { start, stop, running }
+}