diff --git a/src/lib/loadChatComposer.js b/src/lib/loadChatComposer.js
new file mode 100644
index 0000000..ac4f78c
--- /dev/null
+++ b/src/lib/loadChatComposer.js
@@ -0,0 +1,28 @@
+// Chat-Baustein des Kundenportals (public/chat-composer.js + .css) zur Laufzeit laden: Eingabezeile mit Anhaengen,
+// Kamera und Sprachnachricht sowie die Sprechblasen kommen aus einer Quelle fuer Portal und Ticketsystem.
+// Rein (document/window werden injiziert), unter Node testbar.
+
+const pending = new WeakMap()
+
+/** -> Promise<window.ChatComposer>; je document nur ein Ladevorgang, nach einem Fehler neuer Versuch. */
+export function loadChatComposer({ baseUrl, doc = globalThis.document, win = globalThis.window }) {
+  if (win.ChatComposer) return Promise.resolve(win.ChatComposer)
+  if (pending.has(doc)) return pending.get(doc)
+  const promise = new Promise((resolve, reject) => {
+    const link = doc.createElement('link')
+    link.rel = 'stylesheet'
+    link.href = `${baseUrl}/chat-composer.css`
+    doc.head.appendChild(link)
+    const script = doc.createElement('script')
+    script.src = `${baseUrl}/chat-composer.js`
+    script.async = true
+    script.onload = () => (win.ChatComposer ? resolve(win.ChatComposer) : script.onerror())
+    script.onerror = () => {
+      pending.delete(doc)
+      reject(new Error('Der Chat-Baustein konnte nicht geladen werden.'))
+    }
+    doc.head.appendChild(script)
+  })
+  pending.set(doc, promise)
+  return promise
+}
diff --git a/src/lib/teamApi.js b/src/lib/teamApi.js
index c34a9ed..2d1f9c8 100644
--- a/src/lib/teamApi.js
+++ b/src/lib/teamApi.js
@@ -1,14 +1,18 @@
 import { account } from './appwrite'
 import { createFinanceRequest } from './financeRequest'
+import { createJwtCache } from './serverpulsAuth'
 
 /**
  * Client fuer den Team-Eingang des Kundenportals (/api/team): alle Mitarbeiter, Appwrite-JWT (Bearer).
  * Anfrage-Kern (JWT-Cache, Wiederholung bei 401, deutsche Fehlertexte) wie bei den Finanzen: financeRequest.js.
  */
-const PROJECT_ADMIN_URL =
+export const PORTAL_URL =
   import.meta.env.VITE_PROJECT_ADMIN_URL || 'https://project.webklar.com'
 
-const request = createFinanceRequest({ baseUrl: `${PROJECT_ADMIN_URL}/api/team`, createJWT: () => account.createJWT() })
+const request = createFinanceRequest({ baseUrl: `${PORTAL_URL}/api/team`, createJWT: () => account.createJWT() })
+
+// Eigenes JWT fuer Anfragen, die nicht ueber request laufen (Hochladen im Chat-Baustein), 10 Minuten gecacht
+const jwtCache = createJwtCache({ createJWT: () => account.createJWT() })
 
 const enc = encodeURIComponent
 
@@ -29,3 +33,29 @@ export async function createPreviewLink({ subdomain, previewUrl }) {
   const { openUrl } = await request('/preview-link', { method: 'POST', body: { subdomain, previewUrl } })
   return openUrl
 }
+
+// --- Chat (Messenger, Reiter "Chat", Zahl in der Sidebar) ---
+
+/** { chats: [{ customerId, customerName, lastText, lastSender, lastAt, unreadFromCustomer }] } */
+export const listChats = () => request('/chats')
+
+/** { unread } */
+export const getChatUnreadCount = () => request('/chats/unread-count')
+
+/** { messages }; mit since nur neuere (Abfrage im offenen Gespraech) */
+export const getChatMessages = (customerId, since = '') =>
+  request(`/chats/${enc(customerId)}/messages${since ? `?since=${enc(since)}` : ''}`)
+
+/** { message, notice } */
+export const sendChatMessage = (customerId, { text, attachmentIds }) =>
+  request(`/chats/${enc(customerId)}/messages`, { method: 'POST', body: { text, attachmentIds } })
+
+export const markChatRead = (customerId) => request(`/chats/${enc(customerId)}/read`, { method: 'POST', body: {} })
+
+/** Upload-Adresse fuer den Chat-Baustein (POST roh, DELETE <url>/<id>) */
+export const chatUploadUrl = (customerId) => `${PORTAL_URL}/api/team/chats/${enc(customerId)}/attachments`
+
+/** Header fuer den Chat-Baustein (Option requestHeaders) */
+export async function teamAuthHeaders() {
+  return { Authorization: `Bearer ${await jwtCache.get()}` }
+}
diff --git a/tests/unit/loadChatComposer.test.mjs b/tests/unit/loadChatComposer.test.mjs
new file mode 100644
index 0000000..de81fc6
--- /dev/null
+++ b/tests/unit/loadChatComposer.test.mjs
@@ -0,0 +1,49 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import { loadModule } from './load.mjs'
+
+// Chat-Baustein (chat-composer.js/.css) wird zur Laufzeit vom Kundenportal geladen: eine Quelle fuer Portal und WOMS
+const { loadChatComposer } = await loadModule('src/lib/loadChatComposer.js')
+
+function fakeDoc() {
+  const appended = []
+  return {
+    appended,
+    head: { appendChild: (node) => { appended.push(node); return node } },
+    createElement: (tag) => ({ tag, attrs: {}, setAttribute(k, v) { this.attrs[k] = v } }),
+  }
+}
+
+test('haengt CSS und Skript einmal an und liefert window.ChatComposer', async () => {
+  const doc = fakeDoc()
+  const win = {}
+  const first = loadChatComposer({ baseUrl: 'https://project.webklar.com', doc, win })
+  const second = loadChatComposer({ baseUrl: 'https://project.webklar.com', doc, win })
+  assert.equal(doc.appended.length, 2)
+  const link = doc.appended.find((n) => n.tag === 'link')
+  const script = doc.appended.find((n) => n.tag === 'script')
+  assert.equal(link.href || link.attrs.href, 'https://project.webklar.com/chat-composer.css')
+  assert.equal(link.rel || link.attrs.rel, 'stylesheet')
+  assert.equal(script.src || script.attrs.src, 'https://project.webklar.com/chat-composer.js')
+  win.ChatComposer = { create() {} }
+  script.onload()
+  assert.equal(await first, win.ChatComposer)
+  assert.equal(await second, win.ChatComposer)
+})
+
+test('Skript laedt nicht -> deutsche Meldung, naechster Aufruf versucht es neu', async () => {
+  const doc = fakeDoc()
+  const win = {}
+  const p = loadChatComposer({ baseUrl: 'https://p', doc, win })
+  doc.appended.find((n) => n.tag === 'script').onerror()
+  await assert.rejects(p, { message: 'Der Chat-Baustein konnte nicht geladen werden.' })
+  loadChatComposer({ baseUrl: 'https://p', doc, win })
+  assert.equal(doc.appended.filter((n) => n.tag === 'script').length, 2)
+})
+
+test('schon geladen (win.ChatComposer vorhanden) -> nichts anhaengen', async () => {
+  const doc = fakeDoc()
+  const win = { ChatComposer: { create() {} } }
+  assert.equal(await loadChatComposer({ baseUrl: 'https://p', doc, win }), win.ChatComposer)
+  assert.equal(doc.appended.length, 0)
+})