Embeddable Chat Engine & Public Agent Surface

<script
  src="https://app.brainstormer.io/embed.js"
  data-slug="your-agent-slug"
  data-color="#3B39A7"
  data-position="right">
</script>

{
  source: "brainstormer-widget",   // always — filter on this
  v: 1,                            // envelope version
  type: "message:sent",            // see table below
  seq: 3,                          // monotonic per session
  ts: "2026-06-17T10:04:01.244Z",  // ISO timestamp
  agentSlug: "your-agent-slug",
  conversationId: "…" | null,
  role: "user" | "assistant",      // message:* only
  // running session totals (message:* only):
  userMessageCount: 2,
  assistantMessageCount: 1,
  messageCount: 3,
}

// Gate after 5 user messages
BrainstormerWidget.on("message:sent", function (e) {
  if (e.userMessageCount >= 5) showLoginWall();
});

// Subscribe to everything; on() returns an unsubscribe function
const off = BrainstormerWidget.on("*", (e) => console.log(e.type, e));

window.addEventListener("message", (e) => {
  if (e.origin !== "https://app.brainstormer.io") return;
  const evt = e.data;
  if (!evt || evt.source !== "brainstormer-widget") return;
  if (evt.type === "message:received" && evt.assistantMessageCount >= 3) {
    showPaywall();
  }
});

// Lock the chat after the visitor hits your limit…
BrainstormerWidget.on("message:sent", (e) => {
  if (e.userMessageCount >= 5) BrainstormerWidget.setReadOnly(true);
});

// …and unlock once they sign in.
BrainstormerWidget.setReadOnly(false);

iframe.contentWindow.postMessage(
  { source: "brainstormer-host", type: "set-readonly", readOnly: true },
  "https://app.brainstormer.io",
);

interface ChatTransport {
  createConversation(input?): Promise<CreatedConversation>;
  sendMessage(input, handlers, signal?): Promise<void>; // streams over SSE
  uploadAttachment(file, opts?): Promise<AttachmentRef>;
  loadMessages(conversationId, page?): Promise<ChatMessage[]>;
  listConversations(page?): Promise<ChatConversation[]>;
  subscribeEvents(conversationId, handlers): Unsubscribe;
}

data: {"type":"token","content":"Hello"}
data: {"type":"done","response":{ ...ChatResponse }}
data: {"type":"error","message":"...","code":"..."}

{
  "attachment": {
    "id": "uuid",
    "accessToken": "...",
    "fileType": "image",
    "originalFilename": "photo.png",
    "fileSizeBytes": 12345,
    "contentType": "image/png",
    "processingStatus": "queued",
    "createdAt": "..."
  },
  "processingQueued": true
}