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import { SignJWT, importJWK } from "jose";

// POST https://YOUR-PRODUCT-DOMAIN/api/bmai/identity — requires YOUR OWN logged-in product session.
app.post("/api/bmai/identity", requireSession, async (req, res) => {
  // Fresh on EVERY mint. Never persist the launch token/nonce in localStorage,
  // sessionStorage, cookies, React state, or module state: every assistant
  // launch consumes this pair exactly once.
  const nonce = typeof req.body?.nonce === "string" ? req.body.nonce : "";
  if (!/^[A-Za-z0-9_-]{32,200}$/.test(nonce)) return res.status(400).json({ error: "invalid_nonce" });
  const key = await importJWK(JSON.parse(process.env.AI_LAUNCH_PRIVATE_JWK), "ES256");
  const token = await new SignJWT({
      "tenant_id": "00000000-0000-0000-0000-000000000000", // Your product's registered tenant claim
      nonce,                               // equals the sibling field below
      name: req.user.displayName,          // optional low-sensitivity display claim
    })
    .setProtectedHeader({ alg: "ES256", kid: process.env.AI_LAUNCH_KEY_ID })
    .setIssuer("https://YOUR-PRODUCT-DOMAIN (set when you register the provider)")
    .setAudience("busymate-ai")
    .setSubject(req.user.id)               // IMMUTABLE internal account id; never email/phone/session id
    .setJti(crypto.randomUUID())           // one-time (replay-protected)
    .setIssuedAt()
    .setExpirationTime("120s")               // <= registered max age (120s)
    .sign(key);
  res.set("Cache-Control", "no-store");
  res.status(201).json({ token, nonce, expiresIn: 120 });
});

<!-- Floating "bro" launcher for Your product.
     Anonymous chat works immediately on the allowed origins. -->
<script>
  function newLaunchNonce() {
    const bytes = new Uint8Array(32);
    crypto.getRandomValues(bytes);
    return btoa(String.fromCharCode(...bytes))
      .replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/g, "");
  }

  window.BusymateAI = {
    getIdentity: async () => {
      const accessToken = await getProductAccessToken(); // YOUR existing auth helper
      if (!accessToken) return null;
      const nonce = newLaunchNonce();
      const returnTo = new URL(location.href); returnTo.search = ""; returnTo.hash = "";
      const r = await fetch("https://YOUR-PRODUCT-DOMAIN/api/bmai/identity", {
        method: "POST", credentials: "include", cache: "no-store",
        headers: { "content-type": "application/json", authorization: "Bearer " + accessToken },
        body: JSON.stringify({ nonce, returnTo: returnTo.href }),
      });
      if (r.status === 401) return null; // signed out -> anonymous chat
      if (!r.ok) throw new Error("AI identity mint failed (" + r.status + ")");
      // MUST be a newly minted { token, nonce } pair on every call. Never
      // persist either value in localStorage, sessionStorage, cookies, React
      // state, or module state.
      const identity = await r.json();
      if (identity.nonce !== nonce) throw new Error("AI identity nonce mismatch");
      return { token: identity.token, nonce: identity.nonce };
    },
  };

  // Call after YOUR product completes login, logout, access-token/session
  // rotation, or account switch. Do not send an identity postMessage directly.
  window.refreshAssistantIdentity = () =>
    window.BusymateAI?.refreshIdentity?.() ?? Promise.resolve();
</script>
<script
  src="https://your-assistant.busymate.ai/embed/v1.js"
  data-assistant="your-assistant"
  data-label="Ask bro"
  async></script>

// Full-page open with identity in the URL FRAGMENT — never sent in the
// request line, referrer, or logs; the destination strips it before exchange.
function newLaunchNonce() {
  const bytes = new Uint8Array(32);
  crypto.getRandomValues(bytes);
  return btoa(String.fromCharCode(...bytes))
    .replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/g, "");
}

const nonce = newLaunchNonce();
const accessToken = await getProductAccessToken(); // YOUR existing auth helper
if (!accessToken) throw new Error("Sign in before opening an identified assistant");
const returnTo = new URL(location.href); returnTo.search = ""; returnTo.hash = "";
const response = await fetch("https://YOUR-PRODUCT-DOMAIN/api/bmai/identity", {
  method: "POST", credentials: "include", cache: "no-store",
  headers: { "content-type": "application/json", authorization: "Bearer " + accessToken },
  body: JSON.stringify({ nonce, returnTo: returnTo.href }),
});
if (response.status === 401) throw new Error("Sign in before opening an identified assistant");
if (!response.ok) throw new Error("AI identity mint failed (" + response.status + ")");
const identity = await response.json();
if (typeof identity.token !== "string" || typeof identity.nonce !== "string") {
  throw new Error("AI identity mint returned an invalid response");
}
if (identity.nonce !== nonce) throw new Error("AI identity nonce mismatch");

const url = new URL("https://your-assistant.busymate.ai/");
url.hash = new URLSearchParams({
  bmai_token: identity.token,
  bmai_nonce: identity.nonce,
}).toString();
location.assign(url);

// SDK source: https://busymate.ai/sdk/v1/ios/BusymateAI.swift
// Load https://your-assistant.busymate.ai/?channel=ios in a WKWebView.
final class AssistantBridge: NSObject, WKScriptMessageHandler {
  let webView: WKWebView

  func userContentController(_ controller: WKUserContentController,
                             didReceive message: WKScriptMessage) {
    guard message.name == "BusymateAI",
          let body = message.body as? [String: Any],
          body["type"] as? String == "busymate.ai.v1.identity_request"
    else { return }

    Task { // mint through YOUR authenticated API — never a key in the app
      let identity = try await api.mintLaunchIdentity()
      let payload: [String: Any] = [
        "type": "busymate.ai.v1.identity",
        "token": identity.token,
        "nonce": identity.nonce,
      ]
      let data = try JSONSerialization.data(withJSONObject: payload)
      let json = String(decoding: data, as: UTF8.self)
      await webView.evaluateJavaScript("window.postMessage(\(json), '*')")
    }
  }
}

// SDK source: https://busymate.ai/sdk/v1/android/BusymateAI.kt
// Load https://your-assistant.busymate.ai/?channel=android in a WebView.
class AssistantBridge(private val webView: WebView) {
  @JavascriptInterface
  fun postMessage(raw: String) {
    val message = JSONObject(raw)
    if (message.optString("type") != "busymate.ai.v1.identity_request") return

    lifecycleScope.launch { // mint through YOUR authenticated API client
      val identity = api.mintLaunchIdentity()
      val response = JSONObject()
        .put("type", "busymate.ai.v1.identity")
        .put("token", identity.token)
        .put("nonce", identity.nonce)
      webView.evaluateJavascript(
        "window.postMessage(${JSONObject.quote(response.toString())}, '*')", null
      )
    }
  }
}

webView.settings.javaScriptEnabled = true
webView.addJavascriptInterface(AssistantBridge(webView), "BusymateAINative")
// SupportChatNative + support.chat.v1.* remain accepted for shipped apps.

import { mountBusymateAI } from "https://busymate.ai/sdk/v1/index.js";

// productAuth is a narrow preload/Tauri command bridge. It calls YOUR
// authenticated backend; no cookie, signing key, or refresh token is exposed
// to the renderer.
const assistant = await mountBusymateAI({
  assistant: "your-assistant",
  origin: "https://your-assistant.busymate.ai",
  label: "Ask bro",
  getIdentity: () => window.productAuth.mintAssistantIdentity(),
});

window.productAuth.onSessionChanged(() => assistant.refreshIdentity());
assistant.open();

// Electron main process (Tauri: use the equivalent shell/open allowlist):
mainWindow.webContents.setWindowOpenHandler(({ url }) => {
  const target = new URL(url);
  if (target.protocol === "https:" || target.protocol === "http:") {
    void shell.openExternal(target.href);
  }
  return { action: "deny" };
});