diff --git a/copilot/browser.py b/copilot/browser.py
index 5fb6019..b22f8bb 100644
--- a/copilot/browser.py
+++ b/copilot/browser.py
@@ -58,18 +58,32 @@ async () => {
 }
 """
 
-# Best-effort discovery of an MSAL access token from localStorage. Returns null
-# for anonymous sessions (anonymous chat may still work via cookies alone).
+# Discover the Copilot chat MSAL access token from localStorage. The cache holds
+# several tokens for different scopes; the chat WebSocket only accepts the one
+# scoped 'ChatAI.ReadWrite' — a wrong-audience token (e.g. the Graph
+# User.Read/Files.Read token) makes the WS upgrade 401. We therefore PREFER the
+# ChatAI token and only fall back to the first token found if none matches.
+# Returns null for anonymous sessions (anonymous chat may still work via cookies).
 _FIND_TOKEN_JS = """
 () => {
   try {
+    let fallback = null;
     for (let i = 0; i < localStorage.length; i++) {
       const k = localStorage.key(i);
       const v = localStorage.getItem(k);
       if (v && v.indexOf('"credentialType":"AccessToken"') !== -1) {
-        try { const o = JSON.parse(v); if (o && o.secret) return o.secret; } catch (e) {}
+        try {
+          const o = JSON.parse(v);
+          if (o && o.secret) {
+            // Match the chat scope (e.g. '<resource>/ChatAI.ReadWrite'); take the
+            // first non-matching token only as a last-resort fallback.
+            if (o.target && o.target.indexOf('ChatAI') !== -1) return o.secret;
+            if (!fallback) fallback = o.secret;
+          }
+        } catch (e) {}
       }
     }
+    return fallback;
   } catch (e) {}
   return null;
 }
diff --git a/copilot/driver.py b/copilot/driver.py
index 05c7cd1..e1fb9e8 100644
--- a/copilot/driver.py
+++ b/copilot/driver.py
@@ -69,18 +69,25 @@ class Copilot(AbstractProvider):
         if access_token is None and conversation is not None:
             access_token = conversation.access_token
 
+        # Auth model mirrors the browser:
+        #   * REST calls (conversation create, attachment upload) authenticate by
+        #     COOKIE only. Sending the token as an Authorization: Bearer header
+        #     there gets a 401 (browsers never do it), so we don't.
+        #   * the chat WebSocket carries the signed-in identity via its
+        #     ?accessToken= param. This must be the Copilot chat token (MSAL scope
+        #     ChatAI.ReadWrite, selected in browser._FIND_TOKEN_JS): a
+        #     wrong-audience token 401s the WS upgrade, while *no* token makes the
+        #     chat backend treat the session as anonymous -> chat-service-
+        #     unavailable in geo-restricted regions (e.g. India).
         websocket_url = self.websocket_url
-        headers = None
         if access_token:
             websocket_url = f"{websocket_url}&accessToken={quote(access_token)}"
-            headers = {"authorization": f"Bearer {access_token}"}
 
         with Session(
             timeout=timeout,
             proxy=proxy,
             impersonate="chrome",
             cookies=cookies,
-            headers=headers,
         ) as session:
             # Establish cookies + Cloudflare clearance (anonymous is fine).
             session.get(f"{self.url}/")