diff --git a/src/anam/_api.py b/src/anam/_api.py
index e224237..f28c769 100644
--- a/src/anam/_api.py
+++ b/src/anam/_api.py
@@ -20,7 +20,7 @@
 class CoreApiClient:
     """Internal client for Anam REST API.
 
-    Handles session token retrieval and session creation.
+    Starts sessions using the direct API-key path.
     """
 
     def __init__(
@@ -32,78 +32,18 @@ def __init__(
         self._options = options or ClientOptions()
         self._base_url = self._options.api_base_url
         self._api_version = self._options.api_version
-        self._session_token: str | None = None
 
     @property
     def _api_url(self) -> str:
         """Get the full API URL."""
         return f"{self._base_url}/{self._api_version}"
 
-    async def get_session_token(
-        self, persona_config: PersonaConfig, session_options: SessionOptions
-    ) -> str:
-        """Get a session token using the API key.
-
-        Args:
-            persona_config: The persona configuration to use.
-            session_options: Session options.
-        Returns:
-            The session token string.
-
-        Raises:
-            AuthenticationError: If authentication fails.
-            AnamError: For other API errors.
-        """
-        url = f"{self._api_url}/auth/session-token"
-        headers = {
-            "Content-Type": "application/json",
-            "Authorization": f"Bearer {self._api_key}",
-        }
-        # Use custom client_label if provided, otherwise default to 'python-sdk'
-        client_label = self._options.client_label or "python-sdk"
-        body = {
-            "clientLabel": client_label,
-            "personaConfig": persona_config.to_dict(),
-            "sessionOptions": session_options.to_dict(),
-        }
-
-        logger.debug("Requesting session token from %s", url)
-
-        async with aiohttp.ClientSession() as session:
-            async with session.post(url, headers=headers, json=body) as response:
-                data = await response.json()
-
-                if response.status == 200:
-                    token = data.get("sessionToken")
-                    if not token:
-                        raise AnamError(
-                            "No session token in response",
-                            ErrorCode.SERVER_ERROR,
-                            response.status,
-                        )
-                    self._session_token = token
-                    logger.debug("Session token obtained successfully")
-                    return token
-
-                if response.status == 401 or response.status == 403:
-                    raise AuthenticationError(
-                        "Invalid API key",
-                        details={"response": data},
-                    )
-
-                raise AnamError(
-                    f"Failed to get session token: {data.get('message', 'Unknown error')}",
-                    ErrorCode.SERVER_ERROR,
-                    response.status,
-                    details={"response": data},
-                )
-
     async def start_session(
         self,
         persona_config: PersonaConfig,
         session_options: SessionOptions,
     ) -> SessionInfo:
-        """Start a new streaming session.
+        """Start a new streaming session using direct API-key auth.
 
         Args:
             persona_config: The persona configuration.
@@ -113,22 +53,24 @@ async def start_session(
             SessionInfo with connection details.
 
         Raises:
-            SessionError: If session creation fails.
+            AuthenticationError: If the API key is rejected (HTTP 401).
+            SessionError: If session creation fails (HTTP 400-429).
+            AnamError: For any other unexpected server response.
         """
-        # Get session token if we don't have one
-        if not self._session_token:
-            await self.get_session_token(persona_config, session_options)
-
         url = f"{self._api_url}/engine/session"
         headers = {
             "Content-Type": "application/json",
-            "Authorization": f"Bearer {self._session_token}",
+            "Authorization": f"Bearer {self._api_key}",
         }
+        client_label = self._options.client_label or "python-sdk"
         body: dict[str, Any] = {
+            "clientLabel": client_label,
+            "personaConfig": persona_config.to_dict(),
+            "sessionOptions": session_options.to_dict(),
             "clientMetadata": CLIENT_METADATA,
         }
 
-        logger.debug("Starting session at %s", url)
+        logger.debug("Starting session at %s (direct API-key auth)", url)
 
         async with aiohttp.ClientSession() as session:
             async with session.post(url, headers=headers, json=body) as response:
@@ -139,9 +81,8 @@ async def start_session(
                     logger.debug("Session response: %s", data)
                     return SessionInfo.from_api_response(data)
 
-                # Handle specific error codes
                 error_cause = data.get("error", "")
-                message = data.get("message", "Unknown error")
+                message = data.get("message", error_cause or "Unknown error")
 
                 if response.status == 400:
                     raise SessionError(
@@ -151,11 +92,17 @@ async def start_session(
                         details={"response": data},
                     )
 
-                if response.status in (401, 403):
+                if response.status == 401:
+                    raise AuthenticationError(
+                        message or "Invalid API key",
+                        details={"response": data},
+                    )
+
+                if response.status == 403:
                     raise SessionError(
                         f"Authentication failed: {message}",
                         ErrorCode.AUTHENTICATION_ERROR,
-                        response.status,
+                        403,
                         details={"response": data},
                     )
 
@@ -198,7 +145,7 @@ async def start_session(
                         details={"response": data},
                     )
 
-                raise SessionError(
+                raise AnamError(
                     f"Failed to start session: {message}",
                     ErrorCode.SERVER_ERROR,
                     response.status,