fix(auth): send Nous refresh token via header

hermes_cli/auth.py

@@ -3117,10 +3117,10 @@ def _refresh_access_token(
 ) -> Dict[str, Any]:
     response = client.post(
         f"{portal_base_url}/api/oauth/token",
+        headers={"x-nous-refresh-token": refresh_token},
         data={
             "grant_type": "refresh_token",
             "client_id": client_id,
-            "refresh_token": refresh_token,
         },
     )
 

tests/hermes_cli/test_auth_nous_provider.py

@@ -1,7 +1,6 @@
 """Regression tests for Nous OAuth refresh + agent-key mint interactions."""
 
 import json
-import os
 from datetime import datetime, timezone
 from pathlib import Path
 
@@ -862,6 +861,45 @@ def test_refresh_token_reuse_detection_surfaces_actionable_message():
     assert exc_info.value.relogin_required is True
 
 
+def test_refresh_token_exchange_sends_refresh_token_header():
+    """Nous refresh tokens must be sent in a header so sandbox proxies can
+    substitute placeholder credentials without parsing form bodies.
+    """
+    from hermes_cli.auth import _refresh_access_token
+
+    class _FakeResponse:
+        status_code = 200
+
+        def json(self):
+            return {"access_token": "access-2", "refresh_token": "refresh-2"}
+
+    class _FakeClient:
+        def __init__(self):
+            self.kwargs = None
+
+        def post(self, *args, **kwargs):
+            del args
+            self.kwargs = kwargs
+            return _FakeResponse()
+
+    client = _FakeClient()
+
+    payload = _refresh_access_token(
+        client=client,
+        portal_base_url="https://portal.nousresearch.com",
+        client_id="hermes-cli",
+        refresh_token="refresh-1",
+    )
+
+    assert payload["access_token"] == "access-2"
+    assert client.kwargs is not None
+    assert client.kwargs["headers"]["x-nous-refresh-token"] == "refresh-1"
+    assert client.kwargs["data"] == {
+        "grant_type": "refresh_token",
+        "client_id": "hermes-cli",
+    }
+
+
 def test_refresh_non_reuse_error_keeps_original_description():
     """Non-reuse invalid_grant errors must keep their original description untouched.