diff --git a/apps/api/app/services/provider_credentials.py b/apps/api/app/services/provider_credentials.py
index 9c25fbe..7fecc19 100644
--- a/apps/api/app/services/provider_credentials.py
+++ b/apps/api/app/services/provider_credentials.py
@@ -340,7 +340,7 @@ async def save_credential(
     async with pool.acquire() as conn:
         row = await conn.fetchrow(
             """
-            INSERT INTO app.admin_provider_credential (
+            INSERT INTO app.admin_provider_credential AS existing (
               provider, token_encrypted, token_hint, auth_kind, updated_by, updated_at,
               refresh_token_encrypted, extra
             )
@@ -351,8 +351,14 @@ async def save_credential(
               auth_kind = EXCLUDED.auth_kind,
               updated_by = EXCLUDED.updated_by,
               updated_at = now(),
-              refresh_token_encrypted = COALESCE(EXCLUDED.refresh_token_encrypted, refresh_token_encrypted),
-              extra = CASE WHEN EXCLUDED.extra::text = '{}'::jsonb THEN extra ELSE EXCLUDED.extra END,
+              refresh_token_encrypted = COALESCE(
+                EXCLUDED.refresh_token_encrypted,
+                existing.refresh_token_encrypted
+              ),
+              extra = CASE
+                WHEN EXCLUDED.extra = '{}'::jsonb THEN existing.extra
+                ELSE EXCLUDED.extra
+              END,
               last_verified_at = NULL,
               last_verify_ok = NULL,
               last_verify_error = NULL
diff --git a/apps/api/app/test_provider_credentials_service.py b/apps/api/app/test_provider_credentials_service.py
index 559a762..6ece9a5 100644
--- a/apps/api/app/test_provider_credentials_service.py
+++ b/apps/api/app/test_provider_credentials_service.py
@@ -1,7 +1,7 @@
 """provider 자격증명 서비스(암호화·카탈로그) 단위 테스트."""
 
 import unittest
-from unittest.mock import patch
+from unittest.mock import AsyncMock, patch
 
 from pydantic import SecretStr
 
@@ -73,5 +73,53 @@ class CatalogTest(unittest.TestCase):
         self.assertIn("codex", codes)
 
 
+class SaveCredentialQueryTest(unittest.IsolatedAsyncioTestCase):
+    async def test_upsert_preserves_omitted_refresh_and_extra(self):
+        row = {
+            "provider": "openrouter",
+            "token_hint": "…next",
+            "auth_kind": "oauth_token",
+            "updated_by": "admin@example.com",
+            "updated_at": None,
+            "last_verified_at": None,
+            "last_verify_ok": None,
+            "last_verify_error": None,
+            "refresh_token_encrypted": None,
+            "extra": {},
+        }
+        conn = AsyncMock()
+        conn.fetchrow.return_value = row
+
+        class _Acquire:
+            async def __aenter__(self):
+                return conn
+
+            async def __aexit__(self, exc_type, exc, traceback):
+                return False
+
+        class _Pool:
+            def acquire(self):
+                return _Acquire()
+
+        with (
+            patch.object(svc, "ensure_table", AsyncMock()),
+            patch.object(svc, "get_pool", return_value=_Pool()),
+            patch.object(svc.settings, "provider_credential_secret", SecretStr("unit-test-master-secret-0123456789")),
+        ):
+            await svc.save_credential(
+                provider="openrouter",
+                token="new-access-token",
+                auth_kind="oauth_token",
+                updated_by="admin@example.com",
+            )
+
+        query = conn.fetchrow.await_args.args[0]
+        self.assertIn("INSERT INTO app.admin_provider_credential AS existing", query)
+        self.assertIn("EXCLUDED.refresh_token_encrypted,\n                existing.refresh_token_encrypted", query)
+        self.assertIn("WHEN EXCLUDED.extra = '{}'::jsonb THEN existing.extra", query)
+        self.assertEqual(conn.fetchrow.await_args.args[6], None)
+        self.assertEqual(conn.fetchrow.await_args.args[7], "{}")
+
+
 if __name__ == "__main__":
     unittest.main()