diff --git a/backend/test_website_group_mgmt.py b/backend/test_website_group_mgmt.py
index 5ec1fa0..7905eeb 100644
--- a/backend/test_website_group_mgmt.py
+++ b/backend/test_website_group_mgmt.py
@@ -92,3 +92,57 @@ def test_create_and_update_website_group(db_session, monkeypatch):
     # Verify that local binding was updated
     db_session.refresh(b)
     assert b.target_group_name == "UpdatedGroup"
+
+
+def test_update_website_group_route_handles_slash(db_session, monkeypatch):
+    from fastapi.testclient import TestClient
+    from app.main import app
+    from app.database import get_db
+    from app.utils.auth import get_current_user
+
+    w = Website(
+        name="W1",
+        site_type="sub2api",
+        base_url="http://w1",
+        enabled=True,
+        auth_config_json="{}",
+        timeout_seconds=30
+    )
+    db_session.add(w)
+    db_session.commit()
+    db_session.refresh(w)
+
+    called_update = []
+
+    class FakeClient:
+        def __init__(self, *args, **kwargs):
+            pass
+        def __enter__(self):
+            return self
+        def __exit__(self, *args):
+            pass
+        def update_group(self, endpoint_template, group_id, body):
+            called_update.append((endpoint_template, group_id, body))
+            return {"id": group_id, "name": body["name"], "description": body.get("description")}
+
+    monkeypatch.setattr("app.routers.websites._client", lambda website: FakeClient())
+
+    # Set dependency overrides
+    app.dependency_overrides[get_db] = lambda: db_session
+    app.dependency_overrides[get_current_user] = lambda: None
+
+    try:
+        client = TestClient(app)
+        # request URL with urlencoded slash: g%2F123
+        resp = client.put(
+            f"/api/websites/{w.id}/groups/g%2F123",
+            json={"name": "UpdatedGroup", "description": "UpdatedDesc"}
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["id"] == "g/123"
+        assert data["name"] == "UpdatedGroup"
+        assert len(called_update) == 1
+        assert called_update[0][1] == "g/123"
+    finally:
+        app.dependency_overrides.clear()