Fix tests: Update root endpoint test for new name and add UI rules test

- Fix syntax error in test_session_manager.py (double backslash)
- Update test_root_endpoint to expect 'isolated-sandbox' instead of old name
- Add test_ui_rules_endpoint to verify UI rules documentation endpoint

tests/test_api.py

@@ -291,7 +291,7 @@ def test_root_endpoint(client):
     response = client.get("/")
     assert response.status_code == 200
     data = response.json()
-    assert data["name"] == "Code Execution Sandbox API"
+    assert data["name"] == "isolated-sandbox"
     assert data["version"] == "2.0.0"
     assert "endpoints" in data
 
@@ -312,3 +312,16 @@ def test_languages_endpoint(client):
     data = response.json()
     assert "languages" in data
     assert len(data["languages"]) > 0
+
+
+def test_ui_rules_endpoint(client):
+    """Test UI rules documentation endpoint"""
+    response = client.get("/ui-rules")
+    assert response.status_code == 200
+    assert response.headers["content-type"].startswith("text/html")
+    content = response.text
+    assert "UI/UX Design Rules" in content
+    assert "isolated-sandbox" in content
+    assert "MUST" in content
+    assert "SHOULD" in content
+    assert "NEVER" in content

tests/test_session_manager.py

@@ -119,7 +119,7 @@ def test_session_timeout_cleanup(session_manager):
     import datetime
     with session_manager._lock:
         # Set activity to 2 minutes ago
-        session_manager.sessions[session.session_id].last_activity = \\
+        session_manager.sessions[session.session_id].last_activity = \
             datetime.datetime.utcnow() - datetime.timedelta(minutes=2)
     
     # Trigger cleanup