test: add unit tests for load_user_agent_catalog function

- test_user_agent_catalog_file_exists_and_has_required_fields: verifies catalog file exists with correct structure
- test_load_user_agent_catalog_raises_on_invalid_structure: verifies invalid YAML is properly rejected

backend/tests/unit/core/test_agent_init_data.py

@@ -141,3 +141,48 @@ async def test_initialize_data_rolls_back_on_invalid_factory_mapping(
 
     Base.metadata.remove(users_table)
     await engine.dispose()
+
+
+def test_user_agent_catalog_file_exists_and_has_required_fields() -> None:
+    catalog_path = (
+        Path(__file__).resolve().parents[3]
+        / "src"
+        / "core"
+        / "config"
+        / "static"
+        / "database"
+        / "user_agent_catalog.yaml"
+    )
+
+    assert catalog_path.exists(), f"Catalog file not found: {catalog_path}"
+
+    catalog = init_data.load_user_agent_catalog(catalog_path)
+
+    assert "agents" in catalog
+    assert isinstance(catalog["agents"], list)
+    assert len(catalog["agents"]) == 3
+
+    for agent in catalog["agents"]:
+        assert "agent_type" in agent
+        assert "llm_model_code" in agent
+        assert "status" in agent
+        assert "config" in agent
+        assert isinstance(agent["config"], dict)
+
+
+def test_load_user_agent_catalog_raises_on_invalid_structure(
+    tmp_path: Path,
+) -> None:
+    catalog_path = tmp_path / "user_agent_catalog.yaml"
+    catalog_path.write_text(
+        """
+agents:
+  - agent_type: TEST
+    llm_model_code: test-model
+    status: ACTIVE
+""".strip(),
+        encoding="utf-8",
+    )
+
+    with pytest.raises(ValueError, match="Invalid user agent catalog"):
+        init_data.load_user_agent_catalog(catalog_path)