code-review-testing

For agent changes prefer integration tests over unit tests. Integration tests are under `core/suite` and use `test_codex` to set up a test instance of codex. Features that change the agent logic MUST add an integration test: - Provide a list of major logic changes and user-facing behaviors that need to be tested. If unit tests are needed, put them in a dedicated test file (*_tests.rs). Avoid test-only functions in the main implementation. Check whether there are existing helpers to make tests more streamlined and readable.