tests/gateway/test_message_timestamps.py::test_render_user_content_adds_single_context_timestamp
tests/gateway/test_message_timestamps.py::test_render_user_content_deduplicates_existing_timestamp_and_preserves_embedded_time
tests/gateway/test_message_timestamps.py::test_strip_leading_message_timestamps_removes_multiple_prefixes_and_prefers_inner_time
tests/gateway/test_message_timestamps.py::test_coerce_message_timestamp_accepts_datetime_and_epoch
tests/gateway/test_message_timestamps.py::test_persist_user_message_override_keeps_clean_content_and_timestamp_metadata
tests/gateway/test_message_timestamps.py::test_message_timestamps_enabled_defaults_off
tests/gateway/test_message_timestamps.py::test_message_timestamps_enabled_when_opted_in
tests/gateway/test_message_timestamps.py::test_build_history_injects_only_when_enabled