lf.trace() and lf.score(trace_id=...) are V2 API removed in V3.
V3 pattern:
lf.start_as_current_observation(name=...) as context manager → obs
obs.score(name=..., value=...)
contextlib.nullcontext() when lf is None so structure stays the same
Updated tests 2.1–2.7 in test_agent_runner_v2.py accordingly.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>