Avoid contextvar-based log context in SSE generators and treat GeneratorExit as quiet teardown.
Add core/trace.py with trace_event, traced_async_stream, and payload snapshots. Merge TRACE fields into JSON logs; promote claude_session_id, http path/method. Instrument API, messaging/CLI, and OpenAI-compat/native provider paths. Harden log sink with enqueue and stdlib intercept re-entrancy guard. Document behavior in .env.example and README; extend tests.