fix(logging): expose trace fields in file logs

docs/gateway/opentelemetry.md

@@ -150,6 +150,10 @@ When any subkey is enabled, model and tool spans get bounded, redacted
 - **Logs:** OTLP logs respect `logging.level` (file log level). They use the
   diagnostic log-record redaction path, not console formatting. High-volume
   installs should prefer OTLP collector sampling/filtering over local sampling.
+- **File-log correlation:** JSONL file logs include top-level `traceId`,
+  `spanId`, `parentSpanId`, and `traceFlags` when the log call carries a valid
+  diagnostic trace context, which lets log processors join local log lines with
+  exported spans.
 
 ## Exported metrics
 

docs/logging.md

@@ -157,6 +157,13 @@ You can override both via the **`OPENCLAW_LOG_LEVEL`** environment variable (e.g
 `--verbose` only affects console output and WS log verbosity; it does not change
 file log levels.
 
+### Trace correlation
+
+File logs are JSONL. When a log call carries a valid diagnostic trace context,
+OpenClaw writes the trace fields as top-level JSON keys (`traceId`, `spanId`,
+`parentSpanId`, `traceFlags`) so external log processors can correlate the line
+with OTEL spans and provider `traceparent` propagation.
+
 ### Console styles
 
 `logging.consoleStyle`: