SpanRecord

A completed span record, shaped to round-trip through OTLP.

This is kuilt's KMP-native representation of an OpenTelemetry span. It is intentionally minimal: the fields map 1-to-1 to OTLP's Span proto message so a WarpOtlpBridge can serialize them directly with no further transformation.

traceId and spanId carry raw bytes matching the OTLP protobuf wire format:

• traceId — 16 bytes (128-bit), matches OTLP proto3 bytes trace_id.

• spanId — 8 bytes (64-bit), matches OTLP proto3 bytes span_id.

• parentSpanId — 8 bytes for child spans; null for root spans.

ByteString is used rather than ByteArray because the ORSet inside WarpSpanExporter keys by element equality — ByteString provides content-based equals/hashCode, so re-exporting the same span is always a no-op set union.

SpanRecord is the element type stored in the ORSet inside WarpSpanExporter: keyed by spanId, so re-exporting the same span is a no-op (set union is idempotent).

Honest limits

• Clock skew. startEpochNanos and endEpochNanos are the producer's local clock. Long-offline devices may produce timestamps far in the past. A hybrid logical clock (HLC) offset could be estimated on reconnect, but is not yet implemented — this is filed as a follow-up.

• Late traces. Spans that straddle an offline and an online producer only assemble into a complete trace when the offline half syncs. OTLP collectors accept late spans within an assembly window (typically 10 min–1 hr); spans that miss the window are indexed as orphaned roots.