Summary

Create a deep dive guide for distributed tracing covering context propagation, trace sampling, cross-service correlation, and integration with Jaeger/Zipkin/OTLP backends.

Parent Issue

Part of: [EPIC] docs: Address documentation gaps across all ecosystem systems (kcenon/common_system#325)

Background (Why)

monitoring_system includes distributed tracing at include/kcenon/monitoring/tracing/ with distributed_tracer.h and trace_context.h, plus trace exporters for Jaeger, Zipkin, OTLP, and Console. Only basic tracing is covered in QUICK_START.md.

Source files:

• include/kcenon/monitoring/tracing/distributed_tracer.h — Tracer implementation
• include/kcenon/monitoring/tracing/trace_context.h — Context propagation
• include/kcenon/monitoring/exporters/trace_exporters.h — Jaeger, Zipkin, OTLP, Console

Scope (What)

Create docs/guides/DISTRIBUTED_TRACING.md covering:

1. Tracing Architecture

• Span model (trace ID, span ID, parent span ID)
• Context propagation (in-process, cross-process)
• Sampling strategies (always, never, probabilistic, rate-limited)

2. Trace Context

• How context propagates across threads
• HTTP header propagation (W3C TraceContext, B3)
• Context injection and extraction API

3. Creating Spans

• Root spans vs child spans
• Span attributes and events
• Span status and error recording
• Span timing and duration

4. Backend Integration

• Jaeger setup and configuration
• Zipkin setup and configuration
• OTLP direct export
• Console exporter for development

5. Cross-Service Tracing

• Context propagation across network boundaries
• Integration with network_system for automatic propagation
• Correlation with logger_system log entries

6. Advanced Topics

• Custom sampling strategies
• Span enrichment and processing
• Trace storage and querying
• Performance impact and overhead

Acceptance Criteria

• Tracing architecture fully explained
• Context propagation patterns documented
• All 4 trace exporters documented with setup
• Cross-service tracing explained
• At least 3 complete tracing examples