Phase 5: Documentation, deployment configs, integration test infrastructure

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

include/xrpl/proto/xrpl.proto

@@ -91,6 +91,10 @@ message TraceContext {
   optional bytes trace_id = 1;      // 16-byte trace identifier
   optional bytes span_id = 2;       // 8-byte parent span identifier
   optional uint32 trace_flags = 3;  // bit 0 = sampled
+  // TODO: trace_state is reserved for W3C tracestate vendor-specific
+  // key-value pairs but is not yet read or written by
+  // TraceContextPropagator. Wire it when cross-vendor trace
+  // propagation is needed.
   optional string trace_state = 4;  // W3C tracestate header value
 }
 

include/xrpl/telemetry/TraceContextPropagator.h

@@ -6,6 +6,13 @@
     Protocol Buffer TraceContext messages (P2P cross-node propagation).
 
     Only compiled when XRPL_ENABLE_TELEMETRY is defined.
+
+    TODO: These utilities are not yet wired into the P2P message flow.
+    To enable cross-node distributed traces, call injectToProtobuf() in
+    PeerImp when sending TMTransaction/TMProposeSet messages, and call
+    extractFromProtobuf() in the corresponding message handlers to
+    reconstruct the parent span context before starting a child span.
+    This was deferred to validate single-node tracing performance first.
 */
 
 #ifdef XRPL_ENABLE_TELEMETRY