Merge branch 'pratik/otel-phase1c-rpc-integration' into pratik/otel-phase2-rpc-tracing

Brings review fixes: no-alloc GetCurrent hot path, activateIfLive helper,
non-copyable storage, accurate drop-counter doc.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/libxrpl/telemetry/CoroAwareContextStorage.cpp

@@ -12,6 +12,8 @@
 
 #include <xrpl/telemetry/CoroAwareContextStorage.h>
 
+#include <xrpl/basics/LocalValue.h>
+
 #include <opentelemetry/context/context.h>
 #include <opentelemetry/context/runtime_context.h>
 #include <opentelemetry/nostd/unique_ptr.h>
@@ -21,6 +23,20 @@ namespace xrpl::telemetry {
 opentelemetry::context::Context
 CoroAwareContextStorage::GetCurrent() noexcept
 {
+    // Hot path: Log.cpp reads the current context on EVERY log line on EVERY
+    // thread. Peek the raw per-thread/coro store WITHOUT materializing it:
+    // getLocalValues().get() returns nullptr when this thread has no store yet
+    // and never allocates. Dereferencing stack_ (a LocalValue) would instead
+    // heap-allocate the store + a map entry + the vector on first touch, so we
+    // avoid that on the no-span path.
+    //
+    // Behaviour is identical to touching *stack_: a thread with no store has no
+    // active span, and a store whose stack was never pushed yields an empty
+    // vector — both cases map to an empty Context, matching stock
+    // ThreadLocalContextStorage (Top() returns Context() when the stack is
+    // empty). Only when a store already exists do we read the top frame.
+    if (detail::getLocalValues().get() == nullptr)
+        return opentelemetry::context::Context{};
     auto& stack = *stack_;
     return stack.empty() ? opentelemetry::context::Context{} : stack.back();
 }

src/libxrpl/telemetry/DeterministicIdGenerator.cpp

@@ -96,8 +96,10 @@ PendingTraceId::~PendingTraceId() noexcept
     if (!gTlsPendingConsumed)
     {
         // The assert above is stripped in release, so bump a counter too: a
-        // dropped deterministic trace root stays observable via
-        // unconsumedDeterministicIdDrops(). Relaxed: this is a diagnostic tally.
+        // process-wide tally of dropped deterministic trace roots. It is
+        // exposed via unconsumedDeterministicIdDrops() as an extension point
+        // for a future metric or diagnostic to read; nothing wires it to a log
+        // or metric yet. Relaxed: this is a plain diagnostic tally.
         gUnconsumedDeterministicIdDrops.fetch_add(1, std::memory_order_relaxed);
     }
     gTlsPendingTraceId.reset();  // never leak, even in release