fix(telemetry): detach InboundLedger acquire span (created and reset on different threads)

acquireSpan_ is emplaced on the acquiring caller thread but reset() in
done() on a JtLedgerData worker. Detaching strips the thread-local OTel
Scope on the origin thread so destruction on the worker does not corrupt
the origin thread's context stack.

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

src/xrpld/app/ledger/InboundLedger.h

@@ -194,6 +194,10 @@ private:
     /// with the outcome (complete/failed), timeout count, and peer count.
     /// Gives operators visibility into back-fill / fork-recovery cost, which
     /// previously emitted no span or metric.
+    /// Stored detached: emplaced by the acquiring thread, reset on a
+    /// JtLedgerData worker. detached() strips the thread-local Scope so the
+    /// guard can be destroyed on the worker without corrupting the origin
+    /// thread's context stack.
     std::optional<telemetry::SpanGuard> acquireSpan_;
 };
 

src/xrpld/app/ledger/detail/InboundLedger.cpp

@@ -103,8 +103,12 @@ InboundLedger::init(ScopedLockType& collectionLock)
     // observable. Finalized in done() with the outcome and timeout count.
     {
         using namespace telemetry;
+        // Detach the Scope: this guard is emplaced here but reset() on a
+        // JtLedgerData worker thread. Detaching strips the thread-local Scope
+        // so its destruction there does not corrupt this thread's context stack.
         acquireSpan_.emplace(
-            SpanGuard::span(TraceCategory::Ledger, seg::ledger, ledger_span::op::acquire));
+            SpanGuard::span(TraceCategory::Ledger, seg::ledger, ledger_span::op::acquire)
+                .detached());
         if (*acquireSpan_)
         {
             acquireSpan_->setAttribute(ledger_span::attr::ledgerSeq, static_cast<int64_t>(seq_));