refactor(telemetry): extract TX span name constants into TxSpanNames.h

Move scattered string literals from PeerImp.cpp and NetworkOPs.cpp into
compile-time constants in src/xrpld/telemetry/TxSpanNames.h. Follows
the same StaticStr/join() pattern established in Phase 1c for RPC spans.

Constants cover: span prefixes (tx), operations (receive, process),
attribute keys (hash, local, path, suppressed, status, peerId,
peerVersion), and values (sync, async, knownBad).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/xrpld/app/misc/NetworkOPs.cpp

@@ -34,6 +34,7 @@
 #include <xrpld/rpc/DeliveredAmount.h>
 #include <xrpld/rpc/MPTokenIssuanceID.h>
 #include <xrpld/rpc/ServerHandler.h>
+#include <xrpld/telemetry/TxSpanNames.h>
 
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/ToString.h>
@@ -1313,9 +1314,10 @@ NetworkOPsImp::processTransaction(
     FailHard failType)
 {
     using namespace telemetry;
-    auto span = SpanGuard::span(TraceCategory::Transactions, "tx", "process");
-    span.setAttribute("xrpl.tx.hash", to_string(transaction->getID()).c_str());
-    span.setAttribute("xrpl.tx.local", bLocal);
+    auto span =
+        SpanGuard::span(TraceCategory::Transactions, tx_span::prefix::tx, tx_span::op::process);
+    span.setAttribute(tx_span::attr::hash, to_string(transaction->getID()).c_str());
+    span.setAttribute(tx_span::attr::local, bLocal);
 
     auto ev = m_job_queue.makeLoadEvent(jtTXN_PROC, "ProcessTXN");
 
@@ -1325,12 +1327,12 @@ NetworkOPsImp::processTransaction(
 
     if (bLocal)
     {
-        span.setAttribute("xrpl.tx.path", "sync");
+        span.setAttribute(tx_span::attr::path, tx_span::val::sync);
         doTransactionSync(transaction, bUnlimited, failType);
     }
     else
     {
-        span.setAttribute("xrpl.tx.path", "async");
+        span.setAttribute(tx_span::attr::path, tx_span::val::async);
         doTransactionAsync(transaction, bUnlimited, failType);
     }
 }

src/xrpld/overlay/detail/PeerImp.cpp

@@ -21,6 +21,7 @@
 #include <xrpld/overlay/detail/Tuning.h>
 #include <xrpld/peerfinder/PeerfinderManager.h>
 #include <xrpld/peerfinder/Slot.h>
+#include <xrpld/telemetry/TxSpanNames.h>
 
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/SHAMapHash.h>
@@ -1423,10 +1424,11 @@ PeerImp::handleTransaction(
     bool batch)
 {
     using namespace telemetry;
-    auto span = SpanGuard::span(TraceCategory::Transactions, "tx", "receive");
-    span.setAttribute("xrpl.peer.id", static_cast<int64_t>(id_));
+    auto span =
+        SpanGuard::span(TraceCategory::Transactions, tx_span::prefix::tx, tx_span::op::receive);
+    span.setAttribute(tx_span::attr::peerId, static_cast<int64_t>(id_));
     if (auto const version = getVersion(); !version.empty())
-        span.setAttribute("xrpl.peer.version", version.c_str());
+        span.setAttribute(tx_span::attr::peerVersion, version.c_str());
 
     XRPL_ASSERT(eraseTxQueue != batch, ("xrpl::PeerImp::handleTransaction : valid inputs"));
     if (tracking_.load() == Tracking::diverged)
@@ -1446,7 +1448,7 @@ PeerImp::handleTransaction(
     {
         auto stx = std::make_shared<STTx const>(sit);
         uint256 const txID = stx->getTransactionID();
-        span.setAttribute("xrpl.tx.hash", to_string(txID).c_str());
+        span.setAttribute(tx_span::attr::hash, to_string(txID).c_str());
 
         // Charge strongly for attempting to relay a txn with tfInnerBatchTxn
         // LCOV_EXCL_START
@@ -1480,11 +1482,11 @@ PeerImp::handleTransaction(
 
         if (!app_.getHashRouter().shouldProcess(txID, id_, flags, tx_interval))
         {
-            span.setAttribute("xrpl.tx.suppressed", true);
+            span.setAttribute(tx_span::attr::suppressed, true);
             // we have seen this transaction recently
             if (any(flags & HashRouterFlags::BAD))
             {
-                span.setAttribute("xrpl.tx.status", "known_bad");
+                span.setAttribute(tx_span::attr::status, tx_span::val::knownBad);
                 fee_.update(Resource::feeUselessData, "known bad");
                 JLOG(p_journal_.debug()) << "Ignoring known bad tx " << txID;
             }

src/xrpld/telemetry/TxSpanNames.h

@@ -0,0 +1,72 @@
+#pragma once
+
+/** Compile-time span name constants for transaction tracing.
+ *
+ *  Used by PeerImp (overlay) and NetworkOPs (app) for transaction
+ *  lifecycle spans. Built on StaticStr/join() from SpanNames.h.
+ *
+ *  Span hierarchy:
+ *
+ *    Node A (sender)                 Node B (receiver)
+ *    +------------------+            +------------------+
+ *    | tx.process       |  protobuf  | tx.receive       |
+ *    |   injectTo       | ---------> |   extractFrom    |
+ *    |   Protobuf()     | trace_ctx  |   Protobuf()     |
+ *    +------------------+            +------------------+
+ */
+
+#include <xrpl/telemetry/SpanNames.h>
+
+namespace xrpl {
+namespace telemetry {
+namespace tx_span {
+
+// ===== Span prefixes =======================================================
+
+namespace prefix {
+/// "tx" — root prefix for transaction lifecycle spans.
+inline constexpr auto tx = seg::tx;
+}  // namespace prefix
+
+// ===== Span operation suffixes =============================================
+
+namespace op {
+inline constexpr auto receive = makeStr("receive");
+inline constexpr auto process = makeStr("process");
+}  // namespace op
+
+// ===== Attribute keys ======================================================
+
+namespace attr {
+inline constexpr auto xrplTx = join(seg::xrpl, seg::tx);
+
+/// "xrpl.tx.hash"
+inline constexpr auto hash = join(xrplTx, makeStr("hash"));
+/// "xrpl.tx.local"
+inline constexpr auto local = join(xrplTx, makeStr("local"));
+/// "xrpl.tx.path"
+inline constexpr auto path = join(xrplTx, makeStr("path"));
+/// "xrpl.tx.suppressed"
+inline constexpr auto suppressed = join(xrplTx, makeStr("suppressed"));
+/// "xrpl.tx.status"
+inline constexpr auto status = join(xrplTx, makeStr("status"));
+
+inline constexpr auto xrplPeer = join(seg::xrpl, seg::peer);
+
+/// "xrpl.peer.id"
+inline constexpr auto peerId = join(xrplPeer, makeStr("id"));
+/// "xrpl.peer.version"
+inline constexpr auto peerVersion = join(xrplPeer, makeStr("version"));
+}  // namespace attr
+
+// ===== Attribute values ====================================================
+
+namespace val {
+inline constexpr auto sync = makeStr("sync");
+inline constexpr auto async = makeStr("async");
+inline constexpr auto knownBad = makeStr("known_bad");
+}  // namespace val
+
+}  // namespace tx_span
+}  // namespace telemetry
+}  // namespace xrpl