refactor(telemetry): pull consensus-tracing scope-leak out of phase-3

Commit c6c019ed8b ("addressed code review comments") bundled tx-tracing
review fixes with consensus-tracing scaffolding that belongs on
pratik/otel-phase4-consensus-tracing (PR #6426). This commit lifts the
consensus-only parts back out of phase-3 so PR #6425 stays scoped to
transaction tracing. Phase-4 already carries the same content (via prior
phase-3 -> phase-4 merges) plus its own evolution on top, so nothing is
moved across — only removed here.

Removed:
  - src/xrpld/app/consensus/ConsensusSpanNames.h (deleted; phase-4 owns
    it).
  - PeerImp.cpp: revert onMessage(TMProposeSet)/onMessage(TMValidation)
    consensus-attr setAttribute calls to the hardcoded
    "xrpl.consensus.{trusted,round,ledger.seq}" strings used before
    c6c019ed8b. Drop the now-unused
    #include <xrpld/app/consensus/ConsensusSpanNames.h>.
  - RCLConsensus::Adaptor::validate(): remove the
    TODO(observability/secure-OTel) block on validation trace_context.
  - TraceContextPropagator.h: remove the TODO(observability/secure-OTel)
    block on injectToProtobuf().

Tx-tracing parts of c6c019ed8b are intentionally untouched.

No phase-3 caller of telemetry::consensus_span:: remains; verified via
git grep. No test on phase-3 references the removed header.

Signed-off-by: Pratik Mankawde <3397372+pratikmankawde@users.noreply.github.com>

include/xrpl/telemetry/TraceContextPropagator.h

@@ -91,14 +91,6 @@ injectToProtobuf(opentelemetry::context::Context const& ctx, protocol::TraceCont
 
     // Serialize flags
     proto.set_trace_flags(spanCtx.trace_flags().flags());
-
-    // TODO(observability/secure-OTel): the protobuf TraceContext message
-    // also carries `trace_state` (field 4), which is currently neither
-    // populated here nor read by extractFromProtobuf above. The field is
-    // reserved for the secure tracing pipeline outlined in
-    // OpenTelemetryPlan/secure-OTel.md, where an authenticated token in
-    // tracestate will let receivers reject spoofed/poisoned trace context.
-    // Wire trace_state through inject/extract once the consumer lands.
 }
 
 }  // namespace telemetry

src/xrpld/app/consensus/ConsensusSpanNames.h

@@ -1,67 +0,0 @@
-#pragma once
-
-/** Compile-time span name and attribute constants for consensus tracing.
- *
- *  Used by PeerImp (overlay) and RCLConsensus (consensus) for proposal
- *  and validation lifecycle spans. Built on StaticStr/join() from
- *  SpanNames.h and follows the rule-5 underscore form for shared
- *  cross-span attributes (e.g. `consensus_round`, `ledger_seq`).
- *
- *  Phase 3 introduces the receive-side surface used by PeerImp.
- *  Phase 4 will extend this with the proposer/validator-side spans
- *  (`consensus.proposal.send`, `consensus.validation.send`, round
- *  bookkeeping, etc.).
- *
- *  Span hierarchy (cross-node propagation):
- *
- *    Node A (sender)                       Node B (receiver)
- *    +----------------------------+        +-------------------------------+
- *    | consensus.proposal/...send |  proto | consensus.proposal/...receive |
- *    |  inject trace context      | -----> |  proposalReceiveSpan() /      |
- *    |  (RCLConsensus broadcast)  | t_ctx  |  validationReceiveSpan()      |
- *    +----------------------------+        +-------------------------------+
- */
-
-#include <xrpl/telemetry/SpanNames.h>
-
-namespace xrpl::telemetry::consensus_span {
-
-// ===== Span prefixes =======================================================
-
-namespace prefix {
-/// "consensus" — root prefix for consensus lifecycle spans.
-inline constexpr auto consensus = seg::consensus;
-/// "consensus.proposal" — proposal sub-tree.
-inline constexpr auto proposal = join(consensus, makeStr("proposal"));
-/// "consensus.validation" — validation sub-tree.
-inline constexpr auto validation = join(consensus, makeStr("validation"));
-}  // namespace prefix
-
-// ===== Span operation suffixes =============================================
-
-namespace op {
-inline constexpr auto receive = makeStr("receive");
-inline constexpr auto send = makeStr("send");
-}  // namespace op
-
-// ===== Full span names =====================================================
-
-inline constexpr auto proposalReceive = join(prefix::proposal, op::receive);
-inline constexpr auto validationReceive = join(prefix::validation, op::receive);
-
-// ===== Attribute keys ======================================================
-
-namespace attr {
-/// Canonical shared constants (defined in SpanNames.h).
-using ::xrpl::telemetry::attr::ledgerSeq;
-
-/// "trusted" — bare field; whether the proposing/validating node is
-/// in our UNL. Used only on consensus spans, no cross-domain collision.
-inline constexpr auto trusted = makeStr("trusted");
-
-/// "consensus_round" — propose-sequence within a consensus round
-/// (rule-5 underscore form, shared across consensus spans).
-inline constexpr auto round = makeStr("consensus_round");
-}  // namespace attr
-
-}  // namespace xrpl::telemetry::consensus_span

src/xrpld/app/consensus/RCLConsensus.cpp

@@ -898,15 +898,6 @@ RCLConsensus::Adaptor::validate(RCLCxLedger const& ledger, RCLTxSet const& txns,
     val.set_validation(serialized.data(), serialized.size());
     // Inject the current thread's active span context so receiving
     // peers can link their validation.receive span as a child.
-    //
-    // TODO(observability/secure-OTel): the trace_context appended below is
-    // outside the cryptographic signature on `serialized` and is therefore
-    // unauthenticated. Receivers cannot prove it was not tampered with by
-    // a relay. A signed trace context (either folded into the validation
-    // payload or carried by an authenticated trace_state token) is tracked
-    // as a follow-up — see PR #6425 discussion r3317273388 and
-    // OpenTelemetryPlan/secure-OTel.md. Until then, downstream consumers
-    // must treat the validation trace_context as advisory only.
 #ifdef XRPL_ENABLE_TELEMETRY
     {
         auto ctx = opentelemetry::context::RuntimeContext::GetCurrent();

src/xrpld/overlay/detail/PeerImp.cpp

@@ -1,6 +1,5 @@
 #include <xrpld/overlay/detail/PeerImp.h>
 
-#include <xrpld/app/consensus/ConsensusSpanNames.h>
 #include <xrpld/app/consensus/RCLCxPeerPos.h>
 #include <xrpld/app/consensus/RCLValidations.h>
 #include <xrpld/app/ledger/InboundLedgers.h>
@@ -1979,9 +1978,8 @@ PeerImp::onMessage(std::shared_ptr<protocol::TMProposeSet> const& m)
     // Create a receive span that links to the sender's trace context
     // (if propagated). shared_ptr keeps it alive across the job boundary.
     auto span = std::make_shared<telemetry::SpanGuard>(telemetry::proposalReceiveSpan(set));
-    span->setAttribute(telemetry::consensus_span::attr::trusted, isTrusted);
-    span->setAttribute(
-        telemetry::consensus_span::attr::round, static_cast<int64_t>(set.proposeseq()));
+    span->setAttribute("xrpl.consensus.trusted", isTrusted);
+    span->setAttribute("xrpl.consensus.round", static_cast<int64_t>(set.proposeseq()));
 
     std::weak_ptr<PeerImp> const weak = shared_from_this();
     app_.getJobQueue().addJob(
@@ -2565,11 +2563,11 @@ PeerImp::onMessage(std::shared_ptr<protocol::TMValidation> const& m)
         // Create a receive span that links to the sender's trace context
         // (if propagated). shared_ptr keeps it alive across the job boundary.
         auto span = std::make_shared<telemetry::SpanGuard>(telemetry::validationReceiveSpan(*m));
-        span->setAttribute(telemetry::consensus_span::attr::trusted, isTrusted);
+        span->setAttribute("xrpl.consensus.trusted", isTrusted);
         if (val->isFieldPresent(sfLedgerSequence))
         {
             span->setAttribute(
-                telemetry::consensus_span::attr::ledgerSeq,
+                "xrpl.consensus.ledger.seq",
                 static_cast<int64_t>(val->getFieldU32(sfLedgerSequence)));
         }