fix(telemetry): address review findings and PR #6437 comments

Critical fixes:
- Restore accidentally removed mallocTrim call and MallocTrim.h include
- Add missing shouldTraceLedger() to interface and all implementations
- Derive networkId/networkType from config_->NETWORK_ID (0=mainnet,
  1=testnet, 2=devnet) instead of leaving defaults unpopulated
- Clamp sampling_ratio to [0.0, 1.0] in config parser

PR comment fixes:
- Rename rippled -> xrpld in service name defaults, getTracer() calls,
  Docker network, comments, and docs/build/telemetry.md
- Remove exporter config option (only otlp_http supported)
- Add trace_ledger and service_name to example config
- Clarify head-based sampling semantics in config comments
- Add filter descriptions for span intrinsic filters in Grafana datasource
- Add inline comments to Docker Compose services

Docker/config improvements:
- Remove deprecated version: "3.8" from docker-compose.yml
- Pin images: collector 0.121.0, grafana 11.5.2
- Add health_check extension to otel-collector-config.yaml
- Comment out Tempo metrics_generator remote_write (no Prometheus service)
- Add Prometheus datasource caveat in Grafana datasource config

Other:
- Revert unrelated formatting changes in ServiceRegistry.h
- Change Conan telemetry default to False (matches CMake OFF)
- Add CLAUDE.md-required docs (ASCII diagrams, usage examples,
  @note thread-safety) to Telemetry.h and SpanGuard.h

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

src/libxrpl/telemetry/NullTelemetry.cpp

@@ -76,6 +76,12 @@ public:
         return false;
     }
 
+    bool
+    shouldTraceLedger() const override
+    {
+        return false;
+    }
+
 #ifdef XRPL_ENABLE_TELEMETRY
     opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer>
     getTracer(std::string_view) override

src/libxrpl/telemetry/Telemetry.cpp

@@ -93,6 +93,12 @@ public:
         return false;
     }
 
+    bool
+    shouldTraceLedger() const override
+    {
+        return false;
+    }
+
     opentelemetry::nostd::shared_ptr<trace_api::Tracer>
     getTracer(std::string_view) override
     {
@@ -241,6 +247,12 @@ public:
         return setup_.tracePeer;
     }
 
+    bool
+    shouldTraceLedger() const override
+    {
+        return setup_.traceLedger;
+    }
+
     opentelemetry::nostd::shared_ptr<trace_api::Tracer>
     getTracer(std::string_view name) override
     {
@@ -252,7 +264,7 @@ public:
     opentelemetry::nostd::shared_ptr<trace_api::Span>
     startSpan(std::string_view name, trace_api::SpanKind kind) override
     {
-        auto tracer = getTracer("rippled");
+        auto tracer = getTracer("xrpld");
         trace_api::StartSpanOptions opts;
         opts.kind = kind;
         return tracer->StartSpan(std::string(name), opts);
@@ -264,7 +276,7 @@ public:
         opentelemetry::context::Context const& parentContext,
         trace_api::SpanKind kind) override
     {
-        auto tracer = getTracer("rippled");
+        auto tracer = getTracer("xrpld");
         trace_api::StartSpanOptions opts;
         opts.kind = kind;
         opts.parent = parentContext;

src/libxrpl/telemetry/TelemetryConfig.cpp

@@ -9,23 +9,49 @@
 
 #include <xrpl/telemetry/Telemetry.h>
 
+#include <algorithm>
+
 namespace xrpl {
 namespace telemetry {
 
+namespace {
+
+/** Derive a human-readable network type label from the numeric network ID.
+    @param networkId  The network identifier from [network_id] config.
+    @return "mainnet", "testnet", "devnet", or "unknown" for other values.
+*/
+std::string
+networkTypeFromId(std::uint32_t networkId)
+{
+    switch (networkId)
+    {
+        case 0:
+            return "mainnet";
+        case 1:
+            return "testnet";
+        case 2:
+            return "devnet";
+        default:
+            return "unknown";
+    }
+}
+
+}  // namespace
+
 Telemetry::Setup
 setup_Telemetry(
     Section const& section,
     std::string const& nodePublicKey,
-    std::string const& version)
+    std::string const& version,
+    std::uint32_t networkId)
 {
     Telemetry::Setup setup;
 
     setup.enabled = section.value_or<int>("enabled", 0) != 0;
-    setup.serviceName = section.value_or<std::string>("service_name", "rippled");
+    setup.serviceName = section.value_or<std::string>("service_name", "xrpld");
     setup.serviceVersion = version;
     setup.serviceInstanceId = section.value_or<std::string>("service_instance_id", nodePublicKey);
 
-    setup.exporterType = section.value_or<std::string>("exporter", "otlp_http");
     setup.exporterEndpoint =
         section.value_or<std::string>("endpoint", "http://localhost:4318/v1/traces");
 
@@ -33,12 +59,16 @@ setup_Telemetry(
     setup.tlsCertPath = section.value_or<std::string>("tls_ca_cert", "");
 
     setup.samplingRatio = section.value_or<double>("sampling_ratio", 1.0);
+    setup.samplingRatio = std::clamp(setup.samplingRatio, 0.0, 1.0);
 
     setup.batchSize = section.value_or<std::uint32_t>("batch_size", 512u);
     setup.batchDelay =
         std::chrono::milliseconds{section.value_or<std::uint32_t>("batch_delay_ms", 5000u)};
     setup.maxQueueSize = section.value_or<std::uint32_t>("max_queue_size", 2048u);
 
+    setup.networkId = networkId;
+    setup.networkType = networkTypeFromId(networkId);
+
     setup.traceTransactions = section.value_or<int>("trace_transactions", 1) != 0;
     setup.traceConsensus = section.value_or<int>("trace_consensus", 1) != 0;
     setup.traceRpc = section.value_or<int>("trace_rpc", 1) != 0;

src/xrpld/app/main/Application.cpp

@@ -31,6 +31,7 @@
 #include <xrpld/shamap/NodeFamily.h>
 
 #include <xrpl/basics/ByteUtilities.h>
+#include <xrpl/basics/MallocTrim.h>
 #include <xrpl/basics/ResolverAsio.h>
 #include <xrpl/basics/random.h>
 #include <xrpl/beast/asio/io_latency_probe.h>
@@ -265,7 +266,8 @@ public:
                   telemetry::setup_Telemetry(
                       config_->section("telemetry"),
                       "",  // Updated later via setServiceInstanceId()
-                      BuildInfo::getVersionString()),
+                      BuildInfo::getVersionString(),
+                      config_->NETWORK_ID),
                   logs_->journal("Telemetry")))
 
         , m_txMaster(*this)
@@ -1075,6 +1077,8 @@ public:
                                     << "; size after: " << cachedSLEs_.size();
         }
 
+        mallocTrim("doSweep", m_journal);
+
         // Set timer to do another sweep later.
         setSweepTimer();
     }