feat(otlp): decode trace semantic core registry updates

[webern]

Human Summary

This PR adds the decoder for traces remote config semantic registry and wires it into the SemanticRegistryProvider that landed in the previous PR.

AI Summary

#2718 gives OTLP trace translation and APM stats a SemanticRegistryProvider. The provider can read a published registry or use the embedded default, but #2718 alone has no production subscription to publish remote registries. This PR supplies the missing APM_SEMANTIC_CORE_DD product decoder and a SemanticRegistryProvider::subscribe(&client) entry point. It does not construct that subscription during ADP startup; #2724 does that.

A registry JSON document describes one complete set of concept-to-attribute mappings, not a patch. #2718's parser handles one document. Here, SemanticCoreDecoder implements the RC client's ProductDecoder contract: it receives the set of configuration files currently assigned to this product, parses each file, selects a registry, and lets the RC client publish the selected snapshot to provider handles. No extra registry store or applier worker sits between the subscription and its readers.

• With no file assigned (including removal), the decoder selects the embedded registry. If several are assigned, the last valid file in ID order wins and a warning records the unexpected multiplicity. Each valid file gets an acknowledgement; invalid files get an error. If none is valid, the assignment is rejected and the subscription retains its last accepted registry.
• Remote documents retain supported concepts and fallbacks even when some entries are unknown; a warning reports skipped entries. Errors sent back to the Agent do not quote payload contents.
• Tests drive the decoder and subscription with a test publisher, including replacement, removal, rejection, and updated mappings reaching the OTLP source and decoder. Until feat(adp): apply trace products from remote configuration #2724 supplies a subscribed provider (when semantic RC is enabled), production uses embedded mappings.

Change Type

• New feature

How did you test this PR?

• make fmt, cargo check --workspace, cargo check --workspace --tests, make check-docs, make check-clippy at the stack tip.
• Filtered saluki-components tests: 549 passed at the stack tip.

References

• Progresses: Traces(otlp+dd): Apply semantic registry updates from remote config #2433
• Related: feat(remote-config): add a remote configuration client #2713, feat(otlp): semantic registry provider for embedded or live registries #2718

[pr-commenter]

Binary Size Analysis (Agent Data Plane)

Baseline: 216e499 · Comparison: f49a2a4 · diff
Analysis Configuration: stripped binaries · Pass/Fail Threshold: +5%
Sizes: 38.27 MiB (baseline) vs 38.25 MiB (comparison)
Size Change: -18.73 KiB (-0.05%)

✅ Binary size difference within threshold

Changes by Module

Module	File Size	Symbols
core	+48.83 KiB	8966
tracing	-27.40 KiB	9
&mut serde_json	-24.53 KiB	91
saluki_metrics::mapped::MappedMetric<H>	-24.51 KiB	6
saluki_components::destinations::dogstatsd_client_telemetry	+23.16 KiB	31
anon.7bcce2bce1d7289ca2b67a9dabbae1a7.13.llvm.8132447645249006792	+16.18 KiB	1
anon.87e7c38bfd928d17fa28187081c51bf0.2.llvm.240572210426274404	-16.09 KiB	1
axum	-15.72 KiB	415
quick_cache	+14.70 KiB	117
serde_json	+14.64 KiB	457
anon.87e7c38bfd928d17fa28187081c51bf0.768.llvm.240572210426274404	-14.62 KiB	1
anon.7bcce2bce1d7289ca2b67a9dabbae1a7.477.llvm.8132447645249006792	+14.62 KiB	1
saluki_common::task::instrument	+14.41 KiB	18
anon.7bcce2bce1d7289ca2b67a9dabbae1a7.6.llvm.8132447645249006792	+12.84 KiB	1
anon.87e7c38bfd928d17fa28187081c51bf0.766.llvm.240572210426274404	-12.84 KiB	1
anon.9d1057ec6821611763596b0232be6ef0.693.llvm.6678353967787269721	-11.13 KiB	1
prost	-11.03 KiB	321
std	-10.89 KiB	251
anon.abbd254abd65a42f7feba2865e83dd56.694.llvm.4730254534436041901	+10.86 KiB	1
agent_data_plane_config::domains::traces	+9.68 KiB	13

Detailed Symbol Changes

    FILE SIZE        VM SIZE    
 --------------  -------------- 
  [NEW] +59.8Ki  [NEW] +59.7Ki    saluki_components::common::datadog::io::run_endpoint_io_loop::_{{closure}}::ha38a49b72e023545
  [NEW] +42.4Ki  [NEW] +42.2Ki    _<saluki_components::forwarders::otlp::OtlpForwarder as saluki_core::components::forwarders::Forwarder>::run::_{{closure}}::hb872765f165820b0
  [NEW] +40.6Ki  [NEW] +40.5Ki    agent_data_plane::cli::run::create_topology::_{{closure}}::h75562c7ea09bcbff
  [NEW] +37.8Ki  [NEW] +37.6Ki    _<saluki_components::transforms::apm_stats::ApmStats as saluki_core::components::transforms::Transform>::run::_{{closure}}::h79ca62828ea1b270
  [NEW] +34.5Ki  [NEW] +34.4Ki    agent_data_plane::cli::run::handle_run_command::_{{closure}}::h0f7a307e9cc0a16a
  [NEW] +31.0Ki  [NEW] +30.8Ki    agent_data_plane::cli::dogstatsd::run_dogstatsd_command::_{{closure}}::hdfcd4810bc0a3053
  [NEW] +29.0Ki  [NEW] +28.8Ki    datadog_agent_commons::ipc::client::RemoteAgentClient::connect::_{{closure}}::_{{closure}}::_{{closure}}::h0a198a9356f00b58
  [NEW] +28.6Ki  [NEW] +28.5Ki    agent_data_plane::dogstatsd_contexts::artifact::for_each_record::h1b4e32864ddc5f08
  [NEW] +26.6Ki  [NEW] +26.4Ki    saluki_components::destinations::dogstatsd_client_telemetry::DogStatsDClientTelemetry::record_metric::h6e61a932a14c058b
  [NEW] +25.6Ki  [NEW] +25.4Ki    agent_data_plane::internal::remote_agent::run_remote_agent_registration_loop::_{{closure}}::h044bf8d66771780c
  [DEL] -25.6Ki  [DEL] -25.4Ki    agent_data_plane::internal::remote_agent::run_remote_agent_registration_loop::_{{closure}}::h1f55b7becb8f9961
  [DEL] -25.7Ki  [DEL] -25.6Ki    core::ops::function::FnOnce::call_once::h4d6ad556f476b8c9
  [DEL] -28.4Ki  [DEL] -28.2Ki    datadog_agent_commons::ipc::client::RemoteAgentClient::connect::_{{closure}}::_{{closure}}::_{{closure}}::h1bd6a026eeafe819
  [DEL] -28.7Ki  [DEL] -28.6Ki    agent_data_plane::dogstatsd_contexts::artifact::for_each_record::hb60d5262ffff75a0
  [DEL] -31.4Ki  [DEL] -31.2Ki    agent_data_plane::cli::dogstatsd::run_dogstatsd_command::_{{closure}}::h2f5246c806e7f392
  [DEL] -34.9Ki  [DEL] -34.7Ki    agent_data_plane::cli::run::handle_run_command::_{{closure}}::haa79196f741be08a
  [DEL] -35.8Ki  [DEL] -35.6Ki    _<saluki_components::transforms::apm_stats::ApmStats as saluki_core::components::transforms::Transform>::run::_{{closure}}::h8bffda5d06bacbfd
  [DEL] -40.5Ki  [DEL] -40.4Ki    agent_data_plane::cli::run::create_topology::_{{closure}}::h02ed82f16b54dbc0
  [DEL] -44.7Ki  [DEL] -44.5Ki    _<saluki_components::forwarders::otlp::OtlpForwarder as saluki_core::components::forwarders::Forwarder>::run::_{{closure}}::h252ca254b106e4c3
  -0.2% -20.4Ki  -0.5% -49.8Ki    [28882 Others]
  [DEL] -58.6Ki  [DEL] -58.5Ki    saluki_components::common::datadog::io::run_endpoint_io_loop::_{{closure}}::h15a965fc1b5a6f1e
  -0.0% -18.7Ki  -0.1% -48.2Ki    TOTAL

[pr-commenter]

Regression Detector (Agent Data Plane)

Run ID: 375eb543-a95f-4df8-b756-4ce40324151e
Baseline: 216e499a · Comparison: f49a2a4c · diff

Optimization Goals: ✅ No significant changes detected

Fine details of change detection per experiment (5)

Experiments configured erratic: true are tagged (ignored) and skipped when determining which experiments regressed or improved. Experiments which are detected as erratic at runtime are tagged (erratic) to flag that the run's sample dispersion was high, but their regression / improvement signal still counts.

experiment	goal	Δ mean %	links
quality_gates_rss_dsd_ultraheavy	memory	⚪ +0.52	metrics profiles logs
quality_gates_rss_dsd_heavy	memory	⚪ +0.48	metrics profiles logs
quality_gates_rss_dsd_medium	memory	⚪ +0.36	metrics profiles logs
quality_gates_rss_dsd_low	memory	⚪ -0.31	metrics profiles logs
quality_gates_rss_idle	memory	⚪ -0.82	metrics profiles logs

Bounds Checks: ✅ Passed (5)

experiment	check	replicates	observed	links
quality_gates_rss_dsd_heavy	memory_usage	10/10	✅ 228 MiB ≤ 250 MiB	metrics profiles logs
quality_gates_rss_dsd_low	memory_usage	10/10	✅ 51 MiB ≤ 60 MiB	metrics profiles logs
quality_gates_rss_dsd_medium	memory_usage	10/10	✅ 90.5 MiB ≤ 100 MiB	metrics profiles logs
quality_gates_rss_dsd_ultraheavy	memory_usage	10/10	✅ 380 MiB ≤ 420 MiB	metrics profiles logs
quality_gates_rss_idle	memory_usage	10/10	✅ 33.1 MiB ≤ 40 MiB	metrics profiles logs

Explanation

A change is flagged as a regression when |Δ mean %| > 5.00% in the regressing direction for its optimization goal AND SMP marks the experiment as a regression (is_regression: true). Improvements use the matching criteria for the improving direction. Experiments configured erratic: true (tagged (ignored)) are skipped outright; experiments detected as erratic at runtime (tagged (erratic)) still count, since that flag describes sample dispersion rather than directional certainty. The Δ mean % cell is colored accordingly: 🟢 = improvement, 🔴 = regression, ⚪ = neutral. Reduction in CPU or memory is an improvement; reduction in ingress throughput is a regression. Experiments tagged (no analysis) show ⚠️ n/a: SMP ran them but produced no analysis, usually because a replicate failed and exhausted its retries. Check the SMP report for that experiment's replicate failures.

[datadog-official]

More details

The decoder correctly handles registry replacement, removal, partial rejection, deterministic selection, and retention of the last accepted registry.

Was this helpful? React 👍 or 👎

_{Open Bits AI session}

_{🤖 Bits Code Review · Commit f49a2a4 · @DataDog review to ask questions}