[mabdinur]

Motivation

Add coverage for the W3C Trace Context Level 2 trace flags, including the random trace ID flag.

Changes

• Check the sampled bit independently of the random bit using 00, 01, 02, and 03. Reserved-bit acceptance is outside this test's scope.
• Check random-flag preservation for all four sampled/random combinations, asserting the trace ID stays unchanged and the child span has a different parent ID.
• Check that new traces advertise randomness with sampling rates 0 and 1. This tests the specification's SHOULD recommendation; it does not statistically validate trace ID randomness.
• Keep unsupported random-flag behavior declared in the nine language manifests, including Rust rejecting 03 for version 00. These declarations still execute the tests and report expected failures. Enable propagation for Python from the verified 4.16.1 baseline; earlier versions may also support it.

The tests use the existing native Datadog header endpoints. No parametric application or framework changes are needed.

Validation

• ./format.sh: passed.
• Manifest and convention self-tests: 33 passed.
• Python 4.16.1: full Trace Context file validated; all four random-flag propagation combinations pass. New-trace randomness remains an expected failure.
• Node.js 7.0.0-pre: sampled-bit cases pass; random-flag generation and preservation of a set flag remain unsupported.
• Go 2.13.0-dev, final focused run: 4 passed, 4 expected failures, 2 expected passes. All four sampled/random flag combinations preserve the trace and sampling decision.
• Final CI run is green on 346b07e14: 407 successful checks and 74 intentionally skipped. The earlier Java OpenLiberty/JMX flake passed on the fresh run.

Reviewer checklist

• Test logic and specification interpretation reviewed by the feature owners.

[github-actions]

CODEOWNERS have been resolved as:

manifests/cpp.yml                                                       @DataDog/system-tests-reviewers
manifests/dotnet.yml                                                    @DataDog/system-tests-reviewers
manifests/golang.yml                                                    @DataDog/system-tests-reviewers
manifests/java.yml                                                      @DataDog/system-tests-reviewers
manifests/nodejs.yml                                                    @DataDog/system-tests-reviewers
manifests/php.yml                                                       @DataDog/system-tests-reviewers
manifests/python.yml                                                    @DataDog/system-tests-reviewers
manifests/ruby.yml                                                      @DataDog/system-tests-reviewers
manifests/rust.yml                                                      @DataDog/system-tests-reviewers
tests/parametric/test_headers_tracecontext.py                           @DataDog/system-tests-reviewers

[datadog-official]

 

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 346b07e | Docs | View more details | Give us feedback!}

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-06T16:33:12.655545Z	cb0b440	Draft marked ready

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