feat(openfeature): send SDK identity on EVP requests

[vjfridge]

What does this PR do?

Adds request-level SDK identity headers to the OpenFeature EVP transport:

• DD-EVP-ORIGIN: dd-trace-go
• DD-EVP-ORIGIN-VERSION: internal/version.Tag

The payload format and existing EVP routing headers remain unchanged. A transport test captures the request and verifies the method, path, routing headers, SDK identity headers, and raw body.

Motivation

Implements FFL-3015 so flagevaluation requests carry the originating SDK name and release version through the Agent.

Testing

• go test ./openfeature
• go test -race ./openfeature
• go test ./openfeature -run '^TestEVPClientPostRawRequest$' -count=20

[datadog-prod-us1-4]

 

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⚠️ Warnings

❌ Your PR has failed checks. Please review the issues below and take necessary action before merging.

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ℹ️ Info

No other issues found (see more)

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 69.85% (+13.19%)

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[pr-commenter]

Benchmarks

Benchmark execution time: 2026-08-28 01:14:39

Comparing candidate commit 542671c in PR branch vickie/ffl-3015 with baseline commit 92a5cf3 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 335 metrics, 0 unstable metrics, 1 flaky benchmarks without significant changes.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

Known flaky benchmarks

These benchmarks are marked as flaky and will not trigger a failure. Modify FLAKY_BENCHMARKS_REGEX to control which benchmarks are marked as flaky.

Known flaky benchmarks without significant changes:

• scenario:BenchmarkOTLPTraceWriterFlush

[vjfridge]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 🎉

Reviewed commit: 542671c406

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