feat(openfeature): add direct flagevaluation fallback

[leoromanovsky]

Motivation

The base PR gives exposure events direct EVP capability. Agentless Feature Flags also need direct EVP capability for aggregate flagevaluation events when no compatible local receiver exists.

flowchart TD
    A[Agentless Feature Flags] --> E[Exposure writer from PR 12195]
    A --> F[Flagevaluation writer in this PR]
    E --> ER{Compatible local EVP route?}
    F --> FR{Compatible local EVP route?}
    ER -->|Yes| L[Local EVP proxy]
    FR -->|Yes| L
    ER -->|No, API key available| DE[Direct EVP<br/>/api/v2/exposures]
    FR -->|No, API key available| DF[Direct EVP<br/>/api/v2/flagevaluation]
    L --> P[Event Platform]
    DE --> P
    DF --> P

Loading

Changes and Decisions

This stacked PR retains direct EVP exposure delivery from PR #12195 and adds direct EVP flagevaluation delivery.

• Use one Feature Flag transport selector for both exposures and flagevaluations.
• Preserve exposure response compression and disable response compression for flagevaluations.
• Prefer a compatible local EVP proxy for both event types.
• Use authenticated direct EVP intake when no compatible local route exists.
• Switch from local to direct intake only after connection refusal or HTTP 403, 404, or 405.
• Do not replay after timeouts, resets, rate limits, or server errors. This prevents possible duplicate events.
• Keep /api/v2/exposures and /api/v2/flagevaluation as separate direct routes.
• Cover the shared fallback behavior for both event routes.

[datadog-official]

🎯 Code Coverage (details)
• Patch Coverage: 92.75%
• Overall Coverage: 60.42% (+2.01%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 9b8d758 | Docs | View more details | Give us feedback!}

[dd-octo-sts]

🟢 Java Benchmark SLOs — All performance SLOs passed

Suite	Status
Startup	🟢 pass

SLO thresholds are defined here based on automatically generated metrics. A warning is raised when results are within 5% of the threshold.

PR vs. master results

Scenario	Candidate	master	Δ (95% CI of mean)
startup:insecure-bank:iast:Agent	14.87 s	14.69 s	[+0.2%; +2.3%] (maybe worse)
startup:insecure-bank:tracing:Agent	13.71 s	13.66 s	[-0.4%; +1.2%] (no difference)
startup:petclinic:appsec:Agent	17.42 s	17.38 s	[-0.5%; +0.9%] (no difference)
startup:petclinic:iast:Agent	17.37 s	17.52 s	[-1.6%; -0.0%] (maybe better)
startup:petclinic:profiling:Agent	17.41 s	16.53 s	[+0.9%; +9.7%] (maybe worse)
startup:petclinic:sca:Agent	17.42 s	17.16 s	[+0.3%; +2.7%] (maybe worse)
startup:petclinic:tracing:Agent	16.52 s	16.73 s	[-2.1%; -0.4%] (maybe better)

Commit: 9b8d7589 · CI Pipeline · Benchmarking Platform UI

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Load and DaCapo benchmarks can be triggered manually in the GitLab pipeline. Results will appear in the Benchmarking Platform UI after completion.

[datadog-official]

Direct flag-evaluation delivery still negotiates gzip because IntakeApi leaves Accept-Encoding unset when compression is disabled, allowing OkHttp to add gzip automatically. This defeats the explicit no-compression contract on every new direct or fallback route, although the local EVP path correctly sends identity.

_{Open Bits AI session}

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[dd-octo-sts]

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[sarahchen6]

A few small clean-up comments, but otherwise looks good!

[datadog-official]

Ambiguously accepted batches can still be replayed directly through internal HTTP retries or exposure-buffer reuse. Agentless activation can also retain an exposure worker that exits immediately afterward, disabling delivery.

_{Open Bits AI session}

_{🤖 Datadog Autotest · Commit 6616b0c · What is Autotest? · @DataDog review to ask questions · Any feedback? Reach out in #autotest}

[dd-octo-sts]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-08-18 21:51:46 UTC ℹ️ Start processing command /merge

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2026-08-18 21:51:51 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in master is approximately 2h (p90).

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2026-08-18 22:48:35 UTC ℹ️ MergeQueue: This merge request was merged