feat(feign-10.8): toolkit-generated feign HTTP client instrumentation [DO NOT MERGE]

[jordan-wong]

Summary

Toolkit-generated greenfield instrumentation for Feign HTTP client v10.8+. Supersedes #10855 (Feign 8.0, stale) and closed #10980 (Feign 10.8, never independently verified under current methodology).

Generated module

dd-java-agent/instrumentation/feign/feign-10.8-generated/

• FeignClientInstrumentation (sync Client.execute)
• FeignAsyncClientInstrumentation (async AsyncClient.execute)
• FeignClientDecorator extends HttpClientDecorator
• RequestHeaderInjectAdapter (header injection for distributed tracing)
• SpanFinishingCallback (async future completion handler)
• Java tests with JUnit 5 (no Groovy — per R20)

Run details

Toolkit branch	eval/java @ 757979b9
Workflow	new_integration (default)
Maven coordinates	io.github.openfeign:feign-core:10.8
Cost	$26.95
Duration	78 min
Reviewer verdict	approved=True, todos_fixed=2, todos_remaining=0

Research integrity disclosure

metadata/supported-configurations.json (4 entries: DD_TRACE_FEIGN_10_8_ENABLED, DD_TRACE_FEIGN_ANALYTICS_ENABLED, DD_TRACE_FEIGN_ANALYTICS_SAMPLE_RATE, DD_TRACE_FEIGN_ENABLED) was hand-added by the human operator AFTER the toolkit run. The toolkit's R29 rule that would produce these automatically was added later in the same session (commit 757979b9 on eval/java).

settings.gradle.kts line addition is a faithful replay of what the toolkit produced in the eval worktree.

Full caveats: see docs/eval-research/generated/feign-20260623/caveats.md in the apm-instrumentation-toolkit repo (eval/java branch).

Next steps

1. CI must pass on the new module (especially :check, :muzzle, :instrumentationLatestDepTest)
2. Domain expert review on RoutesInstrumentation — typo (please scrutinize sync vs async wrapping per R2, single-module rule per R3)
3. If green + approved: close [DRAFT] APM AI Toolkit: Add Feign HTTP client instrumentation (v8.0+) 2nd run with add-apm-integrations.md #10855 and eval: feign-core 10.8 instrumentation (skill v2, sync+async, Run #6) #10980 as superseded

🤖 Generated with Claude Code

[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	13.88 s	13.97 s	[-1.3%; +0.0%] (no difference)
startup:insecure-bank:tracing:Agent	12.90 s	13.00 s	[-1.7%; +0.1%] (no difference)
startup:petclinic:appsec:Agent	16.99 s	16.74 s	[+0.5%; +2.5%] (maybe worse)
startup:petclinic:iast:Agent	17.00 s	17.02 s	[-0.9%; +0.6%] (no difference)
startup:petclinic:profiling:Agent	16.85 s	16.98 s	[-1.9%; +0.5%] (no difference)
startup:petclinic:sca:Agent	17.02 s	16.76 s	[+0.3%; +2.7%] (maybe worse)
startup:petclinic:tracing:Agent	16.08 s	16.10 s	[-1.2%; +1.1%] (no difference)

Commit: 1aa95fef · CI Pipeline · Benchmarking Platform UI

---

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