[ci-scan-feedback] Add build-break dedup search variation to KBE authoring #132669

Triggering signals

• Scanner re-filed the same PALTests Send-to-Helix SYSTEM_ACCESSTOKEN variable not found build break as 5 separate open KBEs over 3 days: #132545, #132560, #132614, #132648, #132656. Titles drift across runs ("Send to Helix" / "Send job to Helix" / "Send-to-Helix"), defeating in:title prose matching.
• Same pattern for the Mono AOT recursive-generic break: #132559 and #132647 both file JIT.Generics_ro AOT-compile failure under differently-worded titles.
• Scanner 30d closure cohort: 10 of 34 closures wrong (29%), 9 of them duplicate ([ci-scan] Test failure: System.Net.Security.Tests.TlsSessionTests.SslStreamServer_RejectsClientCert_ClientObservesAlert on Nativ [Content truncated due to length] #131368, [ci-scan] Test failure: baseservices/threading/regressions/2164/foreground-shutdown fails Expected 100 Actual 101 on R2R #131418, [ci-scan] Build break: NativeAOT ILC assertion resumedUseArg in importercalls.cpp during Morph - Inlining #131742, [ci-scan] Test failure: GC/API/GC/GetGeneration/GetGeneration.dll fails under interpreter on osx-arm64 #131743, [ci-scan] Test failure: JIT/Methodical/Arrays/misc/arrres_il_r crashes (abort, exit 134) #131744, [ci-scan] Test failure: Loader/ContextualReflection asserts OBJECTREF in preemptive GC mode on browser-wasm interpreter #131980, [ci-scan] Test failure: GC/API/Refresh/Refresh/Refresh fails on gc-standalone (exit 101) #131998, [ci-scan] Build break: ILC KeyNotFoundException in RuntimeFieldHandleNode.GetDehydratableData compiling NativeAOT tests #132392, [ci-scan] NativeAOT ILC crash: KeyNotFoundException in RuntimeFieldHandleNode.GetDehydratableData (Directed_r/Directed_d, exit 1 [Content truncated due to length] #132516). This is a dedup failure, not triage noise — build-break signatures have no test name or assertion, so existing "Search for an existing KBE" variations 1–7 (all test-name/assertion-keyed) never fire.

Proposed edits

• .github/workflows/shared/create-kbe.instructions.md (## Search for an existing KBE, new variation 8 after the bare-signature variation 7): add a build-break-specific dedup search keyed on the two stable tokens — the invariant error phrase (e.g. SYSTEM_ACCESSTOKEN, AOT'd assembly JIT.Generics_ro) and the Build error leg descriptor — searched in:body rather than relying on drifting title prose. Rationale: build breaks are exactly the signatures variations 1–7 miss.
• Same file (summary paragraph after the variations): one sentence documenting what variation 8 catches, matching the existing per-variation summary style.

Expected behavior change

The next scanner run will recognize a build break already filed under a differently-worded title as an existing-kbe hit (matching on error phrase + leg descriptor in:body) and record it instead of filing a fresh KBE — eliminating the SYSTEM_ACCESSTOKEN-style multi-day re-file storms that drove the 30d wrong-closure rate to 29%.

Generated by CI Outer-Loop Failure Scanner — Feedback · opus48 · 539.6 AIC · ⌖ 25.3 AIC · ⊞ 20.6K · ◷

To create a pull request with the changes:

# Download the artifact from the workflow run
gh run download 32641342962 -n agent -D /tmp/agent-32641342962

# Fetch the bundle into a temporary ref, then update the local branch
git fetch /tmp/agent-32641342962/aw-ci-scan-feedback-build-break-dedup.bundle refs/heads/ci-scan-feedback/build-break-dedup:refs/bundles/create-pr-ci-scan-feedback-build-break-dedup-88148e1bf6019fd2-5bc7bb8f
git update-ref refs/heads/ci-scan-feedback/build-break-dedup-88148e1bf6019fd2 refs/bundles/create-pr-ci-scan-feedback-build-break-dedup-88148e1bf6019fd2-5bc7bb8f
git checkout ci-scan-feedback/build-break-dedup-88148e1bf6019fd2
# Ensure the working tree matches the updated branch
git reset --hard
# Remove the temporary bundle ref
git update-ref -d refs/bundles/create-pr-ci-scan-feedback-build-break-dedup-88148e1bf6019fd2-5bc7bb8f

# Push the branch to origin
git push origin ci-scan-feedback/build-break-dedup-88148e1bf6019fd2

# Create the pull request
gh pr create --title '[ci-scan-feedback] Add build-break dedup search variation to KBE authoring' --base main --head ci-scan-feedback/build-break-dedup-88148e1bf6019fd2 --repo dotnet/runtime