[ci-scan-feedback] Add build-break invariant-phrase dedup variation to KBE authoring #132700

Triggering signals

• [ci-scan] Build break: PALTests Send-to-Helix fails with SYSTEM_ACCESSTOKEN variable not found #132545, [ci-scan] Build break: PALTests Send to Helix fails with SYSTEM_ACCESSTOKEN variable not found on runtime-coreclr outerloop #132560, [ci-scan] Build break: PALTests Send job to Helix fails with SYSTEM_ACCESSTOKEN variable not found #132614, [ci-scan] Build break: PALTests Send job to Helix fails with SYSTEM_ACCESSTOKEN variable not found #132648, [ci-scan] Build break: PALTests Send to Helix fails with SYSTEM_ACCESSTOKEN variable not found #132656 — the same PAL-tests SYSTEM_ACCESSTOKEN "Send-to-Helix" build break filed 5× over three days under drifting titles ("Send-to-Helix" / "Send to Helix" / "Send job to Helix"). Rubric finding: build breaks carry no test name, so dedup variations 1–7 (all keyed on a test/assertion) never match. (#132545)
• [ci-scan] Build break: Mono AOT compile of JIT.Generics_ro fails with recursive/invalid generic instantiation on linux-x64 MiniF [Content truncated due to length] #132559, [ci-scan] Build break: Mono FullAOT recursive type definition in JIT.Generics_ro (chaos65204782cs) #132647 — Mono AOT JIT.Generics_ro recursive-generic build break filed 2× under drifting leg descriptors, same root cause as above. (#132559)
• Scanner quality rubric: scan_wrong_rate_30d = 10/35 = 29% 🔴, duplicate-dominated (9 of 10 wrong closures are duplicate), plus 7 open build-break dupes still outstanding.
• Prior tick proposed this dedup edit but it was never landed (no merged PR; [ci-scan-feedback] Add build-break dedup search variation to KBE authoring #132669 is a tracking issue only), so the storm grew.

Proposed edits

• .github/workflows/shared/create-kbe.instructions.md:65-88 — add dedup search variation 8: for build breaks (no test name), search on the invariant error phrase with variable tokens stripped + the leg root; on match record existing-kbe #<n>, otherwise skipped: build-break dup #<n>, needs human review when the leg root is unconfirmed. Rationale: closes the gap that lets SYSTEM_ACCESSTOKEN / JIT.Generics_ro re-file under drifting titles.
• .github/workflows/ci-failure-scan.md:309,357 — add build-break dup #<n>, needs human review to the Step 5 recorded-outcomes list and the Step 6 Recognized skip-reason values so the new variation's tally row stays in-vocabulary.

Expected behavior change

The next scanner run that re-encounters a build break already filed as a KBE will match it via the invariant-phrase search even though the title/leg prose has drifted and there is no test name to key on, recording existing-kbe #<n> (or a bounded build-break dup skip when the leg root is unconfirmed) instead of opening yet another duplicate — collapsing the SYSTEM_ACCESSTOKEN/JIT.Generics_ro re-file storms and lowering the duplicate-driven 29% wrong-closure rate.

Generated by CI Outer-Loop Failure Scanner — Feedback · opus48 · 520.5 AIC · ⌖ 26.5 AIC · ⊞ 20.6K · ◷

To create a pull request with the changes:

# Download the artifact from the workflow run
gh run download 32731248384 -n agent -D /tmp/agent-32731248384

# Fetch the bundle into a temporary ref, then update the local branch
git fetch /tmp/agent-32731248384/aw-ci-scan-feedback-buildbreak-dedup-2026-08-24.bundle refs/heads/ci-scan-feedback-buildbreak-dedup-2026-08-24:refs/bundles/create-pr-ci-scan-feedback-buildbreak-dedup-2026-08-24-f0e3eef11fcf8708-d24c1a3c
git update-ref refs/heads/ci-scan-feedback-buildbreak-dedup-2026-08-24-f0e3eef11fcf8708 refs/bundles/create-pr-ci-scan-feedback-buildbreak-dedup-2026-08-24-f0e3eef11fcf8708-d24c1a3c
git checkout ci-scan-feedback-buildbreak-dedup-2026-08-24-f0e3eef11fcf8708
# 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-buildbreak-dedup-2026-08-24-f0e3eef11fcf8708-d24c1a3c

# Push the branch to origin
git push origin ci-scan-feedback-buildbreak-dedup-2026-08-24-f0e3eef11fcf8708

# Create the pull request
gh pr create --title '[ci-scan-feedback] Add build-break invariant-phrase dedup variation to KBE authoring' --base main --head ci-scan-feedback-buildbreak-dedup-2026-08-24-f0e3eef11fcf8708 --repo dotnet/runtime