[AI discovered CI] Run Tests in Helix: PackageInstall work item fails on release/8.0.1xx

## Build Information

- Current build: [20260902.16 / 1579289](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1579289)
- Branch: `refs/heads/release/8.0.1xx`
- Failing task/work item: `Run Tests in Helix` / `Microsoft.DotNet.PackageInstall.Tests.dll.2`
- Phase: `environment-setup`
- Failure type: `tool-execution-error`
- Evidence sources: `azure-timeline`, `azure-task-log`
- Matching prior build: [20260818.38 / 1558381](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1558381)
- **Failure fingerprint:** `environment-setup|tool-execution-error|run-tests-in-helix|.packages-microsoft.dotnet.helix.sdk-..-beta..-tools-microsoft.dotnet.helix.sdk.multiqueue.targets---error-netcore_engineering_telemetry-test-work-item-microso`

## Failure History

At least 2 independent release-branch builds show the same stable failure signature: 1579289 (2026-09-02) and 1558381 (2026-08-18). The supplied recent-build sequence contains failures on all listed runs; no passing comparison run is included, so the pass/fail boundary and onset are unknown. This is recurrence of the observed work-item failure, not proof of a particular root cause.

## Error Details

Exact current excerpt:

```
.packages\microsoft.dotnet.helix.sdk\8.0.0-beta.26411.4\tools\Microsoft.DotNet.Helix.Sdk.MultiQueue.targets(89,5): error : (NETCORE_ENGINEERING_TELEMETRY=Test) Work item Microsoft.DotNet.PackageInstall.Tests.dll.2 in job has failed.
Failure log: https://helix.dot.net/api/2019-06-17/jobs//workitems/Microsoft.DotNet.PackageInstall.Tests.dll.2/console
```

The collector reported the Azure DevOps test-runs endpoint as unavailable (404), so named test assertion results and any work-item exit code, dump, or result artifact are unavailable in this dossier.

## Root Cause Analysis

**Observed:** The SDK release-branch build fails in the Helix wrapper after `Microsoft.DotNet.PackageInstall.Tests.dll.2` reports failed; the same work item failure is present in at least one independent prior build.

**Assessment:** The proximate cause is a failed Helix PackageInstall test work item surfaced by `MultiQueue.targets`. The evidence does not establish whether the failure is a PackageInstall test defect, test-environment/setup problem, or Helix execution issue. The generic `Run Tests in Helix` parent failure is only a consequence, and no artifact-download cascade is present.

**Confidence:** Medium for recurrence and the proximate failure location; Low for the underlying cause.

**Alternatives / Unknowns:** The Helix console may identify a deterministic test assertion, timeout/crash, dependency/setup failure, or machine/service issue. The current evidence lacks the console contents, exit code, dump/result links, target-branch comparison, and changed-file correlation.

## Suggested Investigation

1. Retrieve and inspect the Helix console and result artifacts for `Microsoft.DotNet.PackageInstall.Tests.dll.2` in builds 1579289 and 1558381, including exit code and dumps if present; compare the first failing operation.
2. Compare the failing work item with a passing PackageInstall work item from the same test scope and inspect the associated test logs and environment setup.
3. Check target-branch/build progression and changed-file correlation around the first observed failure to distinguish an SDK regression from a persistent Helix/test-environment problem.
4. If the console identifies an SDK-owned assertion or deterministic setup error, file/fix at that specific component; otherwise route a broad Helix or machine-pool outage to `dotnet/dnceng`.

> Generated by [🕵️ CI Quality Investigator](https://github.com/dotnet/sdk/actions/runs/33682044170) · gpt56 · 1.21 AIC · ⌖ 0.847 AIC · ⊞ 29.6K · [◷](https://github.com/search?q=repo%3Adotnet%2Fsdk+is%3Aissue+%22gh-aw-workflow-call-id%3A+dotnet%2Fsdk%2Fci-quality-monitor%22&type=issues)