[AI discovered CI] dotnet-new integration tests hang on Linux Helix work item

## Build Information

- **Current build:** [20260908.19](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1587590)
- **Branch:** `refs/heads/main`
- **Failing task/test:** `dotnet-new.IntegrationTests.dll.1` on `Linux x64 - ubuntu.2204.amd64.open`; active test `FeaturesSupport ("console",True,"net8.0","11",False,null,True,True,False,True,True)`
- **Phase:** `test-execution`
- **Failure type:** `timeout`
- **Evidence sources:** `helix-console`, `process-exit-code`, `helix-trx`, `helix-dump`
- **Matching prior build:** [1582866](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1582866)
- **Failure fingerprint:** `test-execution|timeout|dotnet-new.integrationtests.dll.|hang-dump-timeout-of----expired-the-following-tests-were-still-running-when-dump-was-taken-format---test-host-crashed-recovered--test-re`

## Failure History

The stable hang mechanism occurs in 2 independent main-branch builds in the supplied evidence: current build 1587590 and build 1582866. The surrounding sequence includes passes 1583020, 1585309, 1586765, and 1587367; the intervening failures 1583447, 1583620, 1585595, and 1585903 have different mechanisms. This establishes recurrence of the work-item hang, not its underlying cause.

## Error Details

```
Hang dump timeout of '00:48:00' expired
The following tests were still running when dump was taken (format: [] ):
Test host crashed; recovered 175 test result(s) from the TRX streaming sidecar (additional results that were in flight at crash time may be missing).
Test application process did not exit gracefully, exit code is '137'
[00:48:00] FeaturesSupport ("console",True,"net8.0","11",False,null,True,True,False,True,True)
```

- **Exit code:** 137 for the test application; Helix work item exit code 7.
- **Console:** [current console](https://helix.dot.net/api/jobs/9012074a-342b-431e-ab66-59a64abdf2ff/workitems/dotnet-new.IntegrationTests.dll.1/files/console.8d28e996.log?api-version=2019-06-17)
- **Dump:** [current hang dump](https://helix.dot.net/api/jobs/9012074a-342b-431e-ab66-59a64abdf2ff/workitems/dotnet-new.IntegrationTests.dll.1/files/dotnet_103635_hang.dmp?api-version=2019-06-17)
- **TRX:** [current results](https://helix.dot.net/api/jobs/9012074a-342b-431e-ab66-59a64abdf2ff/workitems/dotnet-new.IntegrationTests.dll.1/files/dotnet-new.IntegrationTests_net11.0_x64.trx?api-version=2019-06-17)

## Root Cause Analysis

**Observed:** The Linux dotnet-new test host remained active until the 48-minute blame hang-dump threshold while `FeaturesSupport` was still running. The host was terminated after the dump, and the sidecar recovered 175 results (172 passed, no completed test failures).

**Assessment:** This is a recurring SDK-owned integration-test work-item hang. The evidence establishes the timeout and process termination, but not what blocked the active test or host. The generic `Monitor Helix Jobs` failure is a downstream report, not the cause, and no artifact-download cascade is implicated.

**Confidence:** Medium for recurrence of the hang mechanism; Low for the underlying cause.

**Alternatives / Unknowns:** The active template operation, test-host synchronization, child `dotnet` process, package/feed operation, or Linux resource condition could be responsible. The dossier does not distinguish among them, and it does not establish a product regression or a safe retry.

## Suggested Investigation

1. Analyze the current hang dump and console, then compare the blocked stacks and child processes with build 1582866.
2. Inspect the `dotnet-new` integration-test implementation and template/package operations used by `FeaturesSupport`; rerun the affected work item on the same Linux queue and compare with the target branch.
3. Correlate the two failing commits with changed files and build progression before attributing the hang to an SDK change or environment condition.

> Generated by [🕵️ CI Quality Investigator](https://github.com/dotnet/sdk/actions/runs/34269688947) · gpt56 · 2.37 AIC · ⌖ 0.718 AIC · ⊞ 41.4K · [◷](https://github.com/search?q=repo%3Adotnet%2Fsdk+is%3Aissue+%22gh-aw-workflow-call-id%3A+dotnet%2Fsdk%2Fci-quality-monitor%22&type=issues)