[ci-scan] Test failure: System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse

## Build Information
Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1586034
Build error leg or test failing: net11.0-osx-Debug-arm64-coreclr_checked-OSX.26.Arm64.Open - System.Net.WebSockets.Tests
Pull request: https://github.com/dotnet/runtime/pull/133361

KBE authoring guidance (ci-failure-scan)

- `Error Details` is for readers. The assertion and stack trace are included below so the failure is understandable without opening the raw log.
- Build Analysis parses only the JSON block under `Error Message`.
- `ErrorMessage` entries are case-sensitive ordinal `String.Contains` substrings copied verbatim from the failing log.
- `BuildRetry` is false because this is a recurring test failure rather than a clear infrastructure retry case.

## Error Details

```
System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse [FAIL]
Assert.Equal() Failure: Values differ
Expected: Aborted
Actual: Open
at System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse() in /_/src/libraries/System.Net.WebSockets/tests/WebSocketKeepAliveTests.cs:line 156
--- End of stack trace from previous location ---
```

This recurred after #108298 was closed. That predecessor covered browser/Wasm on Linux, while this occurrence is macOS arm64 CoreCLR.

## Error Message

```json
{
"ErrorMessage": [
"System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse",
"Assert.Equal() Failure: Values differ",
"Expected: Aborted",
"Actual: Open"
],
"ErrorPattern": "",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

Agentic workflow metadata (ci-failure-scan)

Workflow artifact: ci-failure-scan
Artifact kind: kbe-verification
Verified match count: 1 hit in the failed test result

> [!NOTE]
> This issue was generated by GitHub Copilot.

### Known issue validation
**Build: :mag_right:** https://dev.azure.com/dnceng-public/public/_build/results?buildId=1586034
**Error message validated:** `[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse Assert.Equal() Failure: Values differ Expected: Aborted Actual: Open`]
**Result validation:** :white_check_mark: Known issue matched with the provided build.
**Validation performed at:** 9/7/2026 6:15:41 PM UTC

### Report

|Build|Repository|Test|Pull Request|
|---|---|---|---|
|[1597095](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1597095)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1597095&view=ms.vss-test-web.build-test-results-tab&runId=44090930&resultId=129674)||
|[1592095](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1592095)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1592095&view=ms.vss-test-web.build-test-results-tab&runId=43948534&resultId=130763)|dotnet/runtime#133606|
|[1592065](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1592065)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1592065&view=ms.vss-test-web.build-test-results-tab&runId=43948382&resultId=120976)|dotnet/runtime#133656|
|[1591180](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591180)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591180&view=ms.vss-test-web.build-test-results-tab&runId=43926186&resultId=115806)||
|[1589690](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1589690)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1589690&view=ms.vss-test-web.build-test-results-tab&runId=43881840&resultId=130806)|dotnet/runtime#133413|
|[1588512](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1588512)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1588512&view=ms.vss-test-web.build-test-results-tab&runId=43845048&resultId=172087)|dotnet/runtime#133472|
|[1588450](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1588450)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1588450&view=ms.vss-test-web.build-test-results-tab&runId=43842310&resultId=134866)|dotnet/runtime#133450|
|[1587711](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1587711)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1587711&view=ms.vss-test-web.build-test-results-tab&runId=43818308&resultId=135560)|dotnet/runtime#133430|
|[1586433](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1586433)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1586433&view=ms.vss-test-web.build-test-results-tab&runId=43776936&resultId=122043)|dotnet/runtime#133378|
|[1586034](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1586034)|dotnet/runtime|[System.Net.WebSockets.Tests.WebSocketKeepAliveTests.WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1586034&view=ms.vss-test-web.build-test-results-tab&runId=43767062&resultId=140977)|dotnet/runtime#133361|
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|1|8|10|

Start with WebSocketKeepAliveTests.cs at line 156 and inspect WebSocketServer_NoUserReadOrWrite_SendsPingAndReadsPongResponse. Review build 1586034 and the repeated failures in the report, focusing on the net11.0 macOS arm64 CoreCLR leg. Done means the test's expected connection state is reached reliably on that leg and the System.Net.WebSockets test passes.

Written by the indexing model from the issue text.