[Flaky Test] Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.SingleBuild_CoordinatorCapsMaxNodeCount

**Flaky-test key** (automated de-duplication — do not edit):
```text
flaky-test-id: Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.SingleBuild_CoordinatorCapsMaxNodeCount
```

## Evidence

This test was flagged as flaky by the automated flaky-test detector across **3 distinct approved PRs** with **3 different error signatures**, on multiple platforms.

| Field | Value |
|-------|-------|
| Assembly | `MSBuild.Coordinator.UnitTests` |
| Fully-qualified name | `Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.SingleBuild_CoordinatorCapsMaxNodeCount` |
| Distinct sources | 3 (all PRs: #13609, #14240, #14470) |
| Distinct error hashes | 3 (`4039adb7`, `55b6331b`, `ba217936`) |
| Affected legs | CoreOnLinux, CoreOnWindows, FullOnWindows Release |
| Affected TFMs | net10.0, net11.0, net472 |
| First seen | 2026-07-17 |
| Last seen | 2026-07-23 |
| Sample build | [1523327](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1523327) |

### Sample error

```
Shouldly.ShouldAssertException : buildOutput
should contain (case insensitive comparison)
"MaxNodeCount=2"
but was actually
"MSBuild version 18.10.0-ci.26373.1+0be7e952e for .NET Framework
Build started 7/23/2026 1:04:10 PM...."
```

## Next steps

The test will be **quarantined** in a future run via `[ActiveIssue("")]` (from `Microsoft.DotNet.XUnitV3Extensions`, namespace `Xunit`) once this issue is open with a real number. This stamps the `Category=failing` trait, which normal CI excludes and the quarantine pipeline (def 344) picks up to keep collecting signal. The underlying nondeterminism fix will be handled by the auto-fixer workflow or a human.

> [!WARNING]
>
> Firewall blocked 1 domain
>
> The following domain was blocked by the firewall during workflow execution:
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> - `awmgmcpg`
>> To allow these domains, add them to the `network.allowed` list in your workflow frontmatter:
>
> ```yaml
> network:
> allowed:
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> - "awmgmcpg"
> ```
>
> See [Network Configuration](https://github.github.com/gh-aw/reference/network/) for more information.
>
>

> Generated by [Flaky Test Triage](https://github.com/dotnet/msbuild/actions/runs/30157445938) · 190.7 AIC · ⌖ 7.39 AIC · ⊞ 14.8K · [◷](https://github.com/search?q=repo%3Adotnet%2Fmsbuild+is%3Aissue+%22gh-aw-workflow-call-id%3A+dotnet%2Fmsbuild%2Fflaky-test-detector.agent%22&type=issues)

Start with Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.SingleBuild_CoordinatorCapsMaxNodeCount and reproduce the reported output mismatch across the affected platforms or target frameworks. Review the three error signatures and the linked sample build; done means the test is deterministic and reliably verifies MaxNodeCount=2 without recurring failures.

Written by the indexing model from the issue text.