Flaky: ServerFailureCaptureTests oversized-log test misses its log on loaded net472 (Windows CI) #359

Finding

ServerFailureCaptureTests.CaptureAsync_Should_Keep_The_Newest_Bytes_Of_An_Oversized_Server_Log failed once on the Windows CI leg, net472 host. The run was PR #358 (job 116973940668, 2026-10-16T12:38Z), whose changes are only in tests/OpenCode.Sdk.Tools.Tests/ and cannot reach this test. The test took 5.8 s; a MockFileSystem test normally takes milliseconds.

failed CaptureAsync_Should_Keep_The_Newest_Bytes_Of_An_Oversized_Server_Log (5s 847ms)
  [Test Failure] DirectoryNotFoundException: Could not find a part of the path
  'C:\results\server-diagnostics\OpenCode.Sdk.Tests\6e9818521e724e139fee985bfd4310fa\server-logs\opencode.log'.
  from ...\OpenCode.Sdk.Tests.exe (net48|x64)
    at Testably.Abstractions.Testing.FileSystem.FileMock.OpenText(String path)
    at OpenCode.Sdk.Tests.ServerFailureCaptureTests.<ReadAsync>d__6.MoveNext()
    at OpenCode.Sdk.Tests.ServerFailureCaptureTests.<CaptureAsync_Should_Keep_The_Newest_Bytes_Of_An_Oversized_Server_Log>d__2.MoveNext()

The capture wrote no server-logs/opencode.log into the mock artifacts directory, so the test's read found no folder.

Hypothesis (unverified)

ServerFailureCapture bounds each capture step with OwnedOperationDeadline, which waits on the real clock (tests/Shared/Ownership/OwnedOperationDeadline.cs). Under the loaded Windows leg, the log-copy step may have outlived its bound. The step would then be abandoned, leaving no file, and the test reads it as a missing directory. If so, the verdict rides the clock (testing-style §6, "the event decides, never the clock"), and the fix belongs in the test's seam, not in a wider bound.

Disposition

Recorded before any rerun, per the flaky-test rule (quality-gates; Faz 4 manual §10). It was not retried, widened or quarantined. The PR #358 Windows leg is re-run only after this record exists. Owner to be decided by the lead (introduced with #333/#345).