[adpa-ms]

📖 Description

The Windows jobs of the scheduled validation workflow uploaded the whole runner.temp folder, minus bulk binaries, as their logs-* artifact. The runner and the job's actions also use that folder, so the artifact carried the runner's command files, the event payload, the step scripts, and the credentials file actions/checkout writes for the job's token.

• The Windows run step now passes runner.temp/mxc-test-temp to run_backend_validation_tests.ps1 as -TempDirectory, the way the Windows SDK bundle job passes its output directory. The dispatcher points TEMP and TMP at that folder's full path, and the upload takes that folder and mxc-ci.log. Test logs are still collected without naming each file; they now sit under mxc-test-temp/ in the artifact.
• All four checkouts in Validation.Tests.Matrix.Job.yml set persist-credentials: false. Nothing in these jobs uses git credentials after checkout, so checkout removes its credentials file at the end of its own step instead of after the upload.

No regression test is added: this is a CI infrastructure fix, and the before-and-after artifact comparison below is the evidence.

🔗 References

The upload was widened to all of runner.temp in #939.

🔍 Validation

This workflow doesn't run on pull requests, so I dispatched it on this branch with gh workflow run Validation.Tests.Scheduled.yml --ref user/adibpa/copilot-validation-log-upload -f plan=nightly, with the nightly plan temporarily trimmed to seven jobs: windows-24h2 process (x64, arm64) and wslc; windows-prerelease-isolation-session (x64, arm64); ubuntu-24.04 bubblewrap; macos-15 seatbelt. The trim commit has since been dropped.

• Run 40032008671 passed.
• Each Windows artifact holds only mxc-ci.log and mxc-test-temp/. The file names under mxc-test-temp/ match the same jobs' artifacts from main's nightly run 39922643376, apart from GUIDs and process IDs; those main artifacts also held the credentials file and the runner's files.
• Every checkout step logs "Removing auth" before the next step starts.

✅ Checklist

• Signed the Contributor License Agreement
• Updated documentation (if applicable)

📋 Issue Type

• Bug fix

Microsoft Reviewers: Open in CodeFlow

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.

[Copilot]

🟢 Approval recommended

No blocking issues remain, and the linked branch validation run completed successfully.

No open issues 🎉

What changed in this PR

This PR narrows Windows validation artifacts to test output, avoiding collection of runner files and checkout credentials while preserving test-log collection.

Changes:

• Redirect Windows test temporary files to a dedicated mxc-test-temp directory.
• Upload only that directory and mxc-ci.log, and disable credential persistence for all four checkouts.
• Update the CI runbook to describe the revised collection paths.

File	Description
scripts/​ci/​run_backend_validation_tests.ps1	Adds an optional temporary-directory parameter and redirects TEMP and TMP there.
docs/​development/​build-and-test/​ci-validation-infrastructure.md	Documents dedicated test-output storage and narrowed uploads.
.github/​workflows/​Validation.Tests.Matrix.Job.yml	Supplies the test directory, restricts artifact paths, and disables checkout credential persistence.

_{Review effort: Balanced}