hermetic: Windows evidence has an empty host kernel, so Verify rejects it #9314

hermetic-windows "Verify the evidence" rejects otherwise qualified MSVC evidence: hermetic evidence rejected: evidence names no host kernel (ci.yml run 42375312749, windows_x86_64 job 128411581848). The evidence has "host": {"os": "windows", "kernel": ""}.

Where

• tools/testing/hermetic/src/lib.rs host(): reads /proc/sys/kernel/osrelease, then falls back to uname -r. Windows has neither, so kernel is empty.
• The verifier loop over ["os", "arch", "kernel"] in the same file then rejects it.
• host_names_this_machine in src/tests.rs is #[cfg(unix)], so Windows is never checked.

Fix

• On Windows, fill kernel with the OS build, for example the [Version 10.0.x.y] from %SystemRoot%\System32\cmd.exe /c ver. Use an absolute path, because the test PATH is stripped.
• Drop #[cfg(unix)] from host_names_this_machine.
• Proof: in a hermetic-windows ci.yml run, the Verify step is green on both arches.

Found while closing #4825.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Xut2hzpb4qWNZKpDCrwUz7