auto/on/off, defaulting to auto: branches and pull requests cache, refs/tags/v*
builds cold. furyrs asked for exactly that in thread #13 -- a tag run verifies
a release artifact rather than a change, so the clean room is worth two
minutes there and not elsewhere.
An unrecognised value throws instead of silently picking a side, the same
posture as the guest-os: 'Auto' fix: a cache setting that quietly means its
opposite is worse than a failed job.
Verified by running the shipped PowerShell block itself under pwsh across all
seven mode/ref combinations plus the invalid-mode throw, rather than by
reimplementing the logic in the test -- a reimplementation only checks the
model, not the code that ships.
Simone
2678b76297