cryptography ships no win_arm64 wheel, so every Windows ARM64 venv sync
compiles it from the sdist and needs MSVC, Clang, Rust and static OpenSSL.
Only setup-hermes.ps1 (and so activate.ps1) prepared that environment,
between a `pm install --tools-only` and the real sync. install.ps1,
`hermes update` and repair ran the same sync without it and failed in
openssl-sys.
PM owns the sync, so PM prepares it. pm/native_build.py holds the adapter
(moved from scripts/build/windows_deps.py) plus source_build_environment(),
which prepares only on win32-arm64 when the synced project carries the
provider script. A payload has prebuilt dependencies and needs no compiler.
VenvPackage.apply and build_environment pass the result to uv children
only. It carries the bridged pip index settings, which managed_environment
applies only to the ambient environment. The state root stays the store
parent, so existing vcpkg/OpenSSL builds are reused.
setup-hermes.ps1 collapses to one `pm install`: the tools-only split existed
only for this preparation, and pm install already puts its tools on PATH
before the venv sync (pm/cli.py activate check).
Not yet verified live on Windows ARM64.
c98bdb77f5