# dotfiles

Windows development-box provisioning scripts.

`setup-windows.bat` takes a fresh Windows install to a working C++ / native
development environment: editors and shells, Python, the Visual Studio
toolchain (including the Clang and Windows XP targeting toolsets), the Windows
Driver Kit, and a handful of analysis tools (Sysinternals, OpenCppCoverage,
BinSkim, the Windows Performance Toolkit). It also sets the box up to be driven
remotely: OpenSSH Server plus an rsync build for Windows, which is what makes a
throwaway VM reachable from a Linux host.

Runs on **x64 and on ARM64** (Windows 11 on Arm). See
[Running on ARM64](#running-on-arm64) for what differs.

## Files

| File | Purpose |
| --- | --- |
| `setup-windows.bat` | Entry point. Runs the winget installs, then launches the elevated half and prints its log, then runs the non-elevated script. |
| `setup-windows-no-uac.ps1` | The non-elevated, per-user half: WinMerge and BinSkim on the user `PATH`, and the global git config (identity, plus `core.sshCommand`). Can also be run directly from an ordinary prompt. |
| `setup-windows-with-uac.ps1` | The elevated half, started via UAC by the batch file. Enables `ssh-agent`, installs the OpenSSH Client and Server capabilities and starts `sshd`, unpacks the `rsync-windows` release zip for this architecture (`rsync.exe` plus the `ssh.exe` it runs) into `C:\Tools\rsync` on the machine `PATH`, then installs Visual Studio Community with the required components, the WDK, and the Windows Performance Toolkit, and reports whether Intel VTune Profiler is present. Can also be run directly from an Administrator prompt. |
| `setup-windows-7-test-env.bat` | Prepares a **Windows 7 VM** as a test target driven from the host by `VBoxManage guestcontrol`. Copy it into the guest and run it there; it is idempotent, so re-run it after any snapshot restore. The per-user half needs no UAC (crash-dialog suppression, no screen blanking, a staging directory, the shared folder on `Z:`); the machine-wide half is skipped with a notice unless run elevated inside the guest. It then reports what the box can actually test: DWM composition, printers, audio capture devices. |

## Usage

1. **Edit `setup-windows-no-uac.ps1` first.** The global git identity near the
   top of the file is empty:

   ```powershell
   $GitUserName  = ''   # e.g. 'Ada Lovelace'
   $GitUserEmail = ''   # e.g. 'ada@example.com'
   ```

   Fill in your own name and email, or leave them empty to keep your identity
   per-repository - the script skips `user.name` / `user.email` rather than
   writing a placeholder, and says so. Everything else in that script is set
   either way.

2. Run it from a normal (non-elevated) prompt:

   ```bat
   setup-windows.bat
   ```

   It will raise a single UAC prompt for the elevated half. Accept it — declining
   leaves Visual Studio and the WDK uninstalled, and the script says so.

3. Restart your shell afterwards so the updated user `PATH` is picked up, and
   reboot if a step reported that a restart was required.

## Notes

- The elevated half writes a transcript to `setup-windows-uac.log` next to the
  script; the batch file prints it when the elevated window closes. The log is
  gitignored, as it contains local paths.
- **git uses a Win32-OpenSSH client.** `setup-windows-no-uac.ps1` sets
  `core.sshCommand`. Git for Windows otherwise prefers its own bundled MSYS2
  `ssh.exe`, which cannot reach the Windows `ssh-agent` service that the elevated
  half enables - Win32-OpenSSH publishes the agent on a named pipe the MSYS2
  build does not speak. Without this, keys loaded with `ssh-add` from PowerShell
  are invisible to `git`, and a push falls back to hunting for a key file and
  prompting for its passphrase. The value uses forward slashes on purpose: git
  parses `core.sshCommand` with shell quoting rules, in which a backslash is an
  escape character.
- **Which `ssh.exe` git gets.** `C:\Tools\rsync\ssh.exe` — the fast build the
  elevated half unpacks — if it is there, `%WINDIR%/System32/OpenSSH/ssh.exe`
  otherwise. It is the same client with the same `~/.ssh`, agent and
  `known_hosts`; the difference is the stdin pump, and without it anything git
  *pushes* is capped at ~17 MB/s. Candidates are tried by **running** them
  (`ssh -V`), not by `Test-Path`: the fast build needs a `libcrypto.dll` that an
  image without the OpenSSH Client capability does not have, and a client that
  will not start should be found here rather than on the next `git push`.
  This is also why `setup-windows.bat` now runs the elevated half **first** — the
  fast `ssh.exe` has to exist before the git config step can prefer it. The
  non-elevated half still runs even when the elevated one failed; it just falls
  back. Re-run `setup-windows-no-uac.ps1` on its own at any time to re-pick.
- All three scripts are idempotent — re-running skips anything already installed.
  BinSkim in particular checks NuGet for the newest stable version *before*
  downloading: the package is a self-contained .NET build well over 100 MB, and
  re-provisioning an up-to-date box should not pay for it. The installed version
  is tracked in `nupkg-version.txt` beside the tool.
- `setup-windows-no-uac.ps1` runs its steps independently: one failing warns and
  the rest still run, and it exits 1 if any did. The `.bat` reports that and
  carries on to the elevated half, which is the part worth the UAC prompt. Use
  `-Skip` to re-run a subset, e.g. `.\setup-windows-no-uac.ps1 -Skip BinSkim`.
  Run it **non-elevated**: it writes per-user state (the `HKCU` `PATH`, the
  `.gitconfig` under `%USERPROFILE%`), so an elevated run would configure the
  administrator's profile instead. It warns if you do.
- **Remote access.** OpenSSH Server is installed from the Windows on-demand
  capability (10/1809+), set to start automatically, and given an inbound TCP 22
  firewall rule on *all* profiles — a VM's host-only or bridged adapter is
  routinely classified Public, which is the usual reason a running `sshd` is
  unreachable. Windows ships no `rsync`, so a build of it
  ([nuket/rsync-windows](https://github.com/nuket/rsync-windows)) is installed to
  `C:\Tools\rsync` and added to the **machine** `PATH`. That last detail matters:
  the remote end of an `rsync` runs non-interactively, with no login shell, and
  Win32-OpenSSH builds that environment from the registry `PATH` rather than from
  a profile. Key auth needs `~/.ssh/authorized_keys` ACL'd to just you and
  `SYSTEM`; accounts in the Administrators group use
  `C:\ProgramData\ssh\administrators_authorized_keys` instead.
- **rsync brings its own `ssh.exe`.** That release ships as one zip per
  architecture — `rsync-windows-x64.zip` / `rsync-windows-x86.zip`, each holding
  `rsync.exe`, an `ssh.exe`, `COPYING.txt` and `NOTICE-ssh.txt` — and the
  elevated half picks the zip for the host architecture (ARM64 takes the x64 one;
  there is no ARM64 asset), verifies it against the published `.sha256`, unpacks
  the pair together, then **runs** the unpacked `ssh.exe` and removes it if it
  will not start. Together is the point:
  `rsync.exe` prefers an `ssh.exe` sitting in its own directory, and the release
  builds one because the client Windows ships reads its stdin 3 KB at a time,
  which holds a transfer *from* the box at ~17 MB/s however fast the link is.
  Nothing else about it differs — same `~/.ssh`, same `ssh-agent`, same
  `known_hosts` — and a bare `ssh` still resolves to the in-box client, which
  sits ahead of `C:\Tools\rsync` on the `PATH`. It links against the
  `libcrypto.dll` the **OpenSSH Client** capability puts in `System32` (Windows'
  own LibreSSL, which uses AES-NI) and ships no copy of its own, so the elevated
  half installs that capability first and falls back to `rsync.exe` alone,
  warning, on an image that will not offer it.
- The `rsync` download follows the `releases/latest/download/` redirect rather
  than the GitHub API: unauthenticated API calls are rate-limited to 60/hour per
  IP, which a provisioning run behind a shared NAT can genuinely exhaust. To hold
  a box on a known build, pin the tag in `$RsyncUrl`
  (`.../releases/download/<tag>/<asset>`) instead.
- Visual Studio is installed in three labelled passes (base workload, Clang/LLVM,
  XP toolset) so a failure identifies which component group is responsible. The
  last two are optional passes: a failure there warns and provisioning continues,
  because neither is needed to build with MSVC and losing the whole toolchain
  over a component you can add later from the installer UI is the worse outcome.
- **Which Visual Studio generation.** `$VsChannel` near the VS step picks it —
  `17` for VS 2022, `18` for VS 2026 — and `$VsEdition` picks Community /
  Professional / Enterprise. It is **architecture-split by default**: 17 on x64,
  where the `v141`/XP toolset in the component list is the reason to pin a
  generation, and 18 on ARM64, where that toolset cannot exist anyway (no
  ARM64-hosted 14.16 compiler), so nothing holds Arm back to the older one.
- **The aka.ms path differs per generation** — VS 2022 is published under
  `/release/`, VS 2026 under `/stable/`, which `$VsChannelPath` derives. This is
  not cosmetic: `https://aka.ms/vs/18/release/vs_community.exe` is *not* a 404,
  it silently redirects to Bing and returns **200 with an HTML body**. A wrong
  guess there downloads a web page, names it `vs_community.exe`, and fails later
  at `Start-Process` with something that looks nothing like a bad URL. The step
  therefore checks the downloaded file starts with an `MZ` header and throws with
  the URL if it does not.
- `Get-VsInstallPath` scopes its `vswhere` query to that generation
  (`-version "[17.0,18.0)"`). That scoping is load-bearing: a bare
  `vswhere -products *` returns **every** Visual Studio on the box, newest
  first, and on a machine that already has VS 2026 the old unscoped lookup handed
  an 18.x install path to a 17.x bootstrapper as `modify --installPath`, so every
  pass targeted the wrong product. The step now also lists any other generations
  it found and states that it left them alone — when none of them matches
  `$VsChannel` the script is about to fetch a second, largely redundant
  toolchain, and that should be a visible decision. On ARM64, where `$VsChannel`
  is 18, an existing VS 2026 **is** the match and gets modified in place rather
  than duplicated.
- **Windows Performance Analyzer is not part of Visual Studio.** VS has its own
  Performance Profiler, which is a different, `.diagsession`-based tool and
  cannot open an `.etl`. WPA ships with `xperf` and `wpr` in the Windows
  Performance Toolkit, which exists in exactly two places: as an optional
  *feature* of the Windows SDK (`OptionId.WindowsPerformanceToolkit`) and inside
  the Windows ADK, which bundles the same toolkit. Whether the SDK install that
  Visual Studio performs selects that feature varies by version, so the elevated
  half **detects first** — `%ProgramFiles(x86)%\Windows Kits\10\Windows
  Performance Toolkit`, its 64-bit twin, and the ADK location — and only falls
  back to `winget install Microsoft.WindowsADK` when nothing is there. It then
  re-asserts that directory on the machine `PATH` (the toolkit's own installer
  usually does this, and the Start Menu gets *Windows Kits > Windows Performance
  Toolkit* shortcuts for WPA and WPR). To install just the toolkit instead of the
  whole ADK, run the standalone SDK setup with
  `winsdksetup.exe /features OptionId.WindowsPerformanceToolkit /q`. A newer WPA
  also exists in the Microsoft Store (`winget install --id 9N0W1B2BXGNZ --source
  msstore`); it is not installed here because the Store source needs an
  interactive, signed-in session, which the unattended elevated half does not
  have.
- **Intel VTune Profiler is reported, not installed.** The elevated half prints
  whether it is on the box, its version, and the path to `vtune.exe`; if it is
  missing it prints the download page instead (and says so if the CPU is not
  Intel). Automating the install is not worth it here: the offline installer is a
  ~750 MB download from a URL carrying a per-release GUID with no "latest"
  redirect behind it, so every new build would mean editing a hard-coded link,
  and it is only worth having on Intel silicon since hardware event-based
  sampling reads Intel PMU counters. It does install unattended if you want it
  scripted elsewhere:

  ```powershell
  intel-vtune-<version>_offline.exe -a --silent --cli --eula accept
  ```

  **Run it from an administrator account, elevated.** Hardware event-based
  sampling (`uarch-exploration`, `memory-access`, `hotspots -knob
  sampling-mode=hw`) requires it, and VTune warns about that at the top of every
  unelevated run. Worth knowing that the failure it gives there is *"cannot
  recognize the processor"*, which reads like a hardware problem and is not one:
  the drivers (`sepdrv5`, `sepdal`, `vtss`) are installed and running, and VTune
  identifies the PMU through them. There is no group to join to get around it —
  the Linux driver can be handed to a `vtune` group, but on Windows the
  documented answer is to run as administrator.

- **Collect traces from an elevated Administrator session. Non-elevated
  collection was tried here and abandoned.** The attempt was to put one ordinary
  account into `BUILTIN\Performance Log Users`, which appears in the default
  security descriptors ETW keeps per provider GUID under
  `HKLM\SYSTEM\CurrentControlSet\Control\WMI\Security`, and collect without a UAC
  prompt. It does not survive contact with the real workflow: `xperf -on base`
  and `wpr -start` drive the *NT Kernel Logger*, reserved for Administrators and
  LocalSystem, and granting the group `SeSystemProfilePrivilege` ("Profile system
  performance") plus an explicit ACE for `TRACELOG_ACCESS_KERNEL_LOGGER` on
  `SystemTraceControlGuid` — all three in place, across a reboot — still answered

  ```text
  xperf: error: NT Kernel Logger: Access is denied. (0x5).
  ```

  It is not a check an ACE overrides, and the same wall turned up often enough
  elsewhere that the whole approach was dropped rather than carried as a
  half-working path. **Sign in to an administrator account and run `xperf`, `wpr`
  and VTune from an elevated prompt.** Analysis is the exception and never needed
  any of this: `wpa.exe` opens an existing `.etl` as a plain user.

  If an earlier revision of these scripts ran on a box, it left that account in
  the group. Take it back out with:

  ```powershell
  net localgroup "Performance Log Users" DOMAIN\user /delete
  ```

  Two revisions also granted the privilege and the ACE. Undo the privilege in
  `secpol.msc` > Local Policies > User Rights Assignment > "Profile system
  performance" by removing Performance Log Users. The ACEs sit in the
  `{9e814aad-3204-11d2-9a82-006008a86939}` value under
  `HKLM\SYSTEM\CurrentControlSet\Control\WMI\Security`: strip the `LU` entries
  from that descriptor rather than deleting the value, which also carries entries
  for SYSTEM, Administrators and two service accounts.

- The scripts were extracted from a native Windows project, so the component
  selection is tuned for that: Spectre-mitigated runtimes, the v141/XP toolset,
  and driver-kit headers. Trim the component lists in the `.ps1` if you don't
  need them — each group is a plain array near the top.

## Running on ARM64

All three scripts detect the host architecture and adapt. Nothing needs a flag —
run `setup-windows.bat` exactly as on x64. Both PowerShell halves use
`RuntimeInformation.OSArchitecture` rather than `%PROCESSOR_ARCHITECTURE%`,
because an emulated PowerShell reports the *emulated* architecture in the
environment variable and the real one through the API.

**The build toolchain is fully native.** Visual Studio's ARM64 installer, MSVC
and clang-cl are all ARM64 binaries, and MSVC cross-compiles every target from
an ARM64 host with no emulation in the compiler:

```bat
cmake -B build -A ARM64   && cmake --build build --config Release   :: native
cmake -B build -A x64     && cmake --build build --config Release   :: cross
cmake -B build -A Win32   && cmake --build build --config Release   :: cross
```

**ARM64 uses Visual Studio 2026** (`$VsChannel = 18`) while x64 stays on VS 2022.
Nothing forces that split — the Arm box simply has no reason to stay on the older
generation, since the `v141`/XP toolset that pins x64 there cannot run on Arm at
all — so Arm takes the newer MSVC. Note this is a *default*, not a limitation:
VS 2026 does still offer `v141` and `WinXP` as components on x64.

The base component group now names `VC.Tools.x86.x64` **and** `VC.Tools.ARM64`
explicitly instead of relying on `--includeRecommended`, which resolves
differently per host: on an ARM64 machine the workload's recommended set is the
ARM64-targeting toolchain, and the x64 cross-compiler is *not* implied. Spectre
runtimes and ATL are likewise requested for both target families
(`VC.ATL.ARM64.Spectre` is a separate component from `VC.ATL.Spectre`).

**Three native compilers, on purpose.** MSVC and `clang-cl` from Visual Studio,
plus **upstream LLVM** (`winget install LLVM.LLVM`, which resolves to
`LLVM-<ver>-woa64.exe` on ARM64 — "Windows on Arm 64"). Upstream runs on its own
schedule and is usually several major versions ahead of the Clang that VS
bundles, and it installs to `C:\Program Files\LLVM` rather than inside the VS
tree, so the two are genuinely independent. Two Clang majors plus MSVC over the
same sources is what catches the bugs a single toolchain agrees with itself
about. Watch the `PATH` if you use it: a bare `clang-cl` may resolve to upstream
while CMake's `-T ClangCL` keeps using VS's, so pass a full
`-DCMAKE_CXX_COMPILER` when it matters.

**Clang/LLVM is installed on ARM64 too, and it is native there** — MSVC and
`clang-cl` over the same sources is the compiler diversity this box is after.
Two things establish that it is genuinely native rather than an emulated x64
compiler: the `VC.Llvm.Clang` VSIX is `productArch=neutral` with no `chip` or
`machineArch` restriction, so the Arm installer offers it; and MSVC's
`VC\Tools\Llvm` tree is partitioned by **host** architecture, with real ARM64
binaries already in `ARM64\bin`, which is where `clang-cl.exe` lands:

| directory | host |
| --- | --- |
| `VC\Tools\Llvm\bin` | x86 |
| `VC\Tools\Llvm\x64\bin` | x64 |
| `VC\Tools\Llvm\ARM64\bin` | ARM64 |

Unlike the `v141`/XP group, nothing technical is in the way. Upstream LLVM ships
a Windows-on-Arm build independently too — `winget install LLVM.LLVM` resolves to
`LLVM-<ver>-woa64.exe` on ARM64 — if you want a Clang outside Visual Studio.

> Watch for a false positive when checking by hand: `VC\Tools\Llvm\*\bin` holds
> `clang-format.exe` and `clang-tidy.exe` on **any** host, installed or not —
> those ship with the NativeDesktop workload. Their presence does not mean the
> compiler is there; look for `clang-cl.exe`. The verification step does exactly
> that, and warns separately if only a non-native `clang-cl` landed on Arm.

What changes, and why:

| | On ARM64 |
| --- | --- |
| **Native ARM64** | Git, Python, .NET SDK, PowerShell, VS Code, Windows Terminal, WinMerge, Brave, Sysinternals, Claude Code, CMake, Ninja, the VS installer, **MSVC, VS clang-cl and upstream LLVM**, MSBuild, the SDK tools (`rc`, `signtool`), the in-box OpenSSH client, and the Windows Performance Toolkit. |
| **Emulated x64** | `iperf3`, NASM, OpenCppCoverage, BinSkim, `rsync.exe`, Android GPU Inspector, and the WDK/ADK *installers* (the kits they lay down are native). |
| **Emulated, minor** | `py.exe` (python.org ships the launcher shim as x86; it execs the native `python.exe`) and `vswhere.exe` (Microsoft ships x86 only; runs once). |
| **Unavailable** | VirtualBox, the Windows 7 x86 test VM, Intel VTune, and the `v141` / Windows XP targeting toolset. |

### The architecture audit

`setup-windows-no-uac.ps1` ends with an **`ArchAudit`** step that reads the PE
COFF header of every tool the box provisions and reports what you would actually
run, resolved PATH-first. It reads the file itself rather than trusting package
metadata — a multi-architecture package (Sysinternals) ships every build in one
zip under different names, and an installer's metadata says nothing about which
binary landed. Purely informational; it never fails the run. Skip it with
`-Skip ArchAudit`.

Anything emulated with a listed reason prints as expected. Anything emulated
*without* one is called out, with a remedy where a native build exists — which is
how the `ninja` problem below was found.

### Two gotchas the audit surfaces

- **Visual Studio bundles an x64 `ninja.exe` even on ARM64**, and `VsDevCmd.bat`
  **prepends** the VS directories to `PATH`. So inside a Developer Command Prompt
  — exactly where C++ builds happen — the emulated ninja wins over the native one
  `winget install Ninja-build.Ninja` provides. It matters more than a one-off
  tool would, because ninja is re-invoked for every edge in the build graph. Pass
  `-DCMAKE_MAKE_PROGRAM=` the native one, or put its directory ahead of the VS
  one. VS's bundled `cmake.exe` *is* ARM64, so only ninja has this problem.
- **Sysinternals ships every architecture in one zip**, and the ARM64 build is
  not the default-named exe. `ProcessExplorer.zip` contains `procexp.exe` (x86),
  `procexp64.exe` (x64) and `procexp64a.exe` (**ARM64**) — so run the `*64a.exe`
  variants; plain `procexp.exe` runs emulated. (`Microsoft.Sysinternals.Suite`
  has a dedicated `SysinternalsSuite-ARM64.zip` if you prefer the whole set.)

- **x64 emulation is checked, not assumed.** Everything in the "emulated" row
  needs Prism, which is present on Windows 11 on Arm but absent on Windows 10 on
  Arm (x86-only there) and on some Server images. The elevated half tests for
  `System32\xtajit64.dll` up front and warns, rather than letting the failure
  surface much later as a binary that will not start.
- **VirtualBox is skipped.** There is no ARM64 Windows host build, and the x64
  one cannot be rescued by emulation: a hypervisor is kernel-mode, and its x64
  driver will not load on an ARM64 kernel. This is also what makes
  `setup-windows-7-test-env.bat` unreachable from an ARM64 host — it prepares a
  Windows 7 *x86* guest, which neither VirtualBox nor Hyper-V on ARM64 can run.
  (That script itself is unchanged; it runs inside the guest, so it never sees
  the host architecture.)
- **The `v141` / Windows XP toolset is skipped**, and the verification step says
  `n/a` instead of warning about it. The components are still *listed* in the
  catalog on Arm, so this is a deliberate skip rather than a hard unavailability
  — but the 14.16 toolset predates Windows on Arm as a host and ships
  `HostX86`/`HostX64` compilers only, so the best you could get is an
  x86-emulated compiler, and XP targeting is not supported from an Arm host.
  Nothing is lost that this box could have used:
  Windows XP never ran on ARM64, so the only point of an XP-targeting build here
  would be producing x86 binaries, which the current toolset does natively via
  `-A Win32`.
- **OpenCppCoverage is installed but limited.** Unlike the rest of the emulated
  row, this is a real ceiling rather than a slowdown: it collects coverage by
  debugging the process under test and stepping x86/x64 instructions, so it
  covers the x86/x64 binaries this box cross-compiles but **not** an ARM64 one.
  Run coverage against the x64 build. The script prints this rather than leaving
  you to discover it.
- **BinSkim is emulated and that is fine.** The NuGet package publishes `win-x64`
  only (its other RIDs are `linux-x64`, `linux-arm64`, `osx-x64`). BinSkim *reads*
  PE headers and load configs, so its own architecture is independent of the
  binaries it analyses — an emulated x64 BinSkim checks ARM64 binaries perfectly
  well. The RID list is ordered preference, so a future `win-arm64` build is
  picked up with no further change.
- **`rsync` gets the x64 zip, and its `ssh.exe` is verified by running it.** The
  release publishes x64 and x86 assets and no ARM64 one. x64 is still the right
  pick — a transfer is bounded by the socket, not by emulated CPU, so lifting the
  in-box client's 3 KB stdin cap wins by far more than emulation costs. But that
  `ssh.exe` links against a `System32\libcrypto.dll` which on ARM64 is an **ARM64**
  binary, so it may not load at all. That matters more than it sounds:
  `rsync.exe` *prefers* an `ssh.exe` in its own directory, so a present-but-broken
  one does not degrade to the in-box client — it breaks rsync outright, with an
  error that names a dead remote shell rather than `ssh.exe`. The elevated half
  therefore runs `ssh -V` after unpacking and **deletes** the binary if it will
  not start, so `rsync` falls back to the native in-box client. The
  `core.sshCommand` step in the non-elevated half already picked its candidate by
  running it, and is unchanged.
- **Intel VTune reports `n/a`** rather than printing a download link: there is no
  Windows-on-Arm build, and its value is reading Intel PMU counters. Use the
  Windows Performance Toolkit (`wpr`/`xperf` to collect, `wpa` to analyse), or
  Arm Performance Studio / Streamline for Arm PMU sampling.
- **NASM is still installed** (as emulated x64) because this box cross-compiles
  x86/x64, where NASM is the assembler that builds them. If you only target
  ARM64, nothing uses it — the ARM64 assembler is `armasm64.exe`, which ships
  with MSVC.
- **`vswhere` stays under the 32-bit Program Files** on ARM64 too
  (`%ProgramFiles(x86)%\Microsoft Visual Studio\Installer`), so that path is
  unchanged. The VS Installer is x86-registered there by contract even though the
  installer binaries themselves are native.
- **The WDK registry probe reads both hives.** `wdksetup.exe` is 32-bit and
  writes under `WOW6432Node` on x64, but which hive a kit lands in has varied
  across versions and architectures, and reading only one made an installed WDK
  look absent — costing a needless multi-GB reinstall on every run.
