winrt — pure-Go Windows Hello (WinRT) for the fleet

github.com/go-mswin/winrt is a thin, pure-Go CGO=0 wrapper over the reference WinRT projection github.com/saltosystems/winrt-go (itself built on the pure-Go COM/WinRT runtime github.com/go-ole/go-ole). It targets 64-bit Windows (amd64 + arm64). No cgo.

It does not reimplement WinRT. RoInitialize / RoGetActivationFactory, HSTRING creation, the IInspectable/IUnknown vtable calls and the IAsyncOperation machinery all come from winrt-go + go-ole, the maintained reference libraries (per the fleet's "use the reference library" rule). This module adds only:

• a committed, winrt-go-gen–generated projection of Windows.Security.Credentials.UI.UserConsentVerifier (Windows Hello), so the build is reproducible offline — see internal/ui (regenerate with the //go:generate directive there);
• two ergonomic helpers that run the async operations to completion and decode the WinRT enums into Go values:

// Available reports whether Windows Hello can prompt (never shows UI).
ok, err := winrt.Available()

// RequireUserConsent surfaces the Hello prompt and reports whether the user
// verified. Returns (false, nil) — not an error — when Hello is unavailable,
// so callers treating biometry as a best-effort factor can proceed.
verified, err := winrt.RequireUserConsent("Unlock your SSH key passphrase")

The OS-independent core (the WinRT enum types + String methods, apartment constants, ErrUnsupported) builds on every GOOS and is covered to 100%; the live glue is //go:build windows. Off Windows, Available / RequireUserConsent return ErrUnsupported.

Verified

On the Win11 ARM64 QEMU VM: RoInitialize OK, the UserConsentVerifier activation factory resolves (with the correct metadata IID af4f3f91-564c-4ddc-b8b5-973447627c65), CheckAvailabilityAsync runs to completion and decodes its enum. The interactive biometric prompt needs an enrolled Hello device and is not headless-testable (the LAContext -34018 pattern).

Consumers

openweft/weft-app-windows and openweft/weft-loom-app-windows — one owned, correct Hello gate instead of duplicated hand-rolled combase calls.

License

BSD-3-Clause — copyright the go-mswin authors.