scale-code

scale-code is now a Wails-based desktop GUI for the Stamps.com / Endicia USB postal scale.

Supported hardware today:

• USB\VID_1446&PID_6A73&REV_1000
• USB\VID_1446&PID_6A73
• USB\VID_1446&PID_6A78 (reserved for future-compatible devices)

The app keeps the original Go HID logic, but moves it into a reusable backend service so the desktop UI can auto-connect, stream readings, reconnect after unplug/replug, and expose diagnostics.

Features

• Desktop GUI with Wails v2 and Svelte + TypeScript
• Live weight display in oz, lb, g, and kg
• Auto-connect and manual reconnect
• Raw scale output without calibration or correction layers
• Diagnostics view with detected devices, raw report bytes, and current settings
• Fake backend mode for UI work without hardware

Project Layout

.
├── app.go
├── main.go
├── wails.json
├── internal/
│   ├── config/
│   └── scale/
├── frontend/
│   ├── src/
│   └── package.json
├── build/
│   ├── linux/
│   └── windows/
└── cmd/
    └── scale-code-cli/

Development

Prerequisites

• Go 1.24+
• Node.js 24+
• npm 11+
• Wails CLI for wails dev / wails build

This repo compiles with plain go build, but wails dev and packaged desktop builds still require the Wails CLI to be installed on the machine. Because the HID library depends on CGO, production builds also require CGO_ENABLED=1 and a working C compiler in PATH. A Windows build without CGO will launch, but it will never enumerate the scale. The Windows helper tries to load the Visual Studio build environment automatically, then attempts MSVC first with CC=cl and CXX=cl. It preflights runtime/cgo before starting the Wails package build. If MSVC fails, it retries with CC=gcc and CXX=g++ when gcc is available, including common MSYS2/MinGW install paths. The helper temporarily writes these values through go env -w so Wails subprocesses inherit the same CGO toolchain, then restores the previous Go settings. For this HID dependency stack, Go cgo may still require the GCC-compatible fallback because MSVC rejects some GCC-style cgo flags.

If MSVC fails and no GCC fallback is installed, run:

.\build-helpers\build-windows.ps1 -InstallMissingGcc

That switch uses winget to install MSYS2 and the UCRT64 GCC package, then retries the GCC fallback. If build\bin\scale-code.exe is still running, the build and clean helpers will stop early with a clear message. Use -StopRunningApp to let the helper close the running app before replacing or cleaning the output.

Frontend

cd frontend
npm install
npm run build

Backend validation

go test ./...
go build ./...

Temporary CLI

The legacy-style debug entrypoint is still available while the GUI is being hardened:

go run ./cmd/scale-code-cli

Fake backend mode

Use this for frontend work without a scale connected:

$env:SCALE_CODE_FAKE = "1"
wails dev

Running The GUI

Once the Wails CLI is installed:

wails dev

For a local release-style frontend build before that:

cd frontend
npm run build
cd ..
go build .

Linux Permissions

Do not run the GUI as root as the normal solution.

Install the included udev rule:

sudo cp build/linux/99-scale-code.rules /etc/udev/rules.d/
sudo udevadm control --reload-rules
sudo udevadm trigger

Then unplug and replug the scale before reopening the app.

The app surfaces this message when Linux permissions block access:

Scale found, but permission denied. Install the udev rule, unplug/replug the scale, then reopen the app.

Windows Notes

• The app now enumerates all HID devices first, then filters by supported VID/PID instead of relying only on a direct hid.Enumerate(vendor, product) call.
• No WinUSB / Zadig instructions are included. The intended path is the default HID stack.
• The diagnostics panel is the first place to check if Windows shows the hardware ID but the HID layer still exposes zero matching devices.

Current Validation

Validated locally in this workspace:

• go test ./...
• go build ./...
• npm run check
• npm run build

Not validated yet in this workspace:

• wails dev
• wails build -platform windows/amd64
• Real hardware streaming through the new GUI
• Linux udev flow on an actual Linux desktop

License

MIT