Mute HyperX QuadCast S at logon and sync Windows mute to it

Sets the mic's own hardware mute (USB Audio SET_CUR mute on feature
unit 6, via IDeviceTopology/IAudioMute) when it appears, and follows its
05 10 xx HID mute reports to keep the Windows endpoint mute in step.
Includes build/install/uninstall scripts and a read-only HID listener.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

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+# quadcast-mute-sync
+
+Makes a **HyperX QuadCast S** start **muted on the mic itself** (light off) every time you log in to Windows, and keeps the **Windows microphone mute in step** with the mic's tap-to-mute button.
+
+HyperX NGENUITY has no "start muted" option, and the QuadCast S always powers up live. This small background app fixes both.
+
+## What it does
+
+| When | Mic (hardware) | Windows mic mute |
+|---|---|---|
+| You log in / the mic is plugged in | muted | on |
+| You tap the mic to unmute | live | off |
+| You tap the mic to mute | muted | on |
+
+The sync is one-way, from the mic to Windows. Changing mute in Windows doesn't change the mic.
+
+## Install
+
+Requirements: Windows 10/11, a QuadCast S. No admin rights, no extra runtimes (it builds with the C# compiler that ships with Windows' .NET Framework 4).
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\install.ps1
+```
+
+This builds `bin\QuadCastMuteSync.exe`, copies it to `%USERPROFILE%\QuadCastMuteSync`, registers a per-user logon task named **QuadCastMuteSync**, and starts it right away. Pass `-InstallDir <folder>` to install somewhere else.
+
+Uninstall:
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\uninstall.ps1
+```
+
+## Command line
+
+```
+QuadCastMuteSync.exe run       # background mode (what the logon task runs)
+QuadCastMuteSync.exe mute      # mute mic + Windows now
+QuadCastMuteSync.exe unmute    # unmute mic + Windows now
+QuadCastMuteSync.exe status    # show Windows mute and the KS mute nodes
+```
+
+`run` writes a short log to `log.txt` next to the exe. It waits for the mic if it isn't connected yet, and mutes it again whenever it is reconnected, since the mic powers up live.
+
+## How it works
+
+Found by capturing the NGENUITY software with USBPcap + Wireshark while toggling mute.
+
+The QuadCast S shows up as two USB devices:
+
+| Device | Role |
+|---|---|
+| `03F0:0294` | USB Audio device (the microphone) |
+| `03F0:028C` | Controller: RGB, plus a vendor HID collection that reports mute |
+
+**Muting the mic.** NGENUITY sends a standard USB Audio Class request to the audio device:
+
+```
+bmRequestType 0x21  bRequest 0x01 (SET_CUR)
+wValue 0x0100 (MUTE_CONTROL, channel 0)  wIndex 0x0600 (feature unit 6, interface 0)
+data 01 = mute, 00 = unmute
+```
+
+The mic's firmware treats this like a tap, so the light changes too. Windows' `usbaudio` driver exposes that feature unit as a KS *Mute* node (`.../00020006`), so the app sets it through Core Audio `IDeviceTopology` → `IAudioMute`. No driver, WinUSB or admin rights needed. The Windows endpoint mute (`IAudioEndpointVolume`) is a separate software mute, which is why Windows mute and the mic button normally don't follow each other.
+
+**Reading the mic's state.** Every mute change, from a tap or from software, makes the controller send an 8-byte input report on its vendor collection (usage page `0xFFFF`):
+
+```
+05 10 01 ...   mic is live
+05 10 00 ...   mic is muted
+```
+
+The app blocks on reads from that collection and sets the Windows endpoint mute to match.
+
+## Limitations
+
+- Only tested on the QuadCast S (`03F0:0294` / `03F0:028C`). The QuadCast 2 uses a different protocol.
+- The KS node id `/00020006` is what Windows assigned on the test machine. If `status` lists different ids for you, pass the right suffix: `QuadCastMuteSync.exe run /000200xx`.
+- If the mic shows up under a name without "QuadCast", the audio endpoint won't be found.
+- After sleep/resume the mic usually keeps its state. If it comes back live, it's because the device re-enumerated, and the app mutes it again.
+
+## Tools
+
+`tools/hidlisten.ps1` is a read-only listener that prints every input report from HyperX (`VID 03F0`) HID interfaces. It's useful for checking the mute reports on another unit or model.
+
+```powershell
+powershell -ExecutionPolicy Bypass -File .\tools\hidlisten.ps1 -Seconds 30
+```