feat(daemon): complete Phase 2 Solo WSL core

.github/workflows/ci.yml

@@ -3,6 +3,7 @@ name: CI
 on:
   pull_request:
   push:
+    branches: [main]
 
 permissions:
   contents: read
@@ -12,6 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+      - run: sudo apt-get update && sudo apt-get install -y libasound2-dev pkg-config
       - run: cargo fmt --check
       - run: cargo clippy --workspace --all-targets -- -D warnings
       - run: cargo test --workspace

CONTRIBUTING.md

@@ -15,12 +15,96 @@ sudo apt-get install -y build-essential
 
 On Fedora, install `gcc` and `make`.
 
+Phase 2’s direct ALSA adapter also needs development headers and `pkg-config`.
+On Debian/Ubuntu/WSL:
+
+```sh
+sudo apt-get install -y pkg-config libasound2-dev
+```
+
+On Fedora, install `pkgconf-pkg-config` and `alsa-lib-devel`.
+
+Phase 2 read-only hardware discovery also needs command-line tools. On
+Debian/Ubuntu/WSL:
+
+```sh
+sudo apt-get install -y usbutils alsa-utils
+```
+
+`usbutils` provides `lsusb`; `alsa-utils` provides `amixer`. `libasound2-dev`
+is for compiling the Rust ALSA binding, not for the `amixer` command. On Fedora,
+install `usbutils` and `alsa-utils`.
+
 ## Setup
 
 ```sh
 rustup show
 ```
 
+## Route a Scarlett Solo into WSL2
+
+Do this only when ready for Phase 2 read-only discovery. While attached, the
+Solo is unavailable to Windows applications. This grants WSL direct USB access;
+it does not write device state.
+
+1. In an elevated PowerShell window, install/update WSL and `usbipd-win`:
+
+   ```powershell
+   wsl --update
+   winget install usbipd
+   ```
+
+2. Plug in the Solo, then list USB devices from elevated PowerShell. Identify
+   its `BUSID` by its Focusrite description; do not copy serial numbers into
+   issues, fixtures, or commits.
+
+   ```powershell
+   usbipd list
+   usbipd bind --busid <BUSID>
+   ```
+
+   `bind` shares that USB port persistently. It needs elevation; attaching does
+   not. If the device is already shared, skip `bind`.
+
+3. Start the intended WSL2 distro, then attach from a normal PowerShell window:
+
+   ```powershell
+   usbipd attach --wsl --busid <BUSID>
+   ```
+
+4. In WSL, verify Linux sees the Solo, then run only bounded read-only probes
+   from [hardware support](docs/hardware-support.md#discovery-procedure):
+
+   ```sh
+   lsusb
+   cat /proc/asound/cards
+   amixer -c <card> controls
+   ```
+
+   If `amixer -c <card> controls` fails but its `sudo` form works, grant the
+   current WSL user read/write access to ALSA controls, then open a new shell:
+
+   ```sh
+   sudo usermod -aG audio "$USER"
+   exit
+   ```
+
+   Reopen the WSL distro and confirm `id` lists `audio`. This only changes
+   local device-node permission; it does not change Solo state. Do not use
+   `sudo` for later discovery once normal access works.
+
+5. When finished, return it to Windows:
+
+   ```powershell
+   usbipd detach --busid <BUSID>
+   ```
+
+Attach is not persistent: repeat it after WSL restart or USB unplug/replug.
+Do not run `alsactl store`, control writes, routing/clock changes, firmware
+updates, or resets without explicit approval. See Microsoft’s current
+[WSL USB guide](https://learn.microsoft.com/windows/wsl/connect-usb) and
+[usbipd-win instructions](https://github.com/dorssel/usbipd-win).
+
 ## Checks
 
 ```sh

crates/focusrited/Cargo.toml

@@ -6,3 +6,4 @@ rust-version.workspace = true
 license.workspace = true
 
 [dependencies]
+alsa = "0.12.0"