# NixOS Install Guide (wipe NVMe, install from flake on Integral300)

This guide assumes:
- You are currently on Ubuntu
- You will WIPE the entire NVMe: /dev/nvme0n1
- You will install NixOS with:
  - UEFI + systemd-boot
  - Btrfs with subvolumes (@ and @home)
  - No encryption
  - zram swap (configured in NixOS config)
- Your config repo is a flake with output: `#sam-4screen-desktop`
- Integral300 (ext4) is available and will be mounted on NixOS at: /data
  - UUID: 27febd74-20aa-4a3a-92c1-6fdd1ad7e88e
- Dotfiles will live on the installed system at:
  - `~/dotfiles` (NOT on /data)

Important constraints:
- `hosts/sam-4screen-desktop/hardware-configuration.nix` is currently a placeholder.
  You MUST generate and copy the real one during install before running nixos-install.

---

## A) On Ubuntu: prepare and push the config repo to Gitea

1) Go to your repo folder (example):
   - If your repo is on Integral300 already:
     - `cd /media/sam/Integral300/<your-repo-folder>`
   - Otherwise clone it to Integral300:
     - `cd /media/sam/Integral300`
     - `git clone ssh://git@<your-gitea-host>:<port>/<owner>/<repo>.git nixos-config`
     - `cd nixos-config`

2) Ensure the flake evaluates:
   - `nix --version`
   - `nix flake show`

3) Commit your changes:
   - `git status`
   - `git add -A`
   - `git commit -m "chore: prep install guide + HM config"`

4) Push to Gitea:
   - `git push`

If you don’t have `flake.lock` yet, you can create it:
- `nix flake lock`
Then commit/push it too.

---

## B) Boot NixOS installer (ISO)

1) Boot the NixOS ISO (graphical or minimal).
2) Open a terminal.

---

## C) Wipe / partition / format / mount (CLI method)

WARNING: This wipes the whole NVMe. Double-check the disk is correct.

### 1) Identify disks
- `lsblk -f`
Confirm:
- NVMe target: /dev/nvme0n1 (about 953G)
- Integral300 disk by UUID is present: 27febd74-20aa-4a3a-92c1-6fdd1ad7e88e

### 2) Wipe and create partitions
This creates:
- p1 = EFI (1GiB)
- p2 = Btrfs (rest)

Commands:
- `sudo wipefs -a /dev/nvme0n1 || true`
- `sudo sgdisk --zap-all /dev/nvme0n1`

- `sudo sgdisk -n 1:1MiB:+1GiB -t 1:EF00 -c 1:EFI /dev/nvme0n1`
- `sudo sgdisk -n 2:0:0       -t 2:8300 -c 2:NIXOS /dev/nvme0n1`

Verify:
- `sudo fdisk -l /dev/nvme0n1`

### 3) Format
- `sudo mkfs.fat -F32 -n EFI /dev/nvme0n1p1`
- `sudo mkfs.btrfs -L nixos /dev/nvme0n1p2`

### 4) Create Btrfs subvolumes
- `sudo mount /dev/nvme0n1p2 /mnt`
- `sudo btrfs subvolume create /mnt/@`
- `sudo btrfs subvolume create /mnt/@home`
- `sudo umount /mnt`

### 5) Mount target layout for install
- `sudo mount -o subvol=@,compress=zstd,noatime /dev/nvme0n1p2 /mnt`
- `sudo mkdir -p /mnt/home`
- `sudo mount -o subvol=@home,compress=zstd,noatime /dev/nvme0n1p2 /mnt/home`

Mount EFI at /mnt/boot (systemd-boot expects /boot):
- `sudo mkdir -p /mnt/boot`
- `sudo mount /dev/nvme0n1p1 /mnt/boot`

### 6) Mount Integral300 so we can access the flake repo (offline-friendly)
- `sudo mkdir -p /mnt/data`
- `sudo mount /dev/disk/by-uuid/27febd74-20aa-4a3a-92c1-6fdd1ad7e88e /mnt/data`

---

## D) Generate hardware-configuration.nix (REQUIRED)

1) Generate:
- `sudo nixos-generate-config --root /mnt`

2) Copy the generated hardware config into your repo (overwrite placeholder):
- If your repo is at `/mnt/data/nixos-config`:
  - `sudo cp /mnt/etc/nixos/hardware-configuration.nix /mnt/data/nixos-config/hosts/sam-4screen-desktop/hardware-configuration.nix`

If your repo folder name is different, adjust accordingly.

Optional sanity check:
- `sed -n '1,200p' /mnt/data/nixos-config/hosts/sam-4screen-desktop/hardware-configuration.nix`

---

## E) Install NixOS using the flake

From the installer environment, run:
- `sudo nixos-install --flake /mnt/data/nixos-config#sam-4screen-desktop`

Notes:
- The installer may ask you to set a root password. Do so.
- If you prefer not setting root password and using only your user + sudo, say so and we can adjust.

After install:
- `sudo reboot`

---

## F) First boot checklist (post-install)

1) Connect to Wi-Fi:
- `nmtui` (recommended)
- Connect to SSID: "Aussie Broadband 8729"

2) Verify static IP:
- `ip a show wlp4s2`
If it got DHCP, force one reconnect:
- `nmcli networking off; nmcli networking on`
or:
- `nmcli connection down "<connection name>"; nmcli connection up "<connection name>"`

3) Verify SSH works (from another machine):
- `ssh sam@192.168.20.27`

4) Verify /data mounted (this is for your storage drive and for accessing the config repo if you keep it there):
- `mount | grep ' /data '`

5) Put dotfiles onto the system at ~/dotfiles

Option A (recommended): clone dotfiles repo:
- `git clone <your-dotfiles-repo-url> ~/dotfiles`

Option B: copy from Integral300 if they currently only live there:
- `cp -a /data/home_sam_ubuntu/dotfiles ~/dotfiles`

6) Verify dotfiles exist:
- `ls -la ~/dotfiles`

---

## G) After install: commit the new hardware-configuration.nix
Back on your running system (or from Ubuntu before wiping, if you mounted and copied it there):
- `cd /data/nixos-config` (or wherever your repo is)
- `git status`
- `git add hosts/sam-4screen-desktop/hardware-configuration.nix`
- `git commit -m "feat: add generated hardware-configuration for sam-4screen-desktop"`
- `git push`