bootstrap home manager and nix packages on login

files/system/usr/lib/systemd/user/default.target.wants/randofin-nixpkgs-init.service

@@ -0,0 +1 @@
+../randofin-nixpkgs-init.service

files/system/usr/lib/systemd/user/randofin-nixpkgs-init.service

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+[Unit]
+Description=Install Nix Home Manager and packages on first login
+ConditionUser=!root
+ConditionPathExists=!%h/.local/state/randofin-os/nixpkgs-init.done
+
+[Service]
+Type=oneshot
+ExecStart=/usr/libexec/randofin-os/nixpkgs.sh
+ExecStartPost=/usr/bin/mkdir -p %h/.local/state/randofin-os
+ExecStartPost=/usr/bin/touch %h/.local/state/randofin-os/nixpkgs-init.done
+
+[Install]
+WantedBy=default.target

files/system/usr/libexec/randofin-os/nixpkgs.sh

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+#!/usr/bin/env bash
+set -oue pipefail
+nix run github:nix-community/home-manager/release-25.11 -- init --switch
+
+pkgs='uv micro vscodium mc'
+f=~/.config/home-manager/home.nix
+tmp="$(mktemp)"
+{
+  echo "  home.packages = ["
+  for p in $pkgs; do echo "    pkgs.$p"; done
+  echo "  ];"
+} > "$tmp"
+
+sed -i "/^[[:space:]]*home\.packages[[:space:]]*=[[:space:]]*\[/,/^[[:space:]]*];[[:space:]]*$/{
+  /^[[:space:]]*home\.packages[[:space:]]*=/{
+    r $tmp
+  }
+  d
+}" "$f"
+
+rm -f "$tmp"
+
+home-manager switch